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Sample records for enhanced photocatalytic oxidation

  1. Enhanced photocatalytic activity of titania-silica mixed oxide prepared via basic hydrolyzation

    International Nuclear Information System (INIS)

    Xie Chao; Xu Zili; Yang Qiujing; Xue Baoyong; Du Yaoguo; Zhang Jiahua

    2004-01-01

    Two different synthesis routes were applied to prepare TiO 2 -XSiO 2 (X denotes mol% of silica in titania-silica mixed oxides) with different silica concentrations by using ammonia water as hydrolysis catalyst. Through comparing the photocatalytic performance of two sets of mixed oxides, we found that the photocatalytic activity of mixed oxides prepared via the route which can promote homogeneity, was significantly enhanced as compared with that of counterparts prepared via the another route, and the highest photocatalytic activity obtained by adding about 9.1 mol% silica into titania was much higher than that of pure TiO 2 . The mixed oxides were investigated by means of XRD, thermal analysis, UV-vis, FT-IR and XPS. The characterization results suggest that, in comparison with pure TiO 2 , the mixed oxides exhibit smaller crystallite size and higher thermal stability which can elevate the temperature of anatase to rutile phase transformation due to the addition of silica. Furthermore, Broensted acidity, which is associated with the formation of Ti-O-Si hetero linkages where tetrahedrally coordinated silica is chemically mixed with the octahedral titania matrix, may be a very important contribution to the enhanced photocatalytic activity of titania-silica mixed oxides as well

  2. A facile synthesis of nanorods of ZnO/graphene oxide composites with enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Qin, Jiaqian; Zhang, Xinyu; Xue, Yannan; Kittiwattanothai, Nutsakun; Kongsittikul, Pongsakorn; Rodthongkum, Nadnudda; Limpanart, Sarintorn; Ma, Mingzhen; Liu, Riping

    2014-01-01

    Graphical abstract: - Highlights: • Room temperature method to prepare ZnO–GO composites. • ZnO–GO composites exhibit superior absorption ability and photocatalytic performance. • With GO content increasing, the absorption and photocatalytic ability increased. - Abstract: Graphene oxide (GO)–ZnO nanorods composites were successfully synthesized by a facile room-temperature approach using the colloidal coagulation effect. The samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, specific surface area, and UV–vis spectroscopy. The photodegradation of methylene blue (MB) has been investigated in the presence of composites. It is observed that the absorption capacity and photocatalytic effect could be enhanced by adding graphene oxide

  3. Reduced graphene oxide/CeO{sub 2} nanocomposite with enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Jasmeet, E-mail: jasmeet.dayal@gmail.com; Anand, Kanika; Singh, Gurpreet; Hastir, Anita; Virpal,; Singh, Ravi Chand [Laboratory For Sensors and Physics Education, Department of Physics, GND University, Amritsar-143005 (India); Anand, Kanica [Semiconductors Laboratory, Department of Physics, GND University, Amritsar– 143005 (India)

    2015-05-15

    In this work, reduced graphene oxide /cerium oxide (RGO/CeO{sub 2}) nanocomposite was synthesized by in situ reduction of cerium nitrate Ce(NO{sub 3}){sub 3}·6H{sub 2}O in the presence of graphene oxide by hydrazine hydrate (N{sub 2}H{sub 4}.H{sub 2}O). The intrinsic characteristics of as-prepared nanocomposite were studied using powder x-ray diffraction (XRD), Raman spectroscopy and field-emission scanning electron microscopy (FESEM). The photocatalytic degradation of methylene blue (MB) was employed as a model reaction to evaluate the photocatalytic activity of the RGO/CeO{sub 2} nanocomposite. The as-obtained RGO/CeO{sub 2} nanocomposite displays a significantly enhanced photocatalytic degradation of MB dye in comparison with bare CeO{sub 2} nanoparticles under sunlight irradiation, which can be attributed to the improved separation of electron-hole pairs and enhanced adsorption performance due to presence of RGO.

  4. Reduced graphene oxide-CdS nanocomposite with enhanced photocatalytic 4-Nitrophenol degradation

    Science.gov (United States)

    Chakraborty, Koushik; Ibrahim, Sk; Das, Poulomi; Ghosh, Surajit; Pal, Tanusri

    2017-05-01

    We report the photocatalytic activity of reduced graphene oxide cadmium sulfide (RGO-CdS) composite towards the degradation of 4-Nitrophenol (4-NP) under simulated solar light illumination. The solution processable RGO-CdS composite was synthesized by one pot single step low cost solvothermal process, where the reduction of graphene oxide (GO), synthesis and attachment of CdS onto RGO sheets were done simultaneously. The structural and morphological characterization of the RGO-CdS composite and the reduction of GO was confirmed by X-ray diffractometry, TEM imaging and Fourier transform infrared spectroscopy respectively. The photocatalytic efficiency of RGO-CdS composite is 2.6 times higher in compare to controlled CdS. In RGO-CdS composite the photo induced electrons transfer from CdS nanorod to RGO sheets, which reduces the recombination probability of photo generated electron-hole in the CdS. These well separated photoinduced charges enhanced the photocatalytic activity of the RGO-CdS composite. Our study establishes the RGO-CdS composite as a potential photocatalyst for the degradation of organic water pollutant.

  5. Stannic Oxide-Titanium Dioxide Coupled Semiconductor Photocatalyst Loaded with Polyaniline for Enhanced Photocatalytic Oxidation of 1-Octene

    Directory of Open Access Journals (Sweden)

    Hadi Nur

    2007-01-01

    Full Text Available Stannic oxide-titanium dioxide (SnO2–TiO2 coupled semiconductor photocatalyst loaded with polyaniline (PANI, a conducting polymer, possesses a high photocatalytic activity in oxidation of 1-octene to 1,2-epoxyoctane with aqueous hydrogen peroxide. The photocatalyst was prepared by impregnation of SnO2 and followed by attachment of PANI onto a TiO2 powder to give sample PANI-SnO2–TiO2. The electrical conductivity of the system becomes high in the presence of PANI. Enhanced photocatalytic activity was observed in the case of PANI-SnO2–TiO2 compared to PANI-TiO2, SnO2–TiO2, and TiO2. A higher photocatalytic activity in the oxidation of 1-octene on PANI-SnO2–TiO2 than SnO2–TiO2, PANI-TiO2, and TiO2 can be considered as an evidence of enhanced charge separation of PANI-SnO2–TiO2 photocatalyst as confirmed by photoluminescence spectroscopy. It suggests that photoinjected electrons are tunneled from TiO2 to SnO2 and then to PANI in order to allow wider separation of excited carriers.

  6. Enhancement of olive mill wastewater biodegradation by homogeneous and heterogeneous photocatalytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Badawy, M.I.; Gohary, F.El. [Water Pollution Research Department, National Research Centre (NRC), Dokki, Cairo 11312 (Egypt); Ghaly, M.Y., E-mail: ghalynrc@yahoo.com [Chemical Engineering and Pilot Plant Department, National Research Centre (NRC), Dokki, Cairo (Egypt); Ali, M.E.M. [Water Pollution Research Department, National Research Centre (NRC), Dokki, Cairo 11312 (Egypt)

    2009-09-30

    Olive mills wastewater (OMW) is characterized by its high organic content and refractory compounds. In this study, an advanced technology for the treatment of the recalcitrant contaminants of OMW has been investigated. The technique used was either photo-Fenton as homogeneous photocatalytic oxidation or UV/semi-conductor catalyst (such as TiO{sub 2}, ZrO{sub 2} and FAZA) as heterogeneous photocatalytic oxidation for treatment of OMW. For both the processes, the effect of irradiation time, amounts of photocatalysts and semi-conductors, and initial concentration of hydrogen peroxide has been studied. At the optimum conditions, photo-Fenton process achieved COD, TOC, lignin (total phenolic compounds) and total suspended solids (TSSs) removal values of 87%, 84%, 97.44% and 98.31%, respectively. The corresponding values for UV/TiO{sub 2} were 68.8%, 67.3%, 40.19% and 48.9%, respectively, after 80 min irradiation time. The biodegradability expressed by BOD{sub 5}/COD ratio for treated wastewater was ranged from 0.66 to 0.8 compared to 0.19 for raw wastewater indicating enhancement of biodegradation.

  7. Incorporation of N–ZnO/CdS/Graphene oxide composite photocatalyst for enhanced photocatalytic activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Huo, Pengwei, E-mail: huopw1@163.com [School of Chemistry & Chemical Engineering Jiangsu University Zhenjiang, 212013 (China); Institute of Green Chemistry and Chemical Technology, Jiangsu University, Zhenjiang, 212013 (China); Zhou, Mingjun; Tang, Yanfeng [School of Chemistry & Chemical Engineering Jiangsu University Zhenjiang, 212013 (China); Liu, Xinlin [School of Energy & Power Engineering Jiangsu University Zhenjiang, 212013 (China); Ma, Changchang; Yu, Longbao [School of Chemistry & Chemical Engineering Jiangsu University Zhenjiang, 212013 (China); Yan, Yongsheng, E-mail: yys@mail.ujs.edu.cn [School of Chemistry & Chemical Engineering Jiangsu University Zhenjiang, 212013 (China); Institute of Green Chemistry and Chemical Technology, Jiangsu University, Zhenjiang, 212013 (China)

    2016-06-15

    N–ZnO/CdS/Graphene oxide (GO) composite photocatalysts have been successfully synthesized by hydrothermal method. The as-prepared composite photocatalysts were characterized by X-ray diffraction (XRD), Raman, scanning electron microscopy(SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR) spectra, UV–vis diffuse reflectance spectra (UV–vis DRS), thermogravimetry (TG) and photoluminescence (PL). The as-prepared photocatalysts exhibited strong visible light photocatalytic activity toward to degradation of antibiotics under ambient conditions. Particularly, the N–ZnO/CdS/GO composite photocatalysts showed the higher photocatalytic degradation rate (86%) of ciprofloxacin CIP under visible light irradiation than the pure photocatalysts. Compared with degradation of different antibiotics (tetracycline (TC), oxytetracycline hydrochloride (OTC-HCl) and levofloxacin (LEV)), the N–ZnO/CdS/GO composite photocatalysts also exhibited high photocatalytic activities. According to the experiments, the role of GO in the composite photocatalysts acted as an electron conductor, and also enhanced the separation rate of electrons and holes which greatly improved the photocatalytic activity. Lastly, the mechanism of enhanced photocatalytic degradation of CIP was also discussed. - Highlights: • N–ZnO/CdS/GO composite was synthesized by the hydrothermal processes. • N–ZnO/CdS composites prevent pure CdS or ZnO from photocorrosion. • N–ZnO/CdS/GO shows the remarkable photocatalytic activity and stability.

  8. A facile route to porous beta-gallium oxide nanowires-reduced graphene oxide hybrids with enhanced photocatalytic efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Xu, X. [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Lei, M., E-mail: minglei@bupt.edu.cn [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Huang, K.; Liang, C.; Xu, J.C.; Shangguan, Z.C. [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Yuan, Q.X. [Department of Mathematics and Physics, Zhengzhou Institute of Aeronautical Industry Management, Zhengzhou 450015 (China); Ma, L.H. [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Du, Y.X., E-mail: duyinxiao@zzia.edu.cn [Department of Mathematics and Physics, Zhengzhou Institute of Aeronautical Industry Management, Zhengzhou 450015 (China); Fan, D.Y.; Yang, H.J.; Wang, Y.G.; Tang, W.H. [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2015-02-25

    Highlights: • A facile route was developed to fabricate porous β-Ga{sub 2}O{sub 3} NWs-rGO hybrids. • Supercritical water can act as an efficient reductant to situ-reduce GO into RGO. • The Ga{sub 2}O{sub 3} NWs attach on the surface of RGO through a strong coupling forces. • The photocatalytic performance of the hybrids can be obviously improved. - Abstract: A facile route was developed to fabricate porous beta-gallium oxide nanowires (β-Ga{sub 2}O{sub 3} NWs)-reduced graphene oxide (rGO) hybrids using β-Ga{sub 2}O{sub 3} NWs and graphene oxide (GO) as raw materials. The characterization results indicate that supercritical water can act as an efficient reductant to situ-reduce GO into rGO, and porous β-Ga{sub 2}O{sub 3} NWs can further attach on the surface of as-reduced rGO through a strong coupling forces between the β-Ga{sub 2}O{sub 3} NWs and rGO. The photocatalytic performance of the hybrids can be obviously improved (about 74%) for the decomposition of methylene blue (MB) solution after coupling with 1 wt% rGO compared with the pure β-Ga{sub 2}O{sub 3} NWs. The enhanced photocatalytic activity can be attributed to the synergistic effect of extended optical absorption band, the enrichment of MB molecular on the rGO and the valid inhibition of recombination of photo-generated electron–hole pairs induced by the strong coupling interaction between rGO nanosheets and porous β-Ga{sub 2}O{sub 3} NWs.

  9. A facile route to porous beta-gallium oxide nanowires-reduced graphene oxide hybrids with enhanced photocatalytic efficiency

    International Nuclear Information System (INIS)

    Xu, X.; Lei, M.; Huang, K.; Liang, C.; Xu, J.C.; Shangguan, Z.C.; Yuan, Q.X.; Ma, L.H.; Du, Y.X.; Fan, D.Y.; Yang, H.J.; Wang, Y.G.; Tang, W.H.

    2015-01-01

    Highlights: • A facile route was developed to fabricate porous β-Ga 2 O 3 NWs-rGO hybrids. • Supercritical water can act as an efficient reductant to situ-reduce GO into RGO. • The Ga 2 O 3 NWs attach on the surface of RGO through a strong coupling forces. • The photocatalytic performance of the hybrids can be obviously improved. - Abstract: A facile route was developed to fabricate porous beta-gallium oxide nanowires (β-Ga 2 O 3 NWs)-reduced graphene oxide (rGO) hybrids using β-Ga 2 O 3 NWs and graphene oxide (GO) as raw materials. The characterization results indicate that supercritical water can act as an efficient reductant to situ-reduce GO into rGO, and porous β-Ga 2 O 3 NWs can further attach on the surface of as-reduced rGO through a strong coupling forces between the β-Ga 2 O 3 NWs and rGO. The photocatalytic performance of the hybrids can be obviously improved (about 74%) for the decomposition of methylene blue (MB) solution after coupling with 1 wt% rGO compared with the pure β-Ga 2 O 3 NWs. The enhanced photocatalytic activity can be attributed to the synergistic effect of extended optical absorption band, the enrichment of MB molecular on the rGO and the valid inhibition of recombination of photo-generated electron–hole pairs induced by the strong coupling interaction between rGO nanosheets and porous β-Ga 2 O 3 NWs

  10. Enhanced xylene removal by photocatalytic oxidation using fiber-illuminated honeycomb reactor at ppb level

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yi-Ting [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Yu, Yi-Hui [Department of Civil Engineering, National Taiwan University, Taipei 106, Taiwan (China); Nguyen, Van-Huy [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10617, Taiwan (China); Lu, Kung-Te [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Wu, Jeffrey Chi-Sheng, E-mail: cswu@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chang, Luh-Maan [Department of Civil Engineering, National Taiwan University, Taipei 106, Taiwan (China); Kuo, Chi-Wen [Taiwan Semiconductor Manufacturing Company, Hsinchu 30078, Taiwan (China)

    2013-11-15

    Graphical abstract: We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. -- Highlights: • The combination of optical fiber and honeycomb significantly enhanced the performance of VOCs photodegradation. • The removal efficiency of m-xylene is enhanced to 96.5% as compared to 22.0% for UV irradiation alone. • Fiber-illuminated honeycomb reactor is the first step toward an industrial-scale technology on the removal of xylene. -- Abstract: The removal of volatile organic compounds (VOCs) at ppb level is one of the most critical challenges in clean rooms for the semiconductor industry. Photocatalytic oxidation is an innovative and promising technology for ppb-level VOCs degradation. We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. Using the FIHR with Mn-TiO{sub 2} photocatalyst not only increased the m-xylene removal efficiency, but also increased the CO{sub 2} selectivity. Interestingly, Mn-TiO{sub 2} in FIHR also showed a very good reusability, 93% removal efficiency was still achieved in 72-h in reaction. Thus, the FIHR gave very high removal efficiency for xylene at ppb level under room temperature. The FIHR has great potential application in the clean room for the air purification system in the future.

  11. Enhanced xylene removal by photocatalytic oxidation using fiber-illuminated honeycomb reactor at ppb level

    International Nuclear Information System (INIS)

    Wu, Yi-Ting; Yu, Yi-Hui; Nguyen, Van-Huy; Lu, Kung-Te; Wu, Jeffrey Chi-Sheng; Chang, Luh-Maan; Kuo, Chi-Wen

    2013-01-01

    Graphical abstract: We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. -- Highlights: • The combination of optical fiber and honeycomb significantly enhanced the performance of VOCs photodegradation. • The removal efficiency of m-xylene is enhanced to 96.5% as compared to 22.0% for UV irradiation alone. • Fiber-illuminated honeycomb reactor is the first step toward an industrial-scale technology on the removal of xylene. -- Abstract: The removal of volatile organic compounds (VOCs) at ppb level is one of the most critical challenges in clean rooms for the semiconductor industry. Photocatalytic oxidation is an innovative and promising technology for ppb-level VOCs degradation. We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. Using the FIHR with Mn-TiO 2 photocatalyst not only increased the m-xylene removal efficiency, but also increased the CO 2 selectivity. Interestingly, Mn-TiO 2 in FIHR also showed a very good reusability, 93% removal efficiency was still achieved in 72-h in reaction. Thus, the FIHR gave very high removal efficiency for xylene at ppb level under room temperature. The FIHR has great potential application in the clean room for the air purification system in the future

  12. Enhanced photocatalytic properties of ZnO/reduced graphene oxide sheets (rGO) composites with controllable morphology and composition

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yanting, E-mail: 928221565@qq.com; Liu, Lin, E-mail: llspzjnu@163.com; Cui, Tingting, E-mail: wuleiwangyou@163.com; Tong, Guoxiu, E-mail: tonggx@zjnu.cn; Wu, Wenhua, E-mail: tongwu@zjnu.cn

    2017-08-01

    Highlights: • An easy one-step low-temperature chemical etching route for ZnO NR/rGO composites. • Modulation over the ZnO morphology and content in ZnO NR/rGO composites. • Investigating shape and content-dependent optical and photocatalytic properties. • Revealing the enhancement mechanism of optical and photocatalytic properties. - Abstract: ZnO with various morphologies and contents was used to decorate reduced graphene oxide (rGO) sheets via an easy one-step low-temperature chemical etching route to improve photocatalytic properties. The ZnO shape and content in ZnO/rGO composites were adjusted by changing aging time, heating mode, and rGO mass added. Shape and content-dependent optical and photocatalytic properties are observed in ZnO/rGO composites. A moderate amount of ZnO nanorings (NRs) decorated with rGO can significantly improve the light absorption and photo-luminescence emission because of plasmonic resonant absorption and plasmonic nanoantenna radiation, respectively. ZnO NR/rGO composites with a moderate ZnO content of 29.54 wt.% exhibit the optimum photocatalytic activity with a 0.025 min{sup −1} apparent rate constant, which is significantly higher than those of pure rGO (0.0085 min{sup −1}) and ZnO NRs (0.018 min{sup −1}). The improved performance is ascribed to the synergistic effect of enhanced adsorption capacity, plasmonic light absorption, plasmonic nanoantenna radiation, and the prolonged lifetime of photogenerated electron-hole pairs. Our findings not only offer insights into the plasmon enhanced optical and photocatalytic properties of ZnO NR/rGO composites but also suggest the possibility of fabricating ZnO NR/rGO photocatalyst with enhanced performance.

  13. Synthesis of hexagonal ultrathin tungsten oxide nanowires with diameters below 5 nm for enhanced photocatalytic performance

    Science.gov (United States)

    Lu, Huidan; Zhu, Qin; Zhang, Mengying; Yan, Yi; Liu, Yongping; Li, Ming; Yang, Zhishu; Geng, Peng

    2018-04-01

    Semiconductor with one dimension (1D) ultrathin nanostructure has been proved to be a promising nanomaterial in photocatalytic field. Great efforts were made on preparation of monoclinic ultrathin tungsten oxide nanowires. However, non-monoclinic phase tungsten oxides with 1D ultrathin structure, especially less than 5 nm width, have not been reported. Herein, we report the synthesis of hexagonal ultrathin tungsten oxide nanowires (U-WOx NW) by modified hydrothermal method. Microstructure characterization showed that U-WOx NW have the diameters of 1-3 nm below 5 nm and are hexagonal phase sub-stoichiometric WOx. U-WOx NW show absorption tail in the visible and near infrared region due to oxygen vacancies. For improving further photocatalytic performance, Ag co-catalyst was grown directly onto U-WOx NW surface by in situ redox reaction. Photocatalytic measurements revealed hexagonal U-WOx NW have better photodegradation activity, compared with commercial WO3(C-WO3) and oxidized U-WOx NW, ascribe to larger surface area, short diffusion length of photo-generated charge carriers and visible absorption of oxygen-vacancy-rich hexagonal ultrathin nanostructures. Moreover, the photocatalytic activity and stability of U-WOx NW using Ag co-catalyst were further improved.

  14. Enhanced xylene removal by photocatalytic oxidation using fiber-illuminated honeycomb reactor at ppb level.

    Science.gov (United States)

    Wu, Yi-Ting; Yu, Yi-Hui; Nguyen, Van-Huy; Lu, Kung-Te; Wu, Jeffrey Chi-Sheng; Chang, Luh-Maan; Kuo, Chi-Wen

    2013-11-15

    The removal of volatile organic compounds (VOCs) at ppb level is one of the most critical challenges in clean rooms for the semiconductor industry. Photocatalytic oxidation is an innovative and promising technology for ppb-level VOCs degradation. We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. Using the FIHR with Mn-TiO2 photocatalyst not only increased the m-xylene removal efficiency, but also increased the CO2 selectivity. Interestingly, Mn-TiO2 in FIHR also showed a very good reusability, 93% removal efficiency was still achieved in 72-h in reaction. Thus, the FIHR gave very high removal efficiency for xylene at ppb level under room temperature. The FIHR has great potential application in the clean room for the air purification system in the future. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Enhanced photocatalytic degradation of methylene blue by ZnO-reduced graphene oxide composite synthesized via microwave-assisted reaction

    Energy Technology Data Exchange (ETDEWEB)

    Lv Tian [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai, 200062 (China); Pan Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai, 200062 (China); Liu Xinjuan; Lu Ting; Zhu Guang; Sun Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai, 200062 (China)

    2011-10-13

    Highlights: > ZnO-reduced graphene oxide composite is synthesized via microwave assisted reaction. > The method allows a facile, safe and rapid reaction in aqueous media. > A high dye degradation efficiency is achieved under UV light irradiation. - Abstract: A quick and facile microwave-assisted reaction is used to synthesize ZnO-reduced graphene oxide (RGO) hybrid composites by reducing graphite oxide dispersion with zinc nitrate using a microwave synthesis system. Their photocatalytic performance in degradation of methylene blue is investigated and the results show that the RGO plays an important role in the enhancement of photocatalytic performance and the ZnO-RGO composite with 1.1 wt. % RGO achieves a maximum degradation efficiency of 88% in a neutral solution under UV light irradiation for 260 min as compared with pure ZnO (68%) due to the increased light absorption, the reduced charge recombination with the introduction of RGO.

  16. Enhancement photocatalytic activity of spinel oxide (Co, Ni3O4 by combination with carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Kahdum Bashaer J.

    2017-09-01

    Full Text Available In this study, some types of composites consisting of multi-walled carbon nanotubes (MWCNTs and spinel oxide (Co, Ni3O4 were synthesized by simple evaporation method. These composites were characterized by UV–Vis diffuse reflectance spectroscopy, X-rays diffraction(XRD, Scanning electron microscopy (SEM and specific surface area(SBET. The photocatalytic activity of the prepared composites was investigated by the following removal of Bismarck brown G (BBG dye from its aqueous solutions. The obtained results showed that using MWCNTs in combination with spinel oxide to produced composites (spinel/MWCNTs which succeeded in increasing the activity of spinel oxide and exhibited higher photocatalytic activity than spinel oxide alone. Also it was found that, multiwalled carbon nanotubes were successful in increasing the adsorption and improving the activity of photocatalytic degradation of Bismarck brown G dye(BBG. The obtained results showed that spinel/MWCNTs was more active in dye removal in comparison with each of spinel oxide and MWCNTs alone under the same reaction conditions. Also band gap energies for the prepared composites showed lower values in comparison with neat spinel. This point represents a promising observation as these composites can be excited using a lower energy radiation sources.

  17. Enhanced photocatalytic H{sub 2} production on CdS nanorod using cobalt-phosphate as oxidation cocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Di, Tingmin; Zhu, Bicheng; Zhang, Jun; Cheng, Bei [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2016-12-15

    Highlights: • Co-Pi/CdS composites were synthesized by a simple photodeposition method. • The composites showed superior photocatalytic H{sub 2} production activity. • The optimal H{sub 2} production rate of Co-Pi/CdS was even higher than that of Pt-CdS. • Co-Pi is a good oxidation cocatalyst used for capture of photogenerated hole. - Abstract: Employing visible light responsive semiconductor for photocatalytic hydrogen production by water splitting is an efficient way for utilizing renewable solar energy to solve the depletion of fossil fuel and environmental contamination. Herein, we report enhanced photocatalytic H{sub 2}-production performance over CdS nanorod using cobalt-phosphate (Co-Pi) as a water oxdation cocatalyst. The optimal Co-Pi modified CdS nanocomposite photocatalyst with the Co-Pi content of 8.4 mol% has a superior visible light H{sub 2}-production rate of 13.3 mmol h{sup −1} g{sup −1} with an apparent quantum efficiency of 24.3% at 420 nm, which is even higher than that of 1 wt% Pt-CdS (11.3 mmol h{sup −1} g{sup −1}) under the same conditions. The enhanced visible-light photocatalytic H{sub 2} production activity was attributed to the hole trapping and collecting ability of Co-Pi cocatalyst, which could effectively suppress the recombination of photogenerated electron-hole pairs and increase the electron density for hydrogen production. This work shows a possibility of using earth-abundant Co-Pi as cocatalyst for enhancing photocatalytic H{sub 2} production.

  18. Enhanced photocatalytic performance of ZnO nanostructures by electrochemical hybridization with graphene oxide

    Science.gov (United States)

    Pruna, A.; Wu, Z.; Zapien, J. A.; Li, Y. Y.; Ruotolo, A.

    2018-05-01

    Synthesis of zinc oxide (ZnO) nanostructures is reported by electrochemical deposition from an aqueous electrolyte in presence of graphene oxide (GO) with varying oxidation degree. The properties of hybrids were investigated by scanning electron microscopy, X-ray diffraction, Raman, Fourier-Transform Infrared and X-ray photoelectron spectroscopy techniques and photocatalytic measurements. The results indicated the electrodeposition of ZnO in presence of GO with increased oxygen content led to marked differences in the morphology while Raman measurements indicated an increased defect level both in the ZnO and the electrochemically reduced GO (ErGO) within the hybrids. The decrease in C/O atomic ratio of GO (from 0.79 to 0.71) employed for the electrodeposition of ZnO resulted in an increase in photocatalytic efficiency for methylene blue degradation under UV irradiation from 4-folds to 10-folds with respect to non-hybridized ZnO. The observed synergetic effect of cathodic deposition potential and oxygen content in GO towards improving the photocatalytic activity of immobilized ZnO is expected to contribute to further development of more effective deposition approaches for the preparation of high performance hybrid nanostructures.

  19. Enhanced photocatalytic performance and degradation pathway of Rhodamine B over hierarchical double-shelled zinc nickel oxide hollow sphere heterojunction

    Science.gov (United States)

    Zhang, Ying; Zhou, Jiabin; Cai, Weiquan; Zhou, Jun; Li, Zhen

    2018-02-01

    In this study, hierarchical double-shelled NiO/ZnO hollow spheres heterojunction were prepared by calcination of the metallic organic frameworks (MOFs) as a sacrificial template in air via a one-step solvothermal method. Additionally, the photocatalytic activity of the as-prepared samples for the degradation of Rhodamine B (RhB) under UV-vis light irradiation were also investigated. NiO/ZnO microsphere comprised a core and a shell with unique hierarchically porous structure. The photocatalytic results showed that NiO/ZnO hollow spheres exhibited excellent catalytic activity for RhB degradation, causing complete decomposition of RhB (200 mL of 10 g/L) under UV-vis light irradiation within 3 h. Furthermore, the degradation pathway was proposed on the basis of the intermediates during the photodegradation process using liquid chromatography analysis coupled with mass spectroscopy (LC-MS). The improvement in photocatalytic performance could be attributed to the p-n heterojunction in the NiO/ZnO hollow spheres with hierarchically porous structure and the strong double-shell binding interaction, which enhances adsorption of the dye molecules on the catalyst surface and facilitates the electron/hole transfer within the framework. The degradation mechanism of pollutant is ascribed to the hydroxyl radicals (rad OH), which is the main oxidative species for the photocatalytic degradation of RhB. This work provides a facile and effective approach for the fabrication of porous metal oxides heterojunction with high photocatalytic activity and thus can be potentially used in the environmental purification.

  20. A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity.

    Science.gov (United States)

    Li, L H; Deng, Z X; Xiao, J X; Yang, G W

    2015-01-26

    Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.

  1. Enhanced photo-catalytic activity of ordered mesoporous indium oxide nanocrystals in the conversion of CO2 into methanol.

    Science.gov (United States)

    Gondal, M A; Dastageer, M A; Oloore, L E; Baig, U; Rashid, S G

    2017-07-03

    Ordered mesoporous indium oxide nanocrystal (m-In 2 O 3 ) was synthesized by nanocasting technique, in which highly ordered mesoporous silca (SBA-15) was used as structural matrix. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halanda (BJH) studies were carried out on m-In 2 O 3 and the results revealed that this material has a highly ordered mesoporous surface with reduced grain size, increased surface area and surface volume compared to the non porous indium oxide. The diffuse reluctance spectrum exhibited substantially improved light absorption efficiency in m-In 2 O 3 compared to normal indium oxide, however, no considerable change in the band gap energies of these materials was observed. When m-In 2 O 3 was used as a photo-catalyst in the photo-catalytic process of converting carbon dioxide (CO 2 ) into methanol under the pulsed laser radiation of 266-nm wavelengths, an enhanced photo-catalytic activity with the quantum efficiency of 4.5% and conversion efficiency of 46.3% were observed. It was found that the methanol production yield in this chemical process is as high as 485 µlg -1 h -1 after 150 min of irradiation, which is substantially higher than the yields reported in the literature. It is quite clear from the results that the introduction of mesoporosity in indium oxide, and the consequent enhancement of positive attributes required for a photo-catalyst, transformed photo-catalytically weak indium oxide into an effective photo-catalyst for the conversion of CO 2 into methanol.

  2. Shape-control of Zinc Oxide nanoparticles: enhancing photocatalytic activity under UV irradiation

    International Nuclear Information System (INIS)

    Montero-Muñoz, M; Ramos-Ibarra, J E; Huamaní-Coaquira, J A; Rodríguez-Páez, J E; Ramirez, A

    2017-01-01

    Zinc oxide (ZnO) nanostructures with different sizes and morphologies were synthesized using the Controlled Precipitation Method. It follows a standard process, but with different synthesis and washing solvents to modify the features related to the photocatalytic activity. The solid phase evolution during aging step was followed using Infrared Spectroscopy (FTIR) and the solids obtained, after the washing process, were characterized using X-ray diffraction (XRD). The Rietveld refinement indicates a Wurtzite phase (space group P63mc) as majority phase with lattice parameters a = 3.2530 Å and c = 5.2125 Å. Scanning electron microscopy (SEM) image shows a sponge-like morphology for the sample synthesized with ethylene glycol as solvent, acidified with nitric acid and washed with water. The sample synthesized and washed with water shows a needle-like morphology; and the sample synthesized in acetic acid and washed with water shows particles with undefined morphology. The optical properties of the as-prepared ZnO samples were investigated by UV-vis absorption spectroscopy. Finally, the photocatalytic activity of ZnO powders was studied from the initial rate of decomposition of H 2 O 2 in aqueous solution. The best results were obtained with samples synthesized and washed with water; the influence of all the solvents on the morphology of ZnO samples and the effect of the morphologies on the photocatalytic activity are discussed. (paper)

  3. Enhancement of oxygen vacancies and solar photocatalytic activity of zinc oxide by incorporation of nonmetal

    International Nuclear Information System (INIS)

    Patil, Ashokrao B.; Patil, Kashinath R.; Pardeshi, Satish K.

    2011-01-01

    B-doped ZnO and N-doped ZnO powders have been synthesized by mechanochemical method and characterized by TG–DTA, XRD, SEM–EDX, XPS, UV–visible and photoluminescence (PL) spectra. X-ray diffraction data suggests the hexagonal wurtzite structure for modified ZnO crystallites and the incorporation of nonmetal expands the lattice constants of ZnO. The room temperature PL spectra suggest more number of oxygen vacancies exist in nonmetal-doped ZnO than that of undoped zinc oxide. XPS analysis shows the substitution of some of the O atoms of ZnO by nonmetal atoms. Solar photocatalytic activity of B-doped ZnO, N-doped ZnO and undoped ZnO was compared by means of oxidative photocatalytic degradation (PCD) of Bisphenol A (BPA). B-doped ZnO showed better solar PCD efficiency as compare to N-doped ZnO and undoped ZnO. The PCD of BPA follows first order reaction kinetics. The detail mechanism of PCD of Bisphenol A was proposed with the identification of intermediates such as hydroquinone, benzene-1,2,4-triol and 4-(2-hydroxypropan-2-yl) phenol. - Graphical Abstract: B-doped ZnO and N-doped ZnO synthesized by mechanochemical method were characterized by various techniques. Solar photocatalytic degradation of Bisphenol-A is in the order of B-ZnO>N-ZnO>ZnO. Highlights: ► B-doped ZnO and N-doped ZnO powders have been synthesized by mechanochemical method. ► PL spectra suggest oxygen vacancies are in order of B-doped ZnO>N-doped ZnO>ZnO. ► Solar PCD efficiency is in order of B-doped ZnO>N-doped ZnO>ZnO for Bisphenol A.

  4. Ternary reduced-graphene-oxide/Bi2MoO6/Au nanocomposites with enhanced photocatalytic activity under visible light

    International Nuclear Information System (INIS)

    Bi, Jinhong; Fang, Wei; Li, Li; Li, Xiaofen; Liu, Minghua; Liang, Shijing; Zhang, Zizhong; He, Yunhui; Lin, Huaxiang; Wu, Ling; Liu, Shengwei; Wong, Po Keung

    2015-01-01

    A novel ternary nanocomposite photocatalyst consisted of reduced-graphene-oxide (RGO), Bi 2 MoO 6 and plasmonic Au nanoparticles were successfully fabricated by multiple steps including a simple solvothermal process and photochemical reduction process. RGO/Bi 2 MoO 6 /Au was characterized by X-ray powder diffraction patterns, transmission electron microscopy, UV–vis diffuse reflectance spectra, Raman spectroscopy and X-ray photoelectron spectroscopy. In comparison with Bi 2 MoO 6 , RGO/Bi 2 MoO 6 and Au/Bi 2 MoO 6 , RGO/Bi 2 MoO 6 /Au exhibits an enhanced photocatalytic activity for decomposition of Rhodamine B under visible light. The separation efficiency of the photogenerated holes and electrons on Bi 2 MoO 6 is promoted by the combined effect of both RGO and Au in the ternary composite, and thus enhances photocatalytic activity. The scavenger study revealed that both hole and superoxide are the major reactive species for the photocatalytic degradation of Rhodamine B using RGO/Bi 2 MoO 6 /Au photocatalyst. - Graphical abstract: A novel ternary nanocomposite photocatalyst consisted of reduced-graphene-oxide (RGO), Bi 2 MoO 6 and plasmonic Au nanoparticles were successfully fabricated by multiple steps including a simple solvothermal process and photochemical reduction process. The resulted ternary nanocomposites greatly enhanced the visible light photocatalytic properties compared to Bi 2 MoO 6 , RGO/Bi 2 MoO 6 or Au/Bi 2 MoO 6 binary systems. The improved photocatalytic activity was mainly attributed to the synergistic effect of Au and RGO with better separation of the photogenerated holes and electrons, resulting from the surface plasmonic resonance and extra strong electron magnetic field of Au nanoparticles and the high electron conductivity of RGO. - Highlights: • The ternary nanocomposites RGO/Bi 2 MoO 6 /Au were constructed for the first time. • RGO/Bi 2 MoO 6 /Au showed much higher visible photoactivity than RGO (Au)/Bi 2 MoO 6 . • The improved

  5. Enhanced visible light photocatalytic activity of copper-doped titanium oxide-zinc oxide heterojunction for methyl orange degradation

    Science.gov (United States)

    Dorraj, Masoumeh; Alizadeh, Mahdi; Sairi, Nor Asrina; Basirun, Wan Jefrey; Goh, Boon Tong; Woi, Pei Meng; Alias, Yatimah

    2017-08-01

    A novel Cu-doped TiO2 coupled with ZnO nanoparticles (Cu-TiO2/ZnO) was prepared by sol-gel method and subsequent precipitation for methyl orange (MO) photodegradation under visible light irradiation. The compositions and shapes of the as-prepared Cu-TiO2/ZnO nanocomposites were characterized by photoluminescence spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectra and Brunauer-Emmett-Teller adsorption isotherm techniques. The Cu-TiO2/ZnO nanocomposites showed considerably higher photocatalytic activity for MO removal from water under visible light irradiation than that of single-doped semiconductors. The effects of Cu-TiO2 and ZnO mass ratios on the photocatalytic reaction were also studied. A coupling percentage of 30% ZnO exhibited the highest photocatalytic activity. The enhanced photocatalytic activity of the Cu-TiO2/ZnO nanocomposites was mainly attributed to heterojunction formation, which allowed the efficient separation of photoinduced electron-hole pairs at the interface. Moreover, these novel nanocomposites could be recycled during MO degradation in a three-cycle experiment without evident deactivation, which is particularly important in environmental applications.

  6. Enhancement of photocatalytic H2 evolution of eosin Y-sensitized reduced graphene oxide through a simple photoreaction

    Directory of Open Access Journals (Sweden)

    Weiying Zhang

    2014-06-01

    Full Text Available A graphene oxide (GO solution was irradiated by a Xenon lamp to form reduced graphene oxide (RGO. After irradiation, the epoxy, the carbonyl and the hydroxy groups are gradually removed from GO, resulting in an increase of sp2 π-conjugated domains and defect carbons with holes for the formed RGO. The RGO conductivity increases due to the restoration of sp2 π-conjugated domains. The photocatalytic activity of EY-RGO/Pt for hydrogen evolution was investigated with eosin Y (EY as a sensitizer of the RGO and Pt as a co-catalyst. When the irradiation time is increased from 0 to 24 h the activity rises, and then reaches a plateau. Under optimum conditions (pH 10.0, 5.0 × 10−4 mol L−1 EY, 10 μg mL−1 RGO, the maximal apparent quantum yield (AQY of EY-RGO24/Pt for hydrogen evolution rises up to 12.9% under visible light irradiation (λ ≥ 420 nm, and 23.4% under monochromatic light irradiation at 520 nm. Fluorescence spectra and transient absorption decay spectra of the EY-sensitized RGO confirm that the electron transfer ability of RGO increases with increasing irradiation time. The adsorption quantity of EY on the surface of RGO enhances, too. The two factors ultimately result in an enhancement of the photocatalytic hydrogen evolution over EY-RGO/Pt with increasing irradiation time. A possible mechanism is discussed.

  7. Ag-loaded TiO2/reduced graphene oxide nanocomposites for enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Vasilaki, E.; Georgaki, I.; Vernardou, D.; Vamvakaki, M.; Katsarakis, N.

    2015-01-01

    Highlights: • Ag nanoparticles were loaded on TiO 2 by chemical reduction. • TiO 2 /Ag and TiO 2 samples were deposited on reduced graphene oxide (rGO). • Their performance was evaluated via methylene blue removal under visible-light. • TiO 2 /Ag/rGO presented superior activity compared to TiO 2 , TiO 2 /Ag and TiO 2 /rGO. - Abstract: In this work, Ag nanoparticles were loaded by chemical reduction onto TiO 2 P25 under different loadings ranging from 1 up to 4 wt% and hydrothermally deposited on reduced graphene oxide sheets. Chemical reduction was determined to be an effective preparation approach for Ag attachment to titania, leading to the formation of small silver nanoparticles with an average diameter of 4.2 nm. The photocatalytic performance of the hybrid nanocomposite materials was evaluated via methylene blue (MB) dye removal under visible-light irradiation. The rate of dye decolorization was found to depend on the metal loading, showing an increase till a threshold value of 3 wt%, above which the rate drops. Next, the as prepared sample of TiO 2 /Ag of better photocatalytic response, i.e., at a 3 wt% loading value, was hydrothermally deposited on a platform of reduced graphene oxide (rGO) of tunable content (mass ratio). TiO 2 /Ag/rGO coupled nanocomposite presented significantly enhanced photocatalytic activity compared to the TiO 2 /Ag, TiO 2 /rGO composites and bare P25 titania semiconductor photocatalysts. In particular, after 45 min of irradiation almost complete decolorization of the dye was observed for the TiO 2 /Ag/rGO nanocatalyst, while the respective removal efficiency was 92% for TiO 2 /Ag, 93% for TiO 2 /rGO and only 80% for the bare TiO 2 nanoparticles. This simple step by step preparation strategy allows for optimum exploitation of the advanced properties of metal plasmonic effect and reduced graphene oxide as the critical host for boosting the overall photocatalytic activity towards visible-light.

  8. Decoration of BiOI quantum size nanoparticles with reduced graphene oxide in enhanced visible-light-driven photocatalytic studies

    International Nuclear Information System (INIS)

    Liu Zhang; Xu Weicheng; Fang Jianzhang; Xu Xiaoxin; Wu Shuxing; Zhu Ximiao; Chen Zehua

    2012-01-01

    Highlights: ► RGO/BiOI nanocomposites were synthesized by a reverse microemulsion method. ► Quantum sized BiOI nanoparticles can be obtained by this approach. ► Ascorbic acid was used as a reducing agent to reduce GO and seemed to be effective. ► RGO/BiOI presented outstanding visible-light-induced photocatalytic performance. ► Possible photocatalytic mechanism was proposed based on the experimental studies. - Abstract: Herein, a reverse microemulsion route was developed to synthesize bismuth oxyiodide (BiOI) nanocrystals and reduced graphene oxide (RGO) nanocomposites as a highly efficient photocatalyst, and both the formation of BiOI and the reduction of RGO were achieved in situ in microemulsions simultaneously at low temperature (60 °C). The uniform nanocrystal size and structure were indicated by XRD, TEM, and the reduction of GO by ascorbic acid was evidenced by FTIR, XPS, and Raman spectra techniques. The enhanced photoactivity of RGO/BiOI nanocomposites under visible light was attributed to improved light absorption and efficient charge separation and transportation.

  9. Decoration of BiOI quantum size nanoparticles with reduced graphene oxide in enhanced visible-light-driven photocatalytic studies

    Energy Technology Data Exchange (ETDEWEB)

    Liu Zhang, E-mail: liuzhang0126@126.com [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Xu Weicheng [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Fang Jianzhang, E-mail: fangjzh@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); Xu Xiaoxin; Wu Shuxing; Zhu Ximiao; Chen Zehua [School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer RGO/BiOI nanocomposites were synthesized by a reverse microemulsion method. Black-Right-Pointing-Pointer Quantum sized BiOI nanoparticles can be obtained by this approach. Black-Right-Pointing-Pointer Ascorbic acid was used as a reducing agent to reduce GO and seemed to be effective. Black-Right-Pointing-Pointer RGO/BiOI presented outstanding visible-light-induced photocatalytic performance. Black-Right-Pointing-Pointer Possible photocatalytic mechanism was proposed based on the experimental studies. - Abstract: Herein, a reverse microemulsion route was developed to synthesize bismuth oxyiodide (BiOI) nanocrystals and reduced graphene oxide (RGO) nanocomposites as a highly efficient photocatalyst, and both the formation of BiOI and the reduction of RGO were achieved in situ in microemulsions simultaneously at low temperature (60 Degree-Sign C). The uniform nanocrystal size and structure were indicated by XRD, TEM, and the reduction of GO by ascorbic acid was evidenced by FTIR, XPS, and Raman spectra techniques. The enhanced photoactivity of RGO/BiOI nanocomposites under visible light was attributed to improved light absorption and efficient charge separation and transportation.

  10. Rare earth oxide-doped titania nanocomposites with enhanced photocatalytic activity towards the degradation of partially hydrolysis polyacrylamide

    International Nuclear Information System (INIS)

    Li Jinhuan; Yang Xia; Yu Xiaodan; Xu, Leilei; Kang Wanli; Yan Wenhua; Gao Hongfeng; Liu Zhonghe; Guo Yihang

    2009-01-01

    Rare-earth oxide-doped titania nanocomposites (RE 3+ /TiO 2 , where RE = Eu 3+ , Pr 3+ , Gd 3+ , Nd 3+ , and Y 3+ ) were prepared by a one-step sol-gel-solvothermal method. The products exhibited anatase phase structure, mesoporosity, and interesting surface compositions with three oxygen species and two titanium species. The products were used as the photocatalysts to degrade a partially hydrolysis polyacrylamide (HPAM) under UV-light irradiation, a very useful polymer in oil recovery. For comparison, Degussa P25 and as-prepared pure TiO 2 were also tested under the same conditions. The enhanced photocatalytic activity was obtained on as-prepared Eu 3+ (Gd 3+ , Pr 3+ )/TiO 2 composites, and the reasons were explained. Finally, the degradation pathway of HPAM over the RE 3+ /TiO 2 composite was put forward based on the intermediates produced during the photocatalysis procedure.

  11. Fe2.25W0.75O4/reduced graphene oxide nanocomposites for novel bifunctional photocatalyst: One-pot synthesis, magnetically recyclable and enhanced photocatalytic property

    International Nuclear Information System (INIS)

    Guo, Jinxue; Jiang, Bin; Zhang, Xiao; Zhou, Xiaoyu; Hou, Wanguo

    2013-01-01

    Fe 2.25 W 0.75 O 4 /reduced graphene oxide (RGO) composites were prepared for application of novel bifunctional photocatalyst via simple one-pot hydrothermal method, employing graphene oxide (GO), Na 2 WO 4 , FeSO 4 and sodium dodecyl benzene sulfonate (SDBS) as the precursors. Transmission electron microscope (TEM) results indicate that the well-dispersed Fe 2.25 W 0.75 O 4 nanoparticles were deposited on the surface of RGO sheets homogeneously. Magnetic characterization reveals that Fe 2.25 W 0.75 O 4 and Fe 2.25 W 0.75 O 4 /RGO show ferromagnetic behaviors. So this novel bifunctional photocatalyst could achieve magnetic separation and collection with the aid of external magnet. The composites exhibit enhanced photocatalytic performance on degradation of methyl orange (MO) compared with pure Fe 2.25 W 0.75 O 4 under low-power ultraviolet light irradiation due to the introduction of RGO. Moreover, this hybrid catalyst possesses long-term excellent photocatalytic performance due to its good thermal stability. This bifunctional photocatalyst, which combines magnetic property and excellent photocatalytic activity, would be a perfect candidate in applications of catalytic elimination of environmental pollutants and other areas. - Graphical abstract: Magnetically recyclable Fe 2.25 W 0.75 O 4 /reduced graphene oxide nanocomposites with enhanced photocatalytic property Display Omitted - Highlights: ●Fe 2.25 W 0.75 O 4 growth, deposition and GO reduction occurred simultaneously. ●Composite possessed ferromagnetic and enhanced photocatalytic properties. ●Composite is utilized as a magnetically separable and high-efficient photocatalyst. ●Photocatalyst showed good photocatalytic and thermal stability during cyclic use

  12. Enhanced visible light-driven photocatalytic performance of ZnO–g-C_3N_4 coupled with graphene oxide as a novel ternary nanocomposite

    International Nuclear Information System (INIS)

    Jo, Wan-Kuen; Clament Sagaya Selvam, N.

    2015-01-01

    Highlights: • Prepared novel ternary nanocomposite consisting of ZnO, g-C_3N_4, and graphene oxide. • ZnO nanospheres disperse evenly and embed on porous g-C_3N_4-coupled graphene oxide. • Heterojunction of ternary composite account for the enhanced photocatalytic activity. - Abstract: This article reports a novel ternary nanocomposite consisting of ZnO, g-C_3N_4, and graphene oxide (GO) that provides enhanced photocatalytic performance and stability. The ZnO nanospheres disperse evenly and embed themselves in the porous g-C_3N_4. Composites with various g-C_3N_4 and GO to ZnO weight ratios were synthesized and characterized systematically. The results indicated that the absorption of binary g-C_3N_4/ZnO nanocomposites shifted to a lower energy compared to pure ZnO in a fashion consistent with the loading content of g-C_3N_4. Notably, the loading content of GO in the ZnO–g-C_3N_4 composite resulted in increased absorption in the visible range and improved charge separation efficiency, thereby drastically improving photocatalytic activity. Successful hybridization of ternary nanocomposite was confirmed by drastic quenching of fluorescence and broader visible light absorption. The optimal content of g-C_3N_4 in the ZnO–g-C_3N_4 composite was 50%, which exhibited the effective hybridization between ZnO and g-C_3N_4, and high photocatalytic efficiency. However, the photocatalytic degradation of the ternary nanocomposite showed performance that was two times greater than ZnO–g-C_3N_4, exhibiting 99.5% degradation efficiency after just 15 min of light irradiation. The combined heterojunction and synergistic effects of this composite account for the improved photocatalytic activity.

  13. Green synthesis of AgI-reduced graphene oxide nanocomposites: Toward enhanced visible-light photocatalytic activity for organic dye removal

    International Nuclear Information System (INIS)

    Reddy, D. Amaranatha; Lee, Seunghee; Choi, Jiha; Park, Seonhwa; Ma, Rory; Yang, Haesik; Kim, Tae Kyu

    2015-01-01

    Graphical abstract: - Highlights: • A novel green synthesis of AgI-RGO nanocomposites. • Significant improvement of the photocatalytic activity in RGO wrapped composites. • Additive promoted photocatalytic performance in AgI-RGO composites. • AgI-RGO nanocomposites may find applications in luminescent and catalytic devices. - Abstract: Novel reduced graphene oxide (RGO) enwrapped AgI nanocomposites were successfully fabricated by a facile template-free ultrasound-assisted method at room temperature. The structural, morphological, and optical studies demonstrate that the obtained nanostructures have good crystallinity and that the graphene nanosheets are decorated densely with AgI nanostructures. The photocatalytic activity of the composite was evaluated by the degradation of an organic dye, Rhodamine B (RhB), under visible-light irradiation. The results indicate that AgI with incorporated graphene exhibited much higher photocatalytic activity than the pure AgI due to the improved separation efficiency of the photogenerated carriers and that it prolonged the lifetime of the electron–hole pairs due to the chemical bonding between AgI and graphene. AgI (0.4 mg mL −1 of graphene oxide) nanocomposites displayed the highest photocatalytic degradation efficiency and the corresponding catalytic efficiencies within 70 min were ∼96%. Moreover, with the assistance of H 2 O 2 the photocatalytic ability of the as-obtained AgI-RGO nanocomposites was enhanced. The corresponding catalytic efficiencies within 30 min were ∼96.8% (for 1 mL H 2 O 2 ) under the same irradiation conditions. The excellent visible-light photocatalytic efficiency and luminescence properties make the AgI-RGO nanocomposites promising candidates for the removal of organic dyes for water purification and enable their application in near-UV white LEDs

  14. Facile synthesis of well-dispersed Bi_2S_3 nanoparticles on reduced graphene oxide and enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Chen, Yajie; Tian, Guohui; Mao, Guijie; Li, Rong; Xiao, Yuting; Han, Taoran

    2016-01-01

    Highlights: • Well-dispersed Bi_2S_3 nanoparticles on reduced graphene oxide were prepared. • Poly(sodium-p-styrenesul-fonate) can maintain Bi_2S_3 small particle size. • The prepared composites inhibit the recombination of photogenerated charges. • The prepared composites exhibited better visible light photoactivity. - Abstract: Here we present a facile method for the synthesis of highly dispersed Bi_2S_3 nanoparticles (Bi_2S_3 NPs) with an average diameter of ca. 25 ± 3 nm on the surface of reduced graphene oxide (RGO) via a poly(sodium-p-styrenesul-fonate) (PSS) asisted hydrothermal process. Such synthetic strategy can avoid excess aggregates of Bi_2S_3 nanoparticles, meanwhile from effective interfacial contact between Bi_2S_3 nanoparticles and RGO nanosheets, and inhibit the recombination of photogenerated charges. The enhanced charge transfer properties were proved by photoluminescence (PL) measurement. The obtained Bi_2S_3 NPs/RGO composites showed more significant visible light photoactivity for the degradation of 2,4-dichlorophenol and Rhodamine B than that pure Bi_2S_3 and the control sample prepared in the absence of PSS. The enhanced photocatalytic performance could be attributed to the synergistic effect of efficient separation of photogenerated electron-hole pairs, increased catalytic active sites and visible light utilization.

  15. Enhanced photocatalytic performance of KNbO3(100)/reduced graphene oxide nanocomposites investigated using first-principles calculations: RGO reductivity effect

    Science.gov (United States)

    Zhang, Pan; Shen, Yanqing; Wu, Wenjing; Li, Jun; Zhou, Zhongxiang

    2018-03-01

    Although a number of various reduced graphene oxide (RGO)-based nanomaterials with enhanced photocatalytic performance have recently been characterized, the effect of RGO reductivity on their performance is still not clear. Herein, KNbO3(100) surface modification with three RGO sheets of different reductivity is investigated using first-principles calculations, revealing that increasing RGO reductivity enhances the photocatalytic performance of KNbO3(100)/RGO nanocomposites. In contrast to CeO2/RGO nanocomposites, the O atoms of RGO inhibit the photoactivity of KNbO3/RGO nanocomposites by restraining the effect of inducing a red shift of the corresponding photocatalytic absorption spectra by C 2p states. Increased RGO reductivity extends its absorption edge to the visible light region of the optical absorption and also promotes charge transfer from the KNbO3(100) surface to RGO sheets, in contrast to the behavior observed for g-C3N4/RGO composites. Overall, this work provides a reasonable explanation of controversial experimental results obtained previously, paving the way to the development of highly efficient RGO-based photocatalysts and promoting further photocatalytic applications of KNbO3/RGO nanocomposites.

  16. Enhanced visible-light photocatalytic activity for selective oxidation of amines into imines over TiO{sub 2}(B)/anatase mixed-phase nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jun [Institute of Applied Chemistry, Henan Polytechnic University, Jiaozuo 454003 (China); State Key Laboratory Cultivation Base for Gas Geology and Gas Control, School of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo 454003 (China); Yang, Juan, E-mail: yangjuanhpu@yahoo.com [Institute of Applied Chemistry, Henan Polytechnic University, Jiaozuo 454003 (China); Wang, Xiaohan; Zhang, Lei; Li, Yingjie [Institute of Applied Chemistry, Henan Polytechnic University, Jiaozuo 454003 (China)

    2015-09-15

    Graphical abstract: Visible-light photocatalytic activities for selective oxidation of amines into imines are greatly affected by the crystal structure of TiO{sub 2} catalysts and mixed-phase TiO{sub 2}(B)/anatase possess higher photoactivity because of the moderate adsorption ability and efficient charge separation. - Highlights: • Visible-light photocatalytic oxidation of amines to imines is studied over different TiO{sub 2}. • Photocatalytic activities are greatly affected by the crystal structure of TiO{sub 2} nanowires. • Mixed-phase TiO{sub 2}(B)/anatase exhibits higher catalytic activity than single-phase TiO{sub 2}. • Enhanced activity is ascribed to efficient adsorption ability and interfacial charge separation. • Photoinduced charge transfer mechanism on TiO{sub 2}(B)/anatase catalysts is also proposed. - Abstract: Wirelike catalysts of mixed-phase TiO{sub 2}(B)/anatase TiO{sub 2}, bare anatase TiO{sub 2} and TiO{sub 2}(B) are synthesized via calcining precursor hydrogen titanate obtained from hydrothermal process at different temperatures between 450 and 700 °C. Under visible light irradiation, mixed-phase TiO{sub 2}(B)/anatase TiO{sub 2} catalysts exhibit enhanced photocatalytic activity in comparison with pure TiO{sub 2}(B) and anatase TiO{sub 2} toward selective oxidation of benzylamines into imines and the highest photocatalytic activity is achieved by TW-550 sample consisting of 65% TiO{sub 2}(B) and 35% anatase. The difference in photocatalytic activities of TiO{sub 2} samples can be attributed to the different adsorption abilities resulted from their crystal structures and interfacial charge separation driven by surface-phase junctions between TiO{sub 2}(B) and anatase TiO{sub 2}. Moreover, the photoinduced charge transfer mechanism of surface complex is also proposed over mixed-phase TiO{sub 2}(B)/anatase TiO{sub 2} catalysts. Advantages of this photocatalytic system include efficient utilization of solar light, general suitability to

  17. Enhanced visible-light photocatalytic activity for selective oxidation of amines into imines over TiO2(B)/anatase mixed-phase nanowires

    International Nuclear Information System (INIS)

    Dai, Jun; Yang, Juan; Wang, Xiaohan; Zhang, Lei; Li, Yingjie

    2015-01-01

    Graphical abstract: Visible-light photocatalytic activities for selective oxidation of amines into imines are greatly affected by the crystal structure of TiO 2 catalysts and mixed-phase TiO 2 (B)/anatase possess higher photoactivity because of the moderate adsorption ability and efficient charge separation. - Highlights: • Visible-light photocatalytic oxidation of amines to imines is studied over different TiO 2 . • Photocatalytic activities are greatly affected by the crystal structure of TiO 2 nanowires. • Mixed-phase TiO 2 (B)/anatase exhibits higher catalytic activity than single-phase TiO 2 . • Enhanced activity is ascribed to efficient adsorption ability and interfacial charge separation. • Photoinduced charge transfer mechanism on TiO 2 (B)/anatase catalysts is also proposed. - Abstract: Wirelike catalysts of mixed-phase TiO 2 (B)/anatase TiO 2 , bare anatase TiO 2 and TiO 2 (B) are synthesized via calcining precursor hydrogen titanate obtained from hydrothermal process at different temperatures between 450 and 700 °C. Under visible light irradiation, mixed-phase TiO 2 (B)/anatase TiO 2 catalysts exhibit enhanced photocatalytic activity in comparison with pure TiO 2 (B) and anatase TiO 2 toward selective oxidation of benzylamines into imines and the highest photocatalytic activity is achieved by TW-550 sample consisting of 65% TiO 2 (B) and 35% anatase. The difference in photocatalytic activities of TiO 2 samples can be attributed to the different adsorption abilities resulted from their crystal structures and interfacial charge separation driven by surface-phase junctions between TiO 2 (B) and anatase TiO 2 . Moreover, the photoinduced charge transfer mechanism of surface complex is also proposed over mixed-phase TiO 2 (B)/anatase TiO 2 catalysts. Advantages of this photocatalytic system include efficient utilization of solar light, general suitability to amines, reusability and facile separation of nanowires catalysts

  18. Ultrasound assisted synthesis of ZnO/reduced graphene oxide composites with enhanced photocatalytic activity and anti-photocorrosion

    International Nuclear Information System (INIS)

    Peng, Yonggang; Ji, Junling; Chen, Dajun

    2015-01-01

    Graphical abstract: - Highlights: • ZnO/reduced graphene oxide composites were prepared by in situ growth with ultrasound assisted method. • A plausible formation mechanism of ZnO/rGO composites was deduced. • After hybridization with rGO, the photocatalytic activity of ZnO was improved and its photocorrosion was inhibited obviously. - Abstract: A method to improve the photocatalytic activity and suppress the photocorrosion of ZnO was developed by depositing ZnO nanoparticles onto the surface of reduced graphene oxide (rGO) via in situ growth with ultrasound assisted synthesis. The optimum synergetic effect of ZnO/rGO composite was found at a weight ratio of 2% (rGO/ZnO). Compared with ZnO, the photocatalytic activities of ZnO/rGO composite for the degradation of methylene blue (MB) and C.I. acid red 249 (AR249) aqueous solutions under UV light irradiation were increased by 8.6% and 14.7%, respectively. The improved photocatalytic activity was originated from the rapid separation of photogenerated electrons and holes on the interface of rGO and ZnO. The photocorrosion of ZnO was inhibited obviously after hybridization with rGO. Even after six successive cycles under UV irradiation, the photocatalytic activities of ZnO/rGO composite for MB and AR249 still retained 92.9% and 94.8% of that for the first cycling run, while that of ZnO obviously decreased due to serious photocorrosion. The photocorrosion inhibition of ZnO by rGO was attributed to the reduced activation of surface oxygen atom on the surface of ZnO.

  19. Enhanced visible light photocatalytic activity of copper-doped titanium oxide–zinc oxide heterojunction for methyl orange degradation

    Energy Technology Data Exchange (ETDEWEB)

    Dorraj, Masoumeh, E-mail: masidor20@gmail.com [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Alizadeh, Mahdi [UM Power Energy Dedicated Advanced Centre (UMPEDAC), Level 4 Wisma R& D, University of Malaya, Jalan Pantai Baharu, 59990 Kuala Lumpur (Malaysia); Sairi, Nor Asrina, E-mail: asrina@um.edu.my [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); University of Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Basirun, Wan Jefrey [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Goh, Boon Tong [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Woi, Pei Meng; Alias, Yatimah [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); University of Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2017-08-31

    Highlights: • The novel Cu-TiO{sub 2}/ZnO heterojunction nanocomposite was synthesized for the first time via a two-step process. • The Cu-TiO{sub 2}/ZnO heterostructured nanocomposite exhibited an enhanced visible-light-driven photocatalytic activity for MO degradation. • The heterostructured nanocomposite could be recycled during the degradation of MO in a three-cycle experiment with good stability. - Abstract: A novel Cu-doped TiO{sub 2} coupled with ZnO nanoparticles (Cu-TiO{sub 2}/ZnO) was prepared by sol-gel method and subsequent precipitation for methyl orange (MO) photodegradation under visible light irradiation. The compositions and shapes of the as-prepared Cu-TiO{sub 2}/ZnO nanocomposites were characterized by photoluminescence spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectra and Brunauer–Emmett–Teller adsorption isotherm techniques. The Cu-TiO{sub 2}/ZnO nanocomposites showed considerably higher photocatalytic activity for MO removal from water under visible light irradiation than that of single-doped semiconductors. The effects of Cu-TiO{sub 2} and ZnO mass ratios on the photocatalytic reaction were also studied. A coupling percentage of 30% ZnO exhibited the highest photocatalytic activity. The enhanced photocatalytic activity of the Cu-TiO{sub 2}/ZnO nanocomposites was mainly attributed to heterojunction formation, which allowed the efficient separation of photoinduced electron−hole pairs at the interface. Moreover, these novel nanocomposites could be recycled during MO degradation in a three-cycle experiment without evident deactivation, which is particularly important in environmental applications.

  20. Capture of atmospheric CO{sub 2} into (BiO){sub 2}CO{sub 3}/graphene or graphene oxide nanocomposites with enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wendong [Department of Scientific Research Management, Chongqing Normal University, Chongqing, 401331 (China); Dong, Fan, E-mail: dfctbu@126.com [Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environment and Resources, Chongqing Technology and Business University, Chongqing, 400067 (China); Zhang, Wei, E-mail: andyzhangwei@163.com [Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714 (China)

    2015-12-15

    Graphical abstract: Self-assembly of (BiO){sub 2}CO{sub 3} nanoflakes on graphene and graphene oxide nanosheets were realized by a one-pot efficient capture of atmospheric CO{sub 2} at room temperature. - Highlights: • A facile one-step method was developed for graphene-based composites. • The synthesis was conducted by utilization of atmospheric CO{sub 2}. • (BiO){sub 2}CO{sub 3}-graphene and (BiO){sub 2}CO{sub 3}-graphene oxide composites were synthesized. • The nanocomposites exhibited enhanced photocatalytic activity. - Abstract: Self-assembly of (BiO){sub 2}CO{sub 3} nanoflakes on graphene (Ge) and graphene oxide (GO) nanosheets, as an effective strategy to improve the photocatalytic performance of two-dimensional (2D) nanostructured materials, were realized by a one-pot efficient capture of atmospheric CO{sub 2} at room temperature. The as-synthesized samples were characterized by XRD, SEM, TEM, XPS, UV–vis DRS, Time-resolved ns-level PL and BET-BJH measurement. The photocatalytic activity of the obtained samples was evaluated by the removal of NO at the indoor air level under simulated solar-light irradiation. Compared with pure (BiO){sub 2}CO{sub 3}, (BiO){sub 2}CO{sub 3}/Ge and (BiO){sub 2}CO{sub 3}/GO nanocomposites exhibited enhanced photocatalytic activity due to their large surface areas and pore volume, and efficient charge separation and transfer. The present work could provide a simple method to construct 2D nanocomposites by efficient utilization of CO{sub 2} in green synthetic strategy.

  1. Capture of atmospheric CO2 into (BiO)2CO3/graphene or graphene oxide nanocomposites with enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Zhang, Wendong; Dong, Fan; Zhang, Wei

    2015-01-01

    Graphical abstract: Self-assembly of (BiO) 2 CO 3 nanoflakes on graphene and graphene oxide nanosheets were realized by a one-pot efficient capture of atmospheric CO 2 at room temperature. - Highlights: • A facile one-step method was developed for graphene-based composites. • The synthesis was conducted by utilization of atmospheric CO 2 . • (BiO) 2 CO 3 -graphene and (BiO) 2 CO 3 -graphene oxide composites were synthesized. • The nanocomposites exhibited enhanced photocatalytic activity. - Abstract: Self-assembly of (BiO) 2 CO 3 nanoflakes on graphene (Ge) and graphene oxide (GO) nanosheets, as an effective strategy to improve the photocatalytic performance of two-dimensional (2D) nanostructured materials, were realized by a one-pot efficient capture of atmospheric CO 2 at room temperature. The as-synthesized samples were characterized by XRD, SEM, TEM, XPS, UV–vis DRS, Time-resolved ns-level PL and BET-BJH measurement. The photocatalytic activity of the obtained samples was evaluated by the removal of NO at the indoor air level under simulated solar-light irradiation. Compared with pure (BiO) 2 CO 3 , (BiO) 2 CO 3 /Ge and (BiO) 2 CO 3 /GO nanocomposites exhibited enhanced photocatalytic activity due to their large surface areas and pore volume, and efficient charge separation and transfer. The present work could provide a simple method to construct 2D nanocomposites by efficient utilization of CO 2 in green synthetic strategy.

  2. Enhanced visible light-driven photocatalytic performance of ZnO–g-C{sub 3}N{sub 4} coupled with graphene oxide as a novel ternary nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Wan-Kuen; Clament Sagaya Selvam, N., E-mail: clamentloy@gmail.com

    2015-12-15

    Highlights: • Prepared novel ternary nanocomposite consisting of ZnO, g-C{sub 3}N{sub 4}, and graphene oxide. • ZnO nanospheres disperse evenly and embed on porous g-C{sub 3}N{sub 4}-coupled graphene oxide. • Heterojunction of ternary composite account for the enhanced photocatalytic activity. - Abstract: This article reports a novel ternary nanocomposite consisting of ZnO, g-C{sub 3}N{sub 4}, and graphene oxide (GO) that provides enhanced photocatalytic performance and stability. The ZnO nanospheres disperse evenly and embed themselves in the porous g-C{sub 3}N{sub 4}. Composites with various g-C{sub 3}N{sub 4} and GO to ZnO weight ratios were synthesized and characterized systematically. The results indicated that the absorption of binary g-C{sub 3}N{sub 4}/ZnO nanocomposites shifted to a lower energy compared to pure ZnO in a fashion consistent with the loading content of g-C{sub 3}N{sub 4}. Notably, the loading content of GO in the ZnO–g-C{sub 3}N{sub 4} composite resulted in increased absorption in the visible range and improved charge separation efficiency, thereby drastically improving photocatalytic activity. Successful hybridization of ternary nanocomposite was confirmed by drastic quenching of fluorescence and broader visible light absorption. The optimal content of g-C{sub 3}N{sub 4} in the ZnO–g-C{sub 3}N{sub 4} composite was 50%, which exhibited the effective hybridization between ZnO and g-C{sub 3}N{sub 4}, and high photocatalytic efficiency. However, the photocatalytic degradation of the ternary nanocomposite showed performance that was two times greater than ZnO–g-C{sub 3}N{sub 4}, exhibiting 99.5% degradation efficiency after just 15 min of light irradiation. The combined heterojunction and synergistic effects of this composite account for the improved photocatalytic activity.

  3. Fabrication of ZnAl mixed metal-oxides/RGO nanohybrid composites with enhanced photocatalytic activity under visible light

    Science.gov (United States)

    Ni, Jie; Xue, Jinjuan; Shen, Jing; He, Guangyu; Chen, Haiqun

    2018-05-01

    The ZnAl mixed metal-oxides (MMOs)/graphene nanocomposites were successfully fabricated by a facile hydrothermal method combined with a calcination process. The thermal treatment enables simultaneously the formation of ZnO/ZnAl2O4 heterogeneous structure, which are uniformly decorated on the surface of graphene, accompanying with the reduction of graphene oxide. The as-prepared heterostructure photocatalysts were well characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectroscopy (DRS) to conduct investigations into the phase structures, microstructure and optical capability. The ZnAl MMO/RGO20 composite displayed favorable adsorption property and photo-degradation efficiency for Ciprofloxacin (CIP) aqueous solution under visible light. The photo-degradation efficiency of the as-prepared ZnAl MMO/RGO20 was 3.0 and even 4.6 times higher than that of ZnAl MMO and pure ZnAl LDH, respectively. The improvement of photocatalytic performance is ascribed to the synergistic effect of heterogeneous structure coupled with graphene, which realizes efficient charge separation efficiency, enlarged visible light adsorption range, and chemical stability of hybrid nanocomposite. The results of EIS, PL and photocurrent response also explained the best performance of ZnAl MMO/RGO20 nanocomposite. Besides, the mechanism of ZnAl MMO/RGO20 photocatalytic system was proposed and analyzed in detail.

  4. Single-step solvothermal synthesis of mesoporous Ag-TiO2-reduced graphene oxide ternary composites with enhanced photocatalytic activity

    Science.gov (United States)

    Arif Sher Shah, Md. Selim; Zhang, Kan; Park, A. Reum; Kim, Kwang Su; Park, Nam-Gyu; Park, Jong Hyeok; Yoo, Pil J.

    2013-05-01

    With growing interest in the photocatalytic performance of TiO2-graphene composite systems, the ternary phase of TiO2, graphene, and Ag is expected to exhibit improved photocatalytic characteristics because of the improved recombination rate of photogenerated charge carriers and potential contribution of the generation of localized surface plasmon resonance at Ag sites on a surface of the TiO2-graphene binary matrix. In this work, Ag-TiO2-reduced graphene oxide ternary nanocomposites were successfully synthesized by a simple solvothermal process. In a single-step synthetic procedure, the reduction of AgNO3 and graphene oxide and the hydrolysis of titanium tetraisopropoxide were spontaneously performed in a mixed solvent system of ethylene glycol, N,N-dimethylformamide and a stoichiometric amount of water without resorting to the use of typical reducing agents. The nanocomposites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, along with different microscopic and spectroscopic techniques, enabling us to confirm the successful reduction of AgNO3 and graphite oxide to metallic Ag and reduced graphene oxide, respectively. Due to the highly facilitated electron transport of well distributed Ag nanoparticles, the synthesized ternary nanocomposite showed enhanced photocatalytic activity for degradation of rhodamine B dye under visible light irradiation.With growing interest in the photocatalytic performance of TiO2-graphene composite systems, the ternary phase of TiO2, graphene, and Ag is expected to exhibit improved photocatalytic characteristics because of the improved recombination rate of photogenerated charge carriers and potential contribution of the generation of localized surface plasmon resonance at Ag sites on a surface of the TiO2-graphene binary matrix. In this work, Ag-TiO2-reduced graphene oxide ternary nanocomposites were successfully synthesized by a simple solvothermal process. In a single-step synthetic procedure, the reduction

  5. Advanced oxidation technologies : photocatalytic treatment of wastewater

    OpenAIRE

    Chen, J.

    1997-01-01

    7.1. Summary and conclusions

    The last two decennia have shown a growing interest in the photocatalytic treatment of wastewater, and more and more research has been carried out into the various aspects of photocatalysis, varying from highly fundamental aspects to practical application. However, despite all this research, there is still much to investigate. Suggested photocatalytic mechanisms, such as those for oxidation by hydroxyl radicals and for oxidation at the surface of photocata...

  6. Efficient Electron Transfer across a ZnO-MoS2 -Reduced Graphene Oxide Heterojunction for Enhanced Sunlight-Driven Photocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Kumar, Suneel; Reddy, Nagappagari Lakshmana; Kushwaha, Himmat Singh; Kumar, Ashish; Shankar, Muthukonda Venkatakrishnan; Bhattacharyya, Kaustava; Halder, Aditi; Krishnan, Venkata

    2017-09-22

    The development of noble metal-free catalysts for hydrogen evolution is required for energy applications. In this regard, ternary heterojunction nanocomposites consisting of ZnO nanoparticles anchored on MoS 2 -RGO (RGO=reduced graphene oxide) nanosheets as heterogeneous catalysts show highly efficient photocatalytic H 2 evolution. In the photocatalytic process, the catalyst dispersed in an electrolytic solution (S 2- and SO 3 2- ions) exhibits an enhanced rate of H 2 evolution, and optimization experiments reveal that ZnO with 4.0 wt % of MoS 2 -RGO nanosheets gives the highest photocatalytic H 2 production of 28.616 mmol h -1  g cat -1 under sunlight irradiation; approximately 56 times higher than that on bare ZnO and several times higher than those of other ternary photocatalysts. The superior catalytic activity can be attributed to the in situ generation of ZnS, which leads to improved interfacial charge transfer to the MoS 2 cocatalyst and RGO, which has plenty of active sites available for photocatalytic reactions. Recycling experiments also proved the stability of the optimized photocatalyst. In addition, the ternary nanocomposite displayed multifunctional properties for hydrogen evolution activity under electrocatalytic and photoelectrocatalytic conditions owing to the high electrode-electrolyte contact area. Thus, the present work provides very useful insights for the development of inexpensive, multifunctional catalysts without noble metal loading to achieve a high rate of H 2 generation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Enhanced photocatalytic activity of nanocellulose supported zinc oxide composite for RhB dye as well as ciprofloxacin drug under sunlight/visible light

    Science.gov (United States)

    Tavker, Neha; Sharma, Manu

    2018-05-01

    Zinc oxide nanoparticles were synthesised from zinc acetate di-hydrate via co-precipitation method. Nanocellulose was isolated from agrowaste using chemo-mechanical treatments and characterized. Nanocellulose supported zinc oxide composites were prepared through in-situ method by adding different amounts of nanocellulose. The photocatalytic efficiency of pure Zno and nanocellulose supported ZnO was calculated using RhB dye under visible light and sun light. The composites which had nanocellulose in greater ratio showed higher degradation efficiency in sunlight rather than visible light for both; dye and drug. All the composites showed high rate of photodegradation compared to bare ZnO and bare nanocellulose. The enhancement in photocatalytic activity was observed maximum where the amount of cellulose was maximum. The maximum observed rate was 0.025 min-1 using Ciprofloxacin drug due to the increase in lifetime of Z4 sample delaying the electron and hole pair recombination. The degrading efficiency of nanocellulose supported zinc oxide (NC/ZnO) composite for RhB was found to be 35% in visible, 76% in sunlight and 75% for ciprofloxacin under sunlight.

  8. Hydrothermal synthesis of 3D urchin-like Ag/TiO_2/reduced graphene oxide composites and its enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Liu, Yuhuan; Zhou, Yi; Yang, Luyue; Wang, Yutang; Wu, Yiwei; Li, Chaocheng; Lu, Jun

    2016-01-01

    Innovative 3D urchin-like ternary TiO_2 composites, which combine Ag nanoparticles with graphene, have been successfully synthesized through a simple hydrothermal method. This process employed nontoxic and mild dihydrate sodium citrate as a reducing agent. During the hydrothermal process, graphene oxide and AgNO_3 were reduced to reduced graphene oxide (RGO) and Ag, respectively. Subsequently, they were grown on the surface of rutile TiO_2 with a 3D urchin-like microsphere (1.5 μm). The as-prepared 3D urchin-like composites were characterized by X-ray diffraction, SEM and TEM. These techniques were also employed to ensure the morphology of urchin-like and rutile phase of TiO_2. FT-IR, Raman spectroscopy and XPS characterization demonstrated the successful reduction in AgNO_3 and graphite oxide to metallic Ag and RGO. The UV–visible spectrum of the ternary composite displayed strong absorption in the visible light region, which was attributed to the efficient electron transport of well-dispersed Ag nanoparticles (20–40 nm) and the formation of Ti–O–C bond between graphene and titania. The synthesized urchin-like ternary composite exhibited enhanced photocatalytic activity (98.7 %) for Rhodamine B degradation. This work provides a very convenient chemical route to the scalable production of Ag/TiO_2/RGO ternary composite photocatalyst for potential applications in solving the environmental problems and energy issues. Also, the proposed mechanism underlying the photocatalytic degradation of Rhodamine B dyes was discussed.Graphical AbstractFourier transform infrared (FTIR) spectra of pure UT, UTG and Ag–UTG composite. The scheme of proposed mechanism for the photocatalytic degradation of RhB on Ag–UTG.

  9. Hydrothermal synthesis of 3D urchin-like Ag/TiO{sub 2}/reduced graphene oxide composites and its enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuhuan; Zhou, Yi, E-mail: zhouyihn@aliyun.com, E-mail: zhouyihn@163.com; Yang, Luyue [Changsha University of Science and Technology, Department of Chemical and Biological Engineering (China); Wang, Yutang [Changsha University, Hunan Province Key Laboratory of Applied Environmental Photocatalysis (China); Wu, Yiwei; Li, Chaocheng; Lu, Jun [Changsha University of Science and Technology, Department of Chemical and Biological Engineering (China)

    2016-09-15

    Innovative 3D urchin-like ternary TiO{sub 2} composites, which combine Ag nanoparticles with graphene, have been successfully synthesized through a simple hydrothermal method. This process employed nontoxic and mild dihydrate sodium citrate as a reducing agent. During the hydrothermal process, graphene oxide and AgNO{sub 3} were reduced to reduced graphene oxide (RGO) and Ag, respectively. Subsequently, they were grown on the surface of rutile TiO{sub 2} with a 3D urchin-like microsphere (1.5 μm). The as-prepared 3D urchin-like composites were characterized by X-ray diffraction, SEM and TEM. These techniques were also employed to ensure the morphology of urchin-like and rutile phase of TiO{sub 2}. FT-IR, Raman spectroscopy and XPS characterization demonstrated the successful reduction in AgNO{sub 3} and graphite oxide to metallic Ag and RGO. The UV–visible spectrum of the ternary composite displayed strong absorption in the visible light region, which was attributed to the efficient electron transport of well-dispersed Ag nanoparticles (20–40 nm) and the formation of Ti–O–C bond between graphene and titania. The synthesized urchin-like ternary composite exhibited enhanced photocatalytic activity (98.7 %) for Rhodamine B degradation. This work provides a very convenient chemical route to the scalable production of Ag/TiO{sub 2}/RGO ternary composite photocatalyst for potential applications in solving the environmental problems and energy issues. Also, the proposed mechanism underlying the photocatalytic degradation of Rhodamine B dyes was discussed.Graphical AbstractFourier transform infrared (FTIR) spectra of pure UT, UTG and Ag–UTG composite. The scheme of proposed mechanism for the photocatalytic degradation of RhB on Ag–UTG.

  10. One-pot hydrothermal synthesis of mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide hybrid material and its enhanced photocatalytic activity.

    Science.gov (United States)

    Wang, Xinwei; Tian, Hongwei; Cui, Xiaoqiang; Zheng, Weitao; Liu, Yichun

    2014-09-14

    We successfully synthesized mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide (Z(x)CSG) hybrid materials as photocatalysts using a facile one-pot hydrothermal reaction, in which graphene oxide (GO) was easily reduced (RGO), and simultaneously Zn(x)Cd(1-x)S (Z(x)CS) nanoparticles (NPs) with a mesoporous structure were uniformly dispersed on the RGO sheets. By well tuning the band gap from 3.42 to 2.21 eV by changing the molar ratio of Zn/Cd (or Zn content), Z(x)CSG with an optimal zinc content has been found to have a significant absorption in the visible light (VL) region. In addition, under VL irradiation (λ > 420 nm), Z(x)CSG also showed zinc content-dependent photocatalytic efficiencies for the degradation of methylene blue (MB). Our findings are that, among Z(x)CSG, Z(0.4)CSG displayed not only a superior photodegradation efficiency of MB (98%), but also good removal efficiency of total organic carbon (TOC) (67%). Furthermore, Z(0.4)CSG had a high photocatalytic stability, and could be used repeatedly. The enhanced photocatalytic activity for Z(0.4)CSG could be attributed to a synergistic effect between mesoporous Z(x)CS NPs and RGO, including the optimal band gap and the moderate conduction band position for ZxCS (compared to CdS), efficient separation and transfer ability of photogenerated electron/hole pairs in the presence of RGO sheets, and relatively high surface area for both mesoporous Z(x)CS NPs and RGO.

  11. Synthesis and characterization of Ag₃PO₄ immobilized with graphene oxide (GO) for enhanced photocatalytic activity and stability over 2,4-dichlorophenol under visible light irradiation.

    Science.gov (United States)

    Chen, Xiao-juan; Dai, You-zhi; Wang, Xing-yan; Guo, Jing; Liu, Tan-hua; Li, Fen-fang

    2015-07-15

    A series of visible-light responsive photocatalysts prepared using Ag3PO4 immobilized with graphene oxide (GO) with varying GO content were obtained by an electrostatically driven method, and 2,4-dichlorophenol (2,4-DCP) was used to evaluate the performance of the photocatalysts. The composites exhibited superior photocatalytic activity and stability compared with pure Ag3PO4. When the content of GO was 5%, the degradation efficiency of 2,4-DCP could reach 98.95%, and 55.91% of the total organic (TOC) content was removed within 60 min irradiation. Meanwhile, the efficiency of 91.77% was achieved for 2,4-DCP degradation even after four times of recycling in the photocatalysis/Ag3PO4-GO (5%) system. Reactive species of O2(˙-), OH˙ and h(+) were considered as the main participants for oxidizing 2,4-DCP, as confirmed by the free radical capture experiments. And some organic intermediates including 4-chlorophenol (4-CP), hydroquinone (HQ), benzoquinone (BZQ), 2-chlorohydroquinone and hydroxyhydroquinone (HHQ) were detected by comparison with the standard retention times from the high performance liquid chromatography (HPLC). In short, the enhanced photocatalytic property of Ag3PO4-GO was closely related to the strong absorption ability of GO relative to 2,4-DCP, the effective separation of photogenerated electron-hole pairs, and the excellent electron capture capability of GO. Copyright © 2015. Published by Elsevier B.V.

  12. Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO4 composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin.

    Science.gov (United States)

    Yan, Yan; Sun, Shaofang; Song, Yang; Yan, Xu; Guan, Weisheng; Liu, Xinlin; Shi, Weidong

    2013-04-15

    To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO4 composite photocatalysts. The as-produced RGO-BiVO4 composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO4 photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO4 composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO4 particles. The enhancement of photocatalytic activities of RGO-BiVO4 photocatalysts can be attributed to the effective separation of electron-hole pairs rather than the improvement of light absorption. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Photocatalytic paper using zinc oxide nanorods

    International Nuclear Information System (INIS)

    Baruah, Sunandan; Jaisai, Mayuree; Imani, Reza; Nazhad, Mousa M; Dutta, Joydeep

    2010-01-01

    Zinc oxide (ZnO) nanorods were grown on a paper support prepared from soft wood pulp. The photocatalytic activity of a sheet of paper with ZnO nanorods embedded in its porous matrix has been studied. ZnO nanorods were firmly attached to cellulose fibers and the photocatalytic paper samples were reused several times with nominal decrease in efficiency. Photodegradation of up to 93% was observed for methylene blue in the presence of paper filled with ZnO nanorods upon irradiation with visible light at 963 Wm -2 for 120 min. Under similar conditions, photodegradation of approximately 35% was observed for methyl orange. Antibacterial tests revealed that the photocatalytic paper inhibits the growth of Escherichia coli under room lighting conditions.

  14. Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO{sub 4} composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yan [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Sun, Shaofang [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); School of Environmental Science and Engineering, Chang’an University, Yanta Road 126, Xi’an, 710054 (China); Song, Yang; Yan, Xu [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Guan, Weisheng [School of Environmental Science and Engineering, Chang’an University, Yanta Road 126, Xi’an, 710054 (China); Liu, Xinlin [School of Material Science and Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Shi, Weidong, E-mail: swd1978@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China)

    2013-04-15

    Highlights: ► Microwave-assisted in situ growth of RGO-BiVO{sub 4} composite was proposed. ► A relatively small particle size with organic-additives free. ► Graphene was formed during the microwave-heating by oxygen capture. ► GB-2 sample exhibits the highest CIP degradation ratio (3 times over pure BiVO{sub 4}). ► The enhancements of activities result from the effective charge separation. -- Abstract: To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO{sub 4} composite photocatalysts. The as-produced RGO-BiVO{sub 4} composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO{sub 4} photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO{sub 4} composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO{sub 4} particles. The enhancement of photocatalytic activities of RGO-BiVO{sub 4} photocatalysts can be attributed to the effective separation of electron–hole pairs rather than the improvement of light absorption.

  15. Reduced graphene oxide enwrapped pinecone-liked Ag3PO4/TiO2 composites with enhanced photocatalytic activity and stability under visible light

    International Nuclear Information System (INIS)

    Ma, Ni; Qiu, Yiwei; Zhang, Yichao; Liu, Hanyang; Yang, Yana; Wang, Jingwei; Li, Xiaoyun; Cui, Can

    2015-01-01

    Ag 3 PO 4 possesses high photocatalytic activity under visible light, but its application is limited by photogenerated charges recombination, photocorrosion as well as consumption of noble Ag. It is of great interesting to develop new Ag 3 PO 4 -based photocatalysts with high charges separation efficiency, good stability and low content of Ag. In this paper, we report a novel Ag 3 PO 4 /TiO 2 /reduced graphene oxide (Ag 3 PO 4 /TiO 2 /rGO) photocatalyst. It exhibits advantages on both the microstructure and the charges separation. The microstructure shows that TiO 2 spheres of hundreds of nanometers in size are decorated with dense nano-sized Ag 3 PO 4 to form pinecone-liked particles, which are enwrapped by rGO sheets. This novel structure effectively prevents aggregation of nano-sized Ag 3 PO 4 , which not only suppresses the charges recombination in Ag 3 PO 4 but also significantly reduces the content of Ag. Ag 3 PO 4 /TiO 2 /rGO also favors separation of photogenerated charges owing to its two pathways for charges transportation, i.e., the electrons in Ag 3 PO 4 can be transferred to rGO, while the holes in Ag 3 PO 4 can be transferred to TiO 2 . The dual-pathway for charges separation as well as the pinecone-liked Ag 3 PO 4 /TiO 2 microstructure ultimately leads to enhanced photocatalytic activity and stability of Ag 3 PO 4 /TiO 2 /rGO. The photocatalytic performance varies with different contents of Ag 3 PO 4 in the composites, because low content of Ag 3 PO 4 induces weak light absorption while excess Ag 3 PO 4 results in serious charges recombination due to the aggregation of Ag 3 PO 4 nanoparticles. In this work, Ag 3 PO 4 /TiO 2 /rGO with weight ratio of Ag 3 PO 4 against TiO 2 /rGO equals to 0.6 exhibits the highest photocatalytic activity. The percentage of Ag in this composite is around 29 wt%, much lower than 77 wt% in pure Ag 3 PO 4 . - Highlights: • Nano-sized Ag 3 PO 4 were decorated on TiO 2 particles. • Pinecone-liked Ag 3 PO 4 /TiO 2

  16. Melanin-gamma rays assistants for bismuth oxide nanoparticles synthesis at room temperature for enhancing antimicrobial, and photocatalytic activity.

    Science.gov (United States)

    El-Batal, Ahmed I; El-Sayyad, Gharieb S; El-Ghamry, Abbas; Agaypi, Kerolos M; Elsayed, Mohamed A; Gobara, Mohamed

    2017-08-01

    Melanin pigment has been deemed as a natural photoprotector with strong hydrophobicity. It allured considerable compatibility with many applications in medicine, food, and nanotechnology. Penicillium chrysogenium has been devoted to the green synthesis of melanin whereby optimizing its culture and environmental conditions. The impacts of alternative economic L-tyrosine natural sources (unprecedented alternate origins) and gamma radiation were pledged for the potential growing of the pigment. Herein, notable increases in melanin yield (6.4mg/ml; much higher than nonoptimized one by 40 folds) was obtained by optimizing the culture, and environmental requirements [potato starch (3.0%), yeast extract (5.0%), copper sulfate (0.2mM), 0.25% L-tyrosine, 0.1% L-glycine, and 0.1% Tween 20 at pH5.0, and 30°C for 7.0days using 180.0rpm shaking speed]. The addition of banana's peel (2.0%) has been led to increase the melanin production up to (8.3mg/ml; much higher than optimized one by 1.29 folds). It stimulated the induced enzymes, (i.e., tyrosinase) because it contained significant amounts of L-tyrosine, dopamine, and L-DOPA as resources for melanin biosynthesis. Then irradiated P. chrysogenium (2.5kGy) induced the pigment yield to 10.3mg/ml; much higher than optimized one by (1.61 folds). On the other hand, we tailored a methodology involved the product of melanin and gamma rays (25.0kGy) to an eco-friendly synthesis of Bismuth oxide nanoparticles (BiONPs) at the room temperature. Melanin under such alkaline condition functioning as simultaneously hydrolyzes, photoprotection of the Bi seeds, and stabilizer against the uncontrolled growth and the free radicals attack. Whereas the gamma irradiation induced the room temperature condensation reaction to occur, a novel mechanism proposal was discussed. BiONPs were characterized by UV-Vis., DLS, XRD, SEM, EDX, and FTIR. DLS and XRD calculations with TEM analysis exhibited the mean diameter of BiONPs was 29.82nm. Moreover, the as

  17. Nano cobalt oxides for photocatalytic hydrogen production

    KAUST Repository

    Mangrulkar, Priti A.

    2012-07-01

    Nano structured metal oxides including TiO 2, Co 3O 4 and Fe 3O 4 have been synthesized and evaluated for their photocatalytic activity for hydrogen generation. The photocatalytic activity of nano cobalt oxide was then compared with two other nano structured metal oxides namely TiO 2 and Fe 3O 4. The synthesized nano cobalt oxide was characterized thoroughly with respect to EDX and TEM. The yield of hydrogen was observed to be 900, 2000 and 8275 mmol h -1 g -1 of photocatalyst for TiO 2, Co 3O 4 and Fe 3O 4 respectively under visible light. It was observed that the hydrogen yield in case of nano cobalt oxide was more than twice to that of TiO 2 and the hydrogen yield of nano Fe 3O 4 was nearly four times as compared to nano Co 3O 4. The influence of various operating parameters in hydrogen generation by nano cobalt oxide was then studied in detail. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  18. Preparation of TiO₂/Carbon Nanotubes/Reduced Graphene Oxide Composites with Enhanced Photocatalytic Activity for the Degradation of Rhodamine B.

    Science.gov (United States)

    Huang, Yanzhen; Chen, Dongping; Hu, Xinling; Qian, Yingjiang; Li, Dongxu

    2018-06-13

    In this report, ternary titanium dioxide (TiO₂)/carbon nanotubes (CNTs)/reduced graphene oxide (rGO) composites were fabricated by a facile and environmentally friendly one-pot solvethermal method for the removal of Rhodamine B (RhB). Its structures were represented by X-ray powder diffraction (XRD), Raman spectrometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic performance was tested by the degradation efficiency of RhB under UV-vis light irradiation. The experimental results indicated that photocatalytic activity improved as the ratio of CNTs:TiO₂ ranged from 0.5% to 3% but reduced when the content increased to 5% and 10%, and the TiO₂/CNTs/rGO-3% composites showed superior photocatalytic activity compared with the binary ones (i.e., TiO₂/CNTs, TiO₂/rGO) and pristine TiO₂. The rate constant k of the pseudo first-order reaction was about 1.5 times that of TiO₂. The improved photocatalytic activity can be attributed to the addition of rGO and CNTs, which reduced the recombination of photo-induced electron-hole pairs, and the fact that CNTs and rGO, with a high specific surface area and high adsorption ability to efficiently adsorb O₂, H₂O and organics, can increase the hydroxyl content of the photocatalyst surface.

  19. Enhanced Photocatalytic Activity of La3+-Doped TiO2 Nanotubes with Full Wave-Band Absorption

    Science.gov (United States)

    Xia, Minghao; Huang, Lingling; Zhang, Yubo; Wang, Yongqian

    2018-06-01

    TiO2 nanotubes doped with La3+ were synthesized by anodic oxidation method and the photocatalytic activity was detected by photodegrading methylene blue. As-prepared samples improved the absorption of both ultraviolet light and visible light and have a great enhancement on the photocatalytic activity while contrasting with the pristine TiO2 nanotubes. A tentative mechanism for the enhancement of photocatalytic activity with full wave-band absorption is proposed.

  20. Rapid thermal reduced graphene oxide/Pt–TiO{sub 2} nanotube arrays for enhanced visible-light-driven photocatalytic reduction of CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Lan Ching [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Faculty of Engineering and Green Technology, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat, 31900 Kampar, Perak (Malaysia); Leong, Kah Hon [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Saravanan, Pichiah, E-mail: saravananpichiah@um.edu.my [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nanotechnology & Catalysis Research Center (NANOCAT), University of Malaya, 50603 Kuala Lumpur (Malaysia); Ibrahim, Shaliza [Environmental Engineering Laboratory, Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-12-15

    Graphical abstract: - Highlights: • Enhanced visible light character of TNTs was imparted by RGO/Pt via facile route. • Pt NPs contribute exemplary visible light harvesting nature through plasmon effect. • Engulfed RGO promoted enhanced charge-carriers separation. • Synergistic effect of RGO, Pt photoreduced CO{sub 2} to CH{sub 4} with max. of 10.96 μmol m{sup −2}. - Abstract: In this study, a complicate natural photosynthesis process was prototyped through a photocatalysis process by reducing CO{sub 2} to light hydrocarbon, CH{sub 4}. The composite photocatalyst employed for this study utilized Pt nanoparticles (Pt NPs) and rapid thermal reduced graphene oxide (RGO) deposited over the surface of the TiO{sub 2} nanotube arrays (TNTs). The existence and contribution of both Pt NPs and RGO in the composite was confirmed through various analytical techniques including XRD, HRTEM, FESEM, Raman, FTIR, XPS, UV-DRS and photoluminescence (PL) analysis. The TNTs in the composite exhibited pure anatase phase. The absorption bands at around 450 nm obtained from UV-DRS spectrum supported the existence of LSPR phenomenon of Pt NPs. The promising lower work function of RGO promoted the electrons transfer from TNTs to RGO efficiently. The successful depositions of Pt and RGO onto the surface of TNTs contributed for the improved photocatalytic activity (total CH{sub 4} yield of 10.96 μmol m{sup −2}) in the reduction of CO{sub 2} over TNTs and Pt–TNTs. Both of RGO and Pt NPs are equally important to exert a significant impact on the improvement of CH{sub 4} production rates.

  1. Rapid thermal reduced graphene oxide/Pt–TiO2 nanotube arrays for enhanced visible-light-driven photocatalytic reduction of CO2

    International Nuclear Information System (INIS)

    Sim, Lan Ching; Leong, Kah Hon; Saravanan, Pichiah; Ibrahim, Shaliza

    2015-01-01

    Graphical abstract: - Highlights: • Enhanced visible light character of TNTs was imparted by RGO/Pt via facile route. • Pt NPs contribute exemplary visible light harvesting nature through plasmon effect. • Engulfed RGO promoted enhanced charge-carriers separation. • Synergistic effect of RGO, Pt photoreduced CO 2 to CH 4 with max. of 10.96 μmol m −2 . - Abstract: In this study, a complicate natural photosynthesis process was prototyped through a photocatalysis process by reducing CO 2 to light hydrocarbon, CH 4 . The composite photocatalyst employed for this study utilized Pt nanoparticles (Pt NPs) and rapid thermal reduced graphene oxide (RGO) deposited over the surface of the TiO 2 nanotube arrays (TNTs). The existence and contribution of both Pt NPs and RGO in the composite was confirmed through various analytical techniques including XRD, HRTEM, FESEM, Raman, FTIR, XPS, UV-DRS and photoluminescence (PL) analysis. The TNTs in the composite exhibited pure anatase phase. The absorption bands at around 450 nm obtained from UV-DRS spectrum supported the existence of LSPR phenomenon of Pt NPs. The promising lower work function of RGO promoted the electrons transfer from TNTs to RGO efficiently. The successful depositions of Pt and RGO onto the surface of TNTs contributed for the improved photocatalytic activity (total CH 4 yield of 10.96 μmol m −2 ) in the reduction of CO 2 over TNTs and Pt–TNTs. Both of RGO and Pt NPs are equally important to exert a significant impact on the improvement of CH 4 production rates.

  2. Photocatalytic oxide films in the built environment

    Science.gov (United States)

    Österlund, Lars; Topalian, Zareh

    2014-11-01

    The possibility to increase human comfort in buildings is a powerful driving force for the introduction of new technology. Among other things our sense of comfort depends on air quality, temperature, lighting level, and the possibility of having visual contact between indoors and outdoors. Indeed there is an intimate connection between energy, comfort, and health issues in the built environment, leading to a need for intelligent building materials and green architecture. Photocatalytic materials can be applied as coatings, filters, and be embedded in building materials to provide self-cleaning, antibacterial, air cleaning, deodorizing, and water cleaning functions utilizing either solar light or artificial illumination sources - either already present in buildings, or by purposefully designed luminaries. Huge improvements in indoor comfort can thus be made, and also alleviate negative health effects associated with buildings, such as the sick-house syndrome. At the same time huge cost savings can be made by reducing maintenance costs. Photocatalytic oxides can be chemically modified by changing their acid-base surface properties, which can be used to overcome deactivation problems commonly encountered for TiO2 in air cleaning applications. In addition, the wetting properties of oxides can be tailored by surface chemical modifications and thus be made e.g. oleophobic and water repellent. Here we show results of surface acid modified TiO2 coatings on various substrates by means of photo-fixation of surface sulfate species by a method invented in our group. In particular, we show that such surface treatments of photocatalytic concrete made by mixing TiO2 nanoparticles in reactive concrete powders result in concrete surfaces with beneficial self-cleaning properties. We propose that such approaches are feasible for a number of applications in the built environment, including glass, tiles, sheet metals, plastics, etc.

  3. Photocatalytic oxide films in the built environment

    International Nuclear Information System (INIS)

    Österlund, Lars; Topalian, Zareh

    2014-01-01

    The possibility to increase human comfort in buildings is a powerful driving force for the introduction of new technology. Among other things our sense of comfort depends on air quality, temperature, lighting level, and the possibility of having visual contact between indoors and outdoors. Indeed there is an intimate connection between energy, comfort, and health issues in the built environment, leading to a need for intelligent building materials and green architecture. Photocatalytic materials can be applied as coatings, filters, and be embedded in building materials to provide self-cleaning, antibacterial, air cleaning, deodorizing, and water cleaning functions utilizing either solar light or artificial illumination sources – either already present in buildings, or by purposefully designed luminaries. Huge improvements in indoor comfort can thus be made, and also alleviate negative health effects associated with buildings, such as the sick-house syndrome. At the same time huge cost savings can be made by reducing maintenance costs. Photocatalytic oxides can be chemically modified by changing their acid-base surface properties, which can be used to overcome deactivation problems commonly encountered for TiO 2 in air cleaning applications. In addition, the wetting properties of oxides can be tailored by surface chemical modifications and thus be made e.g. oleophobic and water repellent. Here we show results of surface acid modified TiO 2 coatings on various substrates by means of photo-fixation of surface sulfate species by a method invented in our group. In particular, we show that such surface treatments of photocatalytic concrete made by mixing TiO 2 nanoparticles in reactive concrete powders result in concrete surfaces with beneficial self-cleaning properties. We propose that such approaches are feasible for a number of applications in the built environment, including glass, tiles, sheet metals, plastics, etc

  4. Novel magnetically separable AgCl/iron oxide composites with enhanced photocatalytic activity driven by visible light

    International Nuclear Information System (INIS)

    Zhang, Ying; Zhang, Yanrong; Tan, Jue

    2013-01-01

    Highlights: •The AgCl/iron oxide composites were prepared by a chemical precipitation method. •The composites exhibited improved performances in the photodegradation of pollutants. •The visible light photocatalysts could be recycled easily by a magnet. -- Abstract: In this work, AgCl/iron oxide composites were synthesized by a simple chemical precipitation method and calcining process. The composition of the material and magnetic and optical properties of the composites were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating specimen magnetometer (VSM) techniques, which confirms the high crystalline and magnetic behavior of the composites. UV-vis diffuse reflectance spectral (DRS) studies showed that the AgCl/iron oxide composites were of much higher absorption in longer wavelength region compared to bare iron oxide. The AgCl/iron oxide composites showed better performance in the photodegradation of organic dyes Rhodamin B (RhB) under the fluorescent lamp irradiation, which is remarkably superior to the N-TiO 2 . The degradation of microcystin-LR (MC-LR) and phenol was also found to be good owing to its effective electron-hole separation at AgCl/iron oxide interface. The separation of AgCl/iron oxide composites from the treated water was achieved by an external magnetic field as γ-Fe 2 O 3 exhibits enough magnetic power to facilitate the separation

  5. Enhanced photocatalytic degradation activity over TiO{sub 2} nanotubes co-sensitized by reduced graphene oxide and copper(II) meso-tetra(4-carboxyphenyl)porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Meng; Wan, Junmin, E-mail: wwjm2001@126.com; Hu, Zhiwen; Peng, Zhiqin; Wang, Bing

    2016-07-30

    Highlights: • CuTCPP/rGO-TNT photocatalysts are synthesized. • CuTCPP and rGO are helpful to induce interfacial charge transfer at surface junction. • CuTCPP and rGO are favorable for enhancing co-photocatalytic activity. • A deeper insight into the co-photocatalytic mechanism is put forward. • The photocatalyst are proven to be effective and chemically-stable catalysts. - Abstract: In this paper, TiO{sub 2} nanotubes (TNT) co-sensitized with copper(II) meso-tetra(4-carboxyphenyl)porphyrin (CuTCPP) and reduced graphene oxide nanosheets (rGO), which was fabricated through two-step improved hydrothermal method and heating reflux process. The effect of rGO and CuTCPP on the co-photocatalytic behavior of TNT for the degradation of Methylene Blue (MB) were measured under visible light irradiation. The photocatalysts have been characterized and analyzed by high-resolution transmission electron microscopy (TEM), selected area electronic diffraction (SAED), elemental mapping by energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and electron paramagnetic resonance (EPR). The results provide a deeper insight into the co-photocatalytic mechanism of CuTCPP/rGO-TNT nanocomposites. The degradation results showed a purification of more than 95% MB in wastewater, which is about 5 times higher than that of the pure TNT. The results also confirm the prepared CuTCPP/rGO-TNT nanocomposites possess superior co-photocatalytic activities.

  6. Synthesis, characterization and enhanced photocatalytic activity of iron oxide/carbon nanotube/Ag-doped TiO{sub 2} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Marques Neto, José O.; Bellato, Carlos R.; Souza, Carlos H.F. de; Silva, Renê C. da; Rocha, Pablo A., E-mail: bellato@ufv.br [Universidade Federal de Viçosa (UFV), MG (Brazil)

    2017-07-01

    A novel magnetically recoverable catalyst (Fe/MWCNT/TiO{sub 2}-Ag) was prepared in this study by a process that involves few steps. Titanium dioxide doped with silver and iron oxide was deposited on support of multi-walled carbon nanotubes (MWCNT). The synthesized catalysts were characterized by inductively coupled plasma mass spectrometry (ICP-MS), N{sub 2} adsorption/desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), infrared spectroscopy (IR) and UV-Vis diffuse reflectance spectra (DRS). Phenol in aqueous solution (50 mg L{sup -1}) was used as a model compound for evaluation of UV-Vis (filter cut off for λ > 300 nm) photocatalytic activity. The composite catalyst has a high photocatalytic activity, destroying ca. 100% of phenol and removing 85% of total organic carbon in an aqueous solution after 180 min. The Fe/MWCNT/TiO{sub 2}-Ag catalyst remained stable, presenting an 8% decrease in phenol degradation efficiency after ten consecutive photocatalytic cycles. (author)

  7. Sol-gel synthesis of Bi2WO6/graphene thin films with enhanced photocatalytic performance for nitric monoxide oxidation under visible light irradiation

    Science.gov (United States)

    Sun, Chufeng; Wang, Yanbin; Su, Qiong

    2018-06-01

    Bi2WO6 and Bi2WO6/graphene thin films were fabricated by spin coating and post annealing at 600 °C for 2 h. In four different thin film samples, the graphene concentration was controlled as 0, 2, 4 and 6 wt%, respectively. The morphology, grain size and elemental distribution of the thin films were characterized by SEM and TEM. The crystallization and crystal phases were determined by XRD patterns, and the existence of graphene in Bi2WO6/graphene composite thin films were confirmed by Raman spectra. The photocatalytic performance of Bi2WO6 and Bi2WO6/graphene thin films was investigated by oxidizing NO under visible light irradiation. The results showed that Bi2WO6/graphene with 4 wt% of graphene showed the highest photocatalytic performance among all samples. This could be attributed to the increased electron conductivity with the presence of graphene. However, a further increased graphene concentration resulted in a decreased photocatalytic performance.

  8. Effect of different processes and Ti/Zn molar ratios on the structure, morphology, and enhanced photoelectrochemical and photocatalytic performance of Ti3+ self-doped titanium-zinc hybrid oxides

    Science.gov (United States)

    Fu, Rongrong; Wang, Qingyao; Gao, Shanmin; Wang, Zeyan; Huang, Baibiao; Dai, Ying; Lu, Jun

    2015-07-01

    Ti3+ self-doped titanium-zinc hybrid oxides with different phase compositions and morphologies were successfully synthesized using Zn powder as the reductant and Zn source by a chemical-reduction precipitation method with subsequent thermal treatment. The fabricated Ti3+ self-doped TiO2(A)/TiO2(R), TiO2(A)/TiO2(R)/ZnTiO3, and TiO2(A)/ZnO heterojunctions were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The effects of various Ti/Zn molar ratios and preparation processes on the structural, morphological, optical, photocurrent and photocatalytic properties of the resultant samples were investigated systematically. Results reveal that Ti3+ self-doping enhances the photoabsorption capability of titanium-zinc hybrid oxides in the visible-light region. Moreover, different processes and Ti/Zn molar ratios play great influences on the structure, morphology, optical, photocurrent and photocatalytic properties of the final products. Ti3+ self-doped titanium-zinc hybrid oxides exhibit excellent photocurrent and photocatalytic activity than pure TiO2 and ZnTiO3 under visible-light irradiation (λ ≥ 400 nm). The most active Ti3+ self-doped titanium-zinc hybrid oxides photoanode presents significantly improved water splitting performance. The synergistic effect between the Ti3+ self-doped and heterojunctions is responsible for the enhanced performance of these materials.

  9. Oxidative esterification via photocatalytic C-H activation

    Data.gov (United States)

    U.S. Environmental Protection Agency — Direct oxidative esterification of alcohol via photocatalytic C–H activation has been developed using VO@g-C3N4 catalyst; an expeditious esterification of alcohols...

  10. Enhancing ethylbenzene vapors degradation in a hybrid system based on photocatalytic oxidation UV/TiO2–In and a biofiltration process

    International Nuclear Information System (INIS)

    Hinojosa-Reyes, M.; Rodríguez-González, V.; Arriaga, S.

    2012-01-01

    Highlights: ► The best photocatalytic system for EB degradation was based on TiO 2 –In 1%/365 nm. ► A maximum EC of 290 g m −3 h −1 for the hybrid system was obtained. ► The hybrid process enhanced 40% the overall EC of ethylbenzene. ► An overall mineralization of 67% for EB degradation was reached in the hybrid system. - Abstract: The use of hybrid processes for the continuous degradation of ethylbenzene (EB) vapors has been evaluated. The hybrid system consists of an UV/TiO 2 –In photooxidation coupled with a biofiltration process. Both the photocatalytic system using P25-Degussa or indium-doped TiO 2 catalysts and the photolytic process were performed at UV-wavelengths of 254 nm and 365 nm. The experiments were carried out in an annular plug flow photoreactor packed with granular perlite previously impregnated with the catalysts, and in a glass biofilter packed with perlite and inoculated with a microbial consortium. Both reactors were operated at an inlet loading rate of 127 g m −3 h −1 . The greatest degradation rate of EB (0.414 ng m −2 min −1 ) was obtained with the TiO 2 –In 1%/365 nm photocatalytic system. The elimination capacity (EC) obtained in the control biofilter had values ∼60 g m −3 h −1 . Consequently, the coupled system was operated for 15 days, and a maximal EC of 275 g m −3 h −1 . Thus, the results indicate that the use of hybrid processes enhanced the EB vapor degradation and that this could be a promising technology for the abatement of recalcitrant volatile organic compounds.

  11. Enhancing ethylbenzene vapors degradation in a hybrid system based on photocatalytic oxidation UV/TiO{sub 2}-In and a biofiltration process

    Energy Technology Data Exchange (ETDEWEB)

    Hinojosa-Reyes, M. [Instituto Potosino de Investigacion Cientifica y Tecnologica A.C., Division de Ciencias Ambientales, Camino a la Presa San Jose 2055, Lomas 4a seccion, CP. 78216, San Luis Potosi, S.L.P. (Mexico); Rodriguez-Gonzalez, V. [Instituto Potosino de Investigacion Cientifica y Tecnologica A.C., Division de Materiales Avanzados, Camino a la Presa San Jose 2055, Lomas 4a seccion, CP. 78216, San Luis Potosi, S.L.P. (Mexico); Arriaga, S., E-mail: sonia@ipicyt.edu.mx [Instituto Potosino de Investigacion Cientifica y Tecnologica A.C., Division de Ciencias Ambientales, Camino a la Presa San Jose 2055, Lomas 4a seccion, CP. 78216, San Luis Potosi, S.L.P. (Mexico)

    2012-03-30

    Highlights: Black-Right-Pointing-Pointer The best photocatalytic system for EB degradation was based on TiO{sub 2}-In 1%/365 nm. Black-Right-Pointing-Pointer A maximum EC of 290 g m{sup -3} h{sup -1} for the hybrid system was obtained. Black-Right-Pointing-Pointer The hybrid process enhanced 40% the overall EC of ethylbenzene. Black-Right-Pointing-Pointer An overall mineralization of 67% for EB degradation was reached in the hybrid system. - Abstract: The use of hybrid processes for the continuous degradation of ethylbenzene (EB) vapors has been evaluated. The hybrid system consists of an UV/TiO{sub 2}-In photooxidation coupled with a biofiltration process. Both the photocatalytic system using P25-Degussa or indium-doped TiO{sub 2} catalysts and the photolytic process were performed at UV-wavelengths of 254 nm and 365 nm. The experiments were carried out in an annular plug flow photoreactor packed with granular perlite previously impregnated with the catalysts, and in a glass biofilter packed with perlite and inoculated with a microbial consortium. Both reactors were operated at an inlet loading rate of 127 g m{sup -3} h{sup -1}. The greatest degradation rate of EB (0.414 ng m{sup -2} min{sup -1}) was obtained with the TiO{sub 2}-In 1%/365 nm photocatalytic system. The elimination capacity (EC) obtained in the control biofilter had values {approx}60 g m{sup -3} h{sup -1}. Consequently, the coupled system was operated for 15 days, and a maximal EC of 275 g m{sup -3} h{sup -1}. Thus, the results indicate that the use of hybrid processes enhanced the EB vapor degradation and that this could be a promising technology for the abatement of recalcitrant volatile organic compounds.

  12. Photocatalytic Water Oxidation on ZnO: A Review

    Directory of Open Access Journals (Sweden)

    Sharifah Bee Abdul Hamid

    2017-03-01

    Full Text Available The investigation of the water oxidation mechanism on photocatalytic semiconductor surfaces has gained much attention for its potential to unlock the technological limitations of producing H2 from carbon-free sources, i.e., H2O. This review seeks to highlight the available scientific and fundamental understanding towards the water oxidation mechanism on ZnO surfaces, as well as present a summary on the modification strategies carried out to increase the photocatalytic response of ZnO.

  13. Reduced graphene oxide is not a universal promoter for photocatalytic activities of TiO2

    Directory of Open Access Journals (Sweden)

    Hui Ling Tan

    2017-03-01

    Full Text Available Addition of reduced graphene oxide (RGO to P25 TiO2 was made and its impacts on photocatalytic oxidation of various organic substances were studied. Although the presence of RGO in TiO2 can enhance certain TiO2-based photocatalytic reactions, it is not a universal observation that can be expected in all types of organic substances. The factor of photocatalytic activity enhancement is strongly affected by the various functional groups appeared in the organic substances. In this work, it is realised that the length of alkyl chain in alcohols and carboxylic acids have the minimum influence on the overall activity while the number of hydroxyl groups can promote the further activity enhancement in the presence of RGO.

  14. Photocatalytic properties of chemically grown vanadium oxide at 65 °C

    Energy Technology Data Exchange (ETDEWEB)

    Vernardou, D., E-mail: dimitra@iesl.forth.gr [Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Science Department, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Drosos, H.; Fasoulas, J. [Mechanical Engineering Department, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Koudoumas, E. [Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Electrical Engineering Department, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Katsarakis, N. [Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Science Department, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research and Technology—Hellas, P.O. Box 1527, Vassilika Vouton, 711 10 Heraklion, Crete (Greece)

    2014-03-31

    In this paper, the photocatalytic response of amorphous V{sub 2}O{sub 5} coatings prepared by hydrothermal growth at 65 °C is presented. The position of the substrate during the deposition and the pH of the solution were found to affect the coverage and the response of the coatings upon catalysis. The photocatalytic activity of the coatings was tested using stearic acid as a pollutant for an illumination time of 480 min. The materials grown on microscope glass positioned at an angle of 0° with respect to the bottom of the bottle exhibit the best photocatalytic activity, degrading stearic acid by 64% due to the enhanced surface coverage. - Highlights: • Hydrothermally grown amorphous V{sub 2}O{sub 5} coatings at 65 °C • Their properties are dependent on the substrate arrangement. • Their photocatalytic activity is correlated with the oxide coverage.

  15. Photocatalytic properties of chemically grown vanadium oxide at 65 °C

    International Nuclear Information System (INIS)

    Vernardou, D.; Drosos, H.; Fasoulas, J.; Koudoumas, E.; Katsarakis, N.

    2014-01-01

    In this paper, the photocatalytic response of amorphous V 2 O 5 coatings prepared by hydrothermal growth at 65 °C is presented. The position of the substrate during the deposition and the pH of the solution were found to affect the coverage and the response of the coatings upon catalysis. The photocatalytic activity of the coatings was tested using stearic acid as a pollutant for an illumination time of 480 min. The materials grown on microscope glass positioned at an angle of 0° with respect to the bottom of the bottle exhibit the best photocatalytic activity, degrading stearic acid by 64% due to the enhanced surface coverage. - Highlights: • Hydrothermally grown amorphous V 2 O 5 coatings at 65 °C • Their properties are dependent on the substrate arrangement. • Their photocatalytic activity is correlated with the oxide coverage

  16. Comparison of modification strategies towards enhanced charge carrier separation and photocatalytic degradation activity of metal oxide semiconductors (TiO2, WO3 and ZnO)

    Science.gov (United States)

    Kumar, S. Girish; Rao, K. S. R. Koteswara

    2017-01-01

    Metal oxide semiconductors (TiO2, WO3 and ZnO) finds unparalleled opportunity in wastewater purification under UV/visible light, largely encouraged by their divergent admirable features like stability, non-toxicity, ease of preparation, suitable band edge positions and facile generation of active oxygen species in the aqueous medium. However, the perennial failings of these photocatalysts emanates from the stumbling blocks like rapid charge carrier recombination and meager visible light response. In this review, tailoring the surface-bulk electronic structure through the calibrated and veritable approaches such as impurity doping, deposition with noble metals, sensitizing with other compounds (dyes, polymers, inorganic complexes and simple chelating ligands), hydrogenation process (annealing under hydrogen atmosphere), electronic integration with other semiconductors, modifying with carbon nanostructures, designing with exposed facets and tailoring with hierarchical morphologies to overcome their critical drawbacks are summarized. Taking into account the materials intrinsic properties, the pros and cons together with similarities and striking differences for each strategy in specific to TiO2, WO3 & ZnO are highlighted. These subtlety enunciates the primacy for improving the structure-electronic properties of metal oxides and credence to its fore in the practical applications. Future research must focus on comparing the performances of ZnO, TiO2 and WO3 in parallel to get insight into their photocatalytic behaviors. Such comparisons not only reveal the changed surface-electronic structure upon various modifications, but also shed light on charge carrier dynamics, free radical generation, structural stability and compatibility for photocatalytic reactions. It is envisioned that these cardinal tactics have profound implications and can be replicated to other semiconductor photocatalysts like CeO2, In2O3, Bi2O3, Fe2O3, BiVO4, AgX, BiOX (X = Cl, Br & I), Bi2WO6, Bi2MoO6

  17. Porous-ZnO-Nanobelt Film as Recyclable Photocatalysts with Enhanced Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Wang Min

    2010-01-01

    Full Text Available Abstract In this article, the porous-ZnO-nanobelt film was synthesized by oxidizing the ZnSe-nanobelt film in air. The experiment results show that the porous-ZnO-nanobelt film possesses enhanced photocatalytic activity compared with the ZnO-nanobelt film, and can be used as recyclable photocatalysts. The enhanced photocatalytic activity of the porous-ZnO-nanobelt film is attributed to the increased surface area. Therefore, turning the 1D-nanostructure film into porous one may be a feasible approach to meet the demand of photocatalyst application.

  18. Solar Light Responsive Photocatalytic Activity of Reduced Graphene Oxide-Zinc Selenide Nanocomposite

    Science.gov (United States)

    Chakraborty, Koushik; Ibrahim, Sk; Das, Poulomi; Ghosh, Surajit; Pal, Tanusri

    2017-10-01

    Solution processable reduced graphene oxide-zinc selenide (RGO-ZnSe) nanocomposite has been successfully synthesized by an easy one-pot single-step solvothermal reaction. The RGO-ZnSe composite was characterized structurally and morphologically by the study of XRD analysis, SEM and TEM imaging. Reduction in graphene oxide was confirmed by FTIR spectroscopy analysis. Photocatalytic efficiency of RGO-ZnSe composite was investigated toward the degradation of Rhodamine B under solar light irradiation. Our study indicates that the RGO-ZnSe composite is catalytically more active compared to the controlled-ZnSe under the solar light illumination. Here, RGO plays an important role for photoinduced charge separation and subsequently hinders the electron-hole recombination probability that consequently enhances photocatalytic degradation efficiency. We expect that this type of RGO-based optoelectronics materials opens up a new avenue in the field of photocatalytic degradation of different organic water pollutants.

  19. Synthesis of graphene oxide-copper molybdate (GO-CuM) nanocomposites for photocatalytic application

    Science.gov (United States)

    Singh, Gajendar; Bhargava, V. Sai; Sharma, Manu

    2018-05-01

    Transition metal molybdates (TMBs) MMoO4 (M=Ni, Cu, Fe, Zn, Co, etc.) based nanocomposites have been considered as remarkable materials in the field of electronics, optics, catalysis, supercapicitors and energy storage devices. Nanocomposites of TMBs with graphene oxide have also been chosen as an effective material in photocatalytic application. GO-CuM nanocomposites were synthesized by ultra-sonication method at RT, followed by reflux route for preparation of CuM and GO by modified Hemmer's method. As prepared nanocomposites were characterized using analytical techniques such as PXRD, SEM, FT-IR and UV-Visible spectroscopy. The enhanced photocatalytic activity of Methylene blue (MB) dye was observed by GO-CuM nanocomposites as compared to pure copper molybdate. GO-CuM nanocomposites show high photodegradation rate (0.094 min-1) whereas CuM was degraded only 30 % with the rate of 0.0029 min-1. The high photocatalytic efficiency is due to the presence of graphene oxide that helps to delay the charge recombination in photocatalytic reaction The effect of the different amount of graphene oxide on the photocatalytic activity of as prepared photocatalyst has also been investigated.

  20. Continuous photocatalytic fuel production over wide-bandgap metal oxides

    OpenAIRE

    Bazzo, Antonio

    2014-01-01

    Artificial photosynthesis has been proposed as one of the possible solutions to the energetic and chemical-feedstock problems to cope with the anticipated near future depletion of fossil fuel resources. This doctoral thesis deals with the study of promising catalysts and reactor designs to enhance the reaction efficiency and understand the origin of photocatalytic activity. A continuous flow reaction system was designed and constructed to study CO2 photoreduction with H2O and photocatalytic w...

  1. Effects of electromechanical resonance on photocatalytic reduction of the free-hanging graphene oxide sheets

    International Nuclear Information System (INIS)

    Ostovari, F.; Abdi, Y.; Darbari, S.; Ghasemi, F.

    2013-01-01

    In this report we present a simple, low-temperature method which is compatible with standard technology, to achieve graphene-based devices in large quantity. In this approach we take advantage of photocatalytic behavior of TiO 2 to achieve photocatalytic reduction of chemically synthesized graphene oxide (GO) sheets. TiO 2 nanoparticles have been deposited on GO sheets hanging from Au/SiO 2 /Si interdigital electrodes to realize TiO 2 /GO heterostructures. We investigated photocatalytic activity of TiO 2 nanoparticles in the presence of UV-illumination, to reduce the GO sheets. Based on the Raman spectroscopy, the photocatalytic activity of TiO 2 nanoparticles resulted in a decrease in the number of C–O bonds. Electrical measurements show that graphene sheets with the controlled electrical conductivity were obtained, so that higher illumination time led to higher conductivity and better reduction of GO sheets. Also, strain-induced photocatalytic reduction of the GO sheets has been investigated by their electrical characteristics. It has been shown for the first time that the electromechanical-induced strain enhances the photocatalytic behavior of the fabricated TiO 2 /GO heterostructure significantly.

  2. Effects of electromechanical resonance on photocatalytic reduction of the free-hanging graphene oxide sheets

    Energy Technology Data Exchange (ETDEWEB)

    Ostovari, F.; Abdi, Y., E-mail: y.abdi@ut.ac.ir [University of Tehran, Nano-Physics Research Laboratory, Department of Physics (Iran, Islamic Republic of); Darbari, S. [Tarbiat Modarres University (Iran, Islamic Republic of); Ghasemi, F. [University of Tehran, Nano-Physics Research Laboratory, Department of Physics (Iran, Islamic Republic of)

    2013-04-15

    In this report we present a simple, low-temperature method which is compatible with standard technology, to achieve graphene-based devices in large quantity. In this approach we take advantage of photocatalytic behavior of TiO{sub 2} to achieve photocatalytic reduction of chemically synthesized graphene oxide (GO) sheets. TiO{sub 2} nanoparticles have been deposited on GO sheets hanging from Au/SiO{sub 2}/Si interdigital electrodes to realize TiO{sub 2}/GO heterostructures. We investigated photocatalytic activity of TiO{sub 2} nanoparticles in the presence of UV-illumination, to reduce the GO sheets. Based on the Raman spectroscopy, the photocatalytic activity of TiO{sub 2} nanoparticles resulted in a decrease in the number of C-O bonds. Electrical measurements show that graphene sheets with the controlled electrical conductivity were obtained, so that higher illumination time led to higher conductivity and better reduction of GO sheets. Also, strain-induced photocatalytic reduction of the GO sheets has been investigated by their electrical characteristics. It has been shown for the first time that the electromechanical-induced strain enhances the photocatalytic behavior of the fabricated TiO{sub 2}/GO heterostructure significantly.

  3. Enhancement of visible light irradiation photocatalytic activity of ...

    Indian Academy of Sciences (India)

    Mohamed Abdel Salam

    2017-09-25

    Sep 25, 2017 ... Pt/SrTiO3 nanoparticles for the photocatalytic oxidation of cyclohexane was examined and the results ... Oil and natural gas contain many different compounds .... photoreactor was used. ... doping SrTiO3nanoparticles with Pt do not significantly .... Liu S, Liu Z and Kawi S 1998 Liquid-phase oxidation.

  4. In situ grown hierarchical 50%BiOCl/BiOI hollow flowerlike microspheres on reduced graphene oxide nanosheets for enhanced visible-light photocatalytic degradation of rhodamine B

    Science.gov (United States)

    Su, Xiangde; Yang, Jinjin; Yu, Xiang; Zhu, Yi; Zhang, Yuanming

    2018-03-01

    50%BiOCl/BiOI/reduced graphene oxide (50%BiOCl/BiOI/rGO) composite photocatalyst was synthesized successfully by a facile one-step solvothermal route in this work. Reduction of graphene oxide (GO) took place in the process of solvothermal reaction and a new Bi-C bond between rGO and 50%BiOCl/BiOI was formed. The introduction of rGO affected the morphology of 50%BiOCl/BiOI, resulting in the transformation of 50%BiOCl/BiOI from solid microspheres to hollow microspheres. Both the introduction of rGO and formation of 50%BiOCl/BiOI hollow microspheres can facilitate the light absorption. The strong interaction between 50%BiOCl/BiOI and rGO and the electrical conductivity of rGO greatly improved the effective separation of photogenerated carriers. Hence, GOB-5 demonstrated the highest photocatalytic activity which was over twice of the pristine 50%BiOCl/BiOI in the presence of visible light. Mechanism study revealed that 50%BiOCl/BiOI generated electrons and holes in the presence of visible light, and holes together with rad O2- generated from reduction of O2 by electrons degraded the pollutant directly. Overall, this work provides an excellent reference to the synthesis of chemically bonded BiOX/BiOY (X, Y = Cl, Br, I)/rGO nanocomposite and helps to promote their applications in environmental protection and photoelectric conversion.

  5. Advanced oxidation technologies : photocatalytic treatment of wastewater

    NARCIS (Netherlands)

    Chen, J.

    1997-01-01

    7.1. Summary and conclusions

    The last two decennia have shown a growing interest in the photocatalytic treatment of wastewater, and more and more research has been carried out into the various aspects of photocatalysis, varying from highly fundamental aspects to practical application.

  6. Employing RADIANCE to refine indoor photocatalytic oxidation modeling

    NARCIS (Netherlands)

    Pelzers, R.S.; Yu, Q.; Mangkuto, R.A.; Brouwers, H.J.H.

    2013-01-01

    Indoor air quality (IAQ) gained great attention in the last years as one of the foremost environmental concerns and it is therefore imperative that effective methods are developed to conserve IAQ. Currently, the novel technology photocatalytic oxidation (PCO) is a potential alternative. A

  7. Room temperature synthesis and enhanced photocatalytic property of CeO2/ZnO heterostructures

    Science.gov (United States)

    Wang, Chao; Fan, Huiqing; Ren, Xiaohu; Fang, Jiawen

    2018-02-01

    To achieve better photocatalytic performance, we proposed a facile solid-state reaction method to produce CeO2/ZnO heterostructures. Ceria and zinc oxide were synthesized simultaneously by thoroughly grinding the mixture of zinc acetate dihydrate, cerium nitrate hexahydrate and sodium hydroxide. The morphology of the as-prepared heterostructures varies dramatically as different amount of ceria was introduced in the composition. The photocatalytic performance of CeO2/ZnO heterojunctions was 4.6 times higher than that of pure ZnO. The enhanced photocatalytic activity could be ascribed to that more electrons and holes could transport to the surface of catalysts and react with the pollution due to the extended light-responsive range, accelerated migration, increased specific surface area and suppressed recombination of photogenerated carriers.

  8. Photoluminescence quenching and photocatalytic enhancement of ...

    Indian Academy of Sciences (India)

    2017-11-28

    Nov 28, 2017 ... This work reports the synthesis of novel praseodymium (Pr)-doped ZnO nanocrystals with excellent ... nificant role in the field of solar cells, luminescence, electrical, ..... 5.1 Photocatalytic activity mechanism in Pr-doped ZnO.

  9. Reduced graphene oxide enwrapped pinecone-liked Ag{sub 3}PO{sub 4}/TiO{sub 2} composites with enhanced photocatalytic activity and stability under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ni; Qiu, Yiwei; Zhang, Yichao; Liu, Hanyang; Yang, Yana; Wang, Jingwei; Li, Xiaoyun; Cui, Can, E-mail: cancui@zstu.edu.cn

    2015-11-05

    Ag{sub 3}PO{sub 4} possesses high photocatalytic activity under visible light, but its application is limited by photogenerated charges recombination, photocorrosion as well as consumption of noble Ag. It is of great interesting to develop new Ag{sub 3}PO{sub 4}-based photocatalysts with high charges separation efficiency, good stability and low content of Ag. In this paper, we report a novel Ag{sub 3}PO{sub 4}/TiO{sub 2}/reduced graphene oxide (Ag{sub 3}PO{sub 4}/TiO{sub 2}/rGO) photocatalyst. It exhibits advantages on both the microstructure and the charges separation. The microstructure shows that TiO{sub 2} spheres of hundreds of nanometers in size are decorated with dense nano-sized Ag{sub 3}PO{sub 4} to form pinecone-liked particles, which are enwrapped by rGO sheets. This novel structure effectively prevents aggregation of nano-sized Ag{sub 3}PO{sub 4}, which not only suppresses the charges recombination in Ag{sub 3}PO{sub 4} but also significantly reduces the content of Ag. Ag{sub 3}PO{sub 4}/TiO{sub 2}/rGO also favors separation of photogenerated charges owing to its two pathways for charges transportation, i.e., the electrons in Ag{sub 3}PO{sub 4} can be transferred to rGO, while the holes in Ag{sub 3}PO{sub 4} can be transferred to TiO{sub 2}. The dual-pathway for charges separation as well as the pinecone-liked Ag{sub 3}PO{sub 4}/TiO{sub 2} microstructure ultimately leads to enhanced photocatalytic activity and stability of Ag{sub 3}PO{sub 4}/TiO{sub 2}/rGO. The photocatalytic performance varies with different contents of Ag{sub 3}PO{sub 4} in the composites, because low content of Ag{sub 3}PO{sub 4} induces weak light absorption while excess Ag{sub 3}PO{sub 4} results in serious charges recombination due to the aggregation of Ag{sub 3}PO{sub 4} nanoparticles. In this work, Ag{sub 3}PO{sub 4}/TiO{sub 2}/rGO with weight ratio of Ag{sub 3}PO{sub 4} against TiO{sub 2}/rGO equals to 0.6 exhibits the highest photocatalytic activity. The percentage of Ag in

  10. Enhanced photocatalytic properties in well-ordered mesoporous WO3

    KAUST Repository

    Li, Li; Krissanasaeranee, Methira; Pattinson, Sebastian W.; Stefik, Morgan; Wiesner, Ulrich; Steiner, Ullrich; Eder, Dominik

    2010-01-01

    We used polyisoprene-block-ethyleneoxide copolymers as structure-directing agents to synthesise well-ordered and highly-crystalline mesoporous WO 3 architectures that possess improved photocatalytic properties due to enhanced dye-adsorption in absence of diffusion limitation. © 2010 The Royal Society of Chemistry.

  11. Photochemical removal of aniline in aqueous solutions: switching from photocatalytic degradation to photo-enhanced polymerization recovery.

    Science.gov (United States)

    Tang, Heqing; Li, Jing; Bie, Yeqiang; Zhu, Lihua; Zou, Jing

    2010-03-15

    Organic pollutants may be treated by either a degradation process or a recovery process in the view point of sustainable chemistry. Photocatalytic removal of aniline was investigated in aqueous solutions. It was found that the photocatalytic oxidation of aniline resulted in its degradation or polymerization, depending on its concentration. Hence a new treatment strategy was proposed in combination of photocatalytic degradation and polymerization, where the polymerization was in fact a recovery process. When aniline concentration was as low as 0.1 mmol L(-1), it was possible to photocatalytically degrade aniline, which could be further enhanced by increasing solution pH, modifying TiO(2) surface with the addition of anions, or coupling with the photoreduction of added oxidants. When aniline concentration was increased to about 1 mmol L(-1), the photocatalytic oxidation was observed to yield the polymerization of aniline, leading to nanocomposites of polyaniline (PAN) and TiO(2). Alternatively, the photo-enhanced chemical polymerization of aniline at higher concentrations (>or=50 mmol L(-1)) in the presence of chemical oxidants produced PAN nanostructures. The conversion of pollutant aniline to valuable PAN nanostructures or nano-PAN/TiO(2) composites is suggestive for possible applications in the treatment of aniline wastewaters as a sustainable environmental protection measure. (c) 2009 Elsevier B.V. All rights reserved.

  12. Photocatalytic selective oxidation of phenol in suspensions of titanium dioxide with exposed {0 0 1} facets

    International Nuclear Information System (INIS)

    Ye, Hengpeng; Lu, Shaoming

    2013-01-01

    Anatase TiO 2 nanocrystals with exposed {0 0 1} facets were tailored by hydrothermal treatment of Ti(OC 4 H 9 ) 4 –HF–H 2 O mixed solution. The photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption isotherms and X-ray photoelectron spectroscopy (XPS). The effect of structure of the photocatalyst on the photocatalytic selective oxidation of phenol under UV irradiation was studied. The experiment results showed that (1) the percentage of the exposed {0 0 1} facets of the nanocrystal increases with increasing the nominal atomic ratio of fluorine to titanium (R F ), (2) catechol and hydroquinone are main intermediates detected during photocatalytic oxidation of phenol, and (3) both photocatalytic oxidation of phenol and selectivity (yield) of catechol are positively correlated with the percentage of exposed {0 0 1} facets of the high-energy TiO 2 nanocrystals. The enhanced conversion of phenol and selectivity (yield) of catechol were ascribed to the synergistic effects of the exposed high-energy {0 0 1} facets and surface fluorination. This study may provide new insight into the selective oxidation of organics.

  13. Visible-light photocatalytic activity of graphene oxide-wrapped Bi2WO6 hierarchical microspheres

    Science.gov (United States)

    Zhai, Jiali; Yu, Hongwen; Li, Haiyan; Sun, Lei; Zhang, Kexin; Yang, Hongjun

    2015-07-01

    A facile approach of fabricating homogeneous graphene oxide (GO)-wrapped Bi2WO6 microspheres (GO/Bi2WO6) is developed. The transmission electron microscopy (TEM) results show that a heterojunction interface between GO and Bi2WO6. The UV-vis diffuse reflection spectra (DRS) reveal that the as-prepared GO/Bi2WO6 composites own more intensive absorption in the visible light range compared with pure Bi2WO6. These characteristic structural and optical properties endow GO/Bi2WO6 composites with enhanced photocatalytic activity. The enhanced photocatalytic activity of the GO/Bi2WO6 is attributed predominantly to the synergetic effect between GO and Bi2WO6, causing rapid generation and separation of photo-generated charge carriers.

  14. Fabrication of a PANI/CPs composite material: a feasible method to enhance the photocatalytic activity of coordination polymers.

    Science.gov (United States)

    Xu, Xin-Xin; Cui, Zhong-Ping; Qi, Ji; Liu, Xiao-Xia

    2013-03-21

    To improve the photocatalytic activity of a coordination polymer in the visible light region, polyaniline (PANI) was loaded onto its surface through a facile in situ chemical oxidation polymerization process. The resulting PANI loaded coordination polymer composite materials with excellent stability exhibit significantly higher photocatalytic activities than the pure coordination polymer photocatalyst on the degradation of methyl orange (MO) under visible light irradiation. This enhancement can be ascribed to the introduction of PANI on the surface of the coordination polymer, which leads to efficient separation of photogenerated electron-hole pairs as well as a significant expansion of the photoresponse region. Finally, we discussed the influence of acidity on the morphology and photocatalytic activity of the composite material. An optimal condition to obtain the PANI loaded coordination polymer composite material with excellent photocatalytic activity has been obtained.

  15. TiO₂-Based Photocatalytic Geopolymers for Nitric Oxide Degradation.

    Science.gov (United States)

    Strini, Alberto; Roviello, Giuseppina; Ricciotti, Laura; Ferone, Claudio; Messina, Francesco; Schiavi, Luca; Corsaro, Davide; Cioffi, Raffaele

    2016-06-24

    This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin), composite systems (siloxane-hybrid, foamed hybrid), and curing temperatures (room temperature and 60 °C) were investigated for the same photocatalyst content (i.e., 3% TiO₂ by weight of paste). The geopolymer matrices were previously designed for different applications, ranging from insulating (foam) to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features.

  16. Photocatalytic Oxidation of a Volatile Organic Component of Acetaldehyde Using Titanium Oxide Nanotubes

    Directory of Open Access Journals (Sweden)

    Yifeng Wang

    2007-01-01

    Full Text Available Titanium oxide nanotubes are prepared and treated with Au (Au/nanotube sample and Pt (Pt/nanotube sample, and the photoactivity of these catalysts compared to a standard Degussa P25 photocatalyst is investigated. The samples were analyzed using X-ray diffraction, field emission gun scanning transmission electron microscopy (STEM. Both high-resolution TEM images and high-angle annular dark-field (HAAD images were recorded for the specimens. Oxidation of acetaldehyde was used to test the efficiency of the catalysts. Nanotube samples showed better photoactivity than the standard P25, because the P25 titania deactivates quickly. Enhanced reactivity of the nanotube is related to surface charge polarity developed on outer and inner surfaces due to the difference in overlap of oxygen anions that resulted from curving of octahedral sheets. A tentative and qualitative surface polarity model is proposed for enhancing electron-hole pair separation. The inner surface benefits reduction; whereas, the outer surface benefits oxidation reactions. Both the metal identity and the size of the metal particles in the nanotubes affected the photocatalytic activity. Specifically, the addition of platinum increased the activity significantly, and increased the total yield. The addition of gold had lesser impact compared to the platinum. Formation of Pt large nanoparticles on the nanotube surfaces reduces the oxidation reactivity.

  17. Composite TiO2/clays materials for photocatalytic NOx oxidation

    Science.gov (United States)

    Todorova, N.; Giannakopoulou, T.; Karapati, S.; Petridis, D.; Vaimakis, T.; Trapalis, C.

    2014-11-01

    TiO2 photocatalyst received much attention for air purification applications especially for removal of air pollutants like NOx, VOCs etc. It has been established that the activity of the photocatalyst can be significantly enhanced by its immobilization onto suitable substrates like inorganic minerals, porous silica, hydroxyapatite, adsorbent materials like activated carbon, various co-catalysts such as semiconductors, graphene, reduced graphite oxide, etc. In the present work, photocatalytic composite materials consisted of mineral substrate and TiO2 in weight ratio 1:1 were manufactured and examined for oxidation and removal of nitric oxides NOx (NO and NO2). Commercial titania P25 (Evonik-Degussa) and urea-modified P25 were used as photocatalytically active components. Inorganic minerals, namely kunipia, talk and hydrotalcite were selected as supporting materials due to their layered structure and expected high NOx adsorption capability. Al3+ and Ca2+ intercalation was applied in order to improve the dispersion of TiO2 and its loading into the supporting matrix. The X-ray diffraction analysis and Scanning Electron Microscopy revealed the binary structure of the composites and homogeneous dispersion of the photocatalyst into the substrates. The photocatalytic behavior of the materials in NOx oxidation and removal was investigated under UV and visible light irradiation. The composite materials exhibited superior photocatalytic activity than the bare titania under both types of irradiation. Significant visible light activity was recorded for the composites containing urea-modified titania that was accredited to the N-doping of the semiconductor. Among the different substrates, the hydrotalcite caused highest increase in the NOx removal, while among the intercalation ions the Ca2+ was more efficient. The results were related to the improved dispersion of the TiO2 and the synergetic activity of the substrates as NOx adsorbers.

  18. Enhanced visible light photocatalytic degradation of methylene blue by F-doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wei [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Liu, Xinjuan, E-mail: lxj669635@126.com [Shanghai Nanotechnlogy Promotion Center, Shanghai 200237 (China); Center for Coordination Bond and Electronic Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Li, Jinliang; Liu, Junying [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Zhang, Jing; Li, Ping; Chen, Chen [Shanghai Nanotechnlogy Promotion Center, Shanghai 200237 (China); Sun, Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China)

    2014-11-15

    Graphical abstract: F-doped TiO2 is synthesized using a modified sol–gel method for visible photocatalytic degradation of MB with a high degradation rate of 91%. - Highlights: • F-doped TiO{sub 2} are synthesized using a modified sol–gel method. • The photocatalytic degradation of methylene blue by F-doped TiO{sub 2} is investigated. • A high methylene blue degradation rate of 91% is achieved under visible light irradiation. - Abstract: F-doped TiO{sub 2} (F-TiO{sub 2}) were successfully synthesized using a modified sol–gel method. The morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy, and electrochemical impedance spectra, respectively. The results show that F-TiO{sub 2} exhibits an enhanced photocatalytic performance in the degradation of MB with a maximum degradation rate of 91% under visible light irradiation as compared with pure TiO{sub 2} (32%). The excellent photocatalytic activity is due to the contribution from the increased visible light absorption, promoted separation of photo-generated electrons and holes as well as enhanced photocatalytic oxidizing species with the doping of F in TiO{sub 2}.

  19. How Pt nanoparticles affect TiO2-induced gas-phase photocatalytic oxidation reactions

    NARCIS (Netherlands)

    Fraters, B.D.; Amrollahi Buky, Rezvaneh; Mul, Guido

    2015-01-01

    The effect of Pt nanoparticles on the gas-phase photocatalytic oxidation activity of TiO2 is shown to be largely dependent on the molecular functionality of the substrate. We demonstrate that Pt nanoparticles decrease rates in photocatalytic oxidation of propane, whereas a strong beneficial effect

  20. Photocatalytic oxidation of a reactive azo dye and evaluation of the ...

    African Journals Online (AJOL)

    The purpose of this study was to investigate the photocatalytic oxidation of a reactive azo dye and determine the improvement in the biodegradability when photocatalytic oxidation was used as a pretreatment step prior to biological treatment. The results obtained from the experiments adding H2O2/TiO2 show that the ...

  1. Nano cobalt oxides for photocatalytic hydrogen production

    KAUST Repository

    Mangrulkar, Priti A.; Joshi, Meenal M.; Tijare, Saumitra N.; Polshettiwar, Vivek; Labhsetwar, Nitin K.; Rayalu, Sadhana Suresh

    2012-01-01

    of various operating parameters in hydrogen generation by nano cobalt oxide was then studied in detail. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  2. Non-noble metal Cu-loaded TiO2 for enhanced photocatalytic H2 production.

    Science.gov (United States)

    Foo, Wei Jian; Zhang, Chun; Ho, Ghim Wei

    2013-01-21

    Here we have demonstrated the preparation of high-quality, monodispersed and tunable phases of Cu nanoparticles. Structural and chemical composition studies depict the evolution of Cu-Cu(2)O-CuO nanoparticles at various process stages. The loading of Cu and Cu oxide nanoparticles on TiO(2) catalyst has enhanced the photocatalytic H(2) production. Comparatively, H(2) treatment produces well-dispersed Cu nanoparticles with thin oxide shells that show the highest H(2) production amongst the samples. The relatively higher photocatalytic performance is deemed to result from reduced structural defects, higher surface area and dispersivity as well as favorable charge transfer, which inhibits recombination. The Cu nanoparticles are shown to be a promising alternative to noble metal-loaded TiO(2) catalyst systems due to their low cost and high performance in photocatalytic applications.

  3. Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film

    Science.gov (United States)

    Qamar, Mohammad; Drmosh, Qasem; Ahmed, Muhammad I.; Qamaruddin, Muhammad; Yamani, Zain H.

    2015-02-01

    Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were <50 nm, while deposited WO3 particles were <20 nm in size. An enhancement in the photocurrent was observed when the TiO2 surface was modified WO3 nanoparticles. Effect of potential, WO3 amount, and radiations of different wavelengths on the photoelectrochemical activity of TiO2 electrodes was investigated. Photocatalytic activity of TiO2 and WO3-modified TiO2 for the decolorization of methyl orange was tested.

  4. MWCNT/CdS hybrid nanocomposite for enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Chaudhary, Deepti; Khare, Neeraj; Vankar, V. D.

    2016-01-01

    Multi-walled carbon nanotubes (MWCNT)/CdS hybrid nanocomposite were synthesized by one step hydrothermal method. MWCNTs were used as a substrate for the growth of CdS nanoparticles. MWCNT/CdS nanocomposite and pure CdS were characterized by XRD, TEM, UV-vis and photoluminescence spectroscopy. HRTEM study confirms the intimate contact of CdS with MWCNT. The photocatalytic activity of nanocomposite was studied for the degradation of methylene blue dye under UV irradiation. The enhanced photocatalytic activity of MWCNT/CdS nanocomposite as compared to pure CdS has been attributed to reduced recombination of photogenerated charge carriers due to interfacial electron transfer from CdS to MWCNT.

  5. Composite TiO{sub 2}/clays materials for photocatalytic NOx oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Todorova, N.; Giannakopoulou, T.; Karapati, S.; Petridis, D. [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, P.O. Box 60037, 153 10, Ag. Paraskevi, Attiki (Greece); Vaimakis, T. [Department of Chemistry, University of Ioannina, P.O. Box 1186, 451 10, Ioannina (Greece); Trapalis, C., E-mail: trapalis@ims.demokritos.gr [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, P.O. Box 60037, 153 10, Ag. Paraskevi, Attiki (Greece)

    2014-11-15

    Graphical abstract: - Highlights: • Clays-supported TiO{sub 2} photocatalysts are prepared by simple, scalable method. • Visible light active TiO{sub 2} is incorporated in hydrotalcite, talk and kunipia clays. • The alkali substrates facilitate the NOx adsorption to the photocatalytic surface. • Low-content TiO{sub 2} photocatalysts demonstrated high NOx oxidation activity. • Titania/hydrotalcite photocatalyst exhibited remarkable NOx removal activity. - Abstract: TiO{sub 2} photocatalyst received much attention for air purification applications especially for removal of air pollutants like NOx, VOCs etc. It has been established that the activity of the photocatalyst can be significantly enhanced by its immobilization onto suitable substrates like inorganic minerals, porous silica, hydroxyapatite, adsorbent materials like activated carbon, various co-catalysts such as semiconductors, graphene, reduced graphite oxide, etc. In the present work, photocatalytic composite materials consisted of mineral substrate and TiO{sub 2} in weight ratio 1:1 were manufactured and examined for oxidation and removal of nitric oxides NOx (NO and NO{sub 2}). Commercial titania P25 (Evonik-Degussa) and urea-modified P25 were used as photocatalytically active components. Inorganic minerals, namely kunipia, talk and hydrotalcite were selected as supporting materials due to their layered structure and expected high NOx adsorption capability. Al{sup 3+} and Ca{sup 2+} intercalation was applied in order to improve the dispersion of TiO{sub 2} and its loading into the supporting matrix. The X-ray diffraction analysis and Scanning Electron Microscopy revealed the binary structure of the composites and homogeneous dispersion of the photocatalyst into the substrates. The photocatalytic behavior of the materials in NOx oxidation and removal was investigated under UV and visible light irradiation. The composite materials exhibited superior photocatalytic activity than the bare titania

  6. Yttrium bismuth titanate pyrochlore mixed oxides for photocatalytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Merka, Oliver

    2012-10-18

    In this work, the sol-gel synthesis of new non-stoichiometric pyrochlore titanates and their application in photocatalytic hydrogen production is reported. Visible light response is achieved by introducing bismuth on the A site or by doping the B site by transition metal cations featuring partially filled d orbitals. This work clearly focusses on atomic scale structural changes induced by the systematical introduction of non-stoichiometry in pyrochlore mixed oxides and the resulting influence on the activity in photocatalytic hydrogen production. The materials were characterized in detail regarding their optical properties and their atomic structure. The pyrochlore structure tolerates tremendous stoichiometry variations. The non-stoichiometry in A{sub 2}O{sub 3} rich compositions is compensated by distortions in the cationic sub-lattice for the smaller Y{sup 3+} cation and by evolution of a secondary phase for the larger Bi{sup 3+} cation on the A site. For TiO{sub 2} rich compositions, the non-stoichiometry leads to a special vacancy formation in the A and optionally O' sites. It is shown that pyrochlore mixed oxides in the yttrium bismuth titanate system represent very active and promising materials for photocatalytic hydrogen production, if precisely and carefully tuned. Whereas Y{sub 2}Ti{sub 2}O{sub 7} yields stable hydrogen production rates over time, the bismuth richer compounds of YBiTi{sub 2}O{sub 7} and Bi{sub 2}Ti{sub 2}O{sub 7} are found to be not stable under irradiation. This drawback is overcome by applying a special co-catalyst system consisting of a precious metal core and a Cr{sub 2}O{sub 3} shell on the photocatalysts.

  7. Evaluating the Catalytic Effects of Carbon Materials on the Photocatalytic Reduction and Oxidation Reactions of TiO2

    International Nuclear Information System (INIS)

    Khan, Gulzar; Kim, Young Kwang; Choi, Sung Kyu; Han, Dong Suk; Abdelwahab, Ahmed; Park, Hyunwoong

    2013-01-01

    TiO 2 composites with seven different carbon materials (activated carbons, graphite, carbon fibers, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene oxides, and reduced graphene oxides) that are virgin or treated with nitric acid are prepared through an evaporation method. The photocatalytic activities of the as-prepared samples are evaluated in terms of H 2 production from aqueous methanol solution (photo-catalytic reduction: PCR) and degradation of aqueous pollutants (phenol, methylene blue, and rhodamine B) (photocatalytic oxidation: PCO) under AM 1.5-light irradiation. Despite varying effects depending on the kinds of carbon materials and their surface treatment, composites typically show enhanced PCR activity with maximum 50 times higher H 2 production as compared to bare TiO 2 . Conversely, the carbon-induced synergy effects on PCO activities are insignificant for all three substrates. Colorimetric quantification of hydroxyl radicals supports the absence of carbon effects. However, platinum deposition on the binary composites displays the enhanced effect on both PCR and PCO reactions. These differing effects of carbon materials on PCR and PCO reactions of TiO 2 are discussed in terms of physicochemical properties of carbon materials, coupling states of TiO 2 /carbon composites, interfacial charge transfers. Various surface characterizations of composites (UV-Vis diffuse reflectance, SEM, FTIR, surface area, electrical conductivity, and photoluminescence) are performed to gain insight on their photocatalytic redox behaviors

  8. Photocatalytic Iron Oxide Micro-Swimmers for Environmental Remediation

    Science.gov (United States)

    Richard, Cynthia; Simmchen, Juliane; Eychmüller, Alexander

    2018-05-01

    Harvesting energy from photochemical reactions has long been studied as an efficient means of renewable energy, a topic that is increasingly gaining importance also for motion at the microscale. Iron oxide has been a material of interest in recent studies. Thus, in this work different synthesis methods and encapsulation techniques were used to try and optimize the photo-catalytic properties of iron oxide colloids. Photodegradation experiments were carried out following the encapsulation of the nanoparticles and the Fenton effect was also verified. The end goal would be to use the photochemical degradation of peroxide to propel an array of swimmers in a controlled manner while utilizing the Fenton effect for the degradation of dyes or waste in wastewater remediation.

  9. Enhanced photocatalytic disinfection of indoor air

    Energy Technology Data Exchange (ETDEWEB)

    Vohra, Amit; Goswami, D.Y.; Deshpande, D.A.; Block, S.S. [Solar Energy and Energy Conversion Laboratory, Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2006-04-18

    A silver ion doped TiO{sub 2} based photocatalyst, with improved destruction of airborne microbes, has been developed. The performance of the silver ion doped photocatalyst is demonstrated using a catalyst coated filter in a recirculating air experimental facility. Bacillus cereus, Staphylococcus aureus, Escherichia coli, Aspergillus niger, and MS2 Bacteriophage have been used as indexes to demonstrate the high disinfection efficiency of the enhanced photocatalysis process. The microbial destruction performance of the enhanced photocatalyst is found to be an order of magnitude higher than that of a conventional TiO{sub 2} photocatalyst. The process of enhanced photocatalysis can thus be used effectively against high concentrations of airborne microorganisms, making it an attractive option as a defense against bio-terrorism. (author)

  10. Graphene-spindle shaped TiO2 mesocrystal composites: Facile synthesis and enhanced visible light photocatalytic performance

    International Nuclear Information System (INIS)

    Yang, Xiaofei; Qin, Jieling; Li, Yang; Zhang, Rongxian; Tang, Hua

    2013-01-01

    Highlights: • Graphene-TiO 2 mesocrystal composites were fabricated via a facile approach. • Graphene sheets were decorated with spindle-like TiO 2 mesocrystals. • Graphene causes enhanced light absorbance and visible light photocatalytic activity. • Oxygen-containing radicals are believed to responsible for its improved activity. -- Abstract: Graphene (GR)-TiO 2 mesocrystal composites were prepared by a facile template-free process based on the combination of sol–gel and solvothermal methods, and were characterized using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), nitrogen absorption and electron spin resonance (ESR). Visible light photocatalytic performance of GR-TiO 2 composites was evaluated for photocatalytic degradation of organic dye Rhodamine B. It was found that the amount of graphene oxide (GO) added obviously affects morphologies of TiO 2 mesocrystals and photocatalytic activities of as-prepared nanocomposites. Composites prepared in the presence of different amounts of GO all exhibit higher photocatalytic activity than pure TiO 2 mesocrystals and P25, the composite obtained by using 20 mg GO presents the most uniform TiO 2 mesocrystals in the composite and shows the highest photocatalytic efficiency. The mechanism for the generation of TiO 2 mesocrystals in the GR-TiO 2 composite is proposed and possible reasons for the enhancement in visible light photocatalytic efficiency are also discussed

  11. Comparison study on photocatalytic oxidation of pharmaceuticals by TiO{sub 2}-Fe and TiO{sub 2}-reduced graphene oxide nanocomposites immobilized on optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Lu; Wang, Huiyao, E-mail: huiyao@nmsu.edu; Jiang, Wenbin; Mkaouar, Ahmed Radhi; Xu, Pei, E-mail: pxu@nmsu.edu

    2017-07-05

    Highlights: • Incorporating rGO or Fe{sup 3+} ions in TiO{sub 2} photocatalyst could enhance photocatalysis. • TiO{sub 2}-rGO exhibited higher photocatalytic activity under UV irradiation. • TiO{sub 2}-Fe demonstrated more suitable for visible light irradiation. • Reduced recombination rate contributed to enhanced photocatalysis of TiO{sub 2}-rGO. • Narrower band gap accounted for increased photocatalytic activity of TiO{sub 2}-Fe. - Abstract: Incorporating reduced graphene oxide (rGO) or Fe{sup 3+} ions in TiO{sub 2} photocatalyst could enhance photocatalytic degradation of organic contaminants in aqueous solutions. This study characterized the photocatalytic activities of TiO{sub 2}-Fe and TiO{sub 2}-rGO nanocomposites immobilized on optical fibers synthesized by polymer assisted hydrothermal deposition method. The photocatalysts presented a mixture phase of anatase and rutile in the TiO{sub 2}-rGO and TiO{sub 2}-Fe nanocomposites. Doping Fe into TiO{sub 2} particles (2.40 eV) could reduce more band gap energy than incorporating rGO (2.85 eV), thereby enhancing utilization efficiency of visible light. Incorporating Fe and rGO in TiO{sub 2} decreased significantly the intensity of TiO{sub 2} photoluminescence signals and enhanced the separation rate of photo-induced charge carriers. Photocatalytic performance of the synthesized nanocomposites was measured by the degradation of three pharmaceuticals under UV and visible light irradiation, including carbamazepine, ibuprofen, and sulfamethoxazole. TiO{sub 2}-rGO exhibited higher photocatalytic activity for the degradation of pharmaceuticals under UV irradiation, while TiO{sub 2}-Fe demonstrated more suitable for visible light oxidation. The results suggested that the enhanced photocatalytic performance of TiO{sub 2}-rGO could be attributed to reduced recombination rate of photoexcited electrons-hole pairs, but for TiO{sub 2}-Fe nanocomposite, narrower band gap would contribute to increased photocatalytic

  12. Enhanced photocatalytic activity of ZnO–graphene nanocomposites prepared by microwave synthesis

    International Nuclear Information System (INIS)

    Herring, Natalie P.; Almahoudi, Serial H.; Olson, Chelsea R.; El-Shall, M. Samy

    2012-01-01

    This work reports a simple one-step synthesis of ZnO nanopyramids supported on reduced graphene oxide (RGO) nanosheets using microwave irradiation (MWI) of zinc acetate and GO in the presence of a mixture of oleic acid and oleylamine. The rapid decomposition of zinc acetate by MWI in the presence of the mixture of oleic acid and oleylamine results in the formation of hexagonal ZnO nanopyramids. GO has a high affinity for absorbing MWI, which results in a high local heating effect around the GO nanosheets and facilitates the reduction of GO by the oleylamine. The RGO nanosheets act as heterogeneous surface sites for the nucleation and growth of the ZnO nanopyramids. Using ligand exchange, the ZnO–RGO nanocomposites can be dispersed in an aqueous medium, thus allowing their use as photocatalysts for the degradation of the malachite green dye in water. The ZnO–RGO nanocomposites show enhanced photocatalytic activity for the degradation of the dye over the unsupported ZnO nanopyramids. The enhanced activity is attributed to efficient charge transfer of the photogenerated electrons in the conduction band of ZnO to graphene. This enhances the oxidative pathway of the holes generated in the valence band of ZnO which can effectively lead to the degradation and mineralization of the malachite green. The ZnO nanopyramids supported on RGO could have improved performance in other photocatalytic reactions and also in solar energy conversion.

  13. Shape-Enhanced Photocatalytic Activities of Thoroughly Mesoporous ZnO Nanofibers

    KAUST Repository

    Ren, Xiaolong

    2016-06-24

    1D mesoporous materials have attracted extensive interest recently, owning to their fascinating properties and versatile applications. However, it remains as a grand challenge to develop a simple and efficient technique to produce oxide nanofibers with mesoporous architectures, controlled morphologies, large surface areas, and optimal performances. In this work, a facile foaming-assisted electrospinning strategy with foaming agent of tea saponin is used to produce thoroughly mesoporous ZnO nanofibers with high purity and controlled morphology. Interestingly, mesoporous fibers with elliptical cross-section exhibit the significantly enhanced photocatalytic activity for hydrogen production, as compared to the counterparts with circular and rectangular cross-sections, and they also perform better than the commercial ZnO nanopowders. The unexpected shape dependence of photocatalytic activities is attributed to the different stacking modes of the mesoporous fibers, and a geometrical model is developed to account for the shape dependence. This work represents an important step toward producing thoroughly mesoporous ZnO nanofibers with tailored morphologies, and the discovery that fibers with elliptical cross-section render the best performance provides a valuable guideline for improving the photocatalytic performance of such mesoporous nanomaterials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. TiO2 structures doped with noble metals and/or graphene oxide to improve the photocatalytic degradation of dichloroacetic acid.

    Science.gov (United States)

    Ribao, Paula; Rivero, Maria J; Ortiz, Inmaculada

    2017-05-01

    Noble metals have been used to improve the photocatalytic activity of TiO 2 . Noble metal nanoparticles prevent charge recombination, facilitating electron transport due to the equilibration of the Fermi levels. Furthermore, noble metal nanoparticles show an absorption band in the visible region due to a high localized surface plasmon resonance (LSPR) effect, which contributes to additional electron movements. Moreover, systems based on graphene, titanium dioxide, and noble metals have been used, considering that graphene sheets can carry charges, thereby reducing electron-hole recombination, and can be used as substrates of atomic thickness. In this work, TiO 2 -based nanocomposites were prepared by blending TiO 2 with noble metals (Pt and Ag) and/or graphene oxide (GO). The nanocomposites were mainly characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman spectroscopy, and photocurrent analysis. Here, the photocatalytic performance of the composites was analyzed via oxidizing dichloroacetic acid (DCA) model solutions. The influence of the noble metal load on the composite and the ability of the graphene sheets to improve the photocatalytic activity were studied, and the composites doped with different noble metals were compared. The results indicated that the platinum structures show the best photocatalytic degradation, and, although the presence of graphene oxide in the composites is supposed to enhance their photocatalytic performance, graphene oxide does not always improve the photocatalytic process. Graphical abstract It is a schematic diagram. Where NM is Noble Metal and LSPR means Localized Surface Plasmon Resonance.

  15. Photocatalytic oxidation of organic compounds via waveguide-supported titanium dioxide films

    Science.gov (United States)

    Miller, Lawrence W.

    A photochemical reactor based on titanium dioxide (TiO2)-coated silica optical fibers was constructed to explore the use of waveguide-supported TiO2 films for photocatalytic oxidation of organic compounds. The reactor was used for the photocatalytic oxidation of 4-chlorophenol in water. It was confirmed that TiO2 films could be securely attached to silica optical fibers. The 4-chlorophenol (100 mumol/L in water) was successfully oxidized on the TiO2 surface when UV light (310 nm--380 nm) was propagated through the fibers to the films. Rates of 4-chlorophenol oxidation and UV light flux to the fibers were measured. The quantum efficiency of 4-chlorophenol oxidation [defined as the change in 4-chlorophenol concentration divided by the UV light absorbed by the catalyst] was determined as a function of TiO2 catalyst film thickness and internal incident angle of propagating UV light. A maximum quantum efficiency of 2.8% was measured when TiO2 film thickness was ca. 80 nm and the maximum internal incident angle of propagating light was 84°. Quantum efficiency increased with increasing internal angle of incidence of propagating light and decreased with TiO2 film thickness. UV-Visible internal reflection spectroscopy was used to determine whether UV light propagated through TiO2-coated silica waveguides in an ATR mode. Propagation of UV light in an ATR mode was confirmed by the similarities between internal reflection spectra of phenolphthalein obtained with uncoated and TiO2-coated silica crystals. Planar silica waveguides coated with TiO2 were employed in a photocatalytic reactor for the oxidation of formic acid (833 mumol/L in water). It was shown that the quantum yield of formic acid oxidation [defined as the moles of formic acid oxidized divided by the moles of UV photons absorbed by the catalyst] on the waveguide-supported TiO2 surface is enhanced when UV light propagates through the waveguides in an ATR mode. A maximum quantum yield of 3.9% was found for formic

  16. Synthesis, structural and optical properties of ZnO spindle/reduced graphene oxide composites with enhanced photocatalytic activity under visible light irradiation

    Science.gov (United States)

    Prabhu, S.; Pudukudy, M.; Sohila, S.; Harish, S.; Navaneethan, M.; Navaneethan, D.; Ramesh, R.; Hayakawa, Y.

    2018-05-01

    In the present work, spindle-shaped ZnO and reduced graphene oxide sheets were successfully synthesized by a hydrothermal method and then ZnO/r-GO composite was prepared by a direct solution mixing method. Various characterization results confirmed the interior and surface decoration of spindle-shaped ZnO on the reduced graphene oxide sheets. The phase formation, crystalline structure, morphology, surface states and optical properties were characterized using Powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Vis spectroscopy. The X-ray diffraction analysis showed the formation of the hexagonal wurtzite crystalline structure of ZnO with high crystalline quality. The band gap of the ZnO/r-GO composite was found to be low (3.03eV) compared to the band gap of spindle shaped ZnO (3.13 eV), as calculated from optical studies. The spindle-like morphology of the single crystalline ZnO was clearly shown in the electron microscopic images. The chemical bonding and surface states of the samples were studied using XPS measurement. Moreover, a possible growth mechanism for the ZnO spindle was proposed. The catalytic activity of the as-synthesized samples was evaluated for the photodegradation of methylene blue under visible light irradiation. Among the synthesized samples, the ZnO/r-GO composite showed higher degradation efficiency of 93% and successfully reused for four consecutive run without any activity loss.

  17. Preparation and enhanced photocatalytic activity of carbon nitride/titania(001 vs 101 facets)/reduced graphene oxide (g-C{sub 3}N{sub 4}/TiO{sub 2}/rGO) hybrids under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Meina [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Yu, Jianhua [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Tobacoo Monopoly Bureau, Guangxi Zhuang Autonomous Rejion, Nanning, 530022 (China); Hu, Qun; Su, Wenli [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Fan, Minguang, E-mail: fanmg@gxu.edu.cn [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Guangxi Key Laboratory Petrochemical Rescource Processing and Process Intensification Technology, Nanning 530004 (China); Li, Bin [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Dong, Lihui, E-mail: donglihui2005@126.com [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China)

    2016-12-15

    Graphical abstract: Schematic for the enhanced photocatalytic activity of CN/T/rGO hybrids upon visible light irradiation. - Highlights: • g-C{sub 3}N{sub 4}/TiO{sub 2}(001 vs 101 Facets)/rGO were prepared via one-step solvothermal route. • Performance evaluation was carried out under visible light irradiation. • Samples show excellent photocatalytic activities and stablity. • A possible photocatalytic mechanism is proposed. • The structural effects of g-C{sub 3}N{sub 4}/TiO{sub 2}/rGO explain excellent performance. - Abstract: Herein, a novel photocatalyst, anatase TiO{sub 2} nanoparticles with both exposed (101) and (001) facets synchronously incorporated with g-C{sub 3}N{sub 4} and graphene, was successfully prepared via a simple one-step solvothermal route. The morphology and structure of as-prepared composites were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS). Efficiency of the prepared samples was investigated by monitoring the degradation of Methyl Orange (MO), Rhodamine B (RhB) and phenol under visible light irradiation. Improved photocatalytic activity in g-C{sub 3}N{sub 4}/TiO{sub 2}/rGO is observed owing to higher specific surface area and enhanced visible light absorption capability. Most importantly, the in situ g-C{sub 3}N{sub 4} and rGO doping might enhance the interaction among g-C{sub 3}N{sub 4}, TiO{sub 2} (001 vs 101) and rGO, which generates more synergistic heteroconjunctions in g-C{sub 3}N{sub 4}/TiO{sub 2}/rGO facilitating a fast electron transfer at the interface among them. This synergistic approach could prove useful for the design and development of other visible light active photocatalysts with high chemical stability.

  18. Next Generation Hybrid Photo-Catalytic Oxidation (PCO) for Trace Contaminant Control

    Data.gov (United States)

    National Aeronautics and Space Administration — Photocatalytic oxidation (PCO) is a primary candidate as an alternative to thermal-catalytic or sorbent- based technologies for VOC trace contaminant control due to...

  19. Experimental research on photocatalytic oxidation air purification technology applied to aircraft cabins

    DEFF Research Database (Denmark)

    Sun, Yuexia; Fang, Lei; Wyon, David Peter

    2008-01-01

    The experiment presented in this report was performed in a simulated aircraft cabin to evaluate the air cleaning effects of two air purification devices that used photocatalytic oxidation (PCO) technology. Objective physical, chemical and physiological measurements and subjective human assessment...

  20. Ternary composite of TiO2 nanotubes/Ti plates modified by g-C3N4 and SnO2 with enhanced photocatalytic activity for enhancing antibacterial and photocatalytic activity.

    Science.gov (United States)

    Faraji, Masoud; Mohaghegh, Neda; Abedini, Amir

    2018-01-01

    A series of g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plates were fabricated via simple dipping of TiO 2 nanotubes/Ti in a solution containing SnCl 2 and g-C 3 N 4 nanosheets and finally annealing of the plates. Synthesized plates were characterized by various techniques. The SEM analysis revealed that the g-C 3 N 4 -SnO 2 nanosheets with high physical stability have been successfully deposited onto the surface of TiO 2 nanotubes/Ti plate. Photocatalytic activity was investigated using two probe chemical reactions: oxidative decomposition of acetic acid and oxidation of 2-propanol under irradiation. Antibacterial activities for Escherichia coli (E. coli) bacteria were also investigated in dark and under UV/Vis illuminations. Detailed characterization and results of photocatalytic and antibacterial activity tests revealed that semiconductor coupling significantly affected the photocatalyst properties synthesized and hence their photocatalytic and antibacterial activities. Modification of TiO 2 nanotubes/Ti plates with g-C 3 N 4 -SnO 2 deposits resulted in enhanced photocatalytic activities in both chemical and microbial systems. The g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate exhibited the highest photocatalytic and antibacterial activity, probably due to the heterojunction between g-C 3 N 4 -SnO 2 and TiO 2 nanotubes/Ti in the ternary composite plate and thus lower electron/hole recombination rate. Based on the obtained results, a photocatalytic and an antibacterial mechanism for the degradation of E. coli bacteria and chemical pollutants over g-C 3 N 4 -SnO 2 /TiO 2 nanotubes/Ti plate were proposed and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Application of zinc oxide fiber in the photocatalytic degradation of methyl orange

    International Nuclear Information System (INIS)

    Gerchman, D.; Alves, A.K.; Berutti, F.A.; Bergmann, C.P.

    2011-01-01

    In this work, zinc oxide fibers were obtained by electrospinning using polyvinylbutyral and zinc nitrate as precursors. After the synthesis, the material was heat treated at different temperatures to evaluate the effect of microstructure on its photocatalytic activity. The fibers obtained after heat treatment were characterized for morphology, phases, crystallinity and photocatalytic activity. The photocatalysis reaction was accompanied by the degradation of methyl orange in the presence of zinc oxide under UV illumination. It was observed that the crystallinity of zincite is a fundamental factor for the control of the photocatalytic activity of this material. (author)

  2. Enhanced photocatalytic performance of TiO{sub 2} nanotube based heterojunction photocatalyst via the coupling of graphene and FTO

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Xiaoyou [College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Yu, Jianyuan [College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Department of Environmental and Chemical Engineering, Tangshan University, Tangshan 063000 (China); Wang, Likun; Fu, Chen; Wang, Jixia; Wang, Li [College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Zhao, Hongli, E-mail: zhaohongli@ysu.edu.cn [College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); State Key Laboratory of Metastable Materials Science and Technology, Qinhuangdao 066004 (China); Yang, Jingkai, E-mail: yangjk@ysu.edu.cn [National Defense Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

    2017-08-15

    Highlights: • The rGO-TONT composites have been deposited onto FTO. • Photocatalytic reaction rate shows 3 times greater than TONT. • Chemical interaction between rGO and TONT was analyzed. • Electron transfer process in rGO-TONT/FTO heterojunction was discussed. - Abstract: The TiO{sub 2} nanotube (TONT) based heterojunction photocatalyst was developed via the coupling of reduced graphene oxide (rGO) and SnO{sub 2}:F film (FTO). Based on the characterization of Raman analysis, XRD, SEM, TEM, XPS and ESR, the crystal phase, morphology, heterojunction interfacial interaction and the photoinduced electron chemical environment of the samples are studied. In the photodegradation of methylene blue (MB) solution under UV irradiation, the rGO-TONT/FTO heterojunction photocatalyst exhibits the improved photocatalytic reaction rate, 3 times greater than that of pure TONT. The enhanced photocatalytic mechanism was discussed by PL. The effectively separate charge in heterojunction structure of rGO-TONT/FTO is responsible for the enhanced photocatalytic activity. Wherein, the abundant oxygen vacancies at TiO{sub 2} surface and the chemically bonded interface in rGO-TONT heterojunction also contributes to the interfacial electron transfer. Besides, the introduction of rGO enhanced its optical absorption capacity.

  3. Nanostructured porous ZnO film with enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Wang Lina; Zheng Yingying; Li Xiaoyun; Dong Wenjun; Tang Weihua; Chen Benyong; Li Chaorong; Li Xiao; Zhang Tierui

    2011-01-01

    Well-defined ZnO nanostructured films have been fabricated directly on Zn foil via hydrothermal synthesis. During the fabrication of the ZnO nanostructured films, the Zn foil serves as the Zn source and also the substrate. Porous nanosheet-based, nanotube-based and nanoflower-based ZnO films can all be easily prepared by adjusting the alkali type, reaction time and reaction temperature. The composition, morphology and structure of ZnO films are characterized by X-ray diffraction, scanning electron microscope and high-resolution transmission electron microscope. The porous ZnO nanosheet-based film exhibits enhanced photocatalytic activity in the degradation of Rhodamine B under UV light irradiation. This can be attributed to the high surface area of the ZnO nanosheet and the large percentage of the exposed [001] facet. Moreover, the self-supporting, recyclable and stable ZnO photocatalytic film can be readily recovered and potentially applied for pollution disposal.

  4. Facile preparation of squarylium dye sensitized TiO{sub 2} nanoparticles and their enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhongyu, E-mail: zhongyuli@mail.tsinghua.edu.cn [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Changzhou Expansion New Stuff Technology Limited Company, Changzhou 213122 (China); Fang, Yongling [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Zhan, Xueqiu [Department of Basic Courses, Wuxi Institute of Technology, Wuxi 214121 (China); Xu, Song [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China)

    2013-07-05

    Highlights: •ISQ dye sensitized TiO{sub 2} nanoparticles were prepared via a facile solution method. •ISQ/TiO{sub 2} nanoparticles exhibited significantly enhanced visible light activity. •ISQ/TiO{sub 2} showed high visible light photocatalytic activity over MB decomposition. •ISQ/TiO{sub 2} nanoparticles exhibited good photocatalytic stability. -- Abstract: A squarylium dye, 1,3-bis[(3,3-dimethylindolin-2-ylidene)methyl]squaraine (ISQ) sensitized TiO{sub 2} nanoparticles photocatalysts with different mass ratio of ISQ to TiO{sub 2} were facilely prepared by blending ISQ and TiO{sub 2} in ethanol solution. The resulting composite photocatalysts were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FT-IR) and UV–vis diffuse reflectance spectroscope (DRS). The visible light photocatalytic activities of ISQ sensitized TiO{sub 2} nanoparticles were evaluated using the degradation of methylene blue (MB) as a photodegradation target. The results showed that photo-response of the ISQ sensitized TiO{sub 2} nanoparticles were remarkably extended to visible-light region, and the ISQ dye sensitized TiO{sub 2} exhibited significantly enhanced photocatalytic activity under visible light irradiation. The maximum photocatalytic activity of the ISQ sensitized TiO{sub 2} was found at a composite photocatalyst (mass ratio of ISQ to TiO{sub 2} was 1:3), and its degradation efficiency of MB reached approximately 98% in 2 h under visible light irradiation. Furthermore, a possible mechanism for the photocatalytic oxidative degradation was also proposed.

  5. The suitability of silicon carbide for photocatalytic water oxidation

    Science.gov (United States)

    Aslam, M.; Qamar, M. T.; Ahmed, Ikram; Rehman, Ateeq Ur; Ali, Shahid; Ismail, I. M. I.; Hameed, Abdul

    2018-04-01

    Silicon carbide (SiC), owing to its extraordinary chemical stability and refractory properties, is widely used in the manufacturing industry. Despite the semiconducting nature and morphology-tuned band gap, its efficacy as photocatalysts has not been thoroughly investigated. The current study reports the synthesis, characterization and the evaluation of the capability of silicon carbide for hydrogen generation from water splitting. The optical characterization of the as-synthesized powder exposed the formation of multi-wavelength absorbing entities in synthetic process. The structural analysis by XRD and the fine microstructure analysis by HRTEM revealed the cubic 3C-SiC (β-SiC) and hexagonal α-polymorphs (2H-SiC and 6H-SiC) as major and minor phases, respectively. The Mott-Schottky analysis verified the n-type nature of the material with the flat band potential of - 0.7 V. In the electrochemical evaluation, the sharp increase in the peak currents in various potential ranges, under illumination, revealed the plausible potential of the material for the oxidation of water and generation of hydrogen. The generation of hydrogen and oxygen, as a consequence of water splitting in the actual photocatalytic experiments, was observed and measured. A significant increase in the yield of hydrogen was noticed in the presence of methanol as h + scavenger, whereas a retarding effect was offered by the Fe3+ entities that served as e - scavengers. The combined effect of both methanol and Fe3+ ions in the photocatalytic process was also investigated. Besides hydrogen gas, the other evolved gasses such as methane and carbon monoxide were also measured to estimate the mechanism of the process.

  6. Photocatalytic and electrochemical performance of three-Dimensional reduced graphene Oxide/WS{sub 2}/Mg-doped ZnO composites

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Weiwei [College of Materials Science and Engineering, Changsha University of Science and Technology, Changsha, 410114 (China); Chen, Xi’an [Zhejiang Key Laboratory of Carbon Materials, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, 325027 (China); Mei, Wei [College of Materials Science and Engineering, Changsha University of Science and Technology, Changsha, 410114 (China); Chen, Chuansheng, E-mail: 1666423158@qq.com [College of Materials Science and Engineering, Changsha University of Science and Technology, Changsha, 410114 (China); Tsang, Yuenhong [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, 999077 (China)

    2017-04-01

    Highlights: • 3D graphene oxide/WS{sub 2}/Mg-doped ZnO composites were prepared by electrostatic self-assembly and coprecipitation methods. • A significant photocatalytic activity enhancement of rGWMZ was observed. • The enhancement for photocatalytic activity is ascribed to the synergistic effect of rGO and WS{sub 2} nanosheets. - Abstract: To improve the dispersion of reduced graphene oxide and enhance the photocatalytic property of reduced graphene oxide/Mg-doped ZnO composites (rGMZ), the reduced graphene oxide/WS{sub 2}/Mg-doped ZnO composites (rGWMZ) were prepared by electrostatic self-assembly and coprecipitation methods. The effects of mass ratio of WS{sub 2} nanosheets to reduced graphene oxide (WS{sub 2}/rGO wt.%) and calcination temperature on the photocatalytic and electrochemical property of rGWMZ composites were investigated. Experimental results showed that the photocatalytic efficiency of rGWMZ composites is three-fold compared with that of rGMZ composites when the WS{sub 2}/rGO wt.% is 20.8% and calcination temperature is 500 °C, in which the degradation ratio Rhodamin B (RhB) can reach 95% within 15 min under the UV light and 90% within 90 min under simulated solar light. In addition, the rGWMZ show larger capacitance and smaller resistance than rGMZ. The enhancement for photocatalytic activity and electrochemical performance of rGWMZ is ascribed to improving the specific surface area, electrical conductivity and electronic storage capability because of the synergistic effect of rGO and WS{sub 2} nanosheets.

  7. Theoretical study on the photocatalytic properties of graphene oxide with single Au atom adsorption

    Science.gov (United States)

    Ju, Lin; Dai, Ying; Wei, Wei; Li, Mengmeng; Jin, Cui; Huang, Baibiao

    2018-03-01

    The photocatalytic properties of graphene oxide (GO) with single Au atom adsorption are studied via the first-principles calculations based on the density functional theory. The present study addresses the origin of enhancement in photocatalytic efficiency of GO derived from single Au atom depositing. Compared with the clean one, the work function of the single Au atom adsorbed GO is lowered due to the charge transfer from Au to GO, indicating enhanced surface activity. The Au atom plays as an electron trapping center and a mediating role in charge transfer from photon excited GO to target species. The photogenerated electron-hole pairs can be separated effectively. For the GO configuration with atomic Au dispersion, there are some states introduced in the band gap, which are predominantly composed of Au 6s states. Through the in-gap state, the photo-generated electron transfer from the valence band of clean GO to the conductive band more easily. In addition, the reduction of the gap in the system is also presented in the current work, which indicates that the single Au atom adsorption improves light absorption for the GO based photocatalyst. These theoretical results are valuable for the future applications of GO materials as photocatalyst for water splitting.

  8. Synthesis of reduced graphene oxide/CeO2 nanocomposites and their photocatalytic properties

    International Nuclear Information System (INIS)

    Ji Zhenyuan; Shen Xiaoping; Li Minzhi; Zhu Guoxing; Zhou Hu; Chen Kangmin

    2013-01-01

    With a unique structure and extraordinary properties, graphene has attracted tremendous attention in the preparation of graphene-based composites for various applications. In this study, two different strategies, including in situ growth and a self-assembly approach, have been developed to load CeO 2 nanoparticles onto reduced graphene oxide (RGO) nanosheets. The microstructure and morphology of the as-synthesized RGO/CeO 2 nanocomposites were investigated by x-ray diffraction, Raman spectroscopy and transmission electron microscopy. The results reveal that CeO 2 nanoparticles with well-controlled size and a uniform distribution on RGO sheets with tunable density can be achieved through the self-assembly approach. The significantly enhanced photocatalytic activity of the RGO/CeO 2 nanocomposites in comparison with bare CeO 2 nanoparticles was revealed by the degradation of methylene blue under simulated sunlight irradiation, which can be attributed to the improved separation of electron–hole pairs and enhanced adsorption performance due to the presence of RGO. A suitable loading content of CeO 2 on RGO was found to be crucial for optimizing the photocatalytic activity of the nanocomposites. It is expected that this convenient assembly approach with high controllability can be extended to the attachment of other functional nanoparticles to RGO sheets, and the resultant RGO-supported highly dispersed nanoparticles are attractive for catalysis, sensing and power source applications. (paper)

  9. Lack of enhanced photocatalytic formation of iodine on particulate semiconductor mixtures.

    Science.gov (United States)

    Karunakaran, C; Anilkumar, P; Vinayagamoorthy, P

    2012-12-01

    Under UV-A light illumination, formation of iodine from iodide ion on the surfaces of anatase TiO(2), ZnO, Fe(2)O(3), CeO(2), MoO(3), Bi(2)O(3), and Nb(2)O(5) increases with the concentration of iodide ion, airflow rate and light intensity and conform to the Langmuir-Hinshelwood kinetic model. Measurement of the particle size of the semiconductor oxides by light scattering method and deduction of the same from the determined specific surface area show that the oxide particles agglomerate in suspension. However, mixtures of any two listed particulate semiconductors do not show enhanced photocatalytic formation of iodine indicating absence of interparticle charge transfer. The results are rationalized. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Superior Photocatalytic Performance of CeO₂ Nanoparticles and Reduced Graphene Oxide Nanocomposite Prepared by Low Cost Co-Precipitation Method.

    Science.gov (United States)

    Jayanthi, Mani; Lavanya, Thirugnanam; Saradha, Nagarajan Anbil; Satheesh, Kaveri; Chenthamarai, SriRangarajan; Jayavel, Ramasamy

    2018-05-01

    In this article, cerium oxide nanoparticles (CeO2 NPs) and reduced graphene oxide nanocomposite have been fabricated through simple, easy and cost effective co-precipitation method. The structural, optical and morphological characterization provides the evidence of successful synthesis of CeO2 NPs and nanocomposite. X-ray photoelectron spectroscopic characterization provides useful information about the concentrations and proportions of Ce3+ and Ce4+ ions in nanoparticles as well as in nanocomposite. These studies provide an insight to understand enhanced photocatalytic activity of nanocomposite. The nanocomposite produces 81% photocatalytic degradation of methyl orange compared to only 45% degradation by CeO2 NPs alone.

  11. 2D double-layer-tube-shaped structure Bi2S3/ZnS heterojunction with enhanced photocatalytic activities

    International Nuclear Information System (INIS)

    Gao, Xiaoming; Wang, Zihang; Fu, Feng; Li, Xiang; Li, Wenhong

    2015-01-01

    Bi 2 S 3 /ZnS heterojunction with 2D double-layer-tube-shaped structures was prepared by the facile synthesis method. The corresponding relationship was obtained among loaded content to phase, morphology, and optical absorption property of Bi 2 S 3 /ZnS composite. The results shown that Bi 2 S 3 loaded could evidently change the crystallinity of ZnS, enhance the optical absorption ability for visible light of ZnS, and improve the morphologies and microstructure of ZnS. The photocatalytic activities of the Bi 2 S 3 /ZnS sample were evaluated for the photodegradation of phenol and desulfurization of thiophene under visible light irradiation. The results showed that Bi 2 S 3 loaded greatly improved the photocatalytic activity of ZnS, and the content of loaded Bi 2 S 3 had an impact on the catalytic activity of ZnS. Moreover, the mechanism of enhanced photocatalytic activity was also investigated by analysis of relative band positions of Bi 2 S 3 and ZnS, and photo-generated hole was main active radicals during photocatalytic oxidation process

  12. 2D double-layer-tube-shaped structure Bi2S3/ZnS heterojunction with enhanced photocatalytic activities

    Science.gov (United States)

    Gao, Xiaoming; Wang, Zihang; Fu, Feng; Li, Xiang; Li, Wenhong

    2015-10-01

    Bi2S3/ZnS heterojunction with 2D double-layer-tube-shaped structures was prepared by the facile synthesis method. The corresponding relationship was obtained among loaded content to phase, morphology, and optical absorption property of Bi2S3/ZnS composite. The results shown that Bi2S3 loaded could evidently change the crystallinity of ZnS, enhance the optical absorption ability for visible light of ZnS, and improve the morphologies and microstructure of ZnS. The photocatalytic activities of the Bi2S3/ZnS sample were evaluated for the photodegradation of phenol and desulfurization of thiophene under visible light irradiation. The results showed that Bi2S3 loaded greatly improved the photocatalytic activity of ZnS, and the content of loaded Bi2S3 had an impact on the catalytic activity of ZnS. Moreover, the mechanism of enhanced photocatalytic activity was also investigated by analysis of relative band positions of Bi2S3 and ZnS, and photo-generated hole was main active radicals during photocatalytic oxidation process.

  13. Photocatalytic fabrics based on reduced graphene oxide and TiO{sub 2} coatings

    Energy Technology Data Exchange (ETDEWEB)

    Molina, J., E-mail: jamopue@doctor.upv.es [Departamento de Ingeniería Textil y Papelera, EPS de Alcoy, Universitat Politècnica de València, Plaza Ferrándiz y Carbonell s/n, 03801 Alcoy (Spain); Department of Textile Engineering, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Fernandes, F., E-mail: b6073@fisica.uminho.pt [Department Physics, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Fernández, J., E-mail: jaferse1@posgrado.upv.es [Departamento de Ingeniería Textil y Papelera, EPS de Alcoy, Universitat Politècnica de València, Plaza Ferrándiz y Carbonell s/n, 03801 Alcoy (Spain); Pastor, M., E-mail: marianapastor88@gmail.com [Department Physics, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Correia, A., E-mail: anacamcorreia@gmail.com [Department Physics, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Souto, A.P., E-mail: souto@det.uminho.pt [Department of Textile Engineering, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Carneiro, J.O., E-mail: carneiro@fisica.uminho.pt [Department Physics, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); and others

    2015-09-15

    Graphical abstract: - Highlights: • Photocatalytic fabrics were produced with reduced graphene oxide (RGO) and TiO{sub 2}. • Charge transfer resistance decreased with the increasing number of RGO layers. • Scanning electrochemical microscopy showed the photoresponse obtained. • Photocatalytic properties were tested with Rhodamine B solutions. • Photocatalytic efficiency increased with the number of RGO layers. - Abstract: The purpose of this work is to obtain photocatalytic fabrics based on reduced graphene oxide (RGO) and TiO{sub 2} coatings on polyester fabrics. The influence of the applied number of RGO coatings on properties such as light absorption, conductivity, electroactivity and photocatalytic properties of the fabrics was established. An improvement of these properties with the number of RGO coatings applied was obtained. FESEM, EDX, XPS and FTIR-ATR showed the incorporation of the TiO{sub 2} nanoparticles on the fabrics. FTIR-ATR showed the formation of a bidentate carboxylic ligand with titanium atoms. The photocatalytic properties of the fabrics were tested with Rhodamine B dye solutions. Photocatalytic efficiency increased with the number of RGO coatings, due to the increased light absorption, and better electrical properties. The charge transfer resistance (R{sub ct}) and its time constant (τ) decreased, indicating a better electron transfer which helps to increase the lifetime of the pair electron/hole.

  14. Solvent-free, visible-light photocatalytic alcohol oxidations applying an organic photocatalyst

    Directory of Open Access Journals (Sweden)

    Martin Obst

    2016-11-01

    Full Text Available A method for the solvent-free photocatalytic conversion of solid and liquid substrates was developed, using a novel rod mill apparatus. In this setup, thin liquid films are realized which is crucial for an effective photocatalytic conversion due to the low penetration depth of light in heterogeneous systems. Several benzylic alcohols were oxidized with riboflavin tetraacetate as photocatalyst under blue light irradiation of the reaction mixture. The corresponding carbonyl compounds were obtained in moderate to good yields.

  15. Mechanistic study of the visible-light-driven photocatalytic inactivation of bacteria by graphene oxide–zinc oxide composite

    International Nuclear Information System (INIS)

    Wu, Dan; An, Taicheng; Li, Guiying; Wang, Wei; Cai, Yuncheng; Yip, Ho Yin; Zhao, Huijun; Wong, Po Keung

    2015-01-01

    Graphical abstract: - Highlights: • The GO–ZnO composites exhibited efficient VLD bacterial inactivation performance. • Strong interfacial interaction existed between GO and ZnO. • GO served as a photosensitizer in the inactivation process. • Excellent antibacterial activity by GO–ZnO composite was shown under sunlight. • An inactivation mechanism based on the GO photosensitizer induction was proposed. - Abstract: The visible-light-driven (VLD) photocatalytic activity of graphene oxide–zinc oxide (GO–ZnO) composite prepared by a simple hydrothermal method was evaluated toward the inactivation of Escherichia coli K-12. The results showed that GO–ZnO composite had excellent VLD photocatalytic bacterial inactivation activity, comparing with those of ZnO and GO, which was attributed to the strong interaction between ZnO and GO in the composite. Accordingly, an interaction induced VLD photocatalytic inactivation mechanism of the strong interaction of GO with ZnO within the GO–ZnO composite was proposed. GO served as a photosensitizer and facilitated the charge separation and transfer, thus boosted the massive production of reactive oxygen species such as ·OH bulk , which was identified as the major reactive species from conduction band of ZnO, and resulted in a remarkable enhancement of bacterial inactivation efficiency. Moreover, GO–ZnO composite showed obviously superior photocatalytic bacterial inactivation within 10 min under natural solar light irradiation, indicating that GO–ZnO composite has great potential in wastewater treatment and environmental protection.

  16. Synthesis and Photocatalytic Properties of Reduced Graphene Oxides Loaded-nano ZnS/CuS Heterostructures

    Directory of Open Access Journals (Sweden)

    ZENG Bin

    2017-12-01

    Full Text Available The reduced graphene oxides(rGO loaded-nano ZnS nanoparticles were fabricated by microwave heating method and by ion exchanged reaction reduced graphene oxides(rGO loaded-nano ZnS/CuS heterostructures were obtained. The structure, morphology were characterized via scanning electron microscopy(SEM, transmission electron microscopy(TEM and X-ray diffraction pattern(XRD. The effect of the mass fraction of graphene oxides, sulfur source and microwave heating time on the morphology and photocatalyitc performance were discussed. The results show that graphene uniformly loaded-nano ZnS/CuS heterostructures are obtained on the condition of graphene mass fraction of 10%, thioacetamide acting as sulfur source, microwave heating time is 30min. rGO-loaded nano ZnS/CuS heterostructures nanoparticles enhance photocatalytic performance with 81.2% decomposition of MO in 150min under visible light, demonstrating the excellent photocatalytic performance. The high visible photocatalytic performances are attributed to photoinduced interfacial charge transfer in the nano heterostructures and their further separation and transfer by rGO.

  17. Comparison of modification strategies towards enhanced charge carrier separation and photocatalytic degradation activity of metal oxide semiconductors (TiO{sub 2}, WO{sub 3} and ZnO)

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. Girish [Department of Physics, Indian Institute of Science, Bengaluru, 560012 Karnataka (India); Department of Chemistry, School of Engineering and Technology, CMR University, Bengaluru, 562149, Karnataka (India); Rao, K.S.R. Koteswara, E-mail: raoksrk@gmail.com [Department of Physics, Indian Institute of Science, Bengaluru, 560012 Karnataka (India)

    2017-01-01

    Graphical abstract: Semiconductor metal oxides: Modifications, charge carrier dynamics and photocatalysis. - Highlights: • TiO{sub 2}, WO{sub 3} and ZnO based photocatalysis is reviewed. • Advances to improve the efficiency are emphasized. • Differences and similarities in the modifications are highlighted. • Charge carrier dynamics for each strategy are discussed. - Abstract: Metal oxide semiconductors (TiO{sub 2}, WO{sub 3} and ZnO) finds unparalleled opportunity in wastewater purification under UV/visible light, largely encouraged by their divergent admirable features like stability, non-toxicity, ease of preparation, suitable band edge positions and facile generation of active oxygen species in the aqueous medium. However, the perennial failings of these photocatalysts emanates from the stumbling blocks like rapid charge carrier recombination and meager visible light response. In this review, tailoring the surface-bulk electronic structure through the calibrated and veritable approaches such as impurity doping, deposition with noble metals, sensitizing with other compounds (dyes, polymers, inorganic complexes and simple chelating ligands), hydrogenation process (annealing under hydrogen atmosphere), electronic integration with other semiconductors, modifying with carbon nanostructures, designing with exposed facets and tailoring with hierarchical morphologies to overcome their critical drawbacks are summarized. Taking into account the materials intrinsic properties, the pros and cons together with similarities and striking differences for each strategy in specific to TiO{sub 2}, WO{sub 3} & ZnO are highlighted. These subtlety enunciates the primacy for improving the structure-electronic properties of metal oxides and credence to its fore in the practical applications. Future research must focus on comparing the performances of ZnO, TiO{sub 2} and WO{sub 3} in parallel to get insight into their photocatalytic behaviors. Such comparisons not only reveal

  18. Liquid-Phase Exfoliation into Monolayered BiOBr Nanosheets for Photocatalytic Oxidation and Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hongjian [Beijing; Huang, Hongwei [Beijing; Xu, Kang [Center; Hao, Weichang [Center; Guo, Yuxi [Beijing; Wang, Shuobo [Beijing; Shen, Xiulin [Beijing; Pan, Shaofeng [Beijing; Zhang, Yihe [Beijing

    2017-09-26

    Monolayered photocatalytic materials have attracted huge research interests in terms of their large specific surface area and ample active sites. Sillén-structured layered BiOX (X = Cl, Br, I) casts great prospects owing to their strong photo-oxidation ability and high stability. Fabrication of monolayered BiOX by a facile, low-cost, and scalable approach is highly challenging and anticipated. Herein, we describe the large-scale preparation of monolayered BiOBr nanosheets with a thickness of ~0.85 nm via a readily achievable liquid-phase exfoliation strategy with assistance of formamide at ambient conditions. The as-obtained monolayered BiOBr nanosheets are allowed diverse superiorities, such as enhanced specific surface area, promoted band structure, and strengthened charge separation. Profiting from these benefits, the advanced BiOBr monolayers not only show excellent adsorption and photodegradation performance for treating contaminants, but also demonstrate a greatly promoted photocatalytic activity for CO2 reduction into CO and CH4. Additionally, monolayered BiOI nanosheets have also been obtained by the same synthetic approach. Our work offers a mild and general approach for preparation of monolayered BiOX, and may have huge potential to be extended to the synthesis of other single-layer two-dimensional materials.

  19. Synthesis of supported silver nano-spheres on zinc oxide nanorods for visible light photocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Saoud, Khaled [Virginia Commonwealth University-Qatar, Doha (Qatar); Alsoubaihi, Rola [Virginia Commonwealth University, Richmond, VA (United States); Bensalah, Nasr [Qatar University, Doha (Qatar); Bora, Tanujjal [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 33, Al-Khoudh-123 (Oman); Bertino, Massimo [Virginia Commonwealth University, Richmond, VA (United States); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 33, Al-Khoudh-123 (Oman)

    2015-03-15

    Highlights: • Synthesis of supported Ag NPs on ZnO nanorods using open vessel microwave reactor. • Use of the Ag/ZnO NPs as an efficient visible light photocatalyst. • Complete degradation of methylene blue in 1 h with 0.5 g/L Ag/ZnO NPs. - Abstract: We report the synthesis of silver (Ag) nano-spheres (NS) supported on zinc oxide (ZnO) nanorods through two step mechanism, using open vessel microwave reactor. Direct reduction of ZnO from zinc nitrates was followed by deposition precipitation of the silver on the ZnO nanorods. The supported Ag/ZnO nanoparticles were then characterized by electron microscopy, X-ray diffraction, FTIR, photoluminescence and UV–vis spectroscopy. The visible light photocatalytic activity of Ag/ZnO system was investigated using a test contaminant, methylene blue (MB). Almost complete removal of MB in about 60 min for doses higher than 0.5 g/L of the Ag/ZnO photocatalyst was achieved. This significant improvement in the photocatalytic efficiency of Ag/ZnO photocatalyst under visible light irradiation can be attributed to the presence of Ag nanoparticles on the ZnO nanoparticles which greatly enhances absorption in the visible range of solar spectrum enabled by surface plasmon resonance effect from Ag nanoparticles.

  20. Fabrication of Z-scheme plasmonic photocatalyst Ag@AgBr/g-C3N4 with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Yang, Yuxin; Guo, Wan; Guo, Yingna; Zhao, Yahui; Yuan, Xing; Guo, Yihang

    2014-01-01

    Graphical abstract: - Highlights: • Z-scheme plasmonic photocatalyst of Ag@AgBr/g-C 3 N 4 is prepared for the first time. • Ag@AgBr/g-C 3 N 4 shows enhanced visible-light photocatalytic activity. • Photocatalytic mechanism based on the experimental results is revealed. • Photocatalytic degradation pathway of MO is put forward. - Abstract: A series of Ag@AgBr grafted graphitic carbon nitride (Ag@AgBr/g-C 3 N 4 ) plasmonic photocatalysts are fabricated through photoreducing AgBr/g-C 3 N 4 hybrids prepared by deposition–precipitation method. The phase and chemical structures, electronic and optical properties as well as morphologies of Ag@AgBr/g-C 3 N 4 heterostructures are well-characterized. Subsequently, the photocatalytic activity of Ag@AgBr/g-C 3 N 4 is evaluated by the degradation of methyl orange (MO) and rhodamin B (RB) under visible-light irradiation. The enhanced photocatalytic activity of Ag@AgBr/g-C 3 N 4 compared with g-C 3 N 4 and Ag@AgBr is obtained and explained in terms of the efficient visible-light utilization efficiency as well as the construction of Z-scheme, which keeps photogenerated electrons and holes with high reduction and oxidation capability, evidenced by photoelectrochemical tests and free radical and hole scavenging experiments. Based on the intermediates identified in the reaction system, the photocatalytic degradation pathway of MO is put forward

  1. Enhanced kinetics of hole transfer and electrocatalysis during photocatalytic oxygen evolution by cocatalyst tuning

    KAUST Repository

    Nurlaela, Ela; Wang, Hai; Shinagawa, Tatsuya; Flanagan, Sean; Ould-Chikh, Samy; Qureshi, Muhammad; Mics, Zoltan; Sautet, Philippe; Le Bahers, Tangui; Canovas, Enrique; Bonn, Mischa; Takanabe, Kazuhiro

    2016-01-01

    Understanding photophysical and electrocatalytic processes during photocatalysis in a powder suspension system is crucial for developing efficient solar energy conversion systems. We report a substantial enhancement by a factor of 3 in photocatalytic effi-ciency for the oxygen evolution reaction (OER) by adding trace amounts (~0.05 wt%) of noble metals (Rh or Ru) to a 2 wt% cobalt oxide-modified Ta3N5 photocatalyst particulate. The optimized system exhibited high quantum efficiencies (QEs) of up to 28 and 8.4% at 500 and 600 nm in 0.1 M Na2S2O8 at pH 14. By isolating the electrochemical components to generate doped cobalt oxide electrodes, the electrocatalytic activity of cobalt oxide when doped with Ru or Rh was improved compared with cobalt oxide, as evidenced by the onset shift for electrochemical OER. Density functional theory (DFT) calculation shows that the ef-fects of a second metal addition perturbs the electronic structure and redox properties in such a way that both hole transfer kinetics and electrocatalytic rates improve. Time resolved terahertz spectroscopy (TRTS) measurement provides evidence of long-lived electron populations (>1 ns; with mobilities μe ~0.1-3 cm2 V-1 s-1), which are not perturbed by the addition of CoOx-related phases. Furthermore, we find that Ta3N5 phases alone suffer ultrafast hole trapping (within 10 ps); the CoOx and M-CoOx decorations most likely induce a kinetic competition between hole transfer toward the CoOx-related phases and trapping in the Ta3N5 phase, which is consistent with the improved OER rates. The present work not only provides a novel way to improve electrocatalytic and photocatalytic performance but also gives additional tools and insight to understand the characteristics of photocatalysts that can be used in a suspension system.

  2. Enhanced kinetics of hole transfer and electrocatalysis during photocatalytic oxygen evolution by cocatalyst tuning

    KAUST Repository

    Nurlaela, Ela

    2016-05-23

    Understanding photophysical and electrocatalytic processes during photocatalysis in a powder suspension system is crucial for developing efficient solar energy conversion systems. We report a substantial enhancement by a factor of 3 in photocatalytic effi-ciency for the oxygen evolution reaction (OER) by adding trace amounts (~0.05 wt%) of noble metals (Rh or Ru) to a 2 wt% cobalt oxide-modified Ta3N5 photocatalyst particulate. The optimized system exhibited high quantum efficiencies (QEs) of up to 28 and 8.4% at 500 and 600 nm in 0.1 M Na2S2O8 at pH 14. By isolating the electrochemical components to generate doped cobalt oxide electrodes, the electrocatalytic activity of cobalt oxide when doped with Ru or Rh was improved compared with cobalt oxide, as evidenced by the onset shift for electrochemical OER. Density functional theory (DFT) calculation shows that the ef-fects of a second metal addition perturbs the electronic structure and redox properties in such a way that both hole transfer kinetics and electrocatalytic rates improve. Time resolved terahertz spectroscopy (TRTS) measurement provides evidence of long-lived electron populations (>1 ns; with mobilities μe ~0.1-3 cm2 V-1 s-1), which are not perturbed by the addition of CoOx-related phases. Furthermore, we find that Ta3N5 phases alone suffer ultrafast hole trapping (within 10 ps); the CoOx and M-CoOx decorations most likely induce a kinetic competition between hole transfer toward the CoOx-related phases and trapping in the Ta3N5 phase, which is consistent with the improved OER rates. The present work not only provides a novel way to improve electrocatalytic and photocatalytic performance but also gives additional tools and insight to understand the characteristics of photocatalysts that can be used in a suspension system.

  3. Photocatalytic oxidation of propylene on La and N codoped TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinfeng; Li, Haiyan; Zong, Lanlan; Li, Qiuye, E-mail: lqybys@163.com; Wang, Xiaodong; Zhang, Min; Yang, Jianjun, E-mail: yangjianjun@henu.edu.cn [Henan University, Key Laboratory for Special Functional Materials (China)

    2015-02-15

    Lanthanum- and nitrogen-codoped TiO{sub 2} photocatalysts was synthesized using orthorhombic nanotubes titanic acid as the precursor by a simple impregnation and subsequent calcination method. The morphology, phase structure, and properties of La- and N-codoped TiO{sub 2} were well characterized by transmission electron microscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, and UV–Vis diffuse reflectance spectra. The La-/N-codoped TiO{sub 2} showed excellent photoactivity of propylene oxidation compared with the single-doped TiO{sub 2} and La-/N-codoped P25 TiO{sub 2} nanoparticles under visible light irradiation. The origin of the enhancement of the visible light-responsive photocatalytic activity was discussed in detail.

  4. Enhanced photocatalytic activity of nano titanium dioxide coated on ethanol-soluble carbon nanotubes

    International Nuclear Information System (INIS)

    Fu, Xiaofei; Yang, Hanpei; He, Kuanyan; Zhang, Yingchao; Wu, Junming

    2013-01-01

    Graphical abstract: Homogenous and dense spreading of TiO 2 on surface modified CNTs and improved photocatalytic performance of TiO 2 was achieved by coupling TiO 2 with ethanol-soluble CNTs. Display Omitted Highlights: ► Ethanol-soluble CNTs were acquired by surface modification. ► Enhanced photoactivity of TiO 2 coated on modified CNTs was obtained. ► Improved activity of TiO 2 is attributed to the intimate contact between TiO 2 and CNTs. ► Dense heterojunctions through Ti–O–CNTs at the interface is proposed. -- Abstract: Surface functionalized carbon nanotubes (CNTs) with ethanol solubility were synthesized and the CNTs–TiO 2 nanocomposites were prepared by coupling of TiO 2 with modified CNTs through a sol–gel method. The as-prepared CNTs and composites were characterized and the composite samples were evaluated for their photocatalytic activity toward the degradation of aqueous methyl orange. It is showed that the acid oxidation of CNTs leads to the embedding of oxygenated functional groups, and as a result, the acid-treated CNTs in turn may serve as chemical reactors for subsequent covalent grafting of octadecylamine. Improved photocatalytic performance of CNTs–TiO 2 composites was obtained, which is mainly attributed to the high dispersion of TiO 2 on ethanol-soluble CNTs and the intimate contact between TiO 2 and CNTs resulted from the dense heterojunctions through the Ti-O-C structure at the interface between TiO 2 and CNTs.

  5. Surface spintronics enhanced photo-catalytic hydrogen evolution: Mechanisms, strategies, challenges and future

    Science.gov (United States)

    Zhang, Wenyan; Gao, Wei; Zhang, Xuqiang; Li, Zhen; Lu, Gongxuan

    2018-03-01

    Hydrogen is a green energy carrier with high enthalpy and zero environmental pollution emission characteristics. Photocatalytic hydrogen evolution (HER) is a sustainable and promising way to generate hydrogen. Despite of great achievements in photocatalytic HER research, its efficiency is still limited due to undesirable electron transfer loss, high HER over-potential and low stability of some photocatalysts, which lead to their unsatisfied performance in HER and anti-photocorrosion properties. In recent years, many spintronics works have shown their enhancing effects on photo-catalytic HER. For example, it was reported that spin polarized photo-electrons could result in higher photocurrents and HER turn-over frequency (up to 200%) in photocatalytic system. Two strategies have been developed for electron spin polarizing, which resort to heavy atom effect and magnetic induction respectively. Both theoretical and experimental studies show that controlling spin state of OHrad radicals in photocatalytic reaction can not only decrease OER over-potential (even to 0 eV) of water splitting, but improve stability and charge lifetime of photocatalysts. A convenient strategy have been developed for aligning spin state of OHrad by utilizing chiral molecules to spin filter photo-electrons. By chiral-induced spin filtering, electron polarization can approach to 74%, which is significantly larger than some traditional transition metal devices. Those achievements demonstrate bright future of spintronics in enhancing photocatalytic HER, nevertheless, there is little work systematically reviewing and analysis this topic. This review focuses on recent achievements of spintronics in photocatalytic HER study, and systematically summarizes the related mechanisms and important strategies proposed. Besides, the challenges and developing trends of spintronics enhanced photo-catalytic HER research are discussed, expecting to comprehend and explore such interdisciplinary research in

  6. Enhanced Photocatalytic Properties of Ag-Loaded N-Doped Tio2 Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Gao Dawei

    2018-03-01

    Full Text Available Highly ordered TiO2 nanotube (TiO2 NT arrays were prepared by anodic oxidizing method on the surface of the Ti substrate. Nitrogen-doped TiO2 nanotube (N-TiO2 NT arrays were carried out by ammonia solution immersion, and Ag nanoparticles loaded N-doped TiO2 nanotube (Ag/N-TiO2 NT arrays were obtained by successive ionic layer adsorption and reaction (SILAR technique. The samples were characterized by the X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, field emission scanning electron microscopy (FESEM, high-resolution transmission electron microscopy (HRTEM, photoluminescence (PL emission spectra, ultraviolet–visible (UV–vis diffuse reflectance spectroscopy (DRS. The result indicated that the diameter and wall thickness of the TiO2 NT are 100–120 and 20–30 nm, respectively. Moreover, the morphology and structure of the highly ordered TiO2 NTs were not affected by N-doping. Furthermore, Ag nanoparticles were evenly deposited on the surface of TiO2 NTs in the form of elemental silver. Finally, the photocatalytic activity of Ag/N-TiO2 NTs was evaluated by degradation of methyl orange (MO under visible-light irradiation. The Ag/N-TiO2 NTs exhibited enhanced photocatalytic properties, which could reach 95% after 90-min irradiation.

  7. Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

    Directory of Open Access Journals (Sweden)

    Subas K. Muduli

    2014-04-01

    Full Text Available A facile, solvothermal synthesis of mesoporous cerium oxide nanospheres is reported for the purpose of the photocatalytic degradation of organic dyes and future applications in sustainable energy research. The earth-abundant, relatively affordable, mixed valence cerium oxide sample, which consists of predominantly Ce7O12, has been characterized by powder X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy, and transmission electron microscopy. Together with N2 sorption experiments, the data confirms that the new cerium oxide material is mesoporous and absorbs visible light. The photocatalytic degradation of rhodamin B is investigated with a series of radical scavengers, suggesting that the mechanism of photocatalytic activity under visible-light irradiation involves predominantly hydroxyl radicals as the active species.

  8. Hydrothermal synthesis of fluorinated anatase TiO_2/reduced graphene oxide nanocomposites and their photocatalytic degradation of bisphenol A

    International Nuclear Information System (INIS)

    Luo, Lijun; Yang, Ye; Zhang, Ali; Wang, Min; Liu, Yongjun; Bian, Longchun; Jiang, Fengzhi; Pan, Xuejun

    2015-01-01

    Graphical abstract: - Highlights: • F–TiO_2–RGO nanocomposites were synthesized via hydrothermal method. • Presence of F ion prevents phase transformation from anatase to rutile. • The adsorbed F"− and RGO improve the photocatalytic activity of TiO_2 synergistically. • The F–TiO_2–RGO nanocomposites were applied to degrade bisphenol A. - Abstract: The surface fluorinated TiO_2/reduced graphene oxide nanocomposites (denoted as F–TiO_2–RGO) were synthesized via hydrothermal method. The as-prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), Raman spectroscopy, Fourier Transform Infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF). The results showed that pure anatase TiO_2 particles were anchored on the surface of reduced graphene oxide. And the HF added during the preparation process can not only prevent phase transformation from anatase to rutile, but also the F"− ion adsorbed on the surface of TiO_2–RGO surface can enhance photocatalytic activity of F–TiO_2–RGO. The photocatalytic activities of F–TiO_2–RGO nanocomposites were evaluated by decomposing bisphenol A under UV light illumination. Under optimal degradation condition, the degradation rate constant of BPA over F–TiO_2–10RGO (0.01501 min"−"1) was 3.41 times than that over P25 (0.00440 min"−"1). The result indicated that the enhanced photocatalytic activity of F–TiO_2–10RGO was ascribed to the adsorbed F ion and RGO in F–TiO_2–RGO composite, which can reduce the recombination rate of the photo-generated electrons and holes synergistically.

  9. Preparation and enhanced photocatalytic activity of carbon nitride/titania(001 vs 101 facets)/reduced graphene oxide (g-C3N4/TiO2/rGO) hybrids under visible light

    Science.gov (United States)

    Huang, Meina; Yu, Jianhua; Hu, Qun; Su, Wenli; Fan, Minguang; Li, Bin; Dong, Lihui

    2016-12-01

    Herein, a novel photocatalyst, anatase TiO2 nanoparticles with both exposed (101) and (001) facets synchronously incorporated with g-C3N4 and graphene, was successfully prepared via a simple one-step solvothermal route. The morphology and structure of as-prepared composites were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Efficiency of the prepared samples was investigated by monitoring the degradation of Methyl Orange (MO), Rhodamine B (RhB) and phenol under visible light irradiation. Improved photocatalytic activity in g-C3N4/TiO2/rGO is observed owing to higher specific surface area and enhanced visible light absorption capability. Most importantly, the in situ g-C3N4 and rGO doping might enhance the interaction among g-C3N4, TiO2 (001 vs 101) and rGO, which generates more synergistic heteroconjunctions in g-C3N4/TiO2/rGO facilitating a fast electron transfer at the interface among them. This synergistic approach could prove useful for the design and development of other visible light active photocatalysts with high chemical stability.

  10. Novel adsorption and photocatalytic oxidation for removal of gaseous toluene by V-doped TiO{sub 2}/PU under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Thanh-Dong; Lee, Byeong-Kyu, E-mail: bklee@ulsan.ac.kr

    2015-12-30

    Highlights: • V doping was used to enhance the photocatalytic activity of TiO{sub 2} photocatalyst. • The enhanced TiO{sub 2} was fixed on porous polyurethane (PU) by chemical bonds. • The PU was used as a substrate to increase the adsorption ability of the photocatalyst. • V-TiO{sub 2}/PU adsorbed and photocatalytically oxidized toluene gas under visible light. • The V/TiO{sub 2} ratio of 6 wt% was optimal for enhancing the photocatalytic activity. - Abstract: In this study, V was used as a dopant to defect into the TiO{sub 2} lattice, leading to formation of Ti{sup 3+} and V{sup 4+} in the lattice. The presence of Ti{sup 3+} and V{sup 4+} introduced into the TiO{sub 2} lattice increased the electron–hole pair generation capacity and electron–hole pair separation efficiency of the TiO{sub 2}, leading to enhancement of the photocatalytic activity of the photocatalyst. Porous polyurethane (PU) was used to immobilize the V-doped TiO{sub 2} by creating chemical bonds. The use of porous substrate contributed to the increased adsorption ability of the enhanced photocatalyst, as well as expanded its application for the removal of toluene from aerosols. Under dark conditions, the V-TiO{sub 2}/PU only exhibited adsorption ability for toluene treatment in aerosol. Under visible light conditions, the V-TiO{sub 2}/PU exhibited high photocatalytic oxidation ability for the removal of toluene in aerosol. The photocatalytic oxidation ability was found to depend on the V to TiO{sub 2} ratio. The optimal V content in V/TiO{sub 2} for enhancing the photocatalytic activity of TiO{sub 2} was determined to be 6 wt%. Even under visible light irradiation, the 6% V-TiO{sub 2}/PU sample could photocatalytically remove 80% of the toluene in 200-ppmV inlet gas, while 89.3% of the removed amount was mineralized into CO{sub 2} and H{sub 2}O.

  11. Synthesis of hierarchical anatase TiO 2 nanostructures with tunable morphology and enhanced photocatalytic activity

    KAUST Repository

    Rahal, Raed; Wankhade, Atul V.; Cha, Dong Kyu; Fihri, Aziz; Ould-Chikh, Samy; Patil, Umesh; Polshettiwar, Vivek

    2012-01-01

    A facile one-pot method to prepare three-dimensional hierarchical nanostructures of titania with good control over their morphologies without the use of hydrofluoric acid is developed. The reaction is performed under microwave irradiation conditions in pure water, and enables enhanced photocatalytic activity. This study indicates that photocatalytic activity depends not only on the surface area but also on the morphology of the titania. © 2012 The Royal Society of Chemistry.

  12. Sequential reduction–oxidation for photocatalytic degradation of tetrabromobisphenol A: Kinetics and intermediates

    International Nuclear Information System (INIS)

    Guo, Yaoguang; Lou, Xiaoyi; Xiao, Dongxue; Xu, Lei; Wang, Zhaohui; Liu, Jianshe

    2012-01-01

    Highlights: ► Sequential photocatalytic reduction–oxidation degradation of TBBPA was firstly examined. ► Different atmospheres were found to have significant effect on debromination reaction. ► A possible sequential photocatalytic reduction–oxidation pathway was proposed. - Abstract: C-Br bond cleavage is considered as a key step to reduce their toxicities and increase degradation rates for most brominated organic pollutants. Here a sequential reduction/oxidation strategy (i.e. debromination followed by photocatalytic oxidation) for photocatalytic degradation of tetrabromobisphenol A (TBBPA), one of the most frequently used brominated flame retardants, was proposed on the basis of kinetic analysis and intermediates identification. The results demonstrated that the rates of debromination and even photodegradation of TBBPA strongly depended on the atmospheres, initial TBBPA concentrations, pH of the reaction solution, hydrogen donors, and electron acceptors. These kinetic data and byproducts identification obtained by GC–MS measurement indicated that reductive debromination reaction by photo-induced electrons dominated under N 2 -saturated condition, while oxidation reaction by photoexcited holes or hydroxyl radicals played a leading role when air was saturated. It also suggested that the reaction might be further optimized for pretreatment of TBBPA-contaminated wastewater by a two-stage reductive debromination/subsequent oxidative decomposition process in the UV-TiO 2 system by changing the reaction atmospheres.

  13. Visible-light photocatalytic activity of graphene oxide-wrapped Bi{sub 2}WO{sub 6} hierarchical microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Jiali; Yu, Hongwen, E-mail: yuhw@iga.ac.cn; Li, Haiyan; Sun, Lei; Zhang, Kexin; Yang, Hongjun

    2015-07-30

    Graphical abstract: - Highlights: • GO/Bi{sub 2}WO{sub 6} are readily fabricated by facile bubbling pretreatment and freeze drying. • GO/Bi{sub 2}WO{sub 6} possess excellent photocatalytic activity under visible light irradiation. • The visible light activity of GO/Bi{sub 2}WO{sub 6} is affected by the amount of GO. • The photostablity of GO is due to the photo-generated electrons transfer to Bi{sub 2}WO{sub 6}. - Abstract: A facile approach of fabricating homogeneous graphene oxide (GO)-wrapped Bi{sub 2}WO{sub 6} microspheres (GO/Bi{sub 2}WO{sub 6}) is developed. The transmission electron microscopy (TEM) results show that a heterojunction interface between GO and Bi{sub 2}WO{sub 6}. The UV–vis diffuse reflection spectra (DRS) reveal that the as-prepared GO/Bi{sub 2}WO{sub 6} composites own more intensive absorption in the visible light range compared with pure Bi{sub 2}WO{sub 6}. These characteristic structural and optical properties endow GO/Bi{sub 2}WO{sub 6} composites with enhanced photocatalytic activity. The enhanced photocatalytic activity of the GO/Bi{sub 2}WO{sub 6} is attributed predominantly to the synergetic effect between GO and Bi{sub 2}WO{sub 6}, causing rapid generation and separation of photo-generated charge carriers.

  14. Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol

    Directory of Open Access Journals (Sweden)

    Jamal Al-Sabahi

    2016-03-01

    Full Text Available Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

  15. Attapulgite-CeO{sub 2}/MoS{sub 2} ternary nanocomposite for photocatalytic oxidative desulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiazhang, E-mail: lixiazhang509@163.com [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory for Environment Functional Materials, Suzhou University of Science and Technology, Suzhou 215009 (China); W.M.Keck Center for Advanced Microscopy and Microanalysis, University of Delaware, Newark, DE 19716 (United States); Zhang, Zuosong [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Yao, Chao [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Lu, Xiaowang [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Zhao, Xiaobing [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory for Environment Functional Materials, Suzhou University of Science and Technology, Suzhou 215009 (China); Ni, Chaoying [W.M.Keck Center for Advanced Microscopy and Microanalysis, University of Delaware, Newark, DE 19716 (United States)

    2016-02-28

    Graphical abstract: - Highlights: • Novel attapulgite(ATP)-CeO{sub 2}/MoS{sub 2} ternary nanocomposites were fabricated. • ATP possessed outstanding adsorption property and enhanced the stability of the network structure. • CeO{sub 2}/MoS{sub 2} couples facilitated the separation of photo-induced electrons and holes. • Mass ratio of CeO{sub 2}/MoS{sub 2} influenced the photocatalytic oxidation desulfurization. - Abstract: Novel attapulgite(ATP)-CeO{sub 2}/MoS{sub 2} ternary nanocomposites were synthesized by microwave assisted assembly method. The structures of the nanocomposites were characterized by XRD, FT-IR, UV–vis, XPS and in situ TEM. The photocatalytic activities of ATP-CeO{sub 2}/MoS{sub 2} composites were investigated by degradating dibenzothiophene (DBT) in gasoline under visible light irradiation. The effect of the mass ratio of CeO{sub 2} to MoS{sub 2} on photocatalytic activity was investigated. The results indicate that the three-dimensional network structure is firmly constructed by ATP skeleton, CeO{sub 2} particles and MoS{sub 2} nanosheet which effectively increase the surface area of the composites and promote the separation of electrons and holes by resulting electronic transmission channels of multi-channel in space. The degradation rate of DBT can reach 95% under 3 h irradiation when the mass ratio of CeO{sub 2}/MoS{sub 2} is 4/10. A plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite is put forward.

  16. Facile Synthesis of Au Nanocube-CdS Core-Shell Nanocomposites with Enhanced Photocatalytic Activity

    Science.gov (United States)

    Liu, Xiao-Li; Liang, Shan; Li, Min; Yu, Xue-Feng; Zhou, Li; Wang, Qu-Qua

    2014-06-01

    Au nanocube-CdS core-shell nanocomposites are prepared by using a one-pot method in aqueous phase with cetyltrimethylammonium bromide as the surfactant. The extinction properties and photocatalytic activity of Au-CdS nanocomposites are investigated. Compared with the pure Au nanocubes, the Au-CdS nanocomposites exhibit enhanced extinction intensity. Compared with CdS nanoparticles, the Au-CdS nanocomposites exhibit improved photocatalytic activity. Furthermore, the photocatalytic efficiency is even better with the increase in the core size of the Au-CdS nanocomposites. Typically, the photocatalytic efficiency of the Au-CdS with 62 nm sized Au nanocubes is about two times higher than that of the pure CdS. It is believed that the Au-CdS nanocomposites may find potential applications in environmental fields, and this synthesis method can be extended to prepare a wide variety of functional composites with Au cores.

  17. Nest-like structures of Sr doped Bi2WO6: Synthesis and enhanced photocatalytic properties

    International Nuclear Information System (INIS)

    Liu Ying; Wang Weimin; Fu Zhengyi; Wang Hao; Wang Yucheng; Zhang Jinyong

    2011-01-01

    Highlights: → Bi 2 WO 6 with 3D nest-like structures was obtained without the presence of templates but after Sr-doping, which represents a marked improvement over previous reports. → The products showed enhanced photocatalytic properties over pure Bi 2 WO 6 . → Samples subsequently thermal treated at 500 deg. C show better photocatalytic activities. - Abstract: A series of Sr-doped Bi 2 WO 6 with three-dimensional (3D) nest-like structures were synthesized through simple hydrothermal route and characterized by XRD, FESEM, TEM, XPS, UV-vis DRS, etc. Morphology observation revealed that the as-synthesized Bi 2 WO 6 were self-assembled three-dimensional (3D) nest-like structures, which were constructed from nanoplates. UV-vis diffuse reflectance spectra indicated that the samples had absorption in both UV and visible light areas. Their photocatalytic activities were evaluated by photodegradation of rhodamine B (RhB) under UV and visible light irradiation (λ > 420 nm). The photocatalytic properties were enhanced after Sr doping. Samples subsequently thermal treated at 500 deg. C showed higher photocatalytic activities. The reasons for the differences in the photocatalytic activities of these nest-like Bi 2 WO 6 microstructures were further investigated.

  18. Photocatalytic activity of PANI loaded coordination polymer composite materials: Photoresponse region extension and quantum yields enhancement via the loading of PANI nanofibers on surface of coordination polymer

    International Nuclear Information System (INIS)

    Cui, Zhongping; Qi, Ji; Xu, Xinxin; Liu, Lu; Wang, Yi

    2013-01-01

    To enhance photocatalytic property of coordination polymer in visible light region, polyaniline (PANI) loaded coordination polymer photocatalyst was synthesized through in-situ chemical oxidation of aniline on the surface of coordination polymer. The photocatalytic activity of PANI loaded coordination polymer composite material for degradation of Rhodamine B (RhB) was investigated. Compared with pure coordination polymer photocatalyst, which can decompose RhB merely under UV light irradiation, PANI loaded coordination polymer photocatalyst displays more excellent photocatalytic activity in visible light region. Furthermore, PANI loaded coordination polymer photocatalyst exhibits outstanding stability during the degradation of RhB. - Graphical abstract: PANI loaded coordination polymer composite material, which displays excellent photocatalytic activity under visible light was firstly synthesized through in-situ chemical oxidation of aniline on surface of coordination polymer. Display Omitted - Highlights: • This PANI loaded coordination polymer composite material represents the first conductive polymer loaded coordination polymer composite material. • PANI/coordination polymer composite material displays more excellent photocatalytic activity for the degradation of MO in visible light region. • The “combination” of coordination polymer and PANI will enable us to design high-activity, high-stability and visible light driven photocatalyst in the future

  19. Solar photocatalytic water oxidation over Ag3PO4/g-C3N4 composite materials mediated by metallic Ag and graphene

    Science.gov (United States)

    Cui, Xingkai; Tian, Lin; Xian, Xiaozhai; Tang, Hua; Yang, Xiaofei

    2018-02-01

    Solar-driven water splitting over semiconductor-based photocatalysts provides direct conversion of solar energy to chemical energy, in which electron-hole separation and charge transport are critical for enhancing the photocatalytic activity of semiconducting materials. Moreover, the search for active photocatalysts that efficiently oxidize water remains a challenging task. Here, we demonstrate that a series of Ag3PO4/Ag/graphene/graphitic carbon nitride (g-C3N4) heterostructured materials can drive photocatalytic water oxidation efficiently under LED illumination. The water oxidation behavior of as-prepared composite photocatalysts in relation to the added amount of g-C3N4 and the roles of electron mediators was investigated in detail. Based on the illuminated Z-scheme photocatalytic mechanism, the photogenerated electrons and holes can be separated effectively and the electron-hole recombination of bulk material is suppressed. The reduced metallic Ag nanoparticles were found to function as the center for the accumulation of electrons from Ag3PO4 and holes from g-C3N4. By exploiting the proper addition of g-C3N4 into the composite, photocatalytic oxygen evolution performance over the heterostructured materials could be suitably tuned, which resulted in highly efficient water oxidation.

  20. Conversion and Estrogenicity of 17β-estradiol During Photolytic/Photocatalytic Oxidation and Catalytic Wet-air Oxidation.

    Science.gov (United States)

    Bistan, Mirjana; Tišler, Tatjana; Pintar, Albin

    2012-06-01

    Estrogen 17β-estradiol (E2), produced by human body and excreted into municipal wastewaters, belongs to the group of endocrine disrupting compounds that are resistant to biological degradation. The aim of this study was to assess the efficiency of E2 removal from aqueous solutions by means of catalytic wet-air oxidation (CWAO) and photolytic/photocatalytic oxidation. CWAO experiments were conducted in a trickle-bed reactor at temperatures up to 230 °C and oxygen partial pressure of 10 bar over TiO2 and Ru/TiO2 solids. Photolytic/photocatalytic oxidation was carried out in a batch slurry reactor employing a TiO2 P-25 (Degussa) catalyst under visible or UV light. HPLC analysis and yeast estrogen screen assay were used to evaluate the removal of E2 and estrogenicity of treated samples. The latter was completely removed during photolytic/photocatalytic oxidation under UV (365 nm) light and photocatalytic oxidation under visible light. In CWAO experiments, complete removal of both E2 and estrogenicity from the feed solution were noticed in the presence of TiO2 and Ru/TiO2 catalysts.

  1. Cuprous oxide created on sepiolite: Preparation, characterization, and photocatalytic activity in treatment of red water from 2,4,6-trinitrotoluene manufacturing

    International Nuclear Information System (INIS)

    Zhu, Qingwei; Zhang, Yihe; Lv, Fengzhu; Chu, Paul K.; Ye, Zhengfan; Zhou, Fengshan

    2012-01-01

    Highlights: ► Cu 2 O crystals were firstly created on the natural sepiolite fibers. ► The structures of the sepiolite are altered when acidized, benefiting the immobility of cuprous oxide crystals. ► The carrier sepiolite improves efficiently the photocatalytic activity of cuprous oxide crystals. ► Cu 2 O/sepiolite composites show superior photocatalytic activity for the degradation of red water. - Abstract: Cuprous oxide is firstly created on acidized sepiolite (AS) by a simple deposition method for photocatalytic degradation of the red water produced from 2,4,6-trinitrotoluene (TNT) manufacturing. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), ultraviolet-visible diffuse reflection absorptive spectroscopy (UV–vis/DRS), and Fourier transform infrared (FT-IR) spectroscopy are used to characterize the photocatalyst composites. Gas chromatography/mass spectrometry (GC/MS) is employed to determine the organic constituents in the red water. The results show that the cuprous oxide particles can be immobilized on the surface of the AS fibers and the structure of the AS is altered when cuprous oxide interacts with AS via chemical reactions besides physical adsorption. The AS improves the optical properties of cuprous oxide and red-shifts the band gap thereby enhancing the utilization of visible light. The Cu 2 O/AS composites demonstrate excellent photocatalytic performance in the degradation of red water. 87.0% of red water can be photocatalytically degraded by Cu 2 O/AS after illumined for 5 h and a majority of organic components of red water except 1,3,5-trinitrobenzene were degraded according to GC–MS analysis.

  2. Indoor air purification using heterogeneous photocatalytic oxidation. Part I: Experimental study

    NARCIS (Netherlands)

    Yu, Q.; Brouwers, H.J.H.

    2009-01-01

    Heterogeneous photocatalytic oxidation (PCO) has shown to be a promising air purifying technology in outdoor conditions using TiO2 as photocatalyst activated with UV light. Also to indoor air quality more and more attention is paid because of the very important role it plays on human health, and it

  3. Using Photocatalytic Oxidation and Analytic Techniques to Remediate Lab Wastewater Containing Methanol

    Science.gov (United States)

    Xiong, Qing; Luo, Mingliang; Bao, Xiaoming; Deng, Yurong; Qin, Song; Pu, Xuemei

    2018-01-01

    This experiment is dedicated to second-year and above undergraduates who are in their experimental session of the analytical chemistry course. Grouped students are required to use a TiO[subscript 2] photocatalytic oxidation process to treat the methanol-containing wastewater that resulted from their previous HPLC experiments. Students learn to…

  4. Studying Impact of Different Precipitating Agents on Crystal Structure, Morphology and Photocatalytic Activity of Bismuth Oxide

    Directory of Open Access Journals (Sweden)

    Yayuk Astuti

    2017-10-01

    How to Cite: Astuti, Y., Arnelli, Pardoyo, Fauziyah, A., Nurhayati, S., Wulansari, A.D., Andianingrum, R., Widiyandari, H., Bhaduri, G.A. (2017. Studying Impact of Different Precipitating Agents on Crystal Structure, Morphology and Photocatalytic Activity of Bismuth Oxide. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (3: 478-484 (doi:10.9767/bcrec.12.3.1144.478-484

  5. Experimental research on photocatalytic oxidation air purification technology applied to aircraft cabins

    DEFF Research Database (Denmark)

    Sun, Yuexia; Fang, Lei; Wyon, David P.

    2005-01-01

    The experiment presented in this report was performed in a simulated aircraft cabin to evalu-ate the air cleaning effects of two air purification devices using Photocatalytic Oxidation (PCO) technology. Objective physical, chemical and physiological measurements and subjec-tive human assessments ...

  6. Indoor air purificaton using heterogeneous photocatalytic oxidation, Part 2: Kinetic study

    NARCIS (Netherlands)

    Yu, Q.; Ballari, M.; Brouwers, H.J.H.

    2010-01-01

    In part I to this article [1], the application of the heterogeneous photocatalytic oxidation (PCO) theory for the indoor air quality improvement was presented. With a modified TiO2 that can be activated by visible light as the photocatalyst coated on a special wall paper, and one typical indoor air

  7. Cyclohexane selective photocatalytic oxidation by anatase TiO2: influence of particle size and crystallinity

    NARCIS (Netherlands)

    Carneiro, J.T.; Carneiro, Joana T.; Almeida, A.R.; Almeida, Ana R.; Moulijn, Jacob A.; Mul, Guido

    2010-01-01

    A systematic study is presented on the effect of crystallite size of Anatase (Hombikat, Sachtleben), varied by calcination at different temperatures up to 800 °C, on photocatalytic activity in cyclohexane selective oxidation. Two different reactors were used to test the materials: a top illumination

  8. Treatment of secondary effluent by sequential combination of photocatalytic oxidation with ceramic membrane filtration.

    Science.gov (United States)

    Song, Lili; Zhu, Bo; Jegatheesan, Veeriah; Gray, Stephen; Duke, Mikel; Muthukumaran, Shobha

    2018-02-01

    The aim of the present work was to experimentally evaluate an alternative advanced wastewater treatment system, which combines the action of photocatalytic oxidation with ceramic membrane filtration. Experiments were carried out using laboratory scale TiO 2 /UV photocatalytic reactor and tubular ceramic microfiltration (CMF) system to treat the secondary effluent (SE). A 100-nm pore size CMF membrane was investigated in cross flow mode under constant transmembrane pressure of 20 kPa. The results show that specific flux decline of CMF membrane with and without TiO 2 /UV photocatalytic treatment was 30 and 50%, respectively, after 60 min of filtration. Data evaluation revealed that the adsorption of organic compounds onto the TiO 2 particles was dependent on the pH of the suspension and was considerably higher at low pH. The liquid chromatography-organic carbon detector (LC-OCD) technique was used to characterise the dissolved organic matter (DOM) present in the SE and was monitored following photocatalysis and CMF. The results showed that there was no removal of biopolymers and slight removal of humics, building blocks and the other oxidation by-products after TiO 2 /UV photocatalytic treatment. This result suggested that the various ions present in the SE act as scavengers, which considerably decrease the efficiency of the photocatalytic oxidation reactions. On the other hand, the CMF was effective for removing 50% of biopolymers with no further removal of other organic components after photocatalytic treatment. Thus, the quantity of biopolymers in SE has an apparent correlation with the filterability of water samples in CMF.

  9. Enhanced visible light photocatalytic property of red phosphorus via surface roughening

    International Nuclear Information System (INIS)

    Li, Weibing; Yue, Jiguang; Hua, Fangxia; Feng, Chang; Bu, Yuyu; Chen, Zhuoyuan

    2015-01-01

    Highlights: • Photocatalytic RhB degradation of red phosphorus was studied for the first time. • Surface rough can increase the photocatalysis reaction active sites. • Surface rough red phosphorus possesses high photocatalytic performance. • Surface rough red phosphorus has high industrial application value. - Abstract: Red phosphorus with rough surface (SRP) was prepared by catalyst-assisted hydrothermal synthesis using Co 2+ catalyst. The photocatalytic Rhodamine B (RhB) degradation of red phosphorus (RP) and SRP was studied for the first time in this work. Rough surface can enhance the dye adsorption ability of RP. About 75% RhB was absorbed by SRP after 30-min adsorption in 100 ml RhB solution with concentration of 10 mg l −1 in dark. After only 10 min of illumination by visible light, more than 95% RhB was degraded, indicating that SRP has a great application potential in the area of photocatalysis. The photocatalytic RhB degradation properties of RP are much weaker than those of SRP. The increase of the number of the active sites for the photocatalytic reactions, the electron mobility and the lifetime of the photogenerated electrons cause the significant improvement of the photocatalytic performance of SRP based on the experimental results obtained

  10. Enhanced visible light photocatalytic property of red phosphorus via surface roughening

    Energy Technology Data Exchange (ETDEWEB)

    Li, Weibing, E-mail: lwbing@qust.edu.cn [School of Environment and Safety Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042 (China); Yue, Jiguang; Hua, Fangxia; Feng, Chang [School of Environment and Safety Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042 (China); Bu, Yuyu; Chen, Zhuoyuan [Key Laboratory of Marine Environmental Corrosion and Bio-fouling, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071 (China)

    2015-10-15

    Highlights: • Photocatalytic RhB degradation of red phosphorus was studied for the first time. • Surface rough can increase the photocatalysis reaction active sites. • Surface rough red phosphorus possesses high photocatalytic performance. • Surface rough red phosphorus has high industrial application value. - Abstract: Red phosphorus with rough surface (SRP) was prepared by catalyst-assisted hydrothermal synthesis using Co{sup 2+} catalyst. The photocatalytic Rhodamine B (RhB) degradation of red phosphorus (RP) and SRP was studied for the first time in this work. Rough surface can enhance the dye adsorption ability of RP. About 75% RhB was absorbed by SRP after 30-min adsorption in 100 ml RhB solution with concentration of 10 mg l{sup −1} in dark. After only 10 min of illumination by visible light, more than 95% RhB was degraded, indicating that SRP has a great application potential in the area of photocatalysis. The photocatalytic RhB degradation properties of RP are much weaker than those of SRP. The increase of the number of the active sites for the photocatalytic reactions, the electron mobility and the lifetime of the photogenerated electrons cause the significant improvement of the photocatalytic performance of SRP based on the experimental results obtained.

  11. Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Kartsonakis, I. A., E-mail: ikartsonakis@ims.demokritos.gr; Kontogiani, P.; Pappas, G. S.; Kordas, G. [NCSR ' DEMOKRITOS' , Sol-Gel Laboratory, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems (Greece)

    2013-06-15

    This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 {+-} 15 and 221 {+-} 10 nm, respectively, were synthesized using emulsion polymerization and the sol-gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue-black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

  12. Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

    International Nuclear Information System (INIS)

    Kartsonakis, I. A.; Kontogiani, P.; Pappas, G. S.; Kordas, G.

    2013-01-01

    This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 ± 15 and 221 ± 10 nm, respectively, were synthesized using emulsion polymerization and the sol–gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue–black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

  13. Photocatalytic and chemical oxidation of organic compounds in supercritical carbon dioxide. Progress report for FY97

    Energy Technology Data Exchange (ETDEWEB)

    Blake, D.M.; Bryant, D.L.; Reinsch, V.

    1997-09-30

    disposal and using makeup scCO{sub 2}. A chemical polishing operation can reduce the release of CO{sub 2} from the process. It can also reduce the consumption of reagents that may be used in the process to enhance extraction and cleaning. A polishing operation will also reduce or avoid formation of an additional waste stream. Photocatalytic and other photochemical oxidation chemistry have not been investigated in scCO{sub 2}. The large base of information for these reactions in water, organic solvents, or air suggest that the chemistry will work in carbon dioxide. There are compelling reasons to believe that the properties of scCO{sub 2} should increase the performance of photocatalytic chemistry over that found in more conventional fluid phases.'

  14. Photocatalytic and chemical oxidation of organic compounds in supercritical carbon dioxide. Progress report for FY97

    International Nuclear Information System (INIS)

    Blake, D.M.; Bryant, D.L.; Reinsch, V.

    1997-01-01

    . A chemical polishing operation can reduce the release of CO 2 from the process. It can also reduce the consumption of reagents that may be used in the process to enhance extraction and cleaning. A polishing operation will also reduce or avoid formation of an additional waste stream. Photocatalytic and other photochemical oxidation chemistry have not been investigated in scCO 2 . The large base of information for these reactions in water, organic solvents, or air suggest that the chemistry will work in carbon dioxide. There are compelling reasons to believe that the properties of scCO 2 should increase the performance of photocatalytic chemistry over that found in more conventional fluid phases.'

  15. Ag modified LaCoO3 perovskite oxide for photocatalytic application

    Science.gov (United States)

    Jayapandi, S.; Prakasini, V. Anitha; Anitha, K.

    2018-04-01

    The present investigation has been carried out to develop a novel photocatalytic material based on lanthanum cobaltite (LaCoO3) and silver (Ag) doped LaCoO3 perovskite oxide. Pure LaCoO3 and 5 Mol% Ag doped LaCoO3 (Ag-LaCoO3) have been synthesized by simple co-precipitation method and characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) and photoluminescence (PL) techniques and its photocatalytic activity was evaluated by photodegradation of methylene blue under sunlight irradiation. The observed XRD, UV and PL results indicate that Ag influences on the crystallite size and absorption coefficient of LaCoO3 perovskite oxide. The percentage of dye degradations was calculated as 60% and 99 % for LaCoO3 and 5 Mol% Ag-LaCoO3 pervoskite oxides respectively for 10 minutes (10 min) exposure to sunlight, which indicates that 5 mol% of Ag-LaCoO3, has better photodegradation activity. Hence, the present investigation confirms that Ag influences the photocatalytic activity of a material and the observations will be helpful for further developing new photocatalytic materials.

  16. Effects of donor doping and acceptor doping on rutile TiO2 particles for photocatalytic O2 evolution by water oxidation

    Science.gov (United States)

    Amano, Fumiaki; Tosaki, Ryosuke; Sato, Kyosuke; Higuchi, Yamato

    2018-02-01

    Crystalline defects of photocatalyst particles may be considered to be the recombination center of photoexcited electrons and holes. In this study, we investigated the photocatalytic activity of cation-doped rutile TiO2 photocatalysts for O2 evolution from an aqueous silver nitrate solution under ultraviolet light irradiation. The photocatalytic activity of rutile TiO2 was enhanced by donor doping of Ta5+ and Nb5+ with a valence higher than that of Ti4+, regardless of increased density of electrons and Ti3+ species (an electron trapped in Ti4+ sites). Conversely, acceptor doping of lower valence cations such as In3+ and Ga3+ decreased photocatalytic activity for O2 evolution by water oxidation. The doping of equal valence cations such as Sn4+ and Ge4+ hardly changed the activity of non-doped TiO2. This study demonstrates that Ti3+ species, which is a crystalline defect, enhanced the photocatalytic activity of semiconductor oxides, for example rutile TiO2 with large crystalline size.

  17. Graphitic carbon nitride/Cu2O heterojunctions: Preparation, characterization, and enhanced photocatalytic activity under visible light

    International Nuclear Information System (INIS)

    Tian, Yanlong; Chang, Binbin; Fu, Jie; Zhou, Baocheng; Liu, Jiyang; Xi, Fengna; Dong, Xiaoping

    2014-01-01

    As a metal-free semiconductor material, graphitic carbon nitride (C 3 N 4 ), the high recombination rate of photogenerated charges and insufficient sunlight absorption limit its solar-based photocatalytic activity. Here, we reported the heterojunctions of C 3 N 4 –Cu 2 O with a p–n junction structure, which was synthesized by a hydrothermal method. The HR-TEM result revealed an intimate interface between C 3 N 4 and Cu 2 O in the heterojunction, and UV–vis diffuse reflection spectra showed their extended spectral response in the visible region compared with pure C 3 N 4 . These excellent structural and spectral properties, as well as p–n junction structures, endowed the C 3 N 4 –Cu 2 O heterojunctions with enhanced photocatalytic activities. The possible photocatalytic mechanism that photogenerated holes as the mainly oxidant species in photocatalysis was proposed base on the trapping experiments. - Highlights: • A hydrothermal method was used to prepare C3N 4 –Cu 2 O heterojunction. • The resulting heterojunction possesses broader absorption in the visible region. • The material owns a high visible light activity and stability for dye degradation

  18. TiO2 promoted by two different non-noble metal cocatalysts for enhanced photocatalytic H2 evolution

    International Nuclear Information System (INIS)

    Lin, Jing-Dong; Yan, Shi; Huang, Qin-Dong; Fan, Mei-Ting; Yuan, You-Zhu; Tan, Timothy Thatt-Yang; Liao, Dai-Wei

    2014-01-01

    TiO 2 photocatalysts modified by cobalt and nickel cocatalysts were prepared via polymerized complex method (PCM) and evaluated by photocatalytic hydrogen evolution. Hydrogen generation in 6 h for the TiO 2 promoted by cobalt and nickel (0.1%Co + 0.2%Ni/TiO 2 ) is about two times (2456 μmol H 2 ) compared to that of TiO 2 promoted only by cobalt (1180 μmol H 2 for 0.1%Co/TiO 2 ) or nickel (1127 μmol H 2 for 0.2%Ni/TiO 2 ), and mechanically mixed TiO 2 promoted by cobalt and TiO 2 promoted by nickel (0.1%Co/TiO 2 :0.2%Ni/TiO 2 = 1:1 (m/m), 1282 μmol H 2 ). The high photocatalytic H 2 evolution activity over TiO 2 promoted by cobalt and nickel is ascribed to enhanced photo response due to the presence of cobalt and nickel impurity level, and effective separation of photogenerated electrons and holes due to the synergistic effect of cobalt and nickel, which serve as active sites for H 2 evolution reaction (HER) and oxidation reaction (OR) respectively. This study demonstrates a viable strategy to design more active photocatalysts for photocatalytic H 2 evolution by substituting noble metals with more abundant elements using as HER and OR cocatalysts, respectively.

  19. In situ generated gas bubble-assisted modulation of the morphologies, photocatalytic, and magnetic properties of ferric oxide nanostructures synthesized by thermal decomposition of iron nitrate

    International Nuclear Information System (INIS)

    Tong Guoxiu; Guan Jianguo; Xiao Zhidong; Huang Xing; Guan Yao

    2010-01-01

    Ferric oxide (Fe 2 O 3 ) complex nanoarchitectures with high BET specific surface area, superior photocatalytic activity and modulated magnetic properties are facilely synthesized via controlled thermal decomposition of iron(III) nitrate nonahydrate. The products are characterized by X-ray diffraction, Fourier-transforming infrared spectra, field-emission scanning electron microscope, field-emission high-resolution transmission electron microscope, and nitrogen physisorption and micrometrics analyzer. The corresponding photocatalytic activity and static magnetic properties are also evaluated by measuring the photocatalytic degradation of Rhodamine B aqueous solution under visible light illumination and vibrating sample magnetometer, respectively. Simply tuning the decomposition temperature can conveniently modulate the adsorbing/desorbing behaviors of the in situ generated gases on the nucleus surfaces, and consequently the crystalline structures and morphologies of the Fe 2 O 3 complex nanoarchitectures. The as-prepared Fe 2 O 3 complex nanoarchitectures show strong crystal structure and/or morphology-dependent photocatalytic and magnetic performances. The Fe 2 O 3 complex nanoarchitectures with high specific surface area and favorable crystallization are found to be beneficial for improving the photocatalytic activity. This work not only reports a convenient and low-cost decomposition procedure and a novel formation mechanism of complex nanoarchitectures but also provides an efficient route to enhance catalytic and magnetic properties of Fe 2 O 3 .

  20. A comprehensive study on photocatalytic activity of supported Ni/Pb sulfide and oxide systems onto natural zeolite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Babaahamdi-Milani, Majid [Department of Chemistry, Shahreza Branch, Islamic Azad University, P.O. Box 311-86145, Shahreza, Isfahan (Iran, Islamic Republic of); Young Researchers and Elite Club, Shahreza Branch, Islamic Azad University, Shahreza (Iran, Islamic Republic of); Nezamzadeh-Ejhieh, Alireza, E-mail: arnezamzadeh@iaush.ac.ir [Department of Chemistry, Shahreza Branch, Islamic Azad University, P.O. Box 311-86145, Shahreza, Isfahan (Iran, Islamic Republic of); Young Researchers and Elite Club, Shahreza Branch, Islamic Azad University, Shahreza (Iran, Islamic Republic of); Razi Chemistry Research Center (RCRC), Shahreza Branch, Islamic Azad University, Isfahan (Iran, Islamic Republic of)

    2016-11-15

    Highlights: • Increase in photocatalytic activity of hybridized/supported PbO/NiO and PbS/NiS systems with respect to semiconductors alone. • Higher efficiency of PbO/NiO than PbS/NiS. • Positive role of p-n junction for enhancement of photocatalytic activity of the used semiconductors. - Abstract: The Ni(II)-Pb(II) exchanged clinoptilolite nanoparticles (NCP) were transformed to corresponding oxides and sulfides via calcination and sulfiding processes, respectively. The obtained catalysts were characterized by XRD, FT-IR, TEM and DRS and used in photodegradation of p-nitrophenol (4-NP) aqueous solution under Hg-lamp irradiation. Results showed considerable increase in activity of the coupled semiconductors with respect to monocomponent one. In NiO-PbO-NCP system, conduction band (CB) of NiO is enough negative for easily migration of photogenerated electrons to CB-PbO level, while such phenomena take place from more negative CB-PbS level to CB-NiS level in NiS-PbS-NCP. These phenomena significantly prevented from electron-hole recombination which increased photocatalytic activity of the coupled semiconductors. Best photodegradation activities obtained by NiO{sub 1.3%}–PbO{sub 14.7%}-NCP and NiS{sub 2.1%}–PbS{sub 10.0%}-NCP, confirming semiconductors' mass-ratio dependence of the photocatalytic process. The supported coupled semiconductors showed blue shifts in band gap energies with respect to the bulk semiconductors which confirm formation of semiconductors nanoparticles inside the zeolite framework. The highest degradation percentage of 4-NP was obtained at: 0.5 g L{sup −1} photocatalysts, 15 mg L{sup −1} 4-NP at pH 7.5.

  1. Preparation of a Leaf-Like BiVO4-Reduced Graphene Oxide Composite and Its Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Shimin Xiong

    2017-01-01

    Full Text Available We prepared a unique leaf-like BiVO4-reduced graphene oxide (BiVO4-rGO composite with prominent adsorption performance and photocatalytic ability by a single-step method. Multiple characterization results showed that the leaf-like BiVO4 with average diameter of about 5 um was well dispersed on the reduced graphene oxide sheet, which enhanced the transportation of photogenerated electrons into BiVO4, thereby leading to efficient separation of photogenerated carriers in the coupled graphene-nanocomposite system. The characterization and experiment results also indicated that the outstanding adsorption ability of such composite was closely associated with the rough surface of the leaf-like BiVO4 and doped rGO. The surface photocurrent spectroscopy and transient photocurrent density measurement results demonstrated that the doped rGO enhanced separation efficiency and transfer rate of photogenerated charges. As a result, the BiVO4-rGO exhibited higher photocatalytic capacity toward the degradation of rhodamine B dye under visible-light irradiation compared with pure BiVO4 and P25.

  2. Enhanced photocatalytic performance of CeO2-TiO2 nanocomposite for degradation of crystal violet dye and industrial waste effluent

    Science.gov (United States)

    Zahoor, Mehvish; Arshad, Amara; Khan, Yaqoob; Iqbal, Mazhar; Bajwa, Sadia Zafar; Soomro, Razium Ali; Ahmad, Ishaq; Butt, Faheem K.; Iqbal, M. Zubair; Wu, Aiguo; Khan, Waheed S.

    2018-03-01

    This study presents the synthesis of CeO2-TiO2 nanocomposite and its potential application for the visible light-driven photocatalytic degradation of model crystal violet dye as well as real industrial waste water. The ceria-titania (CeO2-TiO2) nanocomposite material was synthesised using facile hydrothermal route without the assistance of any template molecule. As-prepared composite was characterised by SEM, TEM, HRTEM, XRD, XPS for surface features, morphological and crystalline characters. The formed nanostructures were determined to possess crystal-like geometrical shape and average size less than 100 nm. The as-synthesised nanocomposite was further investigated for their heterogeneous photocatalytic potential against the oxidative degradation of CV dye taken as model pollutant. The photo-catalytic performance of the as-synthesised material was evaluated both under ultra-violet as well as visible light. Best photocatalytic performance was achieved under visible light with complete degradation (100%) exhibited within 60 min of irradiation time. The kinetics of the photocatalytic process were also considered and the reaction rate constant for CeO2-TiO2 nanocomposite was determined to be 0.0125 and 0.0662 min-1 for ultra-violet and visible region, respectively. In addition, the as-synthesised nanocomposite demonstrated promising results when considered for the photo-catalytic degradation of coloured industrial waste water collected from local textile industry situated in Faisalabad region of Pakistan. Enhanced photo-catalytic performance of CeO2-TiO2 nanocomposite was proposed owing to heterostructure formation leading to reduced electron-hole recombination.

  3. Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Xiaofeng Wu

    2016-02-01

    Full Text Available Semiconductor TiO2 photocatalysis has attracted much attention due to its potential application in solving the problems of environmental pollution. In this paper, thiourea (CH4N2S modified anatase TiO2 nanorods were fabricated by calcination of the mixture of TiO2 nanorods and thiourea at 600 °C for 2 h. It was found that only N element was doped into the lattice of TiO2 nanorods. With increasing the weight ratio of thiourea to TiO2 (R from 0 to 8, the light-harvesting ability of the photocatalyst steady increases. Both the crystallization and photocatalytic activity of TiO2 nanorods increase first and then decrease with increase in R value, and R2 sample showed the highest crystallization and photocatalytic activity in degradation of Brilliant Red X3B (X3B and Rhodamine B (RhB dyes under visible light irradiation (λ > 420 nm. The increased visible-light photocatalytic activity of the prepared N-doped TiO2 nanorods is due to the synergistic effects of the enhanced crystallization, improved light-harvesting ability and reduced recombination rate of photo-generated electron-hole pairs. Note that the enhanced visible photocatalytic activity of N-doped nanorods is not based on the scarification of their UV photocatalytic activity.

  4. Carbon dots/BiOCl films with enhanced visible light photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Weitian; Yu, Xiang; Shen, Yinghua; Chen, Hongbin; Zhu, Yi, E-mail: tzhury@jnu.edu.cn; Zhang, Yuanming [Jinan University, Department of Chemistry (China); Meng, Hui [Jinan University, Siyuan laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Department of Physics (China)

    2017-02-15

    Novel carbon dots with a diameter of 6 nm modified BiOCl (CDs/BiOCl) photocatalyst on FTO was synthesized via a facile immobilization method at room temperature. The crystalline structures, morphologies, optical properties, and photocatalytic properties were studied. The results showed that the CDs/BiOCl films exhibited higher photocatalytic activity than pure BiOCl. The 4 wt% CDs/BiOCl film showed the best photocatalytic activity, which was about eight times than that of pure BiOCl and excellent recyclability even after four recycles. Compared with other film photocatalysts, the photocatalytic activity of 4 wt% CDs/BiOCl was also higher than that of many other photocatalysts. The enhanced activity was ascribed to the enhanced light adsorption and the improvement of charge separation. Holes and superoxide radicals ·O{sub 2}{sup −} were revealed as the dominant reactive species. The photocatalytic mechanism was proposed based on the results.

  5. Fabrication of Z-scheme Ag3PO4/MoS2 composites with enhanced photocatalytic activity and stability for organic pollutant degradation

    International Nuclear Information System (INIS)

    Zhu, Chaosheng; Zhang, Lu; Jiang, Bo; Zheng, Jingtang; Hu, Ping; Li, Sujuan; Wu, Mingbo; Wu, Wenting

    2016-01-01

    Highlights: • Ag 3 PO 4 /MoS 2 composite photocatalysts were prepared by precipitation method. • The composites showed enhanced visible-light photocatalytic activity. • The photocorrosion of Ag 3 PO 4 was inhibited due to the introduction of MoS 2 . • Z-scheme mechanism was proposed to explain the enhanced photoactivity. - Abstract: In this study, highly efficient visible-light-driven Ag 3 PO 4 /MoS 2 composite photocatalysts with different weight ratios of MoS 2 were prepared via the ethanol-water mixed solvents precipitation method and characterized by ICP, XRD, HRTEM, FE-SEM, BET, XPS, UV–vis DRS and PL analysis. Under visible-light irradiation, Ag 3 PO 4 /MoS 2 composites exhibit excellent photocatalytic activity towards the degradation of organic pollutants in aqueous solution. The optimal composite with 0.648 wt% MoS 2 content exhibits the highest photocatalytic activity, which can degrade almost all MB under visible-light irradiation within 60 min. Recycling experiments confirmed that the Ag 3 PO 4 /MoS 2 catalysts had superior cycle performance and stability. The photocatalytic activity enhancement of Ag 3 PO 4 /MoS 2 photocatalysts can be mainly ascribed to the efficient separation of photogenerated charge carriers and the stronger oxidation and reduction ability through a Z-scheme system composed of Ag 3 PO 4 , Ag and MoS 2 , in which Ag particles act as the charge separation center. The high photocatalytic stability is due to the successful inhibition of the photocorrosion of Ag 3 PO 4 by transferring the photogenerated electrons of Ag 3 PO 4 to MoS 2 . The evidence of the Z-scheme photocatalytic mechanism of the composite photocatalysts could be obtained from the active species trapping experiments and the photoluminescence technique.

  6. Gas-Phase Photocatalytic Oxidation of Dimethylamine: The Reaction Pathway and Kinetics

    Directory of Open Access Journals (Sweden)

    Anna Kachina

    2007-01-01

    Full Text Available Gas-phase photocatalytic oxidation (PCO and thermal catalytic oxidation (TCO of dimethylamine (DMA on titanium dioxide was studied in a continuous flow simple tubular reactor. Volatile PCO products of DMA included ammonia, formamide, carbon dioxide, and water. Ammonia was further oxidized in minor amounts to nitrous oxide and nitrogen dioxide. Effective at 573 K, TCO resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The PCO kinetic data fit well to the monomolecular Langmuir-Hinshelwood model, whereas TCO kinetic behaviour matched the first-order process. No deactivation of the photocatalyst during the multiple long-run experiments was observed.

  7. Studies on urine treatment by biological purification using Azolla and UV photocatalytic oxidation

    Science.gov (United States)

    Liu, Xiaofeng; Chen, Min; Bian, Zuliang; Liu, Chung-Chu

    The amount of water consumed in space station operations is very large. In order to reduce the amount of water which must be resupplied from Earth, the space station needs to resolve the problems of water supply. For this reason, the recovery, regeneration and utilization of urine of astronauts are of key importance. Many investigations on this subject have been reported. Our research is based on biological absorption and, purification using UV photocatalytic oxidation techniques to achieve comprehensive treatment for urine. In the treatment apparatus we created, the urine solution is used as part of the nutrient solution for the biological components in our bioregenerative life support system. After being absorbed, the nutrients from the urine were then decomposed, metabolized and purified which creates a favorable condition for the follow-up oxidation treatment by UV photocatalytic oxidation. After these two processes, the treated urine solution reached Chinese national standards for drinking water quality (GB5749-1985).

  8. Growth study and photocatalytic properties of Co-doped tungsten oxide mesocrystals

    International Nuclear Information System (INIS)

    Sun, Shibin; Chang, Xueting; Li, Zhenjiang

    2012-01-01

    Cobalt-doped tungsten oxide mesocrystals with different morphologies have been successfully generated using a solvothermal method with tungsten hexachloride and cobalt chloride salts as precursors. The resulting mesocrystals were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Brunauer–Emmet–Teller analysis of nitrogen sorptometer, and UV–vis diffuse reflectance spectroscopy. The photocatalytic properties of the cobalt-doped tungsten oxide mesocrystals were evaluated on the basis of their ability to degrade methyl orange in an aqueous solution under simulated sunlight irradiation. Results showed that the cobalt doping had obvious effect on the morphologies of the final products, and lenticular and blocky cobalt-doped tungsten oxide mesocrystals could be obtained with 1.0 wt.% and 2.0 wt.% cobalt doping, respectively. The cobalt-doped tungsten oxides exhibited superior photocatalytic activities to that of the undoped tungsten oxide. - Graphical abstract: Schematic illustrations of the growth of the bundled nanowires, lenticular mesocrystals, and blocky mesocrystals. Highlights: ► Co-doped W 18 O 49 mesocrystals were synthesized using a solvothermal method. ► The Co doping has obvious effect on the morphology of the final mesocrystals. ► The Co-doped W 18 O 49 exhibited superior photocatalytic activity to the undoped W 18 O 49 .

  9. Growth study and photocatalytic properties of Co-doped tungsten oxide mesocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Shibin [College of Logistics Engineering, Shanghai Maritime University, Shanghai 200135 (China); College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China); Chang, Xueting, E-mail: xuetingchang@yahoo.cn [College of Logistics Engineering, Shanghai Maritime University, Shanghai 200135 (China); Li, Zhenjiang [College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China)

    2012-11-15

    Cobalt-doped tungsten oxide mesocrystals with different morphologies have been successfully generated using a solvothermal method with tungsten hexachloride and cobalt chloride salts as precursors. The resulting mesocrystals were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmet-Teller analysis of nitrogen sorptometer, and UV-vis diffuse reflectance spectroscopy. The photocatalytic properties of the cobalt-doped tungsten oxide mesocrystals were evaluated on the basis of their ability to degrade methyl orange in an aqueous solution under simulated sunlight irradiation. Results showed that the cobalt doping had obvious effect on the morphologies of the final products, and lenticular and blocky cobalt-doped tungsten oxide mesocrystals could be obtained with 1.0 wt.% and 2.0 wt.% cobalt doping, respectively. The cobalt-doped tungsten oxides exhibited superior photocatalytic activities to that of the undoped tungsten oxide. - Graphical abstract: Schematic illustrations of the growth of the bundled nanowires, lenticular mesocrystals, and blocky mesocrystals. Highlights: Black-Right-Pointing-Pointer Co-doped W{sub 18}O{sub 49} mesocrystals were synthesized using a solvothermal method. Black-Right-Pointing-Pointer The Co doping has obvious effect on the morphology of the final mesocrystals. Black-Right-Pointing-Pointer The Co-doped W{sub 18}O{sub 49} exhibited superior photocatalytic activity to the undoped W{sub 18}O{sub 49}.

  10. Role of Platinum Deposited on TiO2 in Photocatalytic Methanol Oxidation and Dehydrogenation Reactions

    Directory of Open Access Journals (Sweden)

    Luma M. Ahmed

    2014-01-01

    Full Text Available Titania modified nanoparticles have been prepared by the photodeposition method employing platinum particles on the commercially available titanium dioxide (Hombikat UV 100. The properties of the prepared photocatalysts were investigated by means of the Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, atomic force microscopy (AFM, and UV-visible diffuse spectrophotometry (UV-Vis. XRD was employed to determine the crystallographic phase and particle size of both bare and platinised titanium dioxide. The results indicated that the particle size was decreased with the increasing of platinum loading. AFM analysis showed that one particle consists of about 9 to 11 crystals. UV-vis absorbance analysis showed that the absorption edge shifted to longer wavelength for 0.5% Pt loading compared with bare titanium dioxide. The photocatalytic activity of pure and Pt-loaded TiO2 was investigated employing the photocatalytic oxidation and dehydrogenation of methanol. The results of the photocatalytic activity indicate that the platinized titanium dioxide samples are always more active than the corresponding bare TiO2 for both methanol oxidation and dehydrogenation processes. The loading with various platinum amounts resulted in a significant improvement of the photocatalytic activity of TiO2. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole charge carriers.

  11. New porous titanium–niobium oxide for photocatalytic degradation of bromocresol green dye in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Chaleshtori, Maryam Zarei, E-mail: mzarei@utep.edu [Materials Research and Technology Institute (MRTI), University of Texas at El Paso, 500W. University Ave., El Paso, TX 79968 (United States); Hosseini, Mahsa; Edalatpour, Roya [Materials Research and Technology Institute (MRTI), University of Texas at El Paso, 500W. University Ave., El Paso, TX 79968 (United States); Masud, S.M. Sarif [Department of Chemistry, University of Texas at El Paso, 500W. University Ave., El Paso, TX 79968 (United States); Chianelli, Russell R., E-mail: chianell@utep.edu [Materials Research and Technology Institute (MRTI), University of Texas at El Paso, 500W. University Ave., El Paso, TX 79968 (United States)

    2013-10-15

    Graphical abstract: The photocatalytic activity of different porous titanium–niobium oxides was evaluated toward degradation of bromocresol green (BG) under UV light. A better catalytic activity was observed for all samples at lower pH. Catalysts have a stronger ability for degradation of BG in acid media than in alkaline media. - Highlights: • Different highly structured titanium–niobium oxides have been prepared using improved methods of synthesis. • Photo-degradation of bromocresol green dye (BG) with nanostructure titanium–niobium oxide catalysts was carried out under UV light. • The photo-catalytic activity of all catalysts was higher in lower pH. • Titanium–niobium oxide catalysts are considerably stable and reusable. - Abstract: In this study, high surface area semiconductors, non porous and porous titanium–niobium oxides derived from KTiNbO{sub 5} were synthesized, characterized and developed for their utility as photocatalysts for decontamination with sunlight. These materials were then used in the photocatalytic degradation of bromocresol green dye (BG) in aqueous solution using UV light and their catalytic activities were evaluated at various pHs. For all catalysts, the photocatalytic degradation of BG was most efficient in acidic solutions. Results show that the new porous oxides have large porous and high surface areas and high catalytic activity. A topotactic dehydration treatment greatly improves catalyst performance at various pHs. Stability and long term activity of porous materials (topo and non-topo) in photocatalysis reactions was also tested. These results suggest that the new materials can be used to efficiently purify contaminated water.

  12. Ultrasonic synthesis of fern-like ZnO nanoleaves and their enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Ma, Qing Lan; Xiong, Rui; Zhai, Bao-gai; Huang, Yuan Ming

    2015-01-01

    Graphical abstract: - Highlights: • Fern-like ZnO nanoleaves were synthesized by ultrasonicating Zn microcrystals in water. • A fern-like ZnO nanoleaf is a self-assembly of ZnO nanoplates along one ZnO nanorod. • Fern-like ZnO nanoleaves exhibit enhanced photocatalytic activity than ZnO nanocrystals. • The branched hierarchical structures are responsible for the enhanced photocatalytic activity. - Abstract: Two-dimensional fern-like ZnO nanoleaves were synthesized by ultrasonicating zinc microcrystals in water. The morphology, crystal structure, optical property and photocatalytic activity of the fern-like ZnO nanoleaves were characterized with scanning electron microscopy, X-ray diffraction, transmission electron microscopy, photoluminescence spectroscopy and ultraviolet–visible spectroscopy, respectively. It is found that one fern-like ZnO nanoleaf is composed of one ZnO nanorod as the central trunk and a number of ZnO nanoplates as the side branches in opposite pairs along the central ZnO nanorod. The central ZnO nanorod in the fern-like nanoleaves is about 1 μm long while the side-branching ZnO nanoplates are about 100 nm long and 20 nm wide. Further analysis has revealed that ZnO nanocrystals are the building blocks of the central ZnO nanorod and the side-branching ZnO nanoplates. Under identical conditions, fern-like ZnO nanoleaves exhibit higher photocatalytic activity in photodegrading methyl orange in aqueous solution than spherical ZnO nanocrystals. The first-order photocatalytic rate constant of the fern-like ZnO nanoleaves is about four times as large as that of the ZnO nanoparticles. The branched architecture of the hierarchical nanoleaves is suggested be responsible for the enhanced photocatalytic activity of the fern-like ZnO nanoleaves

  13. Highly efficient visible light photocatalytic reduction of CO2 to hydrocarbon fuels by Cu-nanoparticle decorated graphene oxide.

    Science.gov (United States)

    Shown, Indrajit; Hsu, Hsin-Cheng; Chang, Yu-Chung; Lin, Chang-Hui; Roy, Pradip Kumar; Ganguly, Abhijit; Wang, Chen-Hao; Chang, Jan-Kai; Wu, Chih-I; Chen, Li-Chyong; Chen, Kuei-Hsien

    2014-11-12

    The production of renewable solar fuel through CO2 photoreduction, namely artificial photosynthesis, has gained tremendous attention in recent times due to the limited availability of fossil-fuel resources and global climate change caused by rising anthropogenic CO2 in the atmosphere. In this study, graphene oxide (GO) decorated with copper nanoparticles (Cu-NPs), hereafter referred to as Cu/GO, has been used to enhance photocatalytic CO2 reduction under visible-light. A rapid one-pot microwave process was used to prepare the Cu/GO hybrids with various Cu contents. The attributes of metallic copper nanoparticles (∼4-5 nm in size) in the GO hybrid are shown to significantly enhance the photocatalytic activity of GO, primarily through the suppression of electron-hole pair recombination, further reduction of GO's bandgap, and modification of its work function. X-ray photoemission spectroscopy studies indicate a charge transfer from GO to Cu. A strong interaction is observed between the metal content of the Cu/GO hybrids and the rates of formation and selectivity of the products. A factor of greater than 60 times enhancement in CO2 to fuel catalytic efficiency has been demonstrated using Cu/GO-2 (10 wt % Cu) compared with that using pristine GO.

  14. Enhanced photocatalytic activity of SrTiO3 photocatalyst by topotactic preparation

    Science.gov (United States)

    Cao, Jiafeng; Huang, Xianshan; Liu, Yi; Wu, Jianguang; Ji, Yuexia

    2016-11-01

    Novel SrTiO3 (ST) photocatalysts with different shapes such as plates, rods and cubes were successfully synthesized based on a topotactic approach. The rod-like ST particles formed in situ at the plates show superior photocatalytic activities towards the decomposition of Rhodamine B than the plate-like and the cubic particles under visible-light irradiation, which could be attributed to the crystal orientation exposing highly active sites accompanied by the crystallite growth in molten salt. The results reveal an effective approach for fabrication of novel photocatalysts of perovskite structure with enhanced photocatalytic activities.

  15. Facile Solvothermal Synthesis of BiOCl/ZnO Heterostructures with Enhanced Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Yong-Fang Li

    2014-01-01

    Full Text Available Well-defined nanosheet-assembled (BiOClx(ZnO1−x nanoflowers were synthesized by a solvothermal method. It was found that ZnO nanoparticles were anchored on the flower-like BiOCl nanostructures, as demonstrated by varying the initial compositions of the Bi precursor and the volume ratios of mixed solvents (ethylene glycol to water. The as-prepared (BiOCl0.6(ZnO0.4 nanocomposites showed enhanced photocatalytic activity toward rhodamine B degradation under ultraviolet (UV irradiation. And the photocatalytic mechanism was discussed in detail.

  16. Enhancing Photocatalytic Performance through Tuning the Interfacial Process between -Assembled and Pt-Loaded Microspheres

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2012-01-01

    Full Text Available This work reports on a simple two-step approach to rutile TiO2-assembled microspheres loaded by Pt with an aim to tune semiconductor-metal interfacial processes for enhancing the photocatalytic performance. Systematic sample characterizations and structural analysis indicate that Pt loading did not produce any significant influences on the lattice structure of TiO2-assembled microspheres. Instead, upon Pt loading, Schottky barrier was formed in the interfaces between microspheres and Pt nanoparticles, which inhabited efficiently the recombination of photo-generated electron-hole pairs essential for the photocatalytic activities. In addition, TiO2 microspheres also showed a capacity of electrons storage and releasing as represented by a high dielectric constant, which increased the utility rate of photogenerated electrons. All these structural advantages contribute to the excellent photocatalytic activity under ultraviolet light irradiation. The interfacial process between microspheres and Pt nanoparticles was further tuned through adjusting the loading Pt content of metal Pt. As a consequence, the best photocatalytic activity on TiO2 was obtained at 0.85 wt% Pt loading, above or below which photocatalytic activity was apparently decreased.

  17. Synthesis, characterization and photocatalytic activity of porous manganese oxide doped titania for toluene decomposition

    International Nuclear Information System (INIS)

    Jothiramalingam, R.; Wang, M.K.

    2007-01-01

    The present study describes the photocatalytic degradation of toluene in gas phase on different porous manganese oxide doped titanium dioxide. As synthesized birnessite and cryptomelane type porous manganese oxide were doped with titania and tested for photocatalytic decomposition of toluene in gas phase. The effects of the inlet concentration of toluene, flow rate (retention time) were examined and the relative humidity was maintained constantly. Thermal and textural characterization of manganese oxide doped titania materials were characterized by X-ray diffraction (XRD), thermogravemetry (TG), BET and TEM-EDAX studies. The aim of the present study is to synthesize the porous manganese oxide doped titania and to study its photocatalytic activity for toluene degradation in gas phase. Cryptomelane doped titania catalyst prepared in water medium [K-OMS-2 (W)] is shown the good toluene degradation with lower catalysts loading compared to commercial bulk titania in annular type photo reactor. The higher photocatalytic activity due to various factors such as catalyst preparation method, experimental conditions, catalyst loading, surface area, etc. In the present study manganese oxide OMS doped titania materials prepared by both aqueous and non-aqueous medium, aqueous medium prepared catalyst shows the good efficiency due to the presence of OH bonded groups on the surface of catalyst. The linear forms of different kinetic equations were applied to the adsorption data and their goodness of fit was evaluated based on the R 2 and standard error. The goodness to the linear fit was observed for Elovich model with high R 2 (≥0.9477) value

  18. Enhanced visible-light photocatalytic activities of Ag{sub 3}PO{sub 4}/MWCNT nanocomposites fabricated by facile in situ precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bo [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Li, Zhongyu, E-mail: zhongyuli@mail.tsinghua.edu.cn [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Changzhou Expansion New Stuff Technology Limited Company, Changzhou 213122 (China); Jilin Institute of Chemical Technology, Jilin 132022 (China); Xu, Song, E-mail: cyanine123@163.com [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Han, Dandan; Lu, Dayong [Jilin Institute of Chemical Technology, Jilin 132022 (China)

    2014-05-01

    Highlights: • Ag{sub 3}PO{sub 4}/MWCNT composites were facilely fabricated via in situ precipitation method. • Ag{sub 3}PO{sub 4}/MWCNT composites exhibited enhanced visible-light photocatalytic activity. • Ag{sub 3}PO{sub 4}/MWCNT composites showed good photostability compared with Ag{sub 3}PO{sub 4} particles. • Possible photocatalytic mechanism under visible-light irradiation was proposed. - Abstract: The Ag{sub 3}PO{sub 4}/MWCNT nanocomposites were facilely fabricated via in situ precipitation method by adding (NH{sub 4}){sub 2}HPO{sub 4} into the mixture of multi-walled carbon nanotube (MWCNT) and AgNO{sub 3} solution under stirring. The as-prepared Ag{sub 3}PO{sub 4}/MWCNT nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), the Brunauer–Emmett–Teller surface area (BET) and UV–vis diffuse reflectance spectroscopy. The TEM results showed that the Ag{sub 3}PO{sub 4} nanoparticles were distributed on the surface of MWCNT uniformly with an average diameter of 70 nm, indicating excellent loading result. The photocatalytic activities of Ag{sub 3}PO{sub 4}/MWCNT nanocomposites were investigated by degrading methylene blue (MB) and malachite green (MG) under visible-light irradiation. It was found that the Ag{sub 3}PO{sub 4}/MWCNT nanocomposite exhibited excellent photocatalytic performance with enhanced photocatalytic efficiency and good photostability compared with bare Ag{sub 3}PO{sub 4}. Furthermore, a possible mechanism for the photocatalytic oxidative degradation was also discussed.

  19. Photocatalytic enhancement of cesium removal by Prussian blue-deposited TiO2.

    Science.gov (United States)

    Kim, Hyuncheol; Kim, Minsun; Kim, Wooyul; Lee, Wanno; Kim, Soonhyun

    2018-06-19

    After the Fukushima nuclear accident, tremendous efforts were made to treat radiocesium, radiostrontium, and other radioactive materials. For the first time, we demonstrate that a TiO 2 photocatalyst can significantly enhance Cs adsorption by Prussian blue-deposited TiO 2 (PB/TiO 2 ) under UV irradiation. In this study, we synthesized PB/TiO 2 using the photodeposition method. After the Cs ions were adsorbed on the PB/TiO 2 in darkness, we then exposed the PB/TiO 2 to UV light irradiation. This resulted in a further increase in Cs ion adsorption of more than 10 times the amount adsorbed in darkness. This photocatalytic-enhanced adsorption of Cs ions was not observed on PB mixed with SiO 2 , nor under visible light irradiation. We investigated the effects of PB concentration, PB/TiO 2 concentration, and gas purging on both dark and photocatalytic-enhanced adsorption of Cs ions by PB/TiO 2 . Based on the results, we suggest that the photocatalytic-enhanced adsorption of Cs ions on PB/TiO 2 is due to photocatalytic reduction of PB, which leads to additional adsorption of Cs ions. The change in solution color before and after the reaction, and the change in solution pH in the dark and during UV irradiation strongly support this suggestion. The photocatalytic-enhanced adsorption of Cs ions was equivalent during radioactive 137 Cs removal, indicating important applications for pollutant removal from contaminated water. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. 2D BiOCl/Bi12O17Cl2 nanojunction: Enhanced visible light photocatalytic NO removal and in situ DRIFTS investigation

    Science.gov (United States)

    Zhang, Wendong; Dong, Xin'an; Jia, Bin; Zhong, Junbo; Sun, Yanjuan; Dong, Fan

    2018-02-01

    Novel two-dimensional (2D) BiOCl/Bi12O17Cl2 nanojunctions were fabricated by a facile one-pot in situ method at room temperature. The as-prepared samples were analyzed by XRD, SEM, TEM, HRTEM, UV-vis DRS, PL, ESR and BET-BJH measurement in detail. The photocatalytic performance of the samples was evaluated by removal of NO at ppb level under visible-light illumination. The result reveals that the BiOCl/Bi12O17Cl2 nanojunctions manifests conspicuously enhanced photocatalytic efficiency for NO removal. The facilitated performance can be ascribed to the well-matched band structure and relatively high specific surface area. In addition, the in situ diffuse reflectance infrared Fourier transform spectroscopy was applied to investigate the adsorption and photocatalytic NO oxidation processes. The reaction mechanism of photocatalytic NO oxidation was proposed based on the observed intermediates. The present work could pave a way to synthesize novel visible light photocatalysts at room temperature for environmental application.

  1. Photocatalytic self-cleaning properties of cellulosic fibers modified by nano-sized zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Moafi, Hadi Fallah; Shojaie, Abdollah Fallah, E-mail: a.f.shojaie@guilan.ac.ir; Zanjanchi, Mohammad Ali

    2011-03-31

    Nano-sized zinc oxide was synthesized and deposited onto cellulosic fibers using the sol-gel process at ambient temperature. The prepared materials were characterized using several techniques including scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction and thermogravimetric analysis. X-ray diffraction studies of the ZnO-coated fiber indicate formation of the hexagonal crystal phase which was satisfactory crystallized on the fiber surface. The electron micrographs show formation of zinc oxide nanoparticles within 10-15 nm in size which have been homogeneously dispersed on the fiber surface. The prepared materials show significant photocatalytic self-cleaning activity, which was monitored by diffuse reflectance spectroscopy. The photoactivity was studied upon measuring the photodegradation of methylene blue and eosin yellowish under UV-Vis irradiation. The photocatalytic activity of the treated fabrics was fully maintained performing several cycles of photodegradation.

  2. Photocatalytic self-cleaning properties of cellulosic fibers modified by nano-sized zinc oxide

    International Nuclear Information System (INIS)

    Moafi, Hadi Fallah; Shojaie, Abdollah Fallah; Zanjanchi, Mohammad Ali

    2011-01-01

    Nano-sized zinc oxide was synthesized and deposited onto cellulosic fibers using the sol-gel process at ambient temperature. The prepared materials were characterized using several techniques including scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction and thermogravimetric analysis. X-ray diffraction studies of the ZnO-coated fiber indicate formation of the hexagonal crystal phase which was satisfactory crystallized on the fiber surface. The electron micrographs show formation of zinc oxide nanoparticles within 10-15 nm in size which have been homogeneously dispersed on the fiber surface. The prepared materials show significant photocatalytic self-cleaning activity, which was monitored by diffuse reflectance spectroscopy. The photoactivity was studied upon measuring the photodegradation of methylene blue and eosin yellowish under UV-Vis irradiation. The photocatalytic activity of the treated fabrics was fully maintained performing several cycles of photodegradation.

  3. Synthesis and photocatalytic properties of different SnO2 microspheres on graphene oxide sheets

    Science.gov (United States)

    Wei, Jia; Xue, Shaolin; Xie, Pei; Zou, Rujia

    2016-07-01

    Different SnO2 microspheres like dandelions, silkworm cocoons and urchins have been synthesized on graphene oxide sheets (GOs) by hydrothermal method at 190 °C for 24 h. The morphologies, structures, chemical compositions and optical properties of the as-grown SnO2 microspheres on GOs (SMGs) were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), X-ray energy dispersive spectrometer (EDS), Raman spectra and UV-vis diffuse reflectance spectra (DRS) techniques. The results of XRD revealed that the as-grown SnO2 microspheres have tetragonal rutile structure. The results of Raman spectra, EDS, XRD, XPS and SEM showed that the SnO2 microspheres were grown on GOs and the average diameter of dandelion-like microsphere was about 1.5 μm. The formation mechanism of SnO2 microspheres grown on GOs was discussed. The photocatalytic activity of the SMGs composites was evaluated by photocatalytic degradation of Rhodamine B (Rh B) aqueous solution under visible light irradiation. The photocatalytic results showed that the dandelion-like SMGs exhibited a much better photocatalytic activity than those of smooth and rough SMGs.

  4. Synthesis of Nickel Oxide Nanoparticles Using Gelatine as a Green Template for Photocatalytic Degradation of Dye

    OpenAIRE

    JAY YANG LEE

    2018-01-01

    Nickel oxide (NiO) nanoparticles were synthesized through sol-gel method with an environmentally friendly templating agent, which is gelatin. The synthesized NiO were characterized to determine the chemical and physical properties of the nanoparticles. The optimum synthesis parameters were used in photocatalytic degradation of Reactive Black 5 and Acid Yellow 25 dye to determine the catalytic activity of the nanoparticles.

  5. Performance Testing of a Photocatalytic Oxidation Module for Spacecraft Cabin Atmosphere Revitalization

    Science.gov (United States)

    Perry, Jay L.; Abney, Morgan B.; Frederick, Kenneth R.; Scott, Joseph P.; Kaiser, Mark; Seminara, Gary; Bershitsky, Alex

    2011-01-01

    Photocatalytic oxidation (PCO) is a candidate process technology for use in high volumetric flow rate trace contaminant control applications in sealed environments. The targeted application for PCO as applied to crewed spacecraft life support system architectures is summarized. Technical challenges characteristic of PCO are considered. Performance testing of a breadboard PCO reactor design for mineralizing polar organic compounds in a spacecraft cabin atmosphere is described. Test results are analyzed and compared to results reported in the literature for comparable PCO reactor designs.

  6. Mesoporous anatase TiO2/reduced graphene oxide nanocomposites: A simple template-free synthesis and their high photocatalytic performance

    International Nuclear Information System (INIS)

    Zhou, Qi; Zhong, Yong-Hui; Chen, Xing; Huang, Xing-Jiu; Wu, Yu-Cheng

    2014-01-01

    Graphical abstract: - Highlights: • Mesoporous TiO 2 nanoparticles with anatase phase were assembled on reduced graphene oxide via a template-free one-step hydrothermal method. • The TiO 2 /rGO nanocomposites have better adsorption capacity and photocatalytic degradation efficiency for dyes removal. • Improved dye adsorption and photogenerated charge separation are responsible for enhanced activity. - Abstract: Mesoporous anatase phase TiO 2 was assembled on reduced graphene oxide (rGO) using a template-free one-step hydrothermal process. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Brunauer–Emmett–Teller (BET) surface area. Morphology of TiO 2 was related to the content of graphene oxide. TiO 2 /rGO nanocomposites exhibited excellent photocatalytic activity for the photo-degradation of methyl orange. The degradation rate was 4.5 times greater than that of pure TiO 2 nanoparticles. This difference was attributed to the thin two-dimensional graphene sheet. The graphene sheet had a large surface area, high adsorption capacity, and acted as a good electron acceptor for the transfer of photo-generated electrons from the conduction band of TiO 2 . The enhanced surface adsorption characteristics and excellent charge transport separation were independent properties of the photocatalytic degradation process

  7. Chromate enhanced visible light driven TiO2 photocatalytic mechanism on Acid Orange 7 photodegradation

    International Nuclear Information System (INIS)

    Wang, Yeoung-Sheng; Shen, Jyun-Hong; Horng, Jao-Jia

    2014-01-01

    Highlights: • Photocatalysis of Cr(VI) and TiO 2 were studied by ESR analysis on DMPO-OH signals. • Mechanism of Cr(VI)-enhanced by visible light was different from that by UV. • O 2 adsorbed on TiO 2 surfaces could react with Cr(VI) to lower photoenergy needed. • Even by UV, no TiO 2 photocatalysis was observed without O 2 solution. • Visible light and Cr(VI) redox reaction could activate TiO 2 and would yield ·OH. - Abstract: When hexavalent chromium (Cr(VI)) is added to a TiO 2 photocatalytic reaction, the decolorization and mineralization efficiencies of azo dyes Acid Orange 7 (AO7) are enhanced even though the mechanism is unclear. This study used 5,5-dimethyl-L-pyrroline-N-oxide (DMPO) as the scavenger and the analysis of Electron Spin Resonance (ESR) to investigate this enhancement effect by observing the hydroxyl radical (·OH) generation of the Cr(VI)/TiO 2 system under UV and visible light (Vis) irradiation. With Cr(VI), the decolorization efficiencies were approximately 95% and 62% under UV and Vis, and those efficiencies were 25% less in the absence of Cr(VI). The phenomena of the DMPO-OH signals during the ESR analysis under Vis 405 and 550 nm irradiation were obviously the enhancement effects of Cr(VI) in aerobic conditions. In anoxic conditions, the catalytic effects of Cr(VI) could not be achieved due to the lack of a redox reaction between Cr(VI) and the adsorbed oxygen at the oxygen vacancy sites on the TiO 2 surfaces . The results suggest that by introducing the agents of redox reactions such as chromate ions, we could lower the photoenergy of TiO 2 needed and allow Vis irradiation to activate photocatalysis

  8. Review of research results for the photocatalytic oxidation of hazardous wastes in air

    Energy Technology Data Exchange (ETDEWEB)

    Nimlos, M R; Wolfrum, E J; Gratson, D A; Watt, A S; Jacoby, W A; Turchi, C

    1995-01-01

    Laboratory experiments of gas-phase photocatalytic oxidation (PCO) at NREL have focused on measurements that can help commercialize this technology for treating gaseous air streams. This effort proceeds earlier NREL work and studies conducted elsewhere which demonstrated the general applicability of PCO. The more recent work has concentrated on: (1) the kinetics of the PCO process; (2) the formation and destruction of intermediates; and (3) possible enhancements to improve the destruction rates. The results from these studies will be used to help design large scale PCO equipment and they will be used to evaluate the economics of the PCO process. For trichloroethylene and ethanol, extensive studies of the rates of destruction have yielded kinetic parameters for the destruction of intermediates as well as the substrate. The kinetics of intermediates is essential for sizing a large scale reactor, as complete conversion to carbon dioxide is often desired. The kinetic data from these laboratory studies has been used for analyzing IT`s pilot PCO reactor and has been used to suggest modifications to this unit. For compounds that are more difficult to destroy (such as the components of BTEX), rate enhancement experiments have been conducted. These compounds represent a very large market for this technology and improvement of the rate of the process should make it competitive. Towards this goal, the enhancement of the destruction of BTEX components have been studied. Experiments have demonstrated that there is a significant increase in the rates of destruction of BTEX with the addition of ozone. Preliminary economic assessments have shown that PCO with ozone may be cost competitive. Future laboratory experiments of PCO will focus on refinements of what has been learned. Rate measurements will also be expanded to include other compounds representing significant markets for the PCO technology.

  9. Hollow mesoporous titania microspheres: New technology and enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhenliang; Wei, Wenrui; Wang, Litong [School of Chemical Engineering, Fuzhou University, Fuzhou 350108 (China); Hong, Ruoyu, E-mail: rhong@suda.edu.cn [School of Chemical Engineering, Fuzhou University, Fuzhou 350108 (China); College of Chemistry, Chemical Engineering and Materials Science & Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China)

    2015-12-01

    Graphical abstract: Schematic of the formation process of HTS. - Highlights: • Amino modified porous PS-DVB microspheres were used as templates to coat TiO{sub 2.} • The coating of TiO{sub 2} was conducted under regular changing atmospheric pressure. • The PS-DVB@TiO{sub 2} was calcinated first under nitrogen and then under air to get HTS. • The resultant products were provided with high surface area and excellent photocatalytic activity under UV irradiation. - Abstract: Hollow titania microspheres (HTS) were fabricated via a sol–gel process by coating the hydrolysis product of titanium tetrabutoxide (TBOT) onto the amino (–NH{sub 2}) modified porous polystyrene cross-linked divinyl benzene (PS-DVB) microspheres under changing atmospheric pressure, followed by calcination in nitrogen and air atmosphere. Particularly, the atmospheric pressure was continuously and regularly changed during the formation process of PS-DVB@TiO{sub 2} microspheres. Then the TiO{sub 2} particles were absorbed into the pores and onto the surface of PS-DVB as well. The resultant HTS (around 2 μm in diameter) featured a high specific surface area (84.37 m{sup 2}/g), anatase crystal and stable hollow microsphere structure, which led to high photocatalysis activity. The photocatalytic degradation of malachite green (MG) organic dye solution was conducted under ultraviolet (UV) light irradiation, which showed a high photocatalytic ability (81% of MG was degraded after UV irradiation for 88 min). Therefore, it could be potentially applied for the treatment of wastewater contaminated by organic pollutants.

  10. Application of Ni-Oxide@TiO₂ Core-Shell Structures to Photocatalytic Mixed Dye Degradation, CO Oxidation, and Supercapacitors.

    Science.gov (United States)

    Lee, Seungwon; Lee, Jisuk; Nam, Kyusuk; Shin, Weon Gyu; Sohn, Youngku

    2016-12-20

    Performing diverse application tests on synthesized metal oxides is critical for identifying suitable application areas based on the material performances. In the present study, Ni-oxide@TiO₂ core-shell materials were synthesized and applied to photocatalytic mixed dye (methyl orange + rhodamine + methylene blue) degradation under ultraviolet (UV) and visible lights, CO oxidation, and supercapacitors. Their physicochemical properties were examined by field-emission scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and UV-visible absorption spectroscopy. It was shown that their performances were highly dependent on the morphology, thermal treatment procedure, and TiO₂ overlayer coating.

  11. Room-temperature in situ fabrication of Bi2O3/g-C3N4 direct Z-scheme photocatalyst with enhanced photocatalytic activity

    Science.gov (United States)

    He, Rongan; Zhou, Jiaqian; Fu, Huiqing; Zhang, Shiying; Jiang, Chuanjia

    2018-02-01

    Constructing direct Z-scheme heterojunction is an effective approach to separating photogenerated charge carriers and improving the activity of semiconductor photocatalysts. Herein, a composite of bismuth(III) oxide (Bi2O3) and graphitic carbon nitride (g-C3N4) was in situ fabricated at room temperature by photoreductive deposition of Bi3+ and subsequent air-oxidation of the resultant metallic Bi. Quantum-sized ω-Bi2O3 nanoparticles approximately 6 nm in diameter were uniformly distributed on the surface of mesoporous g-C3N4. The as-prepared Bi2O3/g-C3N4 composite exhibited higher photocatalytic activity than pure Bi2O3 and g-C3N4 for photocatalytic degradation of phenol under visible light. Reactive species trapping experiments revealed that superoxide radicals and photogenerated holes played important roles in the photocatalytic degradation of phenol. The enhanced photocatalytic activity, identification of reactive species and higher rate of charge carrier recombination (as indicated by stronger photoluminescence intensity) collectively suggest that the charge migration within the Bi2O3/g-C3N4 composite followed a Z-scheme mechanism. Photogenerated electrons on the conduction band of Bi2O3 migrate to the valence band of g-C3N4 and combine with photogenerated holes therein. At the cost of these less reactive charge carriers, the Z-scheme heterojunction enables efficient charge separation, while preserving the photogenerated electrons and holes with stronger redox abilities, which is beneficial for enhanced photocatalytic activity.

  12. Enhanced photocatalytic activity of BiOCl by C70 modification and mechanism insight

    Science.gov (United States)

    Ma, Dongmei; Zhong, Junbo; Li, Jianzhang; Wang, Li; Peng, Rufang

    2018-06-01

    As an excellent photocatalyst which can compete with TiO2, BiOCl has triggered increasing attention. However, the practical application of BiOCl has been significantly limited by the fast recombination of the photoinduced electron-hole charge pairs. In this study, to further enhance the separation efficiency of photoinduced electron-hole charge pairs of BiOCl, a series of efficient BiOCl photocatalysts were prepared by C70 surface modification. The trapping experiments reveal that the main active species were determined to be superoxide radicals (O2rad -) and holes (h+) under simulated sunlight irradiation. The surface photovoltage spectroscopy (SPS) demonstrates that separation of the photoinduced electron-hole pairs has been significantly promoted, forming more radOH, proven by terephthalic acid photoluminescence probing technique. The photocatalytic evaluation results display that the C70/BiOCl photocatalysts exhibit much higher photocatalytic activity in decolorization of rhodamine B (RhB) than that of the bare BiOCl under the simulated sunlight irradiation. The excellent electron acceptability of C70 is conducive to the separation of the photogenerated carriers and results in efficient formation of O2rad -, proven by the results of SPS and electron spin-resonance (ESR), therefore the photocatalytic performance of C70/BiOCl has been greatly improved. Based on all these observations, an enhancement mechanism in photocatalytic performance of C70/BiOCl was proposed.

  13. Facile synthesis of phosphorus doped graphitic carbon nitride polymers with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Zhang, Ligang; Chen, Xiufang; Guan, Jing; Jiang, Yijun; Hou, Tonggang; Mu, Xindong

    2013-01-01

    Graphical abstract: - Highlights: • P-doped g-C 3 N 4 has been prepared by a one-pot green synthetic approach. • The incorporation of P resulted in favorable textural and electronic properties. • Doping with P enhanced the visible-light photocatalytic activity of g-C 3 N 4 . • A postannealing treatment further enhanced the activity of P-doped g-C 3 N 4 . • Photogenerated holes were the main species responsible for the activity. - Abstract: Phosphorus-doped carbon nitride materials were prepared by a one-pot green synthetic approach using dicyandiamide monomer and a phosphorus containing ionic liquid as precursors. The as-prepared materials were subjected to several characterizations and investigated as metal-free photocatalysts for the degradation of organic pollutants (dyes like Rhodamine B, Methyl orange) in aqueous solution under visible light. Results revealed that phosphorus-doped carbon nitride have a higher photocatalytic activity for decomposing Rhodamine B and Methyl orange in aqueous solution than undoped g-C 3 N 4 , which was attributed to the favorable textural, optical and electronic properties caused by doping with phosphorus heteroatoms into carbon nitride host. A facile postannealing treatment further improved the activity of the photocatalytic system, due to the higher surface area and smaller structural size in the postcalcined catalysts. The phosphorus-doped carbon nitride showed high visible-light photocatalytic activity, making them promising materials for a wide range of potential applications in photochemistry

  14. Field solar degradation of pesticides and emerging water contaminants mediated by polymer films containing titanium and iron oxide with synergistic heterogeneous photocatalytic activity at neutral pH.

    Science.gov (United States)

    Mazille, F; Schoettl, T; Klamerth, N; Malato, S; Pulgarin, C

    2010-05-01

    Photocatalytic degradation of phenol, nalidixic acid, mixture of pesticides, and another of emerging contaminants in water was mediated by TiO(2) and iron oxide immobilized on functionalized polyvinyl fluoride films (PVF(f)-TiO(2)-Fe oxide) in a compound parabolic collector (CPC) solar photoreactor. During degradation, little iron leaching (compounds and less efficient for six other compounds. The significant reactivity differences between tested compounds were assigned to the differences in structure namely that the presence of complexing or chelating groups enhanced the rates. PVF(f)-TiO(2)-Fe oxide photoactivity gradually increased during 20 days of experiments. X-ray photoelectron spectroscopy (XPS) measurements revealed significant changes on the catalyst surface. These analyses confirm that during photocatalysis mediated by PVF(f)-TiO(2)-Fe oxide, some iron leaching led to enlargement of the TiO(2) surface exposed to light, increasing its synergy with iron oxides and leading to enhanced pollutant degradation.

  15. Functionalized nanostructures for enhanced photocatalytic performance under solar light

    Directory of Open Access Journals (Sweden)

    Liejin Guo

    2014-07-01

    Full Text Available Photocatalytic hydrogen production from water has been considered to be one of the most promising solar-to-hydrogen conversion technologies. In the last decade, various functionalized nanostructures were designed to address the primary requirements for an efficient photocatalytic generation of hydrogen by using solar energy: visible-light activity, chemical stability, appropriate band-edge characteristics, and potential for low-cost fabrication. Our aim is to present a short review of our recent attempts that center on the above requirements. We begin with a brief introduction of photocatalysts coupling two or more semiconductors, followed by a further discussion of the heterostructures with improved matching of both band structures and crystal lattices. We then elaborate on the heterostructure design of the targeted materials from macroscopic regulation of compositions and phases, to the more precise control at the nanoscale, i.e., materials with the same compositions but different phases with certain band alignment. We conclude this review with perspectives on nanostructure design that might direct future research of this technology.

  16. Preparation of reduced graphene oxide/meso-TiO_2/AuNPs ternary composites and their visible-light-induced photocatalytic degradation n of methylene blue

    International Nuclear Information System (INIS)

    Yang, Yongfang; Ma, Zheng; Xu, Lidong; Wang, Hefang; Fu, Nian

    2016-01-01

    Graphical abstract: Reduced graphene oxide/meso-TiO_2/AuNPs (RGO/meso-TiO_2/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO_2/AuNPs under a hydrothermal condition. The RGO/meso-TiO_2/AuNPs ternary composites show high photocatalytic activity toward MB. - Highlights: • RGO/meso-TiO_2/AuNPs were obtained by addition of graphene oxide to meso-TiO_2/AuNPs. • Au NPs in the mesopores of meso-TiO_2 reduce the recombination of charge carriers. • RGO covered with the surface of the meso-TiO_2 enhance the adsorption of MB. • RGO/meso-TiO_2/AuNPs composites show high photocatalytic performance toward MB. - Abstract: Reduced graphene oxide/meso-TiO_2/AuNPs (RGO/meso-TiO_2/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO_2/AuNPs under hydrothermal conditions. The structure and the morphology of the RGO/meso-TiO_2/AuNPs materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The photocatalytic activity of RGO/meso-TiO_2/AuNPs was evaluated by degradation of methyl blue (MB) under visible-light illumination. The ternary composites present an extended light absorption range, efficient charge separation properties, high adsorption ability for MB and high photocatalytic degradation activity of MB compared to the meso-TiO_2 and meso-TiO_2/AuNPs.

  17. Preparation of reduced graphene oxide/meso-TiO{sub 2}/AuNPs ternary composites and their visible-light-induced photocatalytic degradation n of methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yongfang; Ma, Zheng; Xu, Lidong [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); Wang, Hefang, E-mail: whf0618@163.com [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); Fu, Nian, E-mail: funian3678@163.com [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); College of Physics Science and Technology of Hebei University, Baoding 071002 (China)

    2016-04-30

    Graphical abstract: Reduced graphene oxide/meso-TiO{sub 2}/AuNPs (RGO/meso-TiO{sub 2}/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO{sub 2}/AuNPs under a hydrothermal condition. The RGO/meso-TiO{sub 2}/AuNPs ternary composites show high photocatalytic activity toward MB. - Highlights: • RGO/meso-TiO{sub 2}/AuNPs were obtained by addition of graphene oxide to meso-TiO{sub 2}/AuNPs. • Au NPs in the mesopores of meso-TiO{sub 2} reduce the recombination of charge carriers. • RGO covered with the surface of the meso-TiO{sub 2} enhance the adsorption of MB. • RGO/meso-TiO{sub 2}/AuNPs composites show high photocatalytic performance toward MB. - Abstract: Reduced graphene oxide/meso-TiO{sub 2}/AuNPs (RGO/meso-TiO{sub 2}/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO{sub 2}/AuNPs under hydrothermal conditions. The structure and the morphology of the RGO/meso-TiO{sub 2}/AuNPs materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The photocatalytic activity of RGO/meso-TiO{sub 2}/AuNPs was evaluated by degradation of methyl blue (MB) under visible-light illumination. The ternary composites present an extended light absorption range, efficient charge separation properties, high adsorption ability for MB and high photocatalytic degradation activity of MB compared to the meso-TiO{sub 2} and meso-TiO{sub 2}/AuNPs.

  18. Photocatalytic oxidation dynamics of acetone on TiO2: tight-binding quantum chemical molecular dynamics study

    International Nuclear Information System (INIS)

    Lv Chen; Wang Xiaojing; Agalya, Govindasamy; Koyama, Michihisa; Kubo, Momoji; Miyamoto, Akira

    2005-01-01

    The clarification of the excited states dynamics on TiO 2 surface is important subject for the design of the highly active photocatalysts. In the present study, we applied our novel tight-binding quantum chemical molecular dynamics method to the investigation on the photocatalytic oxidation dynamics of acetone by photogenerated OH radicals on the hydrated anatase TiO 2 surface. The elucidated photocatalytic reaction mechanism strongly supports the previous experimental proposal and finally the effectiveness of our new approach for the clarification of the photocatalytic reaction dynamics employing the large simulation model was confirmed

  19. Enhanced photocatalytic degradation of Safranin-O by heterogeneous nanoparticles for environmental applications

    International Nuclear Information System (INIS)

    El-Kemary, Maged; Abdel-Moneam, Yasser; Madkour, Metwally; El-Mehasseb, Ibrahim

    2011-01-01

    Nanostructure titanium dioxide (TiO 2 ) has been synthesized by hydrolysis of titanium tetrachloride in aqueous solution and Ag-TiO 2 nanoparticles were synthesized by photoreduction method. The resulting materials were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier-transform infrared (FT-IR) and UV-vis absorption spectroscopy. The experimental results showed that the sizes of the synthesized TiO 2 and Ag-TiO 2 particles are in the range of 1.9-3.2 nm and 2-10 nm, respectively. Moreover, Ag-TiO 2 nanoparticles exhibit enhanced photocatalytic activity on photodegradation of Safranin-O (SO) dye as compared to pure TiO 2 . The positive effect of silver on the photocatalytic activity of TiO 2 may be explained by its ability to trap electrons. This process reduces the recombination of light generated electron-hole pairs at TiO 2 surface and therefore enhances the photocatalytic activity of the synthesized TiO 2 nanoparticles. The effects of initial dye and nanoparticle concentrations on the photocatalytic activity have been studied and the results demonstrate that the dye photodegradation follows pseudo-first-order kinetics. The observed maximum degradation efficiency of SO is about 60% for TiO 2 and 96% for Ag-TiO 2 . - Research highlights: → Ag-TiO 2 nanoparticles exhibit enhanced photocatalytic activity on photodegradation of Safranin-O (SO) dye as compared to pure TiO 2 . → Dye photodegradation follows pseudo-first-order kinetics. → Observed maximum degradation efficiency of SO is about 60% for TiO 2 and 96% for Ag-TiO 2 .

  20. TiO2-Based Photocatalytic Geopolymers for Nitric Oxide Degradation

    Science.gov (United States)

    Strini, Alberto; Roviello, Giuseppina; Ricciotti, Laura; Ferone, Claudio; Messina, Francesco; Schiavi, Luca; Corsaro, Davide; Cioffi, Raffaele

    2016-01-01

    This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin), composite systems (siloxane-hybrid, foamed hybrid), and curing temperatures (room temperature and 60 °C) were investigated for the same photocatalyst content (i.e., 3% TiO2 by weight of paste). The geopolymer matrices were previously designed for different applications, ranging from insulating (foam) to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features. PMID:28773634

  1. TiO2-Based Photocatalytic Geopolymers for Nitric Oxide Degradation

    Directory of Open Access Journals (Sweden)

    Alberto Strini

    2016-06-01

    Full Text Available This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin, composite systems (siloxane-hybrid, foamed hybrid, and curing temperatures (room temperature and 60 °C were investigated for the same photocatalyst content (i.e., 3% TiO2 by weight of paste. The geopolymer matrices were previously designed for different applications, ranging from insulating (foam to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM and energy dispersive X-ray (EDS analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features.

  2. Synthesis and photocatalytic properties of different SnO{sub 2} microspheres on graphene oxide sheets

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Jia, E-mail: jojo.1125@hotmail.com [College of Science, Donghua University, Shanghai 201620 (China); Xue, Shaolin, E-mail: slxue@dhu.edu.cn [College of Science, Donghua University, Shanghai 201620 (China); Xie, Pei, E-mail: peipeixie@sina.com [College of Science, Donghua University, Shanghai 201620 (China); Zou, Rujia, E-mail: rujiazou@dhu.edu.cn [College of Science, Donghua University, Shanghai 201620 (China); State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China)

    2016-07-15

    Highlights: • Different SnO{sub 2} microspheres were grown on GOs by hydrothermal method. • The morphology was influenced by volume ratio of ethanol and concentrations of precursor. • The shape of SnO{sub 2} microspheres looks like dandelion. • The photocatalytic property is strongly influenced by the SnO{sub 2} morphology on GOs. - Abstract: Different SnO{sub 2} microspheres like dandelions, silkworm cocoons and urchins have been synthesized on graphene oxide sheets (GOs) by hydrothermal method at 190 °C for 24 h. The morphologies, structures, chemical compositions and optical properties of the as-grown SnO{sub 2} microspheres on GOs (SMGs) were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), X-ray energy dispersive spectrometer (EDS), Raman spectra and UV–vis diffuse reflectance spectra (DRS) techniques. The results of XRD revealed that the as-grown SnO{sub 2} microspheres have tetragonal rutile structure. The results of Raman spectra, EDS, XRD, XPS and SEM showed that the SnO{sub 2} microspheres were grown on GOs and the average diameter of dandelion-like microsphere was about 1.5 μm. The formation mechanism of SnO{sub 2} microspheres grown on GOs was discussed. The photocatalytic activity of the SMGs composites was evaluated by photocatalytic degradation of Rhodamine B (Rh B) aqueous solution under visible light irradiation. The photocatalytic results showed that the dandelion-like SMGs exhibited a much better photocatalytic activity than those of smooth and rough SMGs.

  3. Synthesis and photocatalytic properties of different SnO2 microspheres on graphene oxide sheets

    International Nuclear Information System (INIS)

    Wei, Jia; Xue, Shaolin; Xie, Pei; Zou, Rujia

    2016-01-01

    Highlights: • Different SnO 2 microspheres were grown on GOs by hydrothermal method. • The morphology was influenced by volume ratio of ethanol and concentrations of precursor. • The shape of SnO 2 microspheres looks like dandelion. • The photocatalytic property is strongly influenced by the SnO 2 morphology on GOs. - Abstract: Different SnO 2 microspheres like dandelions, silkworm cocoons and urchins have been synthesized on graphene oxide sheets (GOs) by hydrothermal method at 190 °C for 24 h. The morphologies, structures, chemical compositions and optical properties of the as-grown SnO 2 microspheres on GOs (SMGs) were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), X-ray energy dispersive spectrometer (EDS), Raman spectra and UV–vis diffuse reflectance spectra (DRS) techniques. The results of XRD revealed that the as-grown SnO 2 microspheres have tetragonal rutile structure. The results of Raman spectra, EDS, XRD, XPS and SEM showed that the SnO 2 microspheres were grown on GOs and the average diameter of dandelion-like microsphere was about 1.5 μm. The formation mechanism of SnO 2 microspheres grown on GOs was discussed. The photocatalytic activity of the SMGs composites was evaluated by photocatalytic degradation of Rhodamine B (Rh B) aqueous solution under visible light irradiation. The photocatalytic results showed that the dandelion-like SMGs exhibited a much better photocatalytic activity than those of smooth and rough SMGs.

  4. Noble-metal-free NiO@Ni-ZnO/reduced graphene oxide/CdS heterostructure for efficient photocatalytic hydrogen generation

    Science.gov (United States)

    Chen, Fayun; Zhang, Laijun; Wang, Xuewen; Zhang, Rongbin

    2017-11-01

    Noble-metal-free semiconductor materials are widely used for photocatalytic hydrogen generation because of their low cost. ZnO-based heterostructures with synergistic effects exhibit an effective photocatalytic activity. In this work, NiO@Ni-ZnO/reduced graphene oxide (rGO)/CdS heterostructures are synthesized by a multi-step method. rGO nanosheets and CdS nanoparticles were introduced into the heterostructures via a redox reaction and light-assisted growth, respectively. A novel Ni-induced electrochemical growth method was developed to prepare ZnO rods from Zn powder. NiO@Ni-ZnO/rGO/CdS heterostructures with a wide visible-light absorption range exhibited highly photocatalytic hydrogen generation rates under UV-vis and visible light irradiation. The enhanced photocatalytic activity is attributed to the Ni nanoparticles that act as cocatalysts for capturing photoexcited electrons and the improved synergistic effect between ZnO and CdS due to the rGO nanosheets acting as photoexcited carrier transport channels.

  5. Photocatalytic oxidative desulfurization of dibenzothiophene catalyzed by amorphous TiO2 in ionic liquid

    International Nuclear Information System (INIS)

    Zhu, Wenshuai; Xu, Yehai; Li, Huaming; Dai, Bilian; Xu, Hui; Wang, Chao; Chao, Yanhong; Liu, Hui

    2014-01-01

    Three types of TiO 2 were synthesized by a hydrolysis and calcination method. The catalysts were characterized by X-ray powder diffraction (XRD), diffuse reflectance spectrum (DRS), Raman spectra, and X-ray photoelectron spectroscopy (XPS). The XRD and Raman spectra indicated that amorphous TiO 2 was successfully obtained at 100 .deg. C. The results indicated that amorphous TiO 2 achieved the highest efficiency of desulfurization. The photocatalytic oxidation of dibenzothiophene (DBT), benzothiophene (BT), 4,6-dimethyldibenzothiophene (4,6-DMDBT) and dodecanethiol (RSH) in model oil was studied at room temperature (30 .deg. C) with three catalysts. The system contained amorphous TiO 2 , H 2 O 2 , and [Bmim]BF 4 ionic liquid, ultraviolet (UV), which played vitally important roles in the photocatalytic oxidative desulfurization. Especially, the molar ratio of H 2 O 2 and sulfur (O/S) was only 2 : 1, which corresponded to the stoichiometric reaction. The sulfur removal of DBT-containing model oil with amorphous TiO 2 could reach 96.6%, which was apparently superior to a system with anatase TiO 2 (23.6%) or with anatase - rutile TiO 2 (18.2%). The system could be recycled seven times without a signicant decrease in photocatalytic activity

  6. Photocatalytic oxidative desulfurization of dibenzothiophene catalyzed by amorphous TiO{sub 2} in ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wenshuai; Xu, Yehai; Li, Huaming; Dai, Bilian; Xu, Hui; Wang, Chao; Chao, Yanhong; Liu, Hui [Jiangsu University, Zhenjiang (China)

    2014-02-15

    Three types of TiO{sub 2} were synthesized by a hydrolysis and calcination method. The catalysts were characterized by X-ray powder diffraction (XRD), diffuse reflectance spectrum (DRS), Raman spectra, and X-ray photoelectron spectroscopy (XPS). The XRD and Raman spectra indicated that amorphous TiO{sub 2} was successfully obtained at 100 .deg. C. The results indicated that amorphous TiO{sub 2} achieved the highest efficiency of desulfurization. The photocatalytic oxidation of dibenzothiophene (DBT), benzothiophene (BT), 4,6-dimethyldibenzothiophene (4,6-DMDBT) and dodecanethiol (RSH) in model oil was studied at room temperature (30 .deg. C) with three catalysts. The system contained amorphous TiO{sub 2}, H{sub 2}O{sub 2}, and [Bmim]BF{sub 4} ionic liquid, ultraviolet (UV), which played vitally important roles in the photocatalytic oxidative desulfurization. Especially, the molar ratio of H{sub 2}O{sub 2} and sulfur (O/S) was only 2 : 1, which corresponded to the stoichiometric reaction. The sulfur removal of DBT-containing model oil with amorphous TiO{sub 2} could reach 96.6%, which was apparently superior to a system with anatase TiO{sub 2} (23.6%) or with anatase - rutile TiO{sub 2} (18.2%). The system could be recycled seven times without a signicant decrease in photocatalytic activity.

  7. Engineering Interfacial Energetics: A Novel Hybrid System of Metal Oxide Quantum Dots and Cobalt Complex for Photocatalytic Water Oxidation

    International Nuclear Information System (INIS)

    Niu, Fujun; Shen, Shaohua; Wang, Jian; Guo, Liejin

    2016-01-01

    Graphical abstract: A cobalt complex engineers the interfacial energetics of metal oxide quantum dots (n- or p-type) and electrolytes for highly efficient O_2 generation under visible light irradiation. - Highlights: • A noble-metal-free hybrid photocatalytic system using a single-site cobalt catalyst was developed for O_2 generation. • Considerable activity and excellent stability for O_2 production were achieved by this novel system. • CoSlp engineered the QDs/electrolyte interfacical energetics for efficient hole transfer. - Abstract: Here we reported a novel hybrid photocatalytic water oxidation system, containing metal oxide (n-Fe_2O_3 or p-Co_3O_4) quantum dots (QDs) as light harvester, a salophen cobalt(II) complex (CoSlp) as redox catalyst and persulfate (S_2O_8"2"−) as sacrificial electron acceptor, for oxygen generation from fully aqueous solution. The n-Fe_2O_3 QDs/CoSlp and p-Co_3O_4 QDs/CoSlp systems exhibited good O_2 evolution performances, giving turnover numbers (TONs) of ca. 33 and ca. 35 over CoSlp after visible light irradiation for 72 h, respectively. The excellent photocatalytic performance could be ascribed to the efficient hole transfer from QDs to CoSlp catalyst, leading to reduced photogenerated charge recombination, as well as the CoSlp engineered interfacial band bending of QDs, increasing the driving force or decreasing the energy barrier for hole transfer and then benefiting the following O_2 generation at the QDs/electrolyte interface. The present work successfully demonstrated a novel hybrid system for photocatalytic O_2 evolution from fully aqueous solution; and the essential role of cobalt complexes in engineering the interfacial energetics of semiconductors (n- or p-type) and electrolytes could be informative for designing efficient systems for solar water splitting.

  8. Colloidal titania-silica-iron oxide nanocomposites and the effect from silica thickness on the photocatalytic and bactericidal activities

    Energy Technology Data Exchange (ETDEWEB)

    Chanhom, Padtaraporn [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Charoenlap, Nisanart [Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210 (Thailand); Tomapatanaget, Boosayarat [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Insin, Numpon, E-mail: Numpon.I@chula.ac.th [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

    2017-04-01

    New types of colloidal multifunctional nanocomposites that combine superparamagnetic character and high photocatalytic activity were synthesized and investigated. The superparamagnetic nanocomposites composed of anatase titania, silica, and iron oxide nanoparticles (TSI) were synthesized using thermal decomposition method followed by microemulsion method, without calcination at high temperature. Different techniques including X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize and confirm the structure of the nanocomposites. These nanocomposites showed high photocatalytic activity when used in the photodegradation of methylene blue under irradiation with a black light lamp. Moreover, the nanocomposites exhibited high antibacterial properties. From our study, the nanocomposites can be useful in various applications such as removal of pollutants with readily separation from the environment using an external magnetic field. These composites could effectively photo-degrade the dye at least three cycles without regeneration. The effects of silica shell thickness on the photocatalytic activity was investigated, and the thickness of 6 nm of the silica interlayer is enough for the inhibition of electron translocation between titania and iron oxide nanoparticles and maintaining the efficiency of photocatalytic activity of titania nanoparticles. - Highlights: • New colloidal nanocomposites of iron oxide-silica-titania were prepared. • The nanocomposites exhibited high photocatalytic activity with magnetic response. • The effects of silica thickness on photocatalytic activity were investigated. • Bactericidal activity of the nanocomposites was demonstrated.

  9. Enhanced visible-light-driven photocatalytic performance of porous graphitic carbon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Fei, E-mail: feichang@usst.edu.cn [School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Li, Chenlu; Luo, Jieru; Xie, Yunchao; Deng, Baoqing [School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Hu, Xuefeng, E-mail: xfhu@yic.ac.cn [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China)

    2015-12-15

    Graphical abstract: - Highlights: • Porous g-C{sub 3}N{sub 4} samples were fabricated by a facile pyrolysis method. • As-prepared porous g-C{sub 3}N{sub 4} samples showed remarkably enhanced photocatalytic performance. • Holes and radicals ·O{sub 2}{sup −} exerted dominant roles on the photocatalytic process. - Abstract: In this study, a series of porous graphitic carbon nitride (g-C{sub 3}N{sub 4}) materials were fabricated through a direct pyrolysis of protonated melamine by nitric acid solution. These as-prepared porous samples were characterized by a collection of analytical techniques. It was found that a proper concentration of nitric acid solution involved facilitated to generate samples in tube-like morphology with numerous pores, identified with X-ray diffraction patterns, FT-IR spectra, SEM, TEM, and BET measurements. These g-C{sub 3}N{sub 4} samples were subjected to photocatalytic degradation of dye Rhodamine B (RhB) in aqueous under visible-light irradiation. Under identical conditions, those porous g-C{sub 3}N{sub 4} samples showed significantly improved catalytic performance in comparison with the sample prepared without the introduction of nitric acid. In particularly, the best candidate, sample M1:1, showed an apparent reaction rate nearly 6.2 times that of the unmodified counterpart. The enhancement of photocatalytic performance could be attributed to the favorable porous structure with the enlarged specific surface area and the suitable electronic structure as well. In addition, ESR measurements were conducted for the sake of proposing a photocatalytic degradation mechanism.

  10. Photocatalytic Degradation of Malachite Green Using Nano-sized cerium-iron Oxide

    Directory of Open Access Journals (Sweden)

    K. L. Ameta

    2014-05-01

    Full Text Available Nano-sized cerium-iron oxide nanoparticles has been synthesized, characterized and explored as an efficient photocatalyst for the photocatalytic degradation of malachite green. The effects of different variables on degradation of dye were optimized such as the pH of the dye solution, dye concentration, amount of photocatalyst and light intensity. About 91% degradation of dye of 2×10-5 M concentration was observed after 2 hours at 8.5 pH and 600 Wm-2 light intensity. The reason for the high catalytic activity of the synthesized nanoparticles is ascribed to the high surface area which determines the active sites of the catalyst and accelerates the photocatalytic degradation.

  11. Direct Z-scheme TiO2/CdS hierarchical photocatalyst for enhanced photocatalytic H2-production activity

    Science.gov (United States)

    Meng, Aiyun; Zhu, Bicheng; Zhong, Bo; Zhang, Liuyang; Cheng, Bei

    2017-11-01

    Photocatalytic H2 evolution, which utilizes solar energy via water splitting, is a promising route to deal with concerns about energy and environment. Herein, a direct Z-scheme TiO2/CdS binary hierarchical photocatalyst was fabricated via a successive ionic layer adsorption and reaction (SILAR) technique, and photocatalytic H2 production was measured afterwards. The as-prepared TiO2/CdS hybrid photocatalyst exhibited noticeably promoted photocatalytic H2-production activity of 51.4 μmol h-1. The enhancement of photocatalytic activity was ascribed to the hierarchical structure, as well as the efficient charge separation and migration from TiO2 nanosheets to CdS nanoparticles (NPs) at their tight contact interfaces. Moreover, the direct Z-scheme photocatalytic reaction mechanism was demonstrated to elucidate the improved photocatalytic performance of TiO2/CdS composite photocatalyst. The photoluminescence (PL) analysis of hydroxyl radicals were conducted to provide clues for the direct Z-scheme mechanism. This work provides a facile route for the construction of redox mediator-free Z-scheme photocatalytic system for photocatalytic water splitting.

  12. Facile synthesis of Cu/tetrapod-like ZnO whisker compounds with enhanced photocatalytic properties

    Science.gov (United States)

    Liu, Hong; Liu, Huarong; Fan, Ximei

    2017-09-01

    Cu/tetrapod-like ZnO whisker (T-ZnOw) compounds were successfully synthesized using N2H4 \\cdot H2O as a reducing agent by a simple reduction method without any insert gas at room temperature. The crystal phase composition and morphology of the as-prepared samples were investigated by XRD, SEM and FESEM tests. The photocatalytic property of the as-prepared samples was detected by the degradation of methyl orange (MO) aqueous solution under UV irradiation. It can be found that Cu nanoparticles (CuNPs) dispersed on the surface of T-ZnOw increased with the increasing of Cu/Zn molar ratios (Cu/Zn MRs), and an octahedral structure of CuNPs was obtained when the sample was prepared with less than and equal to 7.30% Cu/Zn MR, but tended to a spherical or nanorod structure of CuNPs densely arranged on the surface of T-ZnOw, which is prepared by Cu/Zn MRs up to 22.00%. All the compounds exhibited excellent photocatalytic activity in decomposing of MO than T-ZnOw, the photocatalytic property of the samples increased with the increasing of Cu/Zn MRs up to 7.30%, while it decreases when further increasing the Cu/Zn MRs. The Schottky barrier of the Cu/T-ZnOw compound can effectively capture photoinduced electrons from the interface and enhanced the photocatalytic property of T-ZnOw.

  13. Core–shell TiO2 microsphere with enhanced photocatalytic activity and improved lithium storage

    International Nuclear Information System (INIS)

    Guo, Hong; Tian, Dongxue; Liu, Lixiang; Wang, Yapeng; Guo, Yuan; Yang, Xiangjun

    2013-01-01

    Inorganic hollow core–shell spheres have attracted considerable interest due to their singular properties and wide range of potential applications. Herein a novel facile generic strategy of combining template assisted and solvothermal alcoholysis is employed to prepare core–void–shell anatase TiO 2 nanoparticle aggregates with an excellent photocatalytic activity, and enhanced lithium storage in large quantities. Amorphous carbon can be loaded on the TiO 2 nanoparticles uniformly under a suitably formulated ethanol/water system in the solvothermal alcoholysis process, and the subsequent calcination results of the formation of core–shell–shell anatase TiO 2 nanoparticle aggregates. The intrinsic core–void–shell nature as well as high porosity of the unique nanostructures contributes greatly to the superior photocatalytic activity and improved performance as anode materials for lithium ion batteries. - Graphical abstract: A novel strategy of combining template assisted and solvothermal alcoholysis is employed to prepare unique core–void–shell anatase TiO 2 nanoparticle aggregates with the superior photocatalytic activity and improved lithium storage. Highlights: ► TiO 2 mesospheres are synthesized by solvothermal alcoholysis. ► It is core–void–shell structure and the thickness of shell is estimated to 80 nm. ► It exhibits a remarkable photocatalytic activity and improved lithium storage

  14. Enhanced photocatalytic CO₂-reduction activity of electrospun mesoporous TiO₂ nanofibers by solvothermal treatment.

    Science.gov (United States)

    Fu, Junwei; Cao, Shaowen; Yu, Jiaguo; Low, Jingxiang; Lei, Yongpeng

    2014-06-28

    Photocatalytic reduction of CO2 into renewable hydrocarbon fuels using semiconductor photocatalysts is considered as a potential solution to the energy deficiency and greenhouse effect. In this work, mesoporous TiO2 nanofibers with high specific surface areas and abundant surface hydroxyl groups are prepared using an electrospinning strategy combined with a subsequent calcination process, followed by a solvothermal treatment. The solvothermally treated mesoporous TiO2 nanofibers exhibit excellent photocatalytic performance on CO2 reduction into hydrocarbon fuels. The significantly improved photocatalytic activity can be attributed to the enhanced CO2 adsorption capacity and the improved charge separation after solvothermal treatment. The highest activity is achieved for the sample with a 2-h solvothermal treatment, showing 6- and 25-fold higher CH4 production rate than those of TiO2 nanofibers without solvothermal treatment and P25, respectively. This work may also provide a prototype for studying the effect of solvothermal treatment on the structure and photocatalytic activity of semiconductor photocatalysts.

  15. Heterojunction BiOI/Bi2MoO6 nanocomposite with much enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Li, Wen Ting; Zheng, Yi Fan; Yin, Hao Yong; Song, Xu Chun

    2015-01-01

    BiOI/Bi 2 MoO 6 heterostructures with different amounts of BiOI were successfully prepared via a facile deposition method. The obtained BiOI/Bi 2 MoO 6 photocatalysts exhibited much higher visible light (λ > 420 nm) induced photocatalytic activity compared with single Bi 2 MoO 6 and BiOI photocatalysts. 20 % BiOI/Bi 2 MoO 6 nanocomposite exhibited the highest photocatalytic activity with almost all RhB decomposed within 70 min. However, excess BiOI covering on the surface of Bi 2 MoO 6 can inversely reduce the photocatalytic activity. The enhanced photocatalytic activities could be resulted from the function of the novel p–n heterojunction interface between Bi 2 MoO 6 and BiOI, which could separate photoinduced carriers efficiently. Possible mechanisms on the basis of the relative band positions were also discussed

  16. Visible-light-driven N-(BiO)2CO3/Graphene oxide composites with improved photocatalytic activity and selectivity for NOx removal

    Science.gov (United States)

    Chen, Meijuan; Huang, Yu; Yao, Jie; Cao, Jun-ji; Liu, Yuan

    2018-02-01

    N-doped (BiO)2CO3 (NBOC)/graphene oxide (GO) composite obtained from three-dimensional hierarchical microspheres is successfully synthesized by one-pot hydrothermal method for the first time. In this synthesis, citrate ion plays a critical role in N doping. The obtained samples are used to degrade gaseous nitrogen oxides (NOx) at parts-per-billion (ppb) level under visible-light irradiation. NBOC-GO composite with 1.0 wt% graphene oxide (GO) displays the highest photocatalytic NO removal efficiency, which is 4.3 times higher than that of pristine (BiO)2CO3. Moreover, NBOC-GO composite significantly inhibits toxic NO2 intermediate production, indicating its high selectivity for NO conversion. Compared with regular GO, N doping considerably improves the catalytic performance of NBOC-GO composite, which increases NO removal by 74.6% and fully inhibits NO2 generation. The improved photocatalytic activity is mainly ascribed to extended optical absorption ability and enhanced separation efficiency of photogenerated charge carriers over NBOC-GO composite. Both results of electron spin resonance and theoretical analysis of band structure indicate that NO removal is dominated by oxidation with rad OH and rad O2- radicals. The photocatalytic activity improvement mechanism over the NBOC-GO composite is proposed accordingly based on systematic characterizations. This study demonstrates a feasible route to fabricating Bi-containing composites with high selectivity and stability for air pollution control and provides a new insight into the associated photocatalytic mechanisms.

  17. Synthesis, Characterization, and Evaluation of Boron-Doped Iron Oxides for the Photocatalytic Degradation of Atrazine under Visible Light

    Directory of Open Access Journals (Sweden)

    Shan Hu

    2012-01-01

    Full Text Available Photocatalytic degradation of atrazine by boron-doped iron oxides under visible light irradiation was investigated. In this work, boron-doped goethite and hematite were successfully prepared by sol-gel method with trimethylborate as boron precursor. The powders were characterized by XRD, UV-vis diffuse reflectance spectra, and porosimetry analysis. The results showed that boron doping could influence the crystal structure, enlarge the BET surface area, improve light absorption ability, and narrow their band-gap energy. The photocatalytic activity of B-doped iron oxides was evaluated in the degradation of atrazine under the visible light irradiation, and B-doped iron oxides showed higher atrazine degradation rate than that of pristine iron oxides. Particularly, B-doped goethite exhibited better photocatalytic activity than B-doped hematite.

  18. Facile synthesis of zinc oxide nanoparticles decorated graphene oxide composite via simple solvothermal route and their photocatalytic activity on methylene blue degradation.

    Science.gov (United States)

    Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Perumal, Suguna; Karthikeyan, Dhanapalan; Lee, Yong Rok

    2016-09-01

    Zinc oxide nanoparticles decorated graphene oxide (ZnO@GO) composite was synthesized by simple solvothermal method where zinc oxide (ZnO) nanoparticles and graphene oxide (GO) were synthesized via simple thermal oxidation and Hummers method, respectively. The obtained materials were thoroughly characterized by various physico-chemical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Raman spectrum shows the intensity of D to G value was close to one which confirms the obtained GO and ZnO@GO composite possesses moderate graphitization. TEM images shows the ZnO nanoparticles mean size of 15±5nm were dispersed over the wrinkled graphene layers. The photocatalytic performance of ZnO@GO composite on degradation of methylene blue (MB) is investigated and the results show that the GO plays an important role in the enhancement of photocatalytic performance. The synthesized ZnO@GO composite achieves a maximum degradation efficiency of 98.5% in a neutral solution under UV-light irradiation for 15min as compared with pure ZnO (degradation efficiency is 49% after 60min of irradiation) due to the increased light absorption, the reduced charge recombination with the introduction of GO. Moreover, the resulting ZnO@GO composite possesses excellent degradation efficiency as compared to ZnO nanoparticles alone on MB. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. The Effects of Oxidation Temperature on the Microstructure and Photocatalytic Activity of the TiO2 Coating

    Directory of Open Access Journals (Sweden)

    Xinxin TANG

    2017-08-01

    Full Text Available Titanium coatings were prepared on the surface of 1mm ZrO2 balls by mechanical ball mill, then the coatings were oxidized to photocatalytic TiO2 films at 400 ~ 600 °C. X-Ray Diffraction, Scanning Electron Microscope, Energy Dispersive Spectroscopy and Optical Microscope were used to analyze the microstructure and crystal form of the films. The photocatalytic activity of the samples was also evaluated. After that, the effects of oxidation temperature on the microstructure and photocatalytic activity of the films were discussed. The results show that the fabricated coatings are uneven, with average thickness of 60 μm. In the process of oxidation, oxygen is imported into the inner coatings by the gaps existed in the Ti coatings, which makes the Ti particles oxidize from surface to core, finally the films with TiO2 + Ti composite microstructure are obtained. The films oxidized at 500 °C have the best photocatalytic performance with the degradation rate of methyl orange solution 79.08 %, this owing to the existence of anatase and the TiO2+Ti composite microstructure. The result will provide theoretical basis for the fabrication of efficient photocatalytic film.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.15590

  20. ZnO quantum dots–decorated ZnO nanowires for the enhancement of antibacterial and photocatalytic performances

    International Nuclear Information System (INIS)

    Wu, Jyh Ming; Tsay, Li-Yi

    2015-01-01

    We demonstrate highly antibacterial activities for killing off Staphylococcus aureus and Escherichia coli using ZnO nanowires decorated with ZnO quantum dots (so-called ZnO QDs/NWs) under visible-light irradiation and dark conditions. The average size of the ZnO QDs is in the range of 3–5 nm; these were uniformly dispersed on the ZnO nanowires’ surface to form the ZnO QDs/NWs. A significant blue-shift effect was observed using photoluminescence (PL) spectra. The size of the ZnO QDs is strongly dependent on the material’s synthesis time. The ZnO QDs/NWs exhibited an excellent photocatalytic activity under visible-light irradiation. The ZnO QDs’ active sites (i.e. the O–H bond and Zn"2"+) accelerate the photogenerated-carrier migration from the QDs to the NWs. As a consequence, the electrons reacted with the dissolved oxygen to form oxygen ions and produced hydroperoxyl radicals to enhance photocatalytic activity. The antibacterial activities (as indicated by R-factor-inhibiting activity) of the ZnO QDs/NWs for killing off Staphylococcus aureus and Escherichia coli is around 4.9 and 5.5 under visible-light irradiation and dark conditions, respectively. The hydroxyl radicals served as an efficient oxidized agent for decomposing the organic dye and microorganism species. The antibacterial activities of the ZnO QDs/NWs in the dark may be attributed to the Zn"2"+ ions that were released from the ZnO QDs and infused into the microbial solution against the growth of bacteria thus disrupting the microorganism. The highly antibacterial and photocatalytic activity of the ZnO QDs/NWs can be well implanted on a screen window, thus offering a promising solution to inhibit the spread of germs under visible-light and dark conditions. (paper)

  1. Enhanced photocatalytic activity of microwave treated TiO2 pillared montmorillonite

    International Nuclear Information System (INIS)

    Sun Shenmei; Jiang Yinshan; Yu Lixin; Li Fangfei; Yang Zhengwen; Hou Tianyi; Hu Daqiang; Xia Maosheng

    2006-01-01

    TiO 2 pillared montmorillonite synthesized by microwave irradiation, exhibited good photocatalytic degradation performance of methyl orange, whose pseudo first order reaction rate constant was nearly four times than that of conventional method, because of its enhanced crystalline, preferred anatase phase and improved porosity performance, which were analysed by X-ray diffraction (XRD), far Fourier transform infrared ray spectroscopy (FTIR) and nitrogen adsorption isotherms

  2. Preparation, characterization and enhanced visible-light photocatalytic activities of BiPO4/BiVO4 composites

    International Nuclear Information System (INIS)

    Wu, Siyuan; Zheng, Hong; Lian, Youwei; Wu, Yiying

    2013-01-01

    Graphical abstract: - Highlights: • BiPO 4 /BiVO 4 composites were successfully prepared by the hydrothermal method. • BiPO 4 /BiVO 4 composites exhibited broad absorption in the visible region. • Visible-light photocatalytic activities of BiPO 4 /BiVO 4 composites were enhanced. • P/V molar ratio and pH value of the reaction affect photocatalytic activity. • The mechanism of enhanced visible-light photocatalytic activities was discussed. - Abstract: BiPO 4 /BiVO 4 composites with different P/V molar ratios were prepared by the hydrothermal method and the effect of pH values of hydrothermal reaction on photocatalytic activity of BiPO 4 /BiVO 4 composite was investigated. The photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and UV–vis diffuse reflectance spectroscopy. The photocatalytic property of BiPO 4 /BiVO 4 was evaluated by photocatalytic degradation of Methylene blue under visible light irradiation. The results showed that the photocatalytic activity of the composites was much higher than that of pure BiPO 4 and BiVO 4 . The rate constant of Methylene blue degradation over BiPO 4 /BiVO 4 (P/V molar ratio of 5:1 and hydrothermal reaction pH value of 1.5) is 1.7 times that of pure BiVO 4 . The photocatalytic activity enhancement of BiPO 4 /BiVO 4 composite is closely related to the BiVO 4 functioning as a sensitizer to adsorb visible light and the heterojunction of BiPO 4 /BiVO 4 acting as an active center for hindering the rapid recombination of electron–hole pairs during the photocatalytic reaction

  3. Synthesis of ZnO decorated graphene nanocomposite for enhanced photocatalytic properties

    Science.gov (United States)

    Gayathri, S.; Jayabal, P.; Kottaisamy, M.; Ramakrishnan, V.

    2014-05-01

    Zinc oxide/Graphene (GZ) composites with different concentrations of ZnO were successfully synthesized through simple chemical precipitation method. The X-ray diffraction pattern and the micro-Raman spectroscopic technique revealed the formation of GZ composite, and the energy dispersive X-ray spectrometry analysis showed the purity of the prepared samples. The ZnO nanoparticles decorated graphene sheets were clearly visible in the field emission scanning electron micrograph. Raman mapping was employed to analyze the homogeneity of the prepared samples. The diffuse-reflectance spectra clearly indicated that the formation of GZ composites promoted the absorption in the visible region also. The photocatalytic activity of ZnO and GZ composites was studied by the photodegradation of Methylene blue dye. The results revealed that the GZ composites exhibited a higher photocatalytic activity than pristine ZnO. Hence, we proposed a simple wet chemical method to synthesize GZ composite and its application on photocatalysis was demonstrated.

  4. Heteronanostructure of Ag particle on titanate nanowire membrane with enhanced photocatalytic properties and bactericidal activities

    International Nuclear Information System (INIS)

    Shang Lu; Li Bingjie; Dong Wenjun; Chen Benyong; Li Chaorong; Tang Weihua; Wang Ge; Wu Jian; Ying Yibin

    2010-01-01

    A novel seed induced method has been developed for syntheses of Ag particles on titanate nanowires, and then the heteronanostructured Ag/titanate nanowires were assembled into porous, flexible membranes. These titanate nanowires were about several hundreds micrometers in length and about 80 nm in diameter. The size of the Ag particle can be tuned within 300-700 nm. The pore size and thickness of the heteronanostructured membrane were easily controlled. An Ag/titanate nanowire membrane reactor has been developed to study the photocatalytic degradation of methamidophos in aqueous solution, and 87.0% of the methamidophos can be degraded in a concurrent filtration and photocatalytic oxidation process. The antibacterial activity was also investigated on the heteronanostructured membrane with UVA light (365 nm) irradiation, and a 99.99% satisfactory antibacterial effect on Escherichia coli was achieved.

  5. Titania nanotube arrays surface-modified with ZnO for enhanced photocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Nageri, Manoj; Kalarivalappil, Vijila; Vijayan, Baiju K.; Kumar, Viswanathan, E-mail: vkumar10@yahoo.co.in

    2016-05-15

    Highlights: • Heterostructures of TNA/ZnO synthesised through potentiostatic anodisation followed by hydrothermal method. • Evaluation of morphological features of the heterostructure with hydrothermal processing time. • Correlation of photocatalytic activity of the hetrostructure with its morphology and surface texture. - Abstract: Well ordered titanium dioxide nanotube arrays (TNA) of average diameter 129 nm and wall thickness of 25 nm were fabricated through potentiostatic anodisation of titanium (Ti) metal substrates. Such TNA were subsequently surface-modified with various amounts of zinc oxide (ZnO) nanopowders using hydrothermal technique to obtain heterogeneous TNA/ZnO nanostructures. The crystalline phase and surface microstructure of the heterostructures were determined by X-ray diffraction, Raman spectroscopy and scanning electron microscopy respectively. The morphology of the heterostructures strongly depended on the hydrothermal conditions employed. The photocatalytic activity of the heterostructures have also been investigated and correlated with their surface morphology and texture.

  6. Noble metal-free RGO/TiO2 composite nanofiber with enhanced photocatalytic H2-production performance

    Science.gov (United States)

    Xu, Difa; Li, Lingling; He, Rongan; Qi, Lifang; Zhang, Liuyang; Cheng, Bei

    2018-03-01

    1D reduced graphene oxide (RGO)/TiO2 nanocomposite fibers were fabricated by a facile two-step method. These samples demonstrated high photocatalytic H2-production activity from methanol aqueous solution, even without the aid of noble metal. When the ratio of RGO is 0.25 wt%, the highest H2-production rate was achieved. It increased by 10 fold than bare TiO2, reaching 149 μmol h-1 g-1 with quantum efficiency (QE) of 0.75%. The reasons were as follows. Firstly, the RGO nanosheets acted as electron acceptors. Secondly, some shallow trap states at the surface or interface of TiO2 were created by the reduction of GO during calcination. Thirdly, the redox potential position of graphene/graphene- was suitable. Fourthly, RGO could efficiently promote the separation of photogenerated electron-hole pairs and significantly enhance the photocatalytic H2-production activity. This interpretation was corroborated by transient photocurrent response. The aforementioned marvelous results provided a probable solution to replace noble metals (such as Pt) by graphene as an effective cocatalyst.

  7. Protonated graphitic carbon nitride coated metal-organic frameworks with enhanced visible-light photocatalytic activity for contaminants degradation

    Science.gov (United States)

    Huang, Jie; Zhang, Xibiao; Song, Haiyan; Chen, Chunxia; Han, Fuqin; Wen, Congcong

    2018-05-01

    Most of the reported composites of g-C3N4/metal-organic frameworks (MOFs) were obtained via exfoliation of g-C3N4 and wrapping the nanosheets on MOFs with weak interaction. In this work, chemical protonation of g-C3N4 and dip-coating was adopted as a feasible pathway to achieve the real combination of g-C3N4 derivatives with a familiar MOF material MIL-100(Fe). Structural, chemical and photophysical properties of the novel hybrid photocatalysts were characterized and compared to those of the parent materials. It was verified that the protonated g-C3N4 species of appropriate content were uniformly coated along the frameworks of MIL-100(Fe) with strong interaction. The optimal materials maintained the intact framework structure, surface property and porosity of MIL-100(Fe), as well as the inherent structural units and physicochemical properties of C3N4. In comparison to the parent materials, the protonated g-C3N4 coated MIL-100(Fe) materials exhibited enhanced photocatalytic activity in degradation of rhodamine B or methylene blue dye, as well as in oxidative denitrogenation for pyridine by molecular oxygen under visible light. Introduction of protonated g-C3N4 on MOFs improved the adsorption ability for contaminant molecules. Furthermore, coating effect provided a platform for rapid photoexcited electrons transfer and superior separation of photogenerated electron-hole pairs. Photocatalytic conversion of the three contaminants followed different mechanisms.

  8. One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres with enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Lingling [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Luo, Zhijun, E-mail: lzj@ujs.edu.cn [School of the Environment, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 (China); Tang, Chao [Maple Leaf International High School, Zhenjiang 212013 (China)

    2013-11-15

    Graphical abstract: Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core–shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs). Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation. - Highlights: • One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres. • Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@CRCSs. • Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits enhanced photocatalytic activity under visible light irradiation. - Abstract: Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core-shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs) have been synthesized via a one-step method. The core–shell nanosturctures of the as-prepared samples were confirmed by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Raman spectroscopy. The formation of Bi@Bi{sub 2}O{sub 3}@CRCSs core–shell nanosturctures should attribute to the synergetic roles of different functional groups of sodium gluconate. Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation (λ > 420 nm) and shows an O{sub 2}-dependent feature. According to trapping experiments of radicals and holes, hydroxyl radicals were not the main active oxidative species in the photocatalytic degradation of MB, but O{sub 2}·{sup −} are the main active oxidative species.

  9. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamdi, Abdullah M.; Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman)

    2015-01-05

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO{sub 2}:I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO{sub 2}:I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO{sub 2} nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO{sub 2} nanoparticles under similar illumination conditions.

  10. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    International Nuclear Information System (INIS)

    Al-Hamdi, Abdullah M.; Sillanpää, Mika; Dutta, Joydeep

    2015-01-01

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO 2 :I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO 2 :I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO 2 nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO 2 nanoparticles under similar illumination conditions

  11. Characterization of thin TiO2 films prepared by plasma enhanced chemical vapour deposition for optical and photocatalytic applications

    International Nuclear Information System (INIS)

    Sobczyk-Guzenda, A.; Gazicki-Lipman, M.; Szymanowski, H.; Kowalski, J.; Wojciechowski, P.; Halamus, T.; Tracz, A.

    2009-01-01

    Thin titanium oxide films were deposited using a radio frequency (RF) plasma enhanced chemical vapour deposition method. Their optical properties and thickness were determined by means of ultraviolet-visible absorption spectrophotometry. Films of the optical parameters very close to those of titanium dioxide have been obtained at the high RF power input. Their optical quality is high enough to allow for their use in a construction of stack interference optical filters. At the same time, these materials exhibit strong photocatalytic effects. The results of structural analysis, carried out by Raman Shift Spectroscopy, show that the coatings posses amorphous structure. However, Raman spectra of the same films subjected to thermal annealing at 450 o C disclose an appearance of a crystalline form, namely that of anatase. Surface morphology of the films has also been characterized by Atomic Force Microscopy revealing granular, broccoli-like topography of the films.

  12. Photocatalytic oxidation of indoor toluene: Process risk analysis and influence of relative humidity, photocatalysts, and VUV irradiation

    International Nuclear Information System (INIS)

    Zhao, Weirong; Dai, Jiusong; Liu, Feifei; Bao, Jiaze; Wang, Yan; Yang, Yong; Yang, Yanan; Zhao, Dongye

    2012-01-01

    Concentrations of 13 gaseous intermediates in photocatalytic oxidation (PCO) of toluene in indoor air were determined in real-time by proton transfer reaction mass spectrometry and desorption intensities of 7 adsorbed intermediates on the surface of photocatalysts were detected by temperature‐programmed desorption‐mass spectrometry. Effects of relative humidity (RH), photocatalysts, and vacuum ultraviolet (VUV) irradiation on the distribution and category of the intermediates and health risk influence index (η) were investigated. RH enhances the formation rate of hydroxide radicals, leading to more intermediates with higher oxidation states in gas phase. N doping promotes the separation of photo-generated electrons and holes and enhances PCO activity accordingly. VUV irradiation results in higher mineralization rate and more intermediates with higher oxidation states and lower toxicity e.g. carboxylic acids. Health risk analysis indicates that higher RH, N doping of TiO 2 , and VUV lead to “greener” intermediates and smaller η. Finally, a conceptual diagram was proposed to exhibit the scenario of η varied with extent of mineralization for various toxicities of inlet pollutants. Highlights: ► 13 volatile intermediates in PCO of toluene were determined in real-time by PTR-MS. ► 7 adsorbed intermediates on surface of photocatalyst were determined by TPD-MS. ► Higher RH, N doping of TiO 2 , and VUV irradiation lead to “greener” intermediates. ► Health risk index relies on extent of mineralization and toxicities of inlet VOCs.

  13. Silver Modified Degussa P25 for the Photocatalytic Removal of Nitric Oxide

    Directory of Open Access Journals (Sweden)

    Neil Bowering

    2007-01-01

    Full Text Available A study of the photocatalytic behaviour of silver modified titanium dioxide materials for the decomposition and reduction of nitric oxide (NO gas has been carried out. The effects of silver loading, calcination temperature, and reaction conditions have been investigated. Prepared photocatalysts were characterised using XRD, TEM, and XPS. A continuous flow reactor was used to determine the photocatalytic activity and selectivity of NO decomposition in the absence of oxygen as well as NO reduction using CO as the reducing agent, over the prepared photocatalysts. XRD and TEM analysis of the photocatalysts showed that crystalline silver nitrate particles were present on the titanium dioxide surface after calcination at temperatures of up to 200∘C. The silver nitrate particles are thermally decomposed to form metallic silver clusters at higher temperatures. XPS analysis of the photocatalysts showed that for each of the temperatures used, both Ag+ and Ag0 were present and that the Ag0/Ag+ ratio increased with increasing calcination temperature. The presence of metallic silver species on the TiO2 surface dramatically increased the selectivity for N2 formation of both decomposition and reduction reactions. When CO was present in the reaction gas, selectivities of over 90% were observed for all the Ag-TiO2 photocatalysts that had been calcined at temperatures above 200∘C. Unfortunately these high selectivities were at the expense of photocatalytic activity, with lower NO conversion rates than those achieved over unmodified TiO2 photocatalysts.

  14. Attapulgite-CeO2/MoS2 ternary nanocomposite for photocatalytic oxidative desulfurization

    Science.gov (United States)

    Li, Xiazhang; Zhang, Zuosong; Yao, Chao; Lu, Xiaowang; Zhao, Xiaobing; Ni, Chaoying

    2016-02-01

    Novel attapulgite(ATP)-CeO2/MoS2 ternary nanocomposites were synthesized by microwave assisted assembly method. The structures of the nanocomposites were characterized by XRD, FT-IR, UV-vis, XPS and in situ TEM. The photocatalytic activities of ATP-CeO2/MoS2 composites were investigated by degradating dibenzothiophene (DBT) in gasoline under visible light irradiation. The effect of the mass ratio of CeO2 to MoS2 on photocatalytic activity was investigated. The results indicate that the three-dimensional network structure is firmly constructed by ATP skeleton, CeO2 particles and MoS2 nanosheet which effectively increase the surface area of the composites and promote the separation of electrons and holes by resulting electronic transmission channels of multi-channel in space. The degradation rate of DBT can reach 95% under 3 h irradiation when the mass ratio of CeO2/MoS2 is 4/10. A plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite is put forward.

  15. Diatomite-immobilized BiOI hybrid photocatalyst: Facile deposition synthesis and enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Li, Baoying; Huang, Hongwei; Guo, Yuxi; Zhang, Yihe

    2015-01-01

    Graphical abstract: - Highlights: • A novel diatomite-immobilized BiOI hybrid photocatalyst has been prepared by a facile one-step deposition process for the first time. • The diatomite-immobilized BiOI hybrid photocatalyst exhibits much better photocatalytic performance. • This enhancement should be attributed to that diatomite can play as an excellent carrier platform to increase the reactive sites and promote the separation of photogenerated electron–hole pairs. • This work shed new light on facile fabrication of novel composite photocatalyst based on natural mineral. - Abstract: A novel diatomite-immobilized BiOI hybrid photocatalyst has been prepared by a facile one-step deposition process for the first time. The structure, morphology and optical property of the products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic performance of the as-prepared BiOI/diatomite photocatalysts was studied by photodegradation of Rhodamine B (RhB) and methylene blue (MB) and monitoring photocurrent generation under visible light (λ > 420 nm). The results revealed that BiOI/diatomite composites exhibit enhanced photocatalytic activity compared to the pristine BiOI sample. This enhancement should be attributed to that diatomite can play as an excellent carrier platform to increase the reactive sites and promote the separation of photogenerated electron–hole pairs. In addition, the corresponding photocatalytic mechanism was proposed based on the active species trapping experiments. This work shed new light on facile fabrication of novel composite photocatalyst based on natural mineral.

  16. Diatomite-immobilized BiOI hybrid photocatalyst: Facile deposition synthesis and enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Baoying; Huang, Hongwei, E-mail: hhw@cugb.edu.cn; Guo, Yuxi; Zhang, Yihe, E-mail: zyh@cugb.edu.cn

    2015-10-30

    Graphical abstract: - Highlights: • A novel diatomite-immobilized BiOI hybrid photocatalyst has been prepared by a facile one-step deposition process for the first time. • The diatomite-immobilized BiOI hybrid photocatalyst exhibits much better photocatalytic performance. • This enhancement should be attributed to that diatomite can play as an excellent carrier platform to increase the reactive sites and promote the separation of photogenerated electron–hole pairs. • This work shed new light on facile fabrication of novel composite photocatalyst based on natural mineral. - Abstract: A novel diatomite-immobilized BiOI hybrid photocatalyst has been prepared by a facile one-step deposition process for the first time. The structure, morphology and optical property of the products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic performance of the as-prepared BiOI/diatomite photocatalysts was studied by photodegradation of Rhodamine B (RhB) and methylene blue (MB) and monitoring photocurrent generation under visible light (λ > 420 nm). The results revealed that BiOI/diatomite composites exhibit enhanced photocatalytic activity compared to the pristine BiOI sample. This enhancement should be attributed to that diatomite can play as an excellent carrier platform to increase the reactive sites and promote the separation of photogenerated electron–hole pairs. In addition, the corresponding photocatalytic mechanism was proposed based on the active species trapping experiments. This work shed new light on facile fabrication of novel composite photocatalyst based on natural mineral.

  17. Hydrothermal synthesis of fluorinated anatase TiO{sub 2}/reduced graphene oxide nanocomposites and their photocatalytic degradation of bisphenol A

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Lijun [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming, 650091 (China); Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650093 (China); Key Laboratory of Resource Clean Conversion in Ethnic Regions, Education Department of Yunnan, School of Chemistry and Biotechnology, Yunnan MinZu University, Kunming, 650500 (China); Yang, Ye [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650093 (China); Zhang, Ali [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming, 650091 (China); Wang, Min; Liu, Yongjun; Bian, Longchun [Advanced Analysis and Measurement Center, Yunnan University, Kunming, 650091 (China); Jiang, Fengzhi, E-mail: fengzhij@ynu.edu.cn [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming, 650091 (China); Pan, Xuejun [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650093 (China)

    2015-10-30

    Graphical abstract: - Highlights: • F–TiO{sub 2}–RGO nanocomposites were synthesized via hydrothermal method. • Presence of F ion prevents phase transformation from anatase to rutile. • The adsorbed F{sup −} and RGO improve the photocatalytic activity of TiO{sub 2} synergistically. • The F–TiO{sub 2}–RGO nanocomposites were applied to degrade bisphenol A. - Abstract: The surface fluorinated TiO{sub 2}/reduced graphene oxide nanocomposites (denoted as F–TiO{sub 2}–RGO) were synthesized via hydrothermal method. The as-prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), Raman spectroscopy, Fourier Transform Infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF). The results showed that pure anatase TiO{sub 2} particles were anchored on the surface of reduced graphene oxide. And the HF added during the preparation process can not only prevent phase transformation from anatase to rutile, but also the F{sup −} ion adsorbed on the surface of TiO{sub 2}–RGO surface can enhance photocatalytic activity of F–TiO{sub 2}–RGO. The photocatalytic activities of F–TiO{sub 2}–RGO nanocomposites were evaluated by decomposing bisphenol A under UV light illumination. Under optimal degradation condition, the degradation rate constant of BPA over F–TiO{sub 2}–10RGO (0.01501 min{sup −1}) was 3.41 times than that over P25 (0.00440 min{sup −1}). The result indicated that the enhanced photocatalytic activity of F–TiO{sub 2}–10RGO was ascribed to the adsorbed F ion and RGO in F–TiO{sub 2}–RGO composite, which can reduce the recombination rate of the photo-generated electrons and holes synergistically.

  18. Photocatalytic and chemical oxidation of organic compounds in supercritical carbon dioxide. 1998 annual progress report

    International Nuclear Information System (INIS)

    Blake, D.M.

    1998-01-01

    'This report summarizes the results of work done during the first 1.3 years of a three year project. During the first nine months effort focussed on the design, construction and testing of a closed recirculating system that can be used to study photochemistry in supercritical carbon dioxide at pressures up to 5,000 psi and temperatures up to about 50 C. This was followed by a period of work in which the photocatalytic oxidation of benzene and acetone in supercritical, liquid, and gaseous carbon dioxide containing dissolved oxygen was demonstrated. The photocatalyst was titanium dioxide supported on glass spheres. This was the first time it was possible to observe photocatalytic oxidation in a supercritical fluid and to compare reaction in the three fluid phases of a solvent. This also demonstrated that it is possible to purify supercritical and liquid carbon dioxide using photochemical oxidation with no chemical additions other than oxygen. The oxidation of benzene produced no intermediates detectable using on line spectroscopic analysis or by gas chromatographic analysis of samples taken from the flow system. The catalyst surface did darken as the reaction proceeded indicating that oxidation products were accumulating on the surface. This is analogous to the behavior of aromatic compounds in air phase photocatalytic oxidation. The reaction of acetone under similar conditions resulted in the formation of low levels of by-products. Two were identified as products of the reaction of acetone with itself (4-methyl-3-penten-2-one and 4-hydroxy-4-methyl-2-pentanone) using gas chromatography with a mass spectrometer detector. Two other by-products also appear to be from the self-reaction of acetone. By-products of this type had not been observed in prior studies of the gas-phase photocatalytic oxidation of acetone. The by-products that have been observed can also be oxidized under the treatment conditions. The above results establish that photocatalytic oxidation of

  19. (0 0 1) Facet-exposed anatase-phase TiO{sub 2} nanotube hybrid reduced graphene oxide composite: Synthesis, characterization and application in photocatalytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xun [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Shi, Tiejun, E-mail: stjhfut@163.com [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Wu, Jing [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Zhou, Haiou [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); School of Materials and Chemical Engineering of Anhui University of Architecture, Hefei 230901 (China)

    2013-12-15

    Reduced graphene oxide (RGO) and TiO{sub 2} nanotube (TNT) with (0 0 1) facet-exposed anatase phase are covalently bonded together to synthesize TNT hybrid RGO (RGO-TNT) through consecutive process such as hydrothermal reaction, HCl washing, lyophilization and heat treatment with graphene oxide (GO), TiO{sub 2} powder and high concentration NaOH solution as the starting materials. The TNT with the diameter between 10 and 20 nm characterized by high resolution transmission electron microscopy (HRTEM) is in anatase phase proven by X-ray diffraction (XRD) and HRTEM. Additionally, the more active (0 0 1) facet is exposed identified by HRTEM. More significantly, TNT is bridged to RGO by C-Ti bond by the measurement of X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) spectra has testified that RGO in RGO-TNT can transfer and accept photoelectrons from TNT. The photocatalytic activity of RGO-TNT for degrading methylene blue (MB) is enhanced by contrast with pure TNT, and changeable by adjusting the mass ratios of GO to TiO{sub 2} powder. Simultaneously, lyophilization is benefit for maintaining the high active surface area of RGO-TNT, which is deeply in relationship with a higher photocatalytic activity. After four running cycles of photocatalytic degradation, RGO-TNT has shown a high stability and perfect reproducibility.

  20. Diatomite-immobilized BiOI hybrid photocatalyst: Facile deposition synthesis and enhanced photocatalytic activity

    Science.gov (United States)

    Li, Baoying; Huang, Hongwei; Guo, Yuxi; Zhang, Yihe

    2015-10-01

    A novel diatomite-immobilized BiOI hybrid photocatalyst has been prepared by a facile one-step deposition process for the first time. The structure, morphology and optical property of the products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic performance of the as-prepared BiOI/diatomite photocatalysts was studied by photodegradation of Rhodamine B (RhB) and methylene blue (MB) and monitoring photocurrent generation under visible light (λ > 420 nm). The results revealed that BiOI/diatomite composites exhibit enhanced photocatalytic activity compared to the pristine BiOI sample. This enhancement should be attributed to that diatomite can play as an excellent carrier platform to increase the reactive sites and promote the separation of photogenerated electron-hole pairs. In addition, the corresponding photocatalytic mechanism was proposed based on the active species trapping experiments. This work shed new light on facile fabrication of novel composite photocatalyst based on natural mineral.

  1. Fabrication of porous silver/titania composite hollow spheres with enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Li, Sa; Halperin, Shakked O.; Wang, Chang-An

    2015-01-01

    Silver/titania composite hollow spheres were first synthesized through an in-situ chemical reaction using functional-grouped carbon spheres as the template in this study. The prepared samples were characterized through an X-ray diffraction, N 2 adsorption–desorption, scanning electron microscopy, transmission electron microscopy and UV–Vis spectrophotometer. The photocatalytic activity of as-prepared samples was evaluated by photocatalytic decolorization of Methyl orange (MO) aqueous solution at ambient temperature under UV light. We found a structure with an optimal Ag:TiO 2 composition that exhibited a photodecomposition rate constant more than twice as high as titania hollow spheres lacking silver, and over three times higher than a commercial photocatalyst. - Highlights: • Ag/silver composites. • Hollow spheres. • Photocatalysis enhancement

  2. Facile synthesis of polyaniline-modified CuS with enhanced adsorbtion and photocatalytic activity

    Science.gov (United States)

    Wang, Xiufang; Chen, Shaohua; Shuai, Ying

    2016-10-01

    Novel hierarchical polyaniline-modified CuS (PANI-CuS) has been synthesized by simple assembling PANI on the surface of flower-like CuS spheres. The PANI modification enhances the adsorption properties of flower-like CuS. The prepared PANI-CuS composites exhibit higher visible-light-driven photocatalytic activities in degradation of rhodamine B (RhB) than that of neat CuS. The unusual photocatalytic activity could be attributed to the great adsorptivity of dyes, the extended photoresponse range, and the high migration efficiency of photoinduced electrons, which may effectively suppress the charge recombination. This work not only provides a simple strategy for fabricating highly efficient and stable CuS-based composites, but also proves that these unique structures are excellent platforms for significantly improving their visible- light-driven photoactivities, holding great promise for their applications in the field of purifying polluted water resources.

  3. Anodic luminescence, structural, photoluminescent, and photocatalytic properties of anodic oxide films grown on niobium in phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Stojadinović, Stevan, E-mail: sstevan@ff.bg.ac.rs [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Tadić, Nenad [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Radić, Nenad [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Stefanov, Plamen [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, 1113 Sofia (Bulgaria); Grbić, Boško [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Vasilić, Rastko [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia)

    2015-11-15

    Graphical abstract: - Highlights: • Anodic luminescence is correlated to the existence of morphological defects in the oxide. • Spectrum under spark discharging reveals only oxygen and hydrogen lines. • Oxide films formed under spark discharging are crystallized and composed of Nb{sub 2}O{sub 5}. • Photocatalytic activity and photoluminescence of Nb{sub 2}O{sub 5} films increase with time. - Abstract: This article reports on properties of oxide films obtained by anodization of niobium in phosphoric acid before and after the dielectric breakdown. Weak anodic luminescence of barrier oxide films formed during the anodization of niobium is correlated to the existence of morphological defects in the oxide layer. Small sized sparks generated by dielectric breakdown of formed oxide film cause rapid increase of luminescence intensity. The luminescence spectrum of obtained films on niobium under spark discharging is composed of continuum radiation and spectral lines caused by electronic spark discharging transitions in oxygen and hydrogen atoms. Oxide films formed before the breakdown are amorphous, while after the breakdown oxide films are partly crystalline and mainly composed of Nb{sub 2}O{sub 5} hexagonal phase. The photocatalytic activity of obtained oxide films after the breakdown was investigated by monitoring the degradation of methyl orange. Increase of the photocatalytic activity with time is related to an increase of oxygen vacancy defects in oxide films formed during the process. Also, higher concentration of oxygen vacancy defects in oxide films results in higher photoluminescence intensity.

  4. Transition metal oxide loaded MCM catalysts for photocatalytic ...

    Indian Academy of Sciences (India)

    Transition metal oxide (TiO2, Fe2O3, CoO) loaded MCM-41 and MCM-48 were synthesized by a two-step .... washed consecutively with water and ethanol, and cal- cined at 823 K for 5 .... conversion was observed in 1 h when the reaction was.

  5. Zinc oxide's hierarchical nanostructure and its photocatalytic properties

    DEFF Research Database (Denmark)

    Kanjwal, Muzafar Ahmed; Sheikh, Faheem A.; Barakat, Nasser A. M.

    2012-01-01

    In this study, a new hierarchical nanostructure that consists of zinc oxide (ZnO) was produced by the electrospinning process followed by a hydrothermal technique. First, electrospinning of a colloidal solution that consisted of zinc nanoparticles, zinc acetate dihydrate and poly(vinyl alcohol...

  6. Electrochemical approach to evaluate the mechanism of photocatalytic water splitting on oxide photocatalysts

    International Nuclear Information System (INIS)

    Matsumoto, Yasumichi; Unal, Ugur; Tanaka, Noriyuki; Kudo, Akihiko; Kato, Hideki

    2004-01-01

    Photoelectrochemical measurements of TiO 2 , NaTaO 3 , and Cr or Sb doped TiO 2 and SrTiO 3 photocatalysts were carried out in H 2 and O 2 saturated electrolytes in order to evaluate the reverse reactions during water photolysis. The poor activity of TiO 2 as a result of reverse photoreactions of O 2 reduction and H 2 oxidation was revealed with the respective high cathodic and anodic photocurrents. The rise in the photocurrents at NaTaO 3 after La doping was in harmony with the doping-induced increase in the photocatalytic activity. NiO loading suppresses the O 2 photoreverse reactions, which declines photocatalytic activity, and/or promotes the photo-oxidation of water, because the O 2 photo-reduction current was scarcely observed near the flatband potential. Photocurrents of O 2 reduction and H 2 oxidation were observed under visible light for the Cr and Sb doped SrTiO 3 and TiO 2 , respectively. These phenomena are in harmony with the previous reports on the photocatalysts examined with sacrificial reagents

  7. Fullerene (C{sub 60})/CdS nanocomposite with enhanced photocatalytic activity and stability

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Qiang [Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Hu, Zhuofeng, E-mail: st04hzhf@gmail.com [Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (China); Zhang, Qian; Li, Boyuan [Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Shen, Zhurui, E-mail: shenzhurui@tju.edu.cn [Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

    2017-05-01

    Highlights: • C{sub 60}/CdS nanocomposite has been fabricated as a novel visible-light-driven photocatalyst. • It exhibits enhanced photocatalytic activity and photostability than that of pure CdS reference. • The C{sub 60} improved the charge separation and transfer of nanocomposite due to its high electron affinity. - Abstract: Herein, the fullerene (C{sub 60})/CdS nanocomposite has been fabricated by a facile one-pot hydrothermal method. Its photocatatlytic hydrogen (H{sub 2}) evolution rate and degradation efficiency of Rhodamine B (Rh B) are evaluated under visible light irradiation (λ ≥ 420 nm). The content of C{sub 60} has been changed from 0.4 wt% to 8 wt%, and the optimal value for photocatalytic activity is determined to be 0.4 wt%. The H{sub 2} evolution rate over this optimal sample reaches 1.73 mmol h{sup −1} g{sup −1} and its apparent degradation rate of Rh B is 0.089 min{sup −1} (degradation efficiency of 97% within 40 min), which is 2.3 times and 1.5 times compared to that of pure CdS reference. Moreover, the photocorrosion of CdS in composite is effectively suppressed, and its photocatalytic activity can be well maintained after three recycles (97.8% retaining for composite vs. 84.4% retaining for CdS). Then, the enhanced photocatalytic activity and stability of C{sub 60}/CdS nanocomposite are further studied by spectroscopic and electrochemical methods. Results show that the C{sub 60} species covering on the surface of CdS can efficiently accelerate the separation and transfer of photoexcited charge carriers, which can improve its activity, and reduce the photocorrosion of CdS.

  8. Preparation of three dimensional graphene foam–WO3 nanocomposite with enhanced visible light photocatalytic activity

    International Nuclear Information System (INIS)

    Azimirad, R.; Safa, S.

    2015-01-01

    Three dimensional graphene foam (3D GF) was synthesized by chemical vapor deposition (CVD) on a nickel foam skeleton. After dissolving the nickel foam, the obtaining 3D GF was used as a highly porous conductive substrate for nucleation and growth of WO 3 particles. Scanning electron microscopy (SEM) and Raman spectroscopy was employed to ensure the quality of the prepared GFs and to judge about the 3D GF–WO 3 chemical structure. The WO 3 characteristic Raman peaks centered at 726, and 809 cm −1 are slightly broadened and displaced to lower wavelength in the 3D GF–WO 3 nanocomposite, as compared to the corresponding peaks of the bare tungsten oxide. This phenomenon confirms the formation of W–C and W–O–C bonds in composite material which is important for faster transferring the photoexcited electrons to graphene 3D network as an exceptional electron acceptor. The 3D GF−WO 3 composite material was applied in photocatalytic degradation of Rhodamine B dye. It was observed that the annealed samples show an excellent photocatalytic performance relative to the as-prepared 3D GF−WO 3 samples and bare WO 3 , which is ascribed to the lower electron/hole recombination through the formation of W–C and W–O–C bonds. - Highlights: • 3D GF synthesized by CVD on a nickel foam as a highly porous conductive substrate. • WO 3 nanoparticles coated on 3D GF by dip-coating. • 3D GF−WO 3 shows an excellent photocatalytic degradation of Rhodamine B dye. • Better photocatalytic properties assigned to the formation of W–C and W–O–C bonds

  9. Constructing three-dimensional porous graphene-carbon quantum dots/g-C3N4 nanosheet aerogel metal-free photocatalyst with enhanced photocatalytic activity

    Science.gov (United States)

    He, Huijuan; Huang, Langhuan; Zhong, Zijun; Tan, Shaozao

    2018-05-01

    Photocatalysis has been widely considered to be an effective way for solving the worldwide environmental pollution issues. Herein, a new type of three-dimensional (3D) ternary graphene-carbon quantum dots/g-C3N4 nanosheet (GA-CQDs/CNN) aerogel visible-light-driven photocatalyst was synthesized via a two-step hydrothermal method. In this unique ternary photocatalyst, both carbon quantum dots (CQDs) and reduced graphene oxide (rGO) could improve the visible light absorption and promote the charge separation. Furthermore, reduced graphene oxide (rGO) could act as a supportor for the 3D framework. Such a ternary system overcame the drawbacks of bulk g-C3N4 (BCN) and achieved the enhanced photocatalytic activity and long-term stability. As a result, the methyl orange (MO) removal ratio of GA-CQDs/CNN-24% was up to 91.1%, which was about 7.6 times higher than that of bulk g-C3N4 (BCN) under the identical conditions. Moreover that GA-CQDs/CNN-24% exhibited inappreciable loss of photocatalytic activity after four-cycle degradation processes. Finally, the photocatalytic mechanism of GA-CQDs/CNN-24% was interpreted both theoretically and experimentally.

  10. Oxidation driven ZnS Core-ZnO shell photocatalysts under controlled oxygen atmosphere for improved photocatalytic solar water splitting

    Science.gov (United States)

    Bak, Daegil; Kim, Jung Hyeun

    2018-06-01

    Zinc type photocatalysts attract great attentions in solar hydrogen production due to their easy availability and benign environmental characteristics. Spherical ZnS particles are synthesized with a facile hydrothermal method, and they are further used as core materials to introduce ZnO shell layer surrounding the core part by partial oxidation under controlled oxygen contents. The resulting ZnS core-ZnO shell photocatalysts represent the heterostructural type II band alignment. The existence of oxide layer also influences on proton adsorption power with an aid of strong base cites derived from highly electronegative oxygen atoms in ZnO shell layer. Photocatalytic water splitting reaction is performed to evaluate catalyst efficiency under standard one sun condition, and the highest hydrogen evolution rate (1665 μmolg-1h-1) is achieved from the sample oxidized at 16.2 kPa oxygen pressure. This highest hydrogen production rate is achieved in cooperation with increased light absorption and promoted charge separations. Photoluminescence analysis reveals that the improved visible light response is obtained after thermal oxidation process due to the oxygen vacancy states in the ZnO shell layer. Therefore, overall photocatalytic efficiency in solar hydrogen production is enhanced by improved charge separations, crystallinity, and visible light responses from the ZnS core-ZnO shell structures induced by thermal oxidation.

  11. The enhanced visible light photocatalytic activity of yttrium-doped BiOBr synthesized via a reactable ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    He, Minqiang; Li, Weibing [School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013 (China); Xia, Jiexiang, E-mail: xjx@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013 (China); Xu, Li; Di, Jun [School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013 (China); Xu, Hui [School of the Environment, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013 (China); Yin, Sheng [School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013 (China); Li, Huaming, E-mail: lhm@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013 (China); Li, Mengna [School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013 (China)

    2015-03-15

    Graphical abstract: Yttrium (Y)-doped BiOBr with different Y doping concentrations has been synthesized via solvothermal method in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br). The photocatalytic activities of the yttrium doped BiOBr samples were evaluated by the degradation of ciprofloxacin (CIP) and rhodamine B (RhB) under visible-light irradiation. The yttrium doped BiOBr exhibited enhanced photocatalytic activity for the degradation of the two types of pollutants, and the 5wt%Y-doped BiOBr showed the highest photocatalytic activity. The enhanced photocatalytic performance could be attributed to the reduced band gap and improved separation of electron–hole pairs. - Highlights: • Yttrium (Y)-doped BiOBr composites have been synthesized via solvothermal method in the presence of reactable ionic liquid [C16mim]Br. • The yttrium doped BiOBr exhibited enhanced photocatalytic activity for the degradation of ciprofloxacin (CIP) and rhodamine B (RhB). • The enhanced photocatalytic performance could be attributed to the reduced band gap and improved separation of electron–hole pairs. - Abstract: Yttrium (Y)-doped BiOBr with different Y doping concentrations has been synthesized via solvothermal method in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C{sub 16}mim]Br). Their structures, morphologies and optical properties were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic activities of the yttrium doped BiOBr samples were evaluated by the degradation of ciprofloxacin (CIP) and rhodamine B (RhB) under visible-light irradiation. The yttrium doped BiOBr exhibited enhanced photocatalytic activity for the degradation of the two types of pollutants, and the 5wt%Y-doped BiOBr showed the highest

  12. TiO2-CdS Nanocomposites: Effect of CdS Oxidation on the Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    A. Hamdi

    2016-01-01

    Full Text Available Nanocomposites TiO2-CdS with different relative contents of CdS (molar ratios Cd/Ti = 0.02, 0.03, 0.05, 0.1, 0.2, and 0.5 were studied. The structural, photophysical, and chemical properties were investigated using XRD, Raman spectroscopy, XPS, GSDR, and LIL. XRD and Raman results confirmed the presence of TiO2 and CdS with intensities dependent on the ratio Cd/Ti. The presence of CdSO4 was detected by XPS at the surface of all TiO2-CdS composites. The relative amount of sulphate was dependent on the CdS loading. Luminescence time-resolved spectra clearly proved the existence of an excitation transfer process from CdS to TiO2 through the luminescence emission from TiO2 after excitation of CdS at λexc=410 nm, where no direct excitation of TiO2 occurs. Photodegradation of a series of aromatic carboxylic acids—benzoic, salicylic, 4-bromobenzoic, 3-phenylpropionic, and veratric acids—showed a great enhancement in the photocatalytic efficiency of the TiO2-CdS composites, which is due, mainly, to the effect of the charge carriers’ increased lifetime. In addition, it was shown that the oxidation of CdS to CdSO4 did not result in the deactivation of the photocatalytic properties and even contributed to enhance the degradation efficiency.

  13. Photocatalytic oxidation of organic compounds in a hybrid system composed of a molecular catalyst and visible light-absorbing semiconductor.

    Science.gov (United States)

    Zhou, Xu; Li, Fei; Li, Xiaona; Li, Hua; Wang, Yong; Sun, Licheng

    2015-01-14

    Photocatalytic oxidation of organic compounds proceeded efficiently in a hybrid system with ruthenium aqua complexes as catalysts, BiVO4 as a light absorber, [Co(NH3)5Cl](2+) as a sacrificial electron acceptor and water as an oxygen source. The photogenerated holes in the semiconductor are used to oxidize molecular catalysts into the high-valent Ru(IV)=O intermediates for 2e(-) oxidation.

  14. Melamine modified P25 with heating method and enhanced the photocatalytic activity on degradation of ciprofloxacin

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huiqin [School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, Jinze; Ma, Changchang [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Guan, Qingfeng [School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China); Lu, Ziyang [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Huo, Pengwei, E-mail: huopw1@163.com [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yan, Yongsheng [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-02-28

    Highlights: • We demonstrated the as-prepared photocatalyst of g-C{sub 3}N{sub 4}-TiO{sub 2} with the commercial TiO{sub 2} (P25) composited melamine under ball milling and calcined. • The enhanced photocatalytic performance could be mainly attributed to the suitable band gap structure with heterojunction of CN-P25. • The possible photocatalytic mechanism of g-C{sub 3}N{sub 4}/P25 under visible light irradiation is proposed. - Abstract: The graphitic carbon nitride (g-C{sub 3}N{sub 4}), as one photocatalyst which possess the suitable band gap, is better for modified TiO{sub 2} and enhanced photocatalytic degradation of organic pollutants. In this work, the g-C{sub 3}N{sub 4}/TiO{sub 2} were successfully prepared via directly calcined the mixture of melamine and P25. The as-prepared g-C{sub 3}N{sub 4}/TiO{sub 2} photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and high resolution electron microscopy (HRTEM), Raman and Fourier transform-infrared spectroscopy (FT-IR). The photocatalytic performances of g-C{sub 3}N{sub 4}/TiO{sub 2} composites were investigated by degradation of ciprofloxacin. The results showed that the g-C{sub 3}N{sub 4} and P25 were successfully composited, and the bond of C–N was well formed, the calcined temperature for as-prepared photocatalysts and the ratio of melamine and P25 were important to the degradation rate of ciprofloxacin. When the mixture of melamine and P25 with 1:2, and calcined temperature at 600 °C, the degradation rate of ciprofloxacin could reach 95% in 60 min. The enhanced photocatalytic performances could be mainly attributed to the suitable band gap structure with heterojunction of CN-P25. Finally, the possible transferred processes of photoelectrons and photoholes were proposed.

  15. Microporous TiO2-WO3/TiO2 films with visible-light photocatalytic activity synthesized by micro arc oxidation and DC magnetron sputtering

    International Nuclear Information System (INIS)

    Wu, Kee-Rong; Hung, Chung-Hsuang; Yeh, Chung-Wei; Wu, Jiing-Kae

    2012-01-01

    Highlights: ► A simple MAO is used to prepare porous WO 3 /TiO 2 layer on Ti sheet as a visible-light enabled catalyst. ► The photocatalytic activity of the WO 3 /TiO 2 is enhanced by sputtering over an N,C-TiO 2 layer. ► This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO 2 -WO 3 /TiO 2 films with a high surface area using a two-step approach. A porous WO 3 /TiO 2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO 2 (N,C-TiO 2 ) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO 2 lattice using direct current magnetron sputtering. The resulting microporous TiO 2 -WO 3 /TiO 2 film with a 0.38-μm-thick N,C-TiO 2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO 2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO 2 -WO 3 /TiO 2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO 3 /TiO 2 can be used as a template of hybrid electrode because it enables rapid fabrication.

  16. In situ photoactivated plasmonic Ag{sub 3}PO{sub 4}@silver as a stable catalyst with enhanced photocatalytic activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongfang; Wang, Jiaxun, E-mail: zdfbb66@aliyun.com [College of Science, Huazhong Agricultural University, Wuhan (China)

    2017-05-15

    Silver orthophosphate (Ag{sub 3}PO{sub 4}) had been reported as an excellent candidate to split water or decompose pollutants with high efficiency in visible light region, yet is not stable due to the reduction of silver ion. In this work, an easy-fabricated method (in situ photoinduced reduction) was provided to enhance the stability of Ag{sub 3}PO{sub 4} for its possible application as a visible-light sensitive photocatalyst. The as-prepared samples were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra, photoluminescence spectra (PL) and Photoelectrochemical measurements. The Ag{sub 3}PO{sub 4}/Ag photocatalysts showed strong photocatalytic activity for decomposition of RhB dye or phenol-X-3B mixture under visible light irradiation (λ> 420 nm) and can be used repeatedly. The possible mechanism for the enhanced photocatalytic properties of the Ag{sub 3}PO{sub 4} /Ag hybrid was also discussed. It was found that •OH and holes take priority over •O{sub 2}{sup -} radicals in serving as the main oxidant in the Ag{sub 3}PO{sub 4}/Ag photocatalytic system. Especially, the experimental results indicate that the surface plasmon resonance of Ag nanoparticles and a large negative charge of PO{sub 4}{sup 3-} ions as well as high separation efficiency of {sup e-} --h{sup +} pairs, facilitated the enhancement of the photocatalytic activity of the Ag{sub 3} PO{sub 4} /Ag composite. The results indicated that Ag{sub 3} PO{sub 4} /Ag is an efficient and stable visible-light-driven photocatalyst. (author)

  17. Synthesis and Characterization of WO3/Graphene Nanocomposites for Enhanced Photocatalytic Activities by One-Step In-Situ Hydrothermal Reaction

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Hu

    2018-01-01

    Full Text Available Tungsten trioxide (WO3 nanorods are synthesized on the surface of graphene (GR sheets by using a one-step in-situ hydrothermal method employing sodium tungstate (Na2WO4·2H2O and graphene oxide (GO as precursors. The resulting WO3/GR nanocomposites are characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The results confirm that the interface between WO3 nanorod and graphene contains chemical bonds. The enhanced optical absorption properties are measured by UV-vis diffuse reflectance spectra. The photocatalytic activity of the WO3/GR nanocomposites under visible light is evaluated by the photodegradation of methylene blue, where the degradation rate of WO3/GR nanocomposites is shown to be double that of pure WO3. This is attributed to the synergistic effect of graphene and the WO3 nanorod, which greatly enhances the photocatalytic performance of the prepared sample, reduces the recombination of the photogenerated electron-hole pairs and increases the visible light absorption efficiency. Finally, the photocatalytic mechanism of the WO3/GR nanocomposites is presented. The synthesis of the prepared sample is convenient, direct and environmentally friendly. The study reports a highly efficient composite photocatalyst for the degradation of contaminants that can be applied to cleaning up the environment.

  18. Synergetic effect of MoS2 and graphene as cocatalysts for enhanced photocatalytic activity of BiPO4 nanoparticles

    Science.gov (United States)

    Lv, Hua; Liu, Yumin; Tang, Haibo; Zhang, Peng; Wang, Jianji

    2017-12-01

    The photodegradation of organic pollutants is an attractive green chemistry technology for water pollution control. Here we prepared a new composite material consisting of BiPO4 nanocrystals grown on layered graphene and MoS2 as a high-performance photocatalyst for the photodegradation of organic pollutants. This composite material was synthesized by a facile one-pot microwave-assisted hydrothermal technique in the presence of layered graphene and MoS2. Through optimizing the loading content of each component, the BiPO4-MoS2/graphene nanocomposite exhibited the highest photocatalytic activity for the degradation of Rhodamine (RhB) when the content of MoS2 and graphene was 2 wt% and 7 wt%, respectively. The enhanced photocatalytic activity of the new composite photocatalyst was attributed to the positive synergetic effect of the layered graphene and MoS2 as cocatalyst, which acted as electron collector and transporter for the interfacial electron transfer from BiPO4 to electron acceptor in the aqueous solution and thus suppressed the charge recombination and made the photogenerated holes more available to participated in the oxidation process. Moreover, the presence of layered MoS2/graphene hybrid could offer more reactive sites and activated the O2 molecular in water to form superoxide radical, thereby resulting in the enhanced photocatalytic activity.

  19. Twin defects engineered Pd cocatalyst on C3N4 nanosheets for enhanced photocatalytic performance in CO2 reduction reaction

    Science.gov (United States)

    Lang, Qingqing; Hu, Wenli; Zhou, Penghui; Huang, Tianlong; Zhong, Shuxian; Yang, Lining; Chen, Jianrong; Bai, Song

    2017-12-01

    Photocatalytic conversion of CO2 to value-added chemicals, a potential route to addressing the depletion of fossil fuels and anthropogenic climate change, is greatly limited by the low-efficient semiconductor photocatalyst. The integration of cocatalyst with light-harvesting semiconductor is a promising approach to enhancing the photocatalytic performance in CO2 reduction reaction. The enhancement is greatly determined by the catalytic active sites on the surface of cocatalyst. Herein, we demonstrate that the photocatalytic performance in the CO2 reduction reaction is greatly promoted by twin defects engineered Pd cocatalyst. In this work, Pd nanoicosahedrons with twin defects were in situ grown on C3N4 nanosheets, which effectively improve the photocatalytic performance in reduction of CO2 to CO and CH4 in comparison with Pd nanotetrahedrons without twin defects. It is proposed that the twin boundary (TB) terminations on the surface of Pd cocatalysts are highly catalytic active sites for CO2 reduction reaction. Based on the proposed mechanism, the photocatalytic activity and selectivity in CO2 reduction were further advanced through reducing the size of Pd icosahedral cocatalyst resulted from the increased surface density of TB terminations. The defect engineering on the surface of cocatalyst represents a novel route in realizing high-performance photocatalytic applications.

  20. Visible light photocatalytic disintegration of waste activated sludge for enhancing biogas production.

    Science.gov (United States)

    Anjum, Muzammil; Al-Talhi, Hasan A; Mohamed, Saleh A; Kumar, Rajeev; Barakat, M A

    2018-06-15

    Biogas production using waste activated sludge (WAS) is one of the most demanding technologies for sludge treatment and generating energy in sustainable manner. The present study deals with the photocatalytic pretreatment of WAS using ZnO-ZnS@polyaniline (ZnO-ZnS@PANI) nanocomposite as means for increasing its degradability for improved biogas production by anaerobic digestion (AD). Photocatalysis accelerated the hydrolysis of WAS and increased the sCOD by 6.7 folds after 6 h and transform tCOD into bioavailable sCOD. After the AD of WAS, a removal of organic matter (60.6%) and tCOD (69.3%) was achieved in photocatalytic pretreated sludge. The biogas production was 1.6 folds higher in photocatalytic sludge with accumulative biogas up to 1645.1 ml L -1 vs after 45 days compared with the raw sludge (1022.4 ml L -1 VS ). Moreover, the photocatalysis decrease the onset of methanogenesis from 25 to 12 days while achieve the maximum conversion rate of reducing sugars into organic acids at that time. These results suggested that photocatalysis is an efficient pretreatment method and ZnO-ZnS@PANI can degrade sludge efficiently for enhance biogas production in anaerobic digestion process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Hexagonal pencil-like CdS nanorods: Facile synthesis and enhanced visible light photocatalytic performance

    Science.gov (United States)

    An, Liang; Wang, Guanghui; Zhao, Lei; Zhou, Yong; Gao, Fang; Cheng, Yang

    2015-07-01

    In the present study, hexagonal pencil-like CdS nanorods have been successfully synthesized through a typical facile and economical one-step hydrothermal method without using any surfactant or template. The product was characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and energy dispersive analysis of X-ray (EDX). The results revealed that the prepared CdS photocatalyst consisted of a large quantity of straight and smooth solid hexagonal nanorods and a few nanoparticles. The photocatalytic activities of CdS nanorods and commercial CdS powders were investigated by the photodegradation of Orange II (OII) in aqueous solution under visible light, and the CdS nanorods presented the highest photocatalytic activity. Its photocatalytic efficiency enhancement was attributed to the improved transmission of photogenerated electron-hole pairs in the CdS nanostructures. The present findings may provide a facile approach to synthesize high efficient CdS photocatalysts.

  2. The SL-assisted synthesis of hierarchical ZnO nanostructures and their enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Miao Tingting; Guo Yuanru; Pan Qingjiang

    2013-01-01

    Hierarchical ZnO nanoparticle-bar, nanomesh-lamina, and quasi-nanosphere structures have been successfully synthesized by the precipitation method with assistance of sodium lignosulphonate (SL). It is shown that the obtained ZnO nanomaterials are well crystallized and possess hexagonal wurtzite structure after calcination. Morphologies of ZnO with particle sizes ranging from 50 to 200 nm can be fabricated by tuning the SL amount in our synthetic route. Plenty of pores have been observed both in nanoparticle-bar and nanomesh-lamina ZnO. This may provide scaffold microenvironments to enhance their photocatalytic activity. It is evident that the synthesized ZnO exhibits good photocatalytic activity of degrading methylene blue, even under a very low-power UV illumination, which allows for the treatment of wastewater containing organic pollutants in an effective way. Among our synthesized nanomaterials, the nanomesh-lamina ZnO has the highest photodegradation efficiency, achieving nearly 100 % degradation only within 1.5 h (UV irradiation power of 12 W). As these ZnO nanomaterials are simply synthesized using SL which is a pulp industry by-product and their intrinsic hierarchical nanostructures show outstanding photocatalytic behavior, we expect the present controllable, environment-friendly, and cost-effective approach to be applied in the synthesis of small-sized ZnO materials.

  3. The SL-assisted synthesis of hierarchical ZnO nanostructures and their enhanced photocatalytic activity

    Science.gov (United States)

    Miao, Ting-Ting; Guo, Yuan-Ru; Pan, Qing-Jiang

    2013-06-01

    Hierarchical ZnO nanoparticle-bar, nanomesh-lamina, and quasi-nanosphere structures have been successfully synthesized by the precipitation method with assistance of sodium lignosulphonate (SL). It is shown that the obtained ZnO nanomaterials are well crystallized and possess hexagonal wurtzite structure after calcination. Morphologies of ZnO with particle sizes ranging from 50 to 200 nm can be fabricated by tuning the SL amount in our synthetic route. Plenty of pores have been observed both in nanoparticle-bar and nanomesh-lamina ZnO. This may provide scaffold microenvironments to enhance their photocatalytic activity. It is evident that the synthesized ZnO exhibits good photocatalytic activity of degrading methylene blue, even under a very low-power UV illumination, which allows for the treatment of wastewater containing organic pollutants in an effective way. Among our synthesized nanomaterials, the nanomesh-lamina ZnO has the highest photodegradation efficiency, achieving nearly 100 % degradation only within 1.5 h (UV irradiation power of 12 W). As these ZnO nanomaterials are simply synthesized using SL which is a pulp industry by-product and their intrinsic hierarchical nanostructures show outstanding photocatalytic behavior, we expect the present controllable, environment-friendly, and cost-effective approach to be applied in the synthesis of small-sized ZnO materials.

  4. Enhanced photocatalytic hydrogen production on three-dimensional gold butterfly wing scales/CdS nanoparticles

    Science.gov (United States)

    Fang, Jing; Song, Guofen; Liu, Qinglei; Zhang, Wang; Gu, Jiajun; Su, Yishi; Su, Huilan; Guo, Cuiping; Zhang, Di

    2018-01-01

    Photocatalytic water splitting via utilizing various semiconductors is recognized as a promising way for hydrogen production. Plasmonic metals with sub-micrometer textures can improve the photocatalytic performance of semiconductors via a localized surface plasmon resonance (LSPR) process. Moreover, arrays of multilayer metallic structures can help generate strong LSPR. However, artificial synthesis has difficulties in constructing novel multilayer metallic arrays down to nanoscales. Here, we use three dimensional (3D) scales from Morpho didius forewings (M) to prepare 3D Au-wings with intact hierarchical bio-structures. For comparison, we use Troides helena forewings (T) which are known for their antireflection quasi-honeycomb structures resulting in strong light absorbing ability. Results show that multilayer rib structures of Au-M can significantly amplify the LSPR of 3D Au and thus can efficiently help the photocatalytic process (9-fold increase). This amplification effect is obviously more superior to the straightforward enhancement of the absorption of incident light (Au-T, 5-fold increase). Thus, our study provides the possibility to prepare highly efficient plasmonic photocatalysts (possessing 3D multilayer rib structures) via an easy method. This work will also be revealing for plasmonic applications in other fields.

  5. Enhanced TiO2 Photocatalytic Processing of Organic Wastes for Green Space Exploration

    Science.gov (United States)

    Udom, I.; Goswami, D. Y.; Ram, M. K.; Stefanakos, E. K.; Heep, A. F.; Kulis, M. J.; McNatt, J. S.; Jaworske, D. A.; Jones, C. A.

    2013-01-01

    The effect of transition metal co-catalysts on the photocatalytic properties of TiO2 was investigated. Ruthenium (Ru), palladium, platinum, copper, silver, and gold, were loaded onto TiO2 powders (anatase and mixed-phase P25) and screened for the decomposition of rhodamine B (RhB) under broad-band irradiation. The morphology and estimated chemical composition of photocatalysts were determined by scanning electron microscopy and energy dispersive spectroscopy, respectively. Brunhauer, Emmett and Teller (BET) analysis measured mass-specific surface area(s). X-ray diffraction analysis was performed to confirm the identity of titania phase(s) present. The BET surface area of anatase TiO2/Ru 1% (9.2 sq m/gm) was one of the highest measured of all photocatalysts prepared in our laboratory. Photolyses conducted under air-saturated and nitrogen-saturated conditions revealed photodegradation efficiencies of 85 and 2 percent, respectively, after 60 min compared to 58 percent with no catalyst. The cause of low photocatalytic activity under an inert atmosphere is discussed. TiO2/Ru 1% showed a superior photocatalytic activity relative to P25-TiO2 under broad-band irradiation. A potential deployment of photocatalytic technologies on a mission could be a reactor with modest enhancement in solar intensity brought about by a trough-style reactor, with reactants and catalyst flowing along the axis of the trough and therefore being illuminated for a controlled duration based on the flow rate.

  6. Photocatalytic Oxidation of NO over Composites of Titanium Dioxide and Zeolite ZSM-5

    Directory of Open Access Journals (Sweden)

    Akram Tawari

    2016-02-01

    Full Text Available Composites of TiO2 (Hombikat, P25, sol-gel synthesis and zeolite ZSM-5 (nSi/nAl = 55 with mass fractions from 25/75 to 75/25 were prepared by mechanical mixing, solid-state dispersion and sol-gel synthesis. Characterization of the composites by X-ray diffraction (XRD, N2-sorption, scanning electron microscopy (SEM, and UV-Vis spectroscopy show that mechanical mixing and solid-state dispersion lead to comparable textural properties of the composites. A homogeneous distribution and intimate contact of small TiO2 particles on the crystal surface of zeolite ZSM-5 were achieved by sol-gel synthesis. The composites were studied in the photocatalytic oxidation (PCO of NO in a flatbed reactor under continuous flow according to ISO 22197-1. The highest NO conversion of 41% at an NO2 selectivity as low as 19% stable for 24 h on-stream was reached over the TiO2/ZSM-5 composite from sol-gel synthesis with equal amounts of the two components after calcination at 523 K. The higher activity and stability for complete NO oxidation than for pure TiO2 from sol-gel synthesis, Hombikat, or P25 is attributed to the adsorptive properties of the zeolite ZSM-5 in the composite catalyst. Increasing the calcination temperature up to 823 K leads to larger TiO2 particles and a lower photocatalytic activity.

  7. Indoor Decontamination Textiles by Photocatalytic Oxidation: A Review

    Directory of Open Access Journals (Sweden)

    Hafeezullah Memon

    2015-01-01

    Full Text Available A large number of researches have been made to make the textile intelligent and smarter; this is achieved by imparting functionality to the textile materials. The indoor environment possesses a variety of pollutants which do not come from the outer environment, but they come from the inner environment itself. Today, the smarter fabrics that may clean the indoor air have been studied by various researchers. The smarter fabrics contain the nanocoating of semiconductor oxides, mostly TiO2; thus the synthesis and application of these nanoparticles on the textile material have been reviewed in this paper. Moreover, there are lots of environmental and health issues regarding nanoparticles that have also been discussed in brief.

  8. Photocatalytic self-cleaning poly(L-lactide) materials based on a hybrid between nanosized zinc oxide and expanded graphite or fullerene

    Energy Technology Data Exchange (ETDEWEB)

    Virovska, Daniela [Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St., bl. 103A, BG-1113 Sofia (Bulgaria); Paneva, Dilyana, E-mail: panevad@polymer.bas.bg [Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St., bl. 103A, BG-1113 Sofia (Bulgaria); Manolova, Nevena [Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St., bl. 103A, BG-1113 Sofia (Bulgaria); Rashkov, Iliya, E-mail: rashkov@polymer.bas.bg [Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St., bl. 103A, BG-1113 Sofia (Bulgaria); Karashanova, Daniela [Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bonchev St., bl. 109, BG-1113 Sofia (Bulgaria)

    2016-03-01

    New self-cleaning materials of polymer fibers decorated with a hybrid between nanosized zinc oxide and expanded graphite (EG) or fullerene (C{sub 60}) were obtained. The new materials were prepared by applying electrospinning in conjunction with electrospraying. Poly(L-lactide) (PLA) was selected as a biocompatible and (bio)degradable polymer carrier. PLA solution was electrospun in combination with electrospraying of a suspension that contained the ZnO/EG or ZnO/C{sub 60} hybrid. Mats with different content of EG or C{sub 60} were obtained. The new materials were characterized by scanning and transmission electron microscopy (SEM and TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). The photocatalytic activity of the materials was evaluated by using model dyes. The formation of a hybrid between ZnO and EG led to enhancement of the photocatalytic activity of the mats at ZnO/EG weight ratios of 90/10 and 85/15. Increase in the photocatalytic activity of the ZnO-containing mats was also achieved by the formation of a hybrid between ZnO and C{sub 60} at a fullerene content of 0.5 and 1.0 wt.% in respect to ZnO weight. The new materials exhibited antibacterial activity as evidenced by the performed studies against Staphylococcus aureus. - Highlights: • New self-cleaning materials are fabricated by electrospinning/electrospraying. • PLA fibers decorated with nanosized ZnO/EG or ZnO/C{sub 60} hybrid are obtained. • Their photocatalytic activity is enhanced as compared to fibers with bare ZnO. • The new materials can be used repeatedly for degradation of MB and RR dyes. • The new self-cleaning materials exhibit antibacterial activity against S. aureus.

  9. Photocatalytic self-cleaning poly(L-lactide) materials based on a hybrid between nanosized zinc oxide and expanded graphite or fullerene

    International Nuclear Information System (INIS)

    Virovska, Daniela; Paneva, Dilyana; Manolova, Nevena; Rashkov, Iliya; Karashanova, Daniela

    2016-01-01

    New self-cleaning materials of polymer fibers decorated with a hybrid between nanosized zinc oxide and expanded graphite (EG) or fullerene (C_6_0) were obtained. The new materials were prepared by applying electrospinning in conjunction with electrospraying. Poly(L-lactide) (PLA) was selected as a biocompatible and (bio)degradable polymer carrier. PLA solution was electrospun in combination with electrospraying of a suspension that contained the ZnO/EG or ZnO/C_6_0 hybrid. Mats with different content of EG or C_6_0 were obtained. The new materials were characterized by scanning and transmission electron microscopy (SEM and TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). The photocatalytic activity of the materials was evaluated by using model dyes. The formation of a hybrid between ZnO and EG led to enhancement of the photocatalytic activity of the mats at ZnO/EG weight ratios of 90/10 and 85/15. Increase in the photocatalytic activity of the ZnO-containing mats was also achieved by the formation of a hybrid between ZnO and C_6_0 at a fullerene content of 0.5 and 1.0 wt.% in respect to ZnO weight. The new materials exhibited antibacterial activity as evidenced by the performed studies against Staphylococcus aureus. - Highlights: • New self-cleaning materials are fabricated by electrospinning/electrospraying. • PLA fibers decorated with nanosized ZnO/EG or ZnO/C_6_0 hybrid are obtained. • Their photocatalytic activity is enhanced as compared to fibers with bare ZnO. • The new materials can be used repeatedly for degradation of MB and RR dyes. • The new self-cleaning materials exhibit antibacterial activity against S. aureus.

  10. Enhanced visible light photocatalytic degradation of Rhodamine B over phosphorus doped graphitic carbon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Bo, E-mail: willycb@163.com; Yan, Juntao; Wang, Chunlei; Ren, Zhandong; Zhu, Yuchan

    2017-01-01

    Highlights: • The phosphorus doped g-C{sub 3}N{sub 4} photocatalysts are synthesized by a co-pyrolysis procedure. • The crystal phase, morphology, and optical property of P doped g-C{sub 3}N{sub 4} are characterized. • The P doped g-C{sub 3}N{sub 4} photocatalysts show the improved photocatalytic activity. • The possible mechanism for enhanced photocatalytic activity is proposed. - Abstract: Phosphorus doped graphitic carbon nitride (g-C{sub 3}N{sub 4}) was easily synthesized using ammonium hexafluorophosphate (NH{sub 4}PF{sub 6}) as phosphorus source, and ammonium thiocyanate (NH{sub 4}SCN) as g-C{sub 3}N{sub 4} precursor, through a direct thermal co-polycondensation procedure. The obtained phosphorus doped g-C{sub 3}N{sub 4} was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), UV–vis diffuse reflectance absorption spectra (UV-DRS), photoelectrochemical measurement and photoluminescence spectra (PL). The photocatalytic activities of phosphorus doped g-C{sub 3}N{sub 4} samples were evaluated by degradation of Rhodamine B (RhB) solution under visible light irradiation. The results showed that the phosphorus doped g-C{sub 3}N{sub 4} had a superior photocatalytic activity than that of pristine g-C{sub 3}N{sub 4}, attributing to the phosphorus atoms substituting carbon atoms of g-C{sub 3}N{sub 4} frameworks to result in light harvesting enhancement and delocalized π-conjugated system of this copolymer, beneficial for the increase of photocatalytic performance. The photoelectrochemical measurements also verified that the charge carrier separation efficiency was promoted by phosphorus doping g-C{sub 3}N{sub 4}. Moreover, the tests of radical scavengers demonstrated that the holes (h{sup +}) and superoxide radicals (·O{sub 2}{sup −}) were the main active species for the

  11. Enhanced visible-light photocatalytic activity of Fe/ZnO for rhodamine B degradation and its photogenerated charge transfer properties

    International Nuclear Information System (INIS)

    Yi, Shasha; Cui, Jiabao; Li, Shuo; Zhang, Lijing; Wang, Dejun; Lin, Yanhong

    2014-01-01

    Highlights: • ZnO and Fe/ZnO nanoflowers were synthesized via a hydrothermal process. • Fe/ZnO nanoflowers show improved photocatalytic activity under the irradiation of visible light. • In the Fe/ZnO system, Fe 3+ and Fe 2+ coexistences in the ZnO host. • The detailed photocatalytic mechanism and the role of Fe in the photodegradation system are discussed. - Abstract: Zinc oxide (ZnO) and iron doped zinc oxide (Fe/ZnO) nanoflowers were successfully synthesized via a simple hydrothermal process. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman scattering, ultraviolet–visible (UV–vis) diffuse spectroscopy and scanning electron microscopy (SEM), and it was found that the dopant ions replaced some of the crystal lattice zinc ions, and furthermore, Fe 3+ and Fe 2+ ions coexist. Photocatalytic activities of the catalysts were assessed based on the degradation of rhodamine B (RhB) in aqueous solution under both UV and visible light irradiation (λ > 420 nm), respectively. All Fe/ZnO samples showed enhanced photocatalytic activity under the irradiation of visible light. On the contrary, Fe/ZnO products displayed poorer performance than that of pure ZnO in the presence of UV light. This phenomenon can be attributed to the coexistence of Fe 3+ and Fe 2+ in the ZnO host. The photophysical mechanism of the UV and visible photocatalytic activity was investigated with the help of surface photovoltage (SPV) and PL measurements, respectively. The results indicated the influence of coexistence of Fe 3+ and Fe 2+ in ZnO host on the separation and transfer behavior of the photogenerated charges in the UV and visible regions, which are distinctly different: under the irradiation of UV light, the recombination of the photogenerated electrons and holes was promoted, whereas the separation and transfer of photogenerated electrons and holes was facilitated under the visible light irradiation. The detailed photocatalytic

  12. Thickness-dependent photocatalytic performance of graphite oxide for degrading organic pollutants under visible light.

    Science.gov (United States)

    Oh, Junghoon; Chang, Yun Hee; Kim, Yong-Hyun; Park, Sungjin

    2016-04-28

    Photocatalysts use sustainable solar light energy to trigger various catalytic reactions. Metal-free nanomaterials have been suggested as cost-effective and environmentally friendly photocatalysts. In this work, we propose thickness-controlled graphite oxide (GO) as a metal-free photocatalyst, which is produced by exfoliating thick GO particles via stirring and sonication. All GO samples exhibit photocatalytic activity for degrading an organic pollutant, rhodamine B under visible light, and the thickest sample shows the best catalytic performance. UV-vis-NIR diffuse reflectance absorption spectra indicate that thicker GO samples absorb more vis-NIR light than thinner ones. Density-functional theory calculations show that GO has a much smaller band gap than that of single-layer graphene oxide, and thus suggest that the largely-reduced band gap is responsible for this trend of light absorption.

  13. Photocatalytic activity of silver oxide capped Ag nanoparticles constructed by air plasma irradiation

    Science.gov (United States)

    Fang, Yingcui; Wu, Qingmeng; Li, Huanhuan; Zhang, Bing; Yan, Rong; Chen, Junling; Sun, Mengtao

    2018-04-01

    We construct a kind of structure of silver oxide capped silver nanoparticles (AgNPs) by cost-efficient air plasma irradiation, and study its visible-light driven photocatalytic activity (PA). By controlling the oxidization time, the relationship between the intensity of the localized surface plasmon resonance (LSPR) and the PA is well established. The PA reaches the maximum when the LSPR of AgNPs is nearly completely damped (according to absorption spectra); however, under this condition, the LSPR still works, confirmed with the high efficient selective transformation of p-Aminothiophenol (PATP) to p, p'-dimercaptoazobenzene (DMAB) under visible light. The mechanism of the LSPR damping induced PA improvement is discussed. We not only provide a cost-efficient approach to construct a LSPR strong damping structure but also promote the understanding of LSPR strong damping and its relationship with photocatalysis.

  14. The effect of water on the performance of TiO2 in photocatalytic selective alkane oxidation

    NARCIS (Netherlands)

    Carneiro, J.T.; Carneiro, Joana T.; Yang, Chieh-Chao; Moulijn, Jacob A.; Mul, Guido

    2011-01-01

    Deactivation of TiO2 is hampering practical implementation of photocatalytic alternatives for energetically intensive selective oxidation processes. In the present study, humidification of the air stream is demonstrated to be a solution to this problem for well-defined photocatalysts, such as

  15. Visible photocatalytic properties of vanadium doped zinc oxide aerogel nanopowder

    Energy Technology Data Exchange (ETDEWEB)

    Slama, R. [Laboratoire de Physique des Materiaux et des Nanomateriaux appliquee a l' Environnement, Faculte des Sciences de Gabes, Universite de Gabes, Cite Erriadh Manara Zrig, 6072 Gabes (Tunisia); Unite de Recherche Environnement, Catalyse et Analyse des procedes URECAP (UR/99/11-20), Ecole Nationale d' Ingenieurs de Gabes, Universite de Gabes, Route de Medenine 6029 Gabes (Tunisia); Ghribi, F. [Laboratoire de Physique des Materiaux et des Nanomateriaux appliquee a l' Environnement, Faculte des Sciences de Gabes, Universite de Gabes, Cite Erriadh Manara Zrig, 6072 Gabes (Tunisia); Houas, A. [Unite de Recherche Environnement, Catalyse et Analyse des procedes URECAP (UR/99/11-20), Ecole Nationale d' Ingenieurs de Gabes, Universite de Gabes, Route de Medenine 6029 Gabes (Tunisia); Barthou, C. [Institut des NanoSciences de Paris (INSP), UPMC Universite Paris 6, CNRS UMR 7588, 140 rue de Lourmel, F-75015 Paris France (France); El Mir, L., E-mail: Lassaad.ElMir@fsg.rnu.tn [Laboratoire de Physique des Materiaux et des Nanomateriaux appliquee a l' Environnement, Faculte des Sciences de Gabes, Universite de Gabes, Cite Erriadh Manara Zrig, 6072 Gabes (Tunisia); College of Sciences, Department of Physics, Al-Imam Muhammad Ibn Saud University, Riyadh 11623 (Saudi Arabia)

    2011-06-30

    Vanadium-doped zinc oxide nanoparticles have been synthesized by sol-gel method. In our approach the water for hydrolysis used in the synthesis of nanopowder was slowly released followed by a thermal drying in ethyl alcohol at 250 deg. C. The obtained nanopowder was characterized by various techniques such as particle size analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence (PL). In the as-prepared state, the powder with an average particle size of 25 nm presents a strong luminescence band in the visible range. From photoluminescence excitation (PLE) the energy position of the obtained PL band depends on the excitation wavelength and this PL band can be also observed under visible excitations. This result is very promising for visible photo catalysis applications, which was confirmed by methylene blue photo-degradation using visible lamp as a light source. - Research Highlights: > We explore the impact of plot size on estimation of a small watershed outputs. > Different lengths and fixed width plots were installed on two slope aspects. > The performance of two similar sets of experimental plots was examined. > The optimal lengths for estimation of sediment and runoff were finally found.

  16. Photocatalytic Role of Zinc Oxide Nanoparticles on Synthetic Activated Carbon to Remove Antibiotic from Aquatic Environment

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Samarghandi

    2017-10-01

    Full Text Available Background & Aims of the Study: The presence of antibiotics in the environment, especially in aquatic environments is a major concern for health and the environment. The advanced oxidation process due to the ease of use, economical advantages and high performance have attracted a lot of attention. The purpose of this study was Evaluating of the photocatalytic role of zinc oxide on synthetic activated carbon to remove antibiotic from aquatic environment. Materials & Methods: This experimental study was done in batch reactor that has a 1 L volume. In this study effect of parameters such as initial pH (3-9, initial concentration of cefazolin (20-200 mg/L, modified photocatalyst concentration (20-100 mg/L and reaction time (10-60 min was investigated. In this study a low-pressure mercury lamp with the power of 55 watts in stainless case has been used. The cefazolin concentrations in different steps were measured using UV-Vis spectrophotometer in Wavelength of 262 nm. Results: The results showed that the highest removal efficiency (96% of cefazolin was at the pH=3, 0.1 mg/L of modified photocatalyst, retention time of 60 min and cefazolin concentrations of 100 mg/L. In the case of changing any of the above mentioned values, process efficiency was decreased. Conclusion: The results showed that the photocatalytic process of zinc oxide nanoparticles on synthetic activated carbon can be used as an advanced oxidation process to effectively remove pollutants like cefazolin and other similar pollutants.

  17. High quantum yield graphene quantum dots decorated TiO_2 nanotubes for enhancing photocatalytic activity

    International Nuclear Information System (INIS)

    Qu, Ailan; Xie, Haolong; Xu, Xinmei; Zhang, Yangyu; Wen, Shengwu; Cui, Yifan

    2016-01-01

    Highlights: • High concentration yellow GQDs and TiO_2 nanotubes were achieved by a simple and green method. • High quantum yield GQDs enhanced the photodegradation capacity of TiO_2 nanotube. • The catalytic performance of GQDs/TiO_2 depends on the GQDs loading. • The improved photocatalytic activity of GQDs/TiO_2 was attributed to three aspects. - Abstract: Graphene quantum dots (GQDs) with high quantum yield (about 23.6% at an excitation wavelength of 320 nm) and GQDs/TiO_2 nanotubes (GQDs/TiO_2 NTs) composites were achieved by a simple hydrothermal method at low temperature. Photoluminescence characterization showed that the GQDs exhibited the down-conversion PL features at excitation from 300 to 420 nm and up-conversion photoluminescence in the range of 600–800 nm. The photocatalytic activity of prepared GQDs/TiO_2 NTs composites on the degradation of methyl orange (MO) was significantly enhanced compared with that of pure TiO_2 nanotubes (TiO_2 NTs). For the composites coupling with 1.5%, 2.5% and 3.5% GQDs, the degradation of MO after 20 min irradiation under UV–vis light irradiation (λ = 380–780 nm) were 80.52%, 94.64% and 51.91%, respectively, which are much higher than that of pure TiO_2 NTs (35.41%). It was inferred from the results of characterization that the improved photocatalytic activity of the GQDs/TiO_2 NTs composites was attributed to the synergetic effect of up-conversion properties of the GQDs, enhanced visible light absorption and efficient separation of photogenerated electron-holes of the GQDs/TiO_2 composite.

  18. Microwave-assisted synthesis of NiS2 nanostructures for supercapacitors and cocatalytic enhancing photocatalytic H2 production

    Science.gov (United States)

    Pang, Huan; Wei, Chengzhen; Li, Xuexue; Li, Guochang; Ma, Yahui; Li, Sujuan; Chen, Jing; Zhang, Jiangshan

    2014-01-01

    Uniform NiS2 nanocubes are successfully synthesized with a microwave-assisted method. Interestingly, NiS2 nanocubes, nanospheres and nanoparticles are obtained by controlling microwave reaction time. NiS2 nanomaterials are primarily applied to supercapacitors and cocatalytic enhancing photocatalytic H2 production. Different morphologies of NiS2 nanostructures show different electrochemical and cocatalytic enhancing H2 production activities. Benefited novel nanostructures, NiS2 nanocube electrodes show a large specific capacitance (695 F g-1 at 1.25 A g-1) and excellent cycling performance (the retention 93.4% of initial specific capacitance after 3000 cycles). More importantly, NiS2 nanospheres show highly cocatalytic enhancing photocatalytic for H2 evolution, in which the photocatalytic H2 production is up to 3400 μmol during 12 hours under irradiation of visible light (λ>420 nm) with an average H2 production rate of 283 μmol h-1.

  19. Graphitic carbon nitride: Synthesis, characterization and photocatalytic decomposition of nitrous oxide

    International Nuclear Information System (INIS)

    Praus, Petr; Svoboda, Ladislav; Ritz, Michal; Troppová, Ivana; Šihor, Marcel; Kočí, Kamila

    2017-01-01

    Graphitic carbon nitride (g-C_3N_4) was synthetized by condensation of melamine at the temperatures of 400–700 °C in air for 2 h and resulting products were characterized and finally tested for the photocatalytic decomposition of nitrous oxide. The characterization methods were elemental analysis, UV–Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), Fourier transform infrared (FTIR) and Raman spectroscopy, measurement of specific surface area (SSA), X-ray powder diffraction (XRD), scanning (SEM) and transmission (TEM) electron microscopy. The XRD patterns, FTIR and Raman spectra proved the presence of g-C_3N_4 at above 550 °C but the optimal synthesis temperature of 600–650 °C was found. Under these conditions graphitic carbon nitride of the overall empirical composition of C_6N_9H_2 was formed. At lower temperatures g-C_3N_4 with a higher content of hydrogen was formed but at higher temperatures g-C_3N_4 was decomposed. At the temperatures above 650 °C, its exfoliation was observed. The photocatalytic experiments showed that the activity of all the samples synthetized at 400–700 °C was very similar, that is, within the range of experimental error (5 %). The total conversion of N_2O reached about 43 % after 14 h. - Highlights: • Graphitic carbon nitride (g-C_3N_4) was thermally synthetized from melamine in the range of 400–700 °C. • The optimal temperature was determined at 600–650 °C. • All synthesis products were properly characterized by physico-chemical methods. • Exfoliation of g-C_3N_4 at above 600 °C was observed. • g-C_3N_4 was used for the photocatalytic decomposition of N_2O.

  20. Advanced Wastewater Photo-oxidation System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Pioneer Astronautics proposes an advanced photocatalytic oxidation reactor for enhancing the reliability and performance of Water Recovery Post Processing systems...

  1. Enhanced photo-stability and photocatalytic activity of Ag3PO4 via modification with BiPO4 and polypyrrole

    Science.gov (United States)

    Cai, Li; Jiang, Hui; Wang, Luxi

    2017-10-01

    Ag3PO4 photocatalysts modified with BiPO4 and polypyrrole (PPy) were successfully synthesized via a combination of co-precipitation hydrothermal technique and oxidative polymerization method. Their morphologies, structures and optical and electronic properties were characterized by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) surface areas, X-ray diffraction (XRD), fourier transform infrared spectra (FT-IR), X-ray photo-electron spectroscopy (XPS), UV-vis diffuse reflection spectra (UV-vis DRS), photocurrent technique and electrochemical impedance spectra (EIS). The typical triphenylmethane dye (malachite green) was chosen as a target organic contaminants to estimate the photocatalytic activities and photo-stabilities of Ag3PO4-BiPO4-PPy heterostructures under visible light irradiation. The results indicated that the existence of BiPO4 and PPy not only showed great influences on the photocatalytic activity, but also significantly enhanced photo-stability of Ag3PO4 in repeated and long-term applications. The degradation conversion of Ag3PO4-BiPO4-PPy heterostructures (ABP-3) was 1.58 times of that of pure Ag3PO4. The photo-corrosion phenomenon of Ag3PO4 was effectively avoided. The photocatalytic activity of up to 87% in the Ag3PO4-BiPO4-PPy heterostructures (ABP-3) can be remained after five repeated cycles, while only about 33% of the degradation efficiency can be reserved in pure Ag3PO4. The possible mechanism of enhanced photo-stability and photocatalytic activity of Ag3PO4-BiPO4-PPy heterostructures was also discussed in this work.

  2. Single-Atom Pt as Co-Catalyst for Enhanced Photocatalytic H2 Evolution.

    Science.gov (United States)

    Li, Xiaogang; Bi, Wentuan; Zhang, Lei; Tao, Shi; Chu, Wangsheng; Zhang, Qun; Luo, Yi; Wu, Changzheng; Xie, Yi

    2016-03-23

    Isolated single-atom platinum (Pt) embedded in the sub-nanoporosity of 2D g-C3 N4 as a new form of co-catalyst is reported. The highly stable single-atom co-catalyst maximizes the atom efficiency and alters the surface trap states of g-C3 N4 , leading to significantly enhanced photocatalytic H2 evolution activity, 8.6 times higher than that of Pt nanoparticles and up to 50 times that for bare g-C3 N4 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Ratova, Marina, E-mail: marina_ratova@hotmail.com [Surface Engineering Group, School of Engineering, Manchester Metropolitan University, Manchester, M1 5GD (United Kingdom); Kelly, Peter J.; West, Glen T. [Surface Engineering Group, School of Engineering, Manchester Metropolitan University, Manchester, M1 5GD (United Kingdom); Tosheva, Lubomira; Edge, Michele [School of Science and the Environment, Manchester Metropolitan University, Manchester M1 5GD (United Kingdom)

    2017-01-15

    Highlights: • Bismuth tungstate coatings were deposited by reactive magnetron sputtering. • Oscillating bowl was introduced to the system to enable coating of nanopartulates. • Deposition of Bi{sub 2}WO{sub 6} enhanced visible light activity of titania nanoparticles. • The best results were obtained for coating with Bi:W ratio of approximately 2:1. • Deposition of Bi{sub 2}WO{sub 6} onto TiO{sub 2} resulted in more efficient electron-hole separation. - Abstract: Titanium dioxide − bismuth tungstate composite materials were prepared by pulsed DC reactive magnetron sputtering of bismuth and tungsten metallic targets in argon/oxygen atmosphere onto anatase and rutile titania nanoparticles. The use of an oscillating bowl placed beneath the two magnetrons arranged in a co-planar closed field configuration enabled the deposition of bismuth tungstate onto loose powders, rather than a solid substrate. The atomic ratio of the bismuth/tungsten coatings was controlled by varying the power applied to each target. The effect of the bismuth tungstate coatings on the phase, optical and photocatalytic properties of titania was investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area measurements, transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy and an acetone degradation test. The latter involved measurements of the rate of CO{sub 2} evolution under visible light irradiation of the photocatalysts, which indicated that the deposition of bismuth tungstate resulted in a significant enhancement of visible light activity, for both anatase and rutile titania particles. The best results were achieved for coatings with a bismuth to tungsten atomic ratio of 2:1. In addition, the mechanism by which the photocatalytic activity of the TiO{sub 2} nanoparticles was enhanced by compounding it with bismuth tungstate was studied by microwave cavity perturbation. The results of these

  4. Enhancing the photocatalytic activity of nanocrystalline TiO2 by co-doping with fluorine and yttrium

    International Nuclear Information System (INIS)

    Zhang, Huarong; Miao, Guashuai; Ma, Xingping; Wang, Bei; Zheng, Haiwu

    2014-01-01

    Highlights: • (F, Y)-codoped TiO 2 nanoparticles were prepared by a simple sol–gel method. • The highest photocatalytic activity (15 times of that over the pure TiO 2 ) was exhibited in the codoped TiO 2 with 0.05% Y doping level. • The Y doping induced oxygen vancancies played a duel role on the photocatalyic activity of the codoped TiO 2 . • The photocatalytic reactive oxygen species are critical to the photocatalytic degradation processes. - Abstract: Fluorine and yttrium codoped TiO 2 nanoparticles were prepared using a simple sol–gel method. The products were characterized with various spectroscopic and analytical techniques to determine their structural, morphological, optical absorption and photocatalytic properties. The results reveal that neither F nor Y doping causes obvious absorption edge shift in TiO 2 . Photoluminescence (PL) emission spectra present that the PL signal is enhanced, suggesting a decrease of photo-generated charge carrier separation efficiency, after the F or Y doping. The synergistic action by the F and Y doping leads to the highest photocatalytic activity for the degradation of methylene blue solution in the 0.05% (F, Y)-codoped sample (15 times of that over the pure TiO 2 ). With the increase of Y doping level, the photocatalytic performance in the codoped samples increases firstly and then decreases. The photocatalytic activity variations after the F and Y doping were interpreted by the formation of photocatalytic reactive oxygen species induced by the dopings

  5. Surface modification and enhanced photocatalytic CO{sub 2} reduction performance of TiO{sub 2}: a review

    Energy Technology Data Exchange (ETDEWEB)

    Low, Jingxiang; Cheng, Bei [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan 430070 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2017-01-15

    Highlights: • Application of modified TiO{sub 2} for photocatalytic CO{sub 2} reduction is summarized. • Different surface modification strategies of TiO{sub 2} are highlighted. • Summary and future perspectives in photocatalytic CO{sub 2} reduction are presented. - Abstract: Recently, the excessive consumption of fossil fuels has caused high emissions of the greenhouse gases, CO{sub 2} into atmosphere and global energy crisis. Mimicking the natural photosynthesis by using semiconductor materials to achieve photocatalytic CO{sub 2} reduction into valuable solar fuels such as CH{sub 4}, HCO{sub 2}H, CH{sub 2}O, and CH{sub 3}OH is known as one of the best solutions for addressing the aforementioned issue. Among various proposed photocatalysts, TiO{sub 2} has been extensively studied over the past several decades for photocatalytic CO{sub 2} reduction because of its cheapness and environmental friendliness. Particularly, surface modification of TiO{sub 2} has attracted numerous interests due to its capability of enhancing the light absorption ability, facilitating the electron-hole separation, tuning the CO{sub 2} reduction selectivity and increasing the CO{sub 2} adsorption and activation ability of TiO{sub 2} for photocatalytic CO{sub 2} reduction. In this review, recent approaches of the surface modification of TiO{sub 2} for photocatalytic CO{sub 2} reduction, including impurity doping, metal deposition, alkali modification, heterojunction construction and carbon-based material loading, are presented. The photocatalytic CO{sub 2} reduction mechanism and pathways of TiO{sub 2} are discussed. The future research direction and perspective of photocatalytic CO{sub 2} reduction over surface-modified TiO{sub 2} are also presented.

  6. Photocatalytic oxidation of methyl orange in water phase by immobilized TiO{sub 2}-carbon nanotube nanocomposite photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yinmao [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); School of Sciences/Beijing Key Lab of Plant Resource Research and Development, Beijing Technology and Business University, Beijing 100048 (China); Tang, Dongyan [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Li, Chensha, E-mail: lichnsa@mail.tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

    2014-03-01

    Highlights: • An immobilized photocatalyst with heterostructure of nanophase CNT-TiO{sub 2} was developed. • The unique 3-D network structure of the photocatalyst resulted in high and available surface area. • The nano-photocatalyst exhibited a high photocatalysis performance. • The immobilized nano-photocatalyst possess the merits of powder nano-photocatalyst. • The immobilized nano-photocatalyst adapts the requirement for clean and convenient manipulation. - Abstract: We developed an immobilized carbon nanotube (CNT)–titanium dioxide (TiO{sub 2}) heterostructure material for the photocatalytic oxidation of methyl orange in aqueous phase. The catalyst material was prepared via sol–gel method using multi-walled CNTs grown on graphite substrate as carriers. The multi-walled CNTs were synthesized from thermal decomposing of hydrocarbon gas directly on thin graphite plate, forming immobilized 3-dimensional network of CNTs. The nanophase TiO{sub 2} was synthesized coating on CNTs to form “coral”-shaped nanocomposite 3-dimensional network on graphite substrate, thus bringing effective porous structure and high specific surface area, and possessing the merit of dispersive powder photocatalysts, which is the fully available surface area, while adapting the requirement for clean and convenient manipulation as an immobilized photocatalyst. Moreover, the CNT–TiO{sub 2} heterostructure reduced the electron–hole pair recombination rate and enhanced the photoabsorption and the adsorption ability, resulting in elevating the photocatalysis efficiency. These synergistic effects due to the hybrid nature of the materials and interphase interaction greatly improved the catalytic activity, and demonstrated superior photocatalytic performances. Our work can be a significant inspiration for developing hybrid nano-phase materials to realize sophisticated functions, and bear tremendous significance for the development and applications of semiconductor nano-materials.

  7. Preparation of a Microspherical Silver-Reduced Graphene Oxide-Bismuth Vanadate Composite and Evaluation of Its Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Mao Du

    2016-03-01

    Full Text Available A novel Ag-reduced graphene oxide (rGO-bismuth vanadate (BiVO4 (AgGB ternary composite was successfully synthesized via a one-step method. The prepared composite was characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM, energy dispersive X-ray (EDX, Brunauer-Emmett-Teller (BET surface area measurement, Raman scattering spectroscopy, and ultraviolet-visible diffuse-reflection spectroscopy (UV-vis DRS. The results showed that bulk monoclinic needle-like BiVO4 and Ag nanoparticles with a diameter of approximately 40 nm formed microspheres (diameter, 5–8 μm with a uniform size distribution that could be loaded on rGO sheets to facilitate the transport of electrons photogenerated in BiVO4, thereby reducing the rate of recombination of photogenerated charge carriers in the coupled AgGB composite system. Ag nanoparticles were dispersed on the surface of the rGO sheets, which exhibited a localized surface plasmon resonance phenomenon and enhanced visible light absorption. The removal efficiency of rhodamine B dye by AgGB (80.2% was much higher than that of pure BiVO4 (51.6% and rGO-BiVO4 (58.3% under visible light irradiation. Recycle experiments showed that the AgGB composite still presented significant photocatalytic activity after five successive cycles. Finally, we propose a possible pathway and mechanism for the photocatalytic degradation of rhodamine B dye using the composite photocatalyst under visible light irradiation.

  8. Controllable synthesis and enhanced photocatalytic properties of Cu2O/Cu31S16 composites

    International Nuclear Information System (INIS)

    Liu, Xueqin; Li, Zhen; Zhang, Qiang; Li, Fei

    2012-01-01

    Highlights: ► Facile sonochemical route. ► The content of Cu 31 S 16 in the Cu 2 O/Cu 31 S 16 can be easily controlled. ► Structure and optical properties of Cu 2 O/Cu 31 S 16 were discussed. ► Enhanced photocatalytic property of Cu 2 O/Cu 31 S 16 . ► Cu 2 O/Cu 31 S 16 core/shell structures were more stable than single Cu 2 O particles. -- Abstract: The controlled synthesis of Cu 2 O/Cu 31 S 16 microcomposites with hierarchical structures had been prepared via a convenient sonochemical route. Ultrasonic irradiation of a mixture of Cu 2 O and (NH 2 ) 2 CS in an aqueous medium yielded Cu 2 O/Cu 31 S 16 composites. The content of Cu 31 S 16 in the Cu 2 O/Cu 31 S 16 can be easily controlled by adjusting the synthesis time. The Cu 31 S 16 layer not only protected and stabilized Cu 2 O particles, but also prohibited the recombination of photogenerated electrons–holes pair between Cu 31 S 16 and Cu 2 O. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) spectra, ultraviolet–visible (UV–Vis) spectroscopy and photoluminescence (PL) spectroscopy were used to characterize the products. Photocatalytic performance of the Cu 2 O/Cu 31 S 16 hierarchical structures was evaluated by measuring the decomposition rate of methyl orange solution under natural light. To the best of our knowledge, this is the first report on the preparation and photocatalytic activity of Cu 2 O/Cu 31 S 16 microcomposite. Additionally, the Cu 2 O/Cu 31 S 16 core/shell structures were more stable than single Cu 2 O particles during photocatalytic process since the photocatalytic activity of the second reused architecture sample was much higher than that of pure Cu 2 O. The Cu 2 O/Cu 31 S 16 microcomposites may be a good promising candidate for wastewater treatment.

  9. Fabrication of visible light-triggered photocatalytic materials from the coupling of n-type zinc oxide and p-type copper oxide

    Science.gov (United States)

    Gorospe, A. B.; Herrera, M. U.

    2017-04-01

    Coupling of copper oxide (CuO) and zinc oxide (ZnO) was done by chemical precipitation method. In this method, copper sulfate pentahydrate and zinc sulfate heptahydrate salt precursors were separately dissolved in distilled water; then were mixed together. The copper sulfate-zinc sulfate solution was then combined with a sodium hydroxide solution. The precipitates were collected and washed in distilled water and ethanol several times, then filtered and dried. The dried sample was grounded, and then undergone heat treatment. After heating, the sample was grounded again. Zinc oxide powder and copper oxide powder were also fabricated using chemical precipitation method. X-Ray Diffraction measurements of the coupled CuO/ZnO powder showed the presence of CuO and ZnO in the fabricated sample. Furthermore, other peaks shown by XRD were also identified corresponding to copper, copper (II) oxide, copper sulfate and zinc sulfate. Results of the photocatalytic activity investigation show that the sample exhibited superior photocatalytic degradation of methyl orange under visible light illumination compared to copper oxide powder and zinc oxide powder. This may be attributed to the lower energy gap at the copper oxide-zinc oxide interface, compared to zinc oxide, allowing visible light to trigger its photocatalytic activity.

  10. Solvothermal synthesis of hierarchical TiO{sub 2} nanostructures with tunable morphology and enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Zhenghua [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Meng, Fanming, E-mail: mrmeng@ahu.edu.cn [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Key laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China); Zhang, Miao [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Wu, Zhenyu [College of Chemistry & Chemical Engineering, Anhui University, Hefei 230601 (China); Sun, Zhaoqi; Li, Aixia [School of Physics and Materials Science, Anhui University, Hefei 230601 (China)

    2016-01-01

    Graphical abstract: - Highlights: • Hierarchical anatase TiO{sub 2} nanostructures with enhanced photocatalytic activity are synthesized by solvothermal method. • A mechanism for enhanced photocatalytic activity of chrysanthemum-like hierarchical TiO{sub 2} nanostructures is proposed. • A possible formation mechanism is suggested to explain the transformation from rose-like to chrysanthemum-like, and to sea-urchin-like. - Abstract: This paper presents controllable growth and photocatalytic activity of TiO{sub 2} hierarchical nanostructures by solvothermal method at different temperatures. It is revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the morphology of TiO{sub 2} can be effectively controlled as rose-like, chrysanthemum-like and sea-urchin-like only changing solvothermal temperature. BET surface area analysis confirms the presence of a mesoporous network in all the nanostructures, and shows high surface area at relatively high temperature. The photocatalytic activities of the photocatalysts are evaluated by the photodegradation of RhB under UV light irradiation. The TiO{sub 2} samples exhibit high activity on the photodegradation of RhB, which is higher than that of the commercial P25. The enhancement in photocatalytic performance can be attributed to the synergetic effect of the surface area, crystallinity, band gap and crystalline size.

  11. Novel GQD-PVP-CdS composite with enhanced visible-light-driven photocatalytic properties

    International Nuclear Information System (INIS)

    Fan, Tao; Li, Yinle; Shen, Jianfeng; Ye, Mingxin

    2016-01-01

    Graphical abstract: - Highlights: • GQD-PVP-CdS composite was prepared for the first time through a facile hydrothermal route. • GQD-PVP-CdS demonstrated outstanding photoactivity under visible light illumination. • GQDs and polymeric material are compounded with CdS nanoparticles simultaneously for the first time. • The addition of GQDs plays pivotal roles in the enhancement of the photoactivity. - Abstract: A facile one-step hydrothermal method to synthesize graphene quantum dots (GQDs)-polyvinyl pyrrolidone (PVP)-CdS nanocomposite was reported. The nanocomposite was thoroughly characterized with X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and ultraviolet–visible spectroscopy. The results confirmed the formation of GQD-PVP-CdS composite with a uniform size (5–10 nm) and a relatively low band gap (E_g = 2.23 eV). Moreover, the as-prepared composite exhibited enhanced photocatalytic activity toward the degradation of organic contaminants, with 92.3% of methyl orange (10 mg/L) removed after 3 hours of visible light illumination. This enhancement in photocatalytic activity was postulated to be attributed to the upconversion property of GQDs and a more efficient charge distribution between GQDs and CdS particles.

  12. Metal Nanoshells for Plasmonically Enhanced Solar to Fuel Photocatalytic Conversion

    Science.gov (United States)

    2016-05-18

    transfer, we anticipate this interlayer will modulate charge transfer from the metal to the semiconductor and vice versa. These new core-shell particles ...enhancement mechanism. In an extensive study using ten different samples, we found that GS-NS@ZIS particles with an LSPR absorption at ~700 nm and a silica...then coated with a thin layer of silica (SiO2), followed by a zinc indium sulfide (ZnIn2S4; ZIS) semiconductor shell. The blended-metal GS-NS cores

  13. Photocatalytic Ethanol Oxidative Dehydrogenation over Pt/TiO2: Effect of the Addition of Blue Phosphors

    Directory of Open Access Journals (Sweden)

    J. J. Murcia

    2012-01-01

    Full Text Available Ethanol oxidative dehydrogenation over Pt/TiO2 photocatalyst, in the presence and absence of blue phosphors, was performed. The catalyst was prepared by photodeposition of Pt on sulphated TiO2. This material was tested in a gas-solid photocatalytic fluidized bed reactor at high illumination efficiency. The effect of the addition of blue phosphors into the fluidized bed has been evaluated. The synthesized catalysts were extensively characterized by different techniques. Pt/TiO2 with a loading of 0.5 wt% of Pt appeared to be an active photocatalyst in the selective partial oxidation of ethanol to acetaldehyde improving its activity and selectivity compared to pure TiO2. In the same way, a notable enhancement of ethanol conversion in the presence of the blue phosphors has been obtained. The blue phosphors produced an increase in the level of ethanol conversion over the Pt/TiO2 catalyst, keeping at the same time the high selectivity to acetaldehyde.

  14. Photocatalytic hydrogen generation enhanced by band gap narrowing and improved charge carrier mobility in AgTaO3 by compensated co-doping.

    Science.gov (United States)

    Li, Min; Zhang, Junying; Dang, Wenqiang; Cushing, Scott K; Guo, Dong; Wu, Nianqiang; Yin, Penggang

    2013-10-14

    The correlation of the electronic band structure with the photocatalytic activity of AgTaO3 has been studied by simulation and experiments. Doping wide band gap oxide semiconductors usually introduces discrete mid-gap states, which extends the light absorption but has limited benefit for photocatalytic activity. Density functional theory (DFT) calculations show that compensated co-doping in AgTaO3 can overcome this problem by increasing the light absorption and simultaneously improving the charge carrier mobility. N/H and N/F co-doping can delocalize the discrete mid-gap states created by sole N doping in AgTaO3, which increases the band curvature and the electron-to-hole effective mass ratio. In particular, N/F co-doping creates a continuum of states that extend the valence band of AgTaO3. N/F co-doping thus improves the light absorption without creating the mid-gap states, maintaining the necessary redox potentials for water splitting and preventing from charge carrier trapping. The experimental results have confirmed that the N/F-codoped AgTaO3 exhibits a red-shift of the absorption edge in comparison with the undoped AgTaO3, leading to remarkable enhancement of photocatalytic activity toward hydrogen generation from water.

  15. Effective Electron Transfer Pathway of the Ternary TiO2/RGO/Ag Nanocomposite with Enhanced Photocatalytic Activity under Visible Light

    Directory of Open Access Journals (Sweden)

    Hongwei Tian

    2017-05-01

    Full Text Available Mesoporous TiO2/reduced graphene oxide/Ag (TiO2/RGO/Ag ternary nanocomposite with an effective electron transfer pathway is obtained by an electrostatic self-assembly method and photo-assisted treatment. Compared with bare mesoporous TiO2 (MT and mesoporous TiO2/RGO (MTG, the ternary mesoporous TiO2/RGO/Ag (MTGA nanocomposite exhibited superior photocatalytic performance for the degradation of methylene blue (MB under visible light, and the degradation rate reached 0.017 min−1, which was 3.4-times higher than that of MTG. What is more, the degradation rate of MTGA nanocomposite after three cycle times is 91.2%, and the composition is unchanged. In addition, we found that the OH•, h+ and especially O2•− contribute to the high photocatalytic activity of MTGA for MB degradation. It is proposed that Ag nanoparticles can form the local surface plasmon resonance (LSPR to absorb the visible light and distract the electrons into MT, and RGO can accept the electrons from MT to accelerate the separation efficiency of photogenerated carriers. The establishment of MTGA ternary nanocomposite makes the three components act synergistically to enhance the photocatalytic performance.

  16. Solid-phase photocatalytic degradation of polyethylene film with manganese oxide OMS-2

    Science.gov (United States)

    Liu, Guanglong; Liao, Shuijiao; Zhu, Duanwei; Cui, Jingzhen; Zhou, Wenbing

    2011-01-01

    Solid-phase photocatalytic degradation of polyethylene (PE) film with cryptomelane-type manganese oxide (OMS-2) as photocatalyst was investigated in the ambient air under ultraviolet and visible light irradiation. The properties of the composite films were compared with those of the pure PE film through performing weight loss monitoring, IR spectroscopy, scanning electron microscopic (SEM) and X-ray photoelectron spectroscopy (XPS). The photoinduced degradation of PE-OMS-2 composite films was higher than that of the pure films, while there has been little change under the visible light irradiation. The weight loss of PE-OMS-2 (1.0 wt%) composite films steadily decreased and reached 16.5% in 288 h under UV light irradiation. Through SEM observation there were some cavities on the surface of composite films, but few change except some surface chalking phenomenon occurred in pure PE film. The degradation rate with ultraviolet irradiation is controllable by adjusting the content of OMS-2 particles in PE plastic. Finally, the mechanism of photocatalytic degradation of the composite films was briefly discussed.

  17. Gold nanorod@iron oxide core-shell heterostructures: synthesis, characterization, and photocatalytic performance.

    Science.gov (United States)

    Li, Yue; Zhao, Junwei; You, Wenlong; Cheng, Danhong; Ni, Weihai

    2017-03-17

    Iron oxides are directly coated on the surface of cetyl-trimethylammonium bromide (CTAB)-capped gold nanorods (AuNRs) in aqueous solutions at room temperature, which results in AuNR@Fe 2 O 3 , AuNR@Fe 3 O 4 , and AuNR@Fe 2 O 3 @Fe 3 O 4 core-shell heterostructures. The iron oxide shells are uniform, smooth, with characteristic porous structure, and their thickness can be readily tuned. The shell formation is highly dependent on the reaction parameters including pH and CTAB concentration. The Fe 2 O 3 shell is amorphous and exhibits nearly zero remanence and coercivity, while the Fe 3 O 4 shell is ferromagnetic with a low saturation magnetization of about 0.5 emu g -1 due to its low crystallinity and the porous structure. At elevated temperatures achieved by plasmonic heating of the Au core, the Fe 2 O 3 shell transforms from amorphous to γ-Fe 2 O 3 and α-Fe 2 O 3 phases, while the Fe 3 O 4 phase disappears because of the oxidation of Fe 2+ . A 1.4-fold increase of photocatalytic performance is observed due to the plasmonic resonance provided by the Au core. The photocatalytic efficiency of Fe 3 O 4 is about 1.7-fold higher than Fe 2 O 3 as more surface defects are present on the Fe 3 O 4 shell, promoting the adsorption and activation of reagents on the surface during the catalytic reactions. This approach can be readily extended to other nanostructures including Au spherical nanoparticles and nanostars. These highly uniform and multifunctional core-shell heterostructures can be of great potential in a variety of energy, magnetic, and environment applications.

  18. Synergistic effect of surface self-doping and Fe species-grafting for enhanced photocatalytic activity of TiO{sub 2} under visible-light

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Lina [Center for Advanced Optoelectronic Functional Materials Research, Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024 (China); Institute of Material Physics, Key Laboratory of Display Materials and Photoelectric Devices of Ministry of Education, Tianjin University of Technology, Tianjin 300384 (China); Wang, Changhua; Wan, Fangxu; Zheng, Han [Center for Advanced Optoelectronic Functional Materials Research, Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024 (China); Zhang, Xintong, E-mail: xtzhang@nenu.edu.cn [Center for Advanced Optoelectronic Functional Materials Research, Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024 (China)

    2017-02-28

    Highlights: • Anatase TiO{sub 2} was modified with Fe-ethoxide through wet impregnation method. • XPS and EPR investigation supported the formation of Vo and Fe species. • Vo improved the optical absorption properties to a larger extent. • Fe species inhibited the charge carrier recombination process. • Synergism between Vo and Fe species enhanced the photocatalytic activity. - Abstract: Surface grafting of transition-metal complexes or oxides is an appealing way to enhance the photocatalytic activity of TiO{sub 2} under visible-light excitation. However, the performance of these co-catalysts assistant TiO{sub 2} photocatalysts is still not sufficient enough due to their relatively weak visible-light absorption. Herein, we report a simple impregnation treatment with ferric ethoxide/ethanol solvent, followed with mild heating which can significantly enhance the visible-light absorption and photocatalytic activity of TiO{sub 2}. XPS and EPR analyses manifest that the oxygen vacancies (V{sub O}s) and Fe-species are simultaneously introduced to the surface of TiO{sub 2}. The chemical state and photocatalytic activity of the Fe-species-grafted TiO{sub 2−x} is dependent on the heating temperature after impregnation. The sample heat-treated at 250 °C exhibits the optimal photocatalytic performance for β-naphthol degradation with rate constant 6.0, 2.7, and 3.9 times higher than that of TiO{sub 2}, TiO{sub 2−x}, and Fe-TiO{sub 2}, respectively. The activity enhancement is discussed on the basis of the synergistic effect and energy-level matching of surface V{sub O}s and Fe-species co-catalyst, i.e. the V{sub O}s defects states increase the visible-light absorption and the Fe-species in the form of FeOOH promote the consumption of photo-generated electrons through multi-electron reduction of adsorbed molecule oxygen.

  19. Enhancement of visible-light photocatalytic activity of silver and mesoporous carbon co-modified Bi2WO6

    International Nuclear Information System (INIS)

    Zhao, Qian; Gong, Ming; Liu, Wangping; Mao, Yulin; Le, Shukun; Ju, Shang; Long, Fei; Liu, Xiufang; Liu, Kai; Jiang, Tingshun

    2015-01-01

    Graphical abstract: - Highlights: • Silver and mesoporous carbon co-modified Bi 2 WO 6 (Ag/Bi 2 WO 6 /CMK-3) composite was prepared. • Photocatalytic activity of Bi 2 WO 6 was remarkably enhanced by co-modification of silver and mesoporous carbon. • The degradation rate of MB can reach ca. 95.1% under visible light irradiation. • The Ag/Bi 2 WO 6 /CMK-3 composite has good stability and potential application prospects. - Abstract: Ordered mesoporous carbon CMK-3 was prepared by hard template method using SBA-15 as template, sucrose as carbon source. Flower/sphere-like Bi 2 WO 6 and CMK-3/Bi 2 WO 6 photocatalysts were synthesized by hydrothermal method, and then Ag/Bi 2 WO 6 and Ag/Bi 2 WO 6 /CMK-3 composite photocatalysts were prepared via a photoreduction process. The samples were characterized by XRD, UV–vis, TEM (HR-TEM), SEM, N 2 physical adsorption and PL and their photocatalytic activities were evaluated by the photocatalytic degradation of methylene blue (MB) under visible light irradiation. The results show that both incorporating of CMK-3 and Ag loading greatly improved the photocatalytic activity of Bi 2 WO 6 , and the content of CMK-3 and silver have an impact on the photocatalytic activity of Bi 2 WO 6 . The photocatalytic activity of Ag/Bi 2 WO 6 /CMK-3 photocatalyst is superior to the activities of CMK-3/Bi 2 WO 6 and Ag/Bi 2 WO 6 under comparable conditions, and Ag/Bi 2 WO 6 /CMK-3 photocatalyst has high stability and is easy to be recycled. Also, the mechanism for the enhancement of the photocatalytic activity of CMK-3 and Ag co-modified Bi 2 WO 6 was also investigated

  20. Enhanced photoelectrochemical and photocatalytic activity in visible-light-driven Ag/BiVO_4 inverse opals

    International Nuclear Information System (INIS)

    Fang, Liang; Nan, Feng; Yang, Ying; Cao, Dawei

    2016-01-01

    BiVO_4 photonic crystal inverse opals (io-BiVO_4) with highly dispersed Ag nanoparticles (NPs) were prepared by the nanosphere lithography method combining the pulsed current deposition method. The incorporation of the Ag NPs can significantly improve the photoelectrochemical and photocatalytic activity of BiVO_4 inverse opals in the visible light region. The photocurrent density of the Ag/io-BiVO_4 sample is 4.7 times higher than that of the disordered sample without the Ag NPs, while the enhancement factor of the corresponding kinetic constant in photocatalytic experiment is approximately 3. The improved photoelectrochemical and photocatalytic activity is benefited from two reasons: one is the enhanced light harvesting owing to the coupling between the slow light and localized surface plasmon resonance effect; the other is the efficient separation of charge carriers due to the Schottky barriers.

  1. Ag_3PO_4 Microcrystals Synthesized by Room-Temperature Solid State Reaction: Enhanced Photocatalytic Activity and Photoelectronchemistry Performance

    International Nuclear Information System (INIS)

    Hao Chen-Chun; Xu Jie; Shi Hong-Long; Fu Jun-Li; Zou Bin; Meng Shan; Wang Wen-Zhong; Jia Ying

    2015-01-01

    Ag_3PO_4 microcrystals with highly enhanced visible light photocatalytic activity are prepared by a facile and simple solid state reaction at room temperature. The composition, morphology and optical properties of the as-prepared Ag_3PO_4 microcrystals are characterized by x-ray diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectra. The photocatalytic properties of Ag_3PO_4 are investigated by the degradation of both methylene blue and methyl orange dyes under visible light irradiation. The as-prepared Ag_3PO_4 microcrystals possess high photocatalytic oxygen production with the rate of 673 μmolh"−"1 g"−"1. Moreover, the as-prepared Ag_3PO_4 microcrystals show an enhanced photoelectrochemistry performance under irradiation of visible light. (paper)

  2. Enhanced photocatalytic activity of C@ZnO core-shell nanostructures and its photoluminescence property

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Tao; Yu, Shanwen; Fang, Xiaoxin; Huang, Honghong; Li, Lun [School of Materials and Chemical Engineering, Hubei University of Technology, Wuhan (China); Wang, Xiuyuan [College of Plant Science and Technology, Huazhong Agricultural University, Wuhan (China); Wang, Huihu, E-mail: wanghuihu@mail.hbut.edu.cn [School of Materials and Chemical Engineering, Hubei University of Technology, Wuhan (China); Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan (China)

    2016-12-15

    Highlights: • C@ZnO nanostructures were synthesized by a facile hydrothermal carbonization method. • Glucose content has a great influence on the microstructure of C@ZnO nanostructures. • An ultrathin amorphous carbon layer enhances the adsorption capacity of C@ZnO. • C@ZnO nanostructures exhibit the improved photocatalytic activity and stability. - Abstract: An ultrathin layer of amorphous carbon coated C@ZnO core-shell nanostructures were synthesized via a facile hydrothermal carbonization process using glucose as precursor in this work. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance UV–vis spectroscopy (DRS) were used for the characterization of as-prepared samples. Photoluminescence (PL) properties of C@ZnO samples were investigated using PL spectroscopy. The microstructure analysis results show that the glucose content has a great influence on the size, morphology, crystallinity and surface chemical states of C@ZnO nanostructures. Moreover, the as-prepared C@ZnO core-shell nanostructures exhibit the enhanced photocatalytic activity and good photostability for methyl orange dye degradation due to its high adsorption ability and its improved optical characteristics.

  3. Hydrothermal synthesis of core–shell TiO_2 to enhance the photocatalytic hydrogen evolution

    International Nuclear Information System (INIS)

    Jiang, Jinghui; Zhou, Han; Zhang, Fan; Fan, Tongxiang; Zhang, Di

    2016-01-01

    Graphical abstract: Core–shell TiO_2 with interior cavity was synthesized by a hydrothermal approach to enhance the photocatalytic performance. - Highlights: • Core–shell TiO_2 with interior cavity can be synthesized by hydrothermal approach. • Multiple reflection of incident light in cavity can increase the absorption. • Rutile can optimize the bandgap and delay the charge recombination. - Abstract: A hydrothermal approach was designed to synthesize core–shell TiO_2 with interior cavity by making sodium dodecyl sulfonate (SDS) as the surfactant and the mixture of water and ethanol as the solvent. The control experiment of solvent reveals ethanol and water are responsible for the formation of sphere and interior cavity, respectively. Besides, SDS can assist the growth of core–shell structure, and the sizes of sphere and interior cavity can be tuned by regulating the reaction time or temperature. UV–vis absorption proves core–shell structure with interior cavity can increase the absorption of incident light to enhance the optical activity of final product. The calculated bandgap and photoluminescence (PL) analyses reveal the coexistence of rutile in final product can optimize the bandgap to 3.03 eV and delay the charge recombination. As a result, an effective photocatalytic hydrogen evolution under full spectrum irradiation can be harvested by the as-synthesized core–shell spheres to reach a quantum yield, approximately 9.57% at 340 nm wavelength.

  4. Black TiO2 synthesized via magnesiothermic reduction for enhanced photocatalytic activity

    Science.gov (United States)

    Wang, Xiangdong; Fu, Rong; Yin, Qianqian; Wu, Han; Guo, Xiaoling; Xu, Ruohan; Zhong, Qianyun

    2018-04-01

    Utilizing solar energy for hydrogen evolution is a great challenge for its insufficient visible-light power conversion. In this paper, we report a facile magnesiothermic reduction of commercial TiO2 nanoparticles under Ar atmosphere and at 550 °C followed by acid treatment to synthesize reduced black TiO2 powders, which possesses a unique crystalline core-amorphous shell structure composed of disordered surface and oxygen vacancies and shows significantly improved optical absorption in the visible region. The unique core-shell structure and high absorption enable the reduced black TiO2 powders to exhibit enhanced photocatalytic activity, including splitting of water in the presence of Pt as a cocatalyst and degradation of methyl blue (MB) under visible light irradiation. Photocatalytic evaluations indicate that the oxygen vacancies play key roles in the catalytic process. The maximum hydrogen production rates are 16.1 and 163 μmol h-1 g-1 under the full solar wavelength range of light and visible light, respectively. This facile and versatile method could be potentially used for large scale production of colored TiO2 with remarkable enhancement in the visible light absorption and solar-driven hydrogen production.

  5. Enhanced visible-light-induced photocatalytic activity of α-Fe2O3 adsorbing redox enzymes

    Directory of Open Access Journals (Sweden)

    Kai Kamada

    2015-03-01

    Full Text Available We report fabrication of hybrid photocatalyst composed of an n-type semiconductor (α-Fe2O3 and a redox enzyme (horseradish peroxidase; HRP, and its performance for oxidation of luminol in an aqueous solution. The hybrid photocatalyst is simply formed via physical adsorption of HRP to an α-Fe2O3 sintered body. Under visible light irradiation, the bare α-Fe2O3 with a narrow bandgap photocatalytically oxidizes luminol along with blue emission that can be used as an indicator of the photocatalytic performance. The blue emission is largely strengthened after the adsorption of HRP, demonstrating that the presence of enzyme improves apparent photocatalytic activity of α-Fe2O3. The favorable effect is derived from synergistic oxidation of luminol by the biocatalysts (HRP as well as by the photocatalyst (α-Fe2O3. In this paper, influence of excitation wavelength, adsorption amount of HRP, and reaction temperature on the overall photocatalytic activity are elucidated, and then a reaction mechanism of the proposed novel hybrid photocatalyst is discussed in detail.

  6. ZnO/spiral-shaped glass for solar photocatalytic oxidation of Reactive Red 120

    Directory of Open Access Journals (Sweden)

    Montaser Y. Ghaly

    2017-05-01

    Full Text Available ZnO/glass spiral (GS was prepared by immobilization of ZnO on GS with facile method, and was characterized by X-ray diffraction analysis (XRD, scanning electron microscope (SEM and the crystallite size of ZnO on GS surface was calculated. SEM showed rod-like shape of ZnO particles on GS surface. Photocatalytic activity of prepared immobilized photocatalyst was investigated for decolourization and degradation of C.I. Reactive Red 120 (RR-120 dye under sunlight. The kinetics of decolourization and degradation removal has been investigated. The effect of pH on decolourization and degradation of dye was studied. The decolourization and degradation of dye were followed by pseudo-first order reaction. The decolourization and degradation of RR-120 dye were enhanced by H2O2 addition to definite dosage beyond that the effect is diminished. Also, the reusability of immobilized ZnO on GS was tested for photocatalytic degradation of dye and it was worth noting that it has high efficiency with slight decrease (5% after five successive runs.

  7. Evaluation of Ultra-Violet Photocatalytic Oxidation for Indoor AirApplications

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, A.T.; Sullivan, D.P.; Fisk, W.J.

    2006-02-01

    Acceptable indoor air quality in office buildings may be achieved with less energy by combining effective air cleaning systems for volatile organic compounds (VOCs) with particle filtration then by relying solely on ventilation. For such applications, ultraviolet photocatalytic oxidation (UVPCO) systems are being developed for VOC destruction. An experimental evaluation of a UVPCO system is reported. The evaluation was unique in that it employed complex mixtures of VOCs commonly found in office buildings at realistically low concentrations. VOC conversion efficiencies varied over a broad range, usually exceeded 20%, and were as high as {approx}80%. Conversion efficiency generally diminished with increased air flow rate. Significant amounts of formaldehyde and acetaldehyde were produced due to incomplete mineralization. The results indicate that formaldehyde and acetaldehyde production rates may need to be reduced before such UVPCO systems can be deployed safely in occupied buildings.

  8. Reusability Performance of Zinc Oxide Nanoparticles for Photocatalytic Degradation of POME

    Science.gov (United States)

    Zarifah Zainuri, Nur; Hanis Hayati Hairom, Nur; Abu Bakar Sidik, Dilaelyana; Misdan, Nurasyikin; Yusof, Norhaniza; Wahab Mohammad, Abdul

    2018-03-01

    Performance and reusability of different zinc oxide nanoparticles (ZnO-PVP and ZnO-PEG) for photocatalytic degradation of palm-mill oil effluent (POME) has been studied. The nanoparticles properties were characterised with fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM results show that ZnO-PEG nanoparticles exhibit the smaller size than ZnO-PVP with less agglomeration. It was found that ZnO-PEG shows better effectiveness than ZnO-PVP in reducing turbidity, colour and increasing the dissolved oxygen (DO). By using two types of reusability methods: (a) oven drying (b) hot water rinsing, the oven drying method portrayed the most efficient route for POME treatment. This research would be a solution to the palm oil industry for photocatalyst recovering as well as reduction of the chemical usage in order to meet the development of advanced and greener technologies.

  9. Enhanced visible light photocatalytic activity of g-C3N4 assisted by hydrogen peroxide

    Science.gov (United States)

    Chen, Quan-Liang; Liu, Yi-Ling; Tong, Li-Ge

    2018-04-01

    Water pollution has caused much attention nowadays. Photocatalysis as a kind of advanced oxidation technology has been widely studied in the field of environmental pollution control. As a stable non-metal photocatalyst, the photocatalytic activity of g-C3N4 assisted by H2O2 was investigated for the degradation of Rhodamine B (RhB) under visible light irradiation. The combination of g-C3N4 and H2O2 has much higher activity than that of pure g-C3N4 or H2O2. Neutral solution is preferred for the high phtotocatalytic activity of g-C3N4 with H2O2. The effect of the amount of catalyst, H2O2 concentration and RhB concentration was investigated. Photocatalytic mechanism study using radical scavenger showed free radicals {{{{O}}}2}- and · OH are the main active species. g-C3N4 assisted by H2O2 showed good photostability and repeatability after five cycles of degradation experiment.

  10. A comparative view of radiation, photo and photocatalytically induced oxidation of water pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Getoff, N [Institute for Theoretical Chemistry and Radiation Chemistry, Univ. of Vienna, Vienna (Austria)

    1997-10-01

    Water resources are presently overloaded with biologically resistant (refractory) pollutants. Several oxidation methods have been developed for their degradation, the most efficient of which is irradiation treatment, particularly that based on e-beam processing in the presence of O{sub 2}/O{sub 3}. The next-best method is photoinduced pollutant oxidation with VUV- and/or UV-light, using H{sub 2}O{sub 2} or H{sub 2}O{sub 2}/O{sub 3} as an additional source of OH radicals. The photocatalytic method, using e.g. TiO{sub 2} as a catalyst in combination with oxidation agents such as H{sub 2}O{sub 2} or H{sub 2}O{sub 2}/O{sub 3}, is also recommended. The suitability of these three methods is illustrated by examples and they are briefly discussed and compared on the basis of the energy consumption and efficiency. Other methods, such as ozone treatment, the photo-Fenton process, ultrasonic and electrochemical treatments, as well as the well known biological process and thermal oxidation of refractory pollutants, are briefly mentioned. (author). 36 refs, 9 figs, 3 tabs.

  11. A comparative view of radiation, photo and photocatalytically induced oxidation of water pollutants

    International Nuclear Information System (INIS)

    Getoff, N.

    1997-01-01

    Water resources are presently overloaded with biologically resistant (refractory) pollutants. Several oxidation methods have been developed for their degradation, the most efficient of which is irradiation treatment, particularly that based on e-beam processing in the presence of O 2 /O 3 . The next-best method is photoinduced pollutant oxidation with VUV- and/or UV-light, using H 2 O 2 or H 2 O 2 /O 3 as an additional source of OH radicals. The photocatalytic method, using e.g. TiO 2 as a catalyst in combination with oxidation agents such as H 2 O 2 or H 2 O 2 /O 3 , is also recommended. The suitability of these three methods is illustrated by examples and they are briefly discussed and compared on the basis of the energy consumption and efficiency. Other methods, such as ozone treatment, the photo-Fenton process, ultrasonic and electrochemical treatments, as well as the well known biological process and thermal oxidation of refractory pollutants, are briefly mentioned. (author)

  12. Rational construction of Z-scheme Ag_2CrO_4/g-C_3N_4 composites with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Luo, Jin; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao

    2016-01-01

    Highlights: • Novel visible-light driven Ag_2CrO_4/g-C_3N_4 composites were synthesized. • Ag_2CrO_4/g-C_3N_4 exhibited enhanced visible-light photocatalytic activity. • The reasons for the enhanced photocatalytic activity were revealed. - Abstract: Novel visible-light driven Z-scheme Ag_2CrO_4/g-C_3N_4 composites with different contents of Ag_2CrO_4 were fabricated by a facile chemical precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy and photoelectrochemical measurements. Compared with individual g-C_3N_4 and Ag_2CrO_4, the Ag_2CrO_4/g-C_3N_4 composites displayed much larger photocatalytic activities for the photocatalytic degradation of methyl orange (MO) solution at room temperature under visible light irradiation (λ > 420 nm). Importantly, the optimum photodegradation rate constant of the Ag_2CrO_4/g-C_3N_4 composite at a theoretical weight content of 8.0% Ag_2CrO_4 for the photodegradation of MO was 0.0068 min"−"1, which was 5.7 and 4.3 times higher than that of pure g-C_3N_4 and Ag_2CrO_4, respectively. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electrons and holes at the Ag_2CrO_4/g-C_3N_4 interface imparted through the Z-scheme electron transfer. Furthermore, radical trap experiments depicted that both the holes and superoxide radical anions were thought to dominate oxidative species of the Ag_2CrO_4/g-C_3N_4 composite for MO degradation under visible light irradiation. Ultimately, a tentative Z-scheme photodegradation mechanism was proposed. This work may be useful for the rational design of new types of Z-scheme photocatalysts and provide some illuminate insights into the Z-scheme transfer mechanism for application in energy

  13. Voids padding induced further enhancement in photocatalytic performance of porous graphene-like carbon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Guohui [Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, Wuhan university, Hubei 430072 (China); Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); Chen, Dong [Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, Wuhan university, Hubei 430072 (China); Luo, Jianmin [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); The Graduate School of Chinese Academy of Science, Beijing, 100049 (China); Zhu, Yunqing [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); Zeng, Yubin, E-mail: zengyubin@whu.edu.cn [Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, Wuhan university, Hubei 430072 (China); Wang, Chuanyi, E-mail: cywang@ms.xjb.ac.cn [Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, Wuhan university, Hubei 430072 (China); Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China)

    2017-08-05

    Highlights: • We synthesized an NH{sub 4}Cl padded C{sub 6}N{sub 9}H{sub 3} by calcining melamine hydrochloride in a vertical pit furnace. • The padded Cl{sup −} serves as a conjugate center to increase the conjugation fidelity of C{sub 6}N{sub 9}H{sub 3}. • Interface electric field can be constructed between Cl{sup −} and NH{sub 4}{sup +} to inhibit the surface recombination of carriers. • NH{sub 4}Cl padded C{sub 6}N{sub 9}H{sub 3} exhibits enhanced photocatalytic activity in terms of NO removal and water splitting. - Abstract: Design of 2-Dimensional nanostructured photocatalyst is an effective way to improve the photocatalytic activity of its bulk counterpart. However, the remaining (or newborn) drawbacks, such as enlarged band gap and the surface recombination of photogenerated charge carries, extremely limited the practical application of nanosheeted photocatalysts in solar energy conversion. In this study, we demonstrated that the voids padding with NH{sub 4}Cl can eliminate part of quantum size effect to reduce the band gap of nanosheeted carbon nitride. In addition, the padded NH{sub 4}Cl can create conjugate center and interface electric field in nanosheeted carbon nitride, and therefore to inhibit the surface recombination of photogenerated charge carries. This work not only provides a facile strategy to eliminate the drawbacks of nanosheeted carbon nitride, but also paves a new way to further improve the photocatalytic activity of other nano-sheeted materials.

  14. Disinfection of Spacecraft Potable Water Systems by Photocatalytic Oxidation Using UV-A Light Emitting Diodes

    Science.gov (United States)

    Birmele, Michele N.; O'Neal, Jeremy A.; Roberts, Michael S.

    2011-01-01

    Ultraviolet (UV) light has long been used in terrestrial water treatment systems for photodisinfection and the removal of organic compounds by several processes including photoadsorption, photolysis, and photocatalytic oxidation/reduction. Despite its effectiveness for water treatment, UV has not been explored for spacecraft applications because of concerns about the safety and reliability of mercury-containing UV lamps. However, recent advances in ultraviolet light emitting diodes (UV LEDs) have enabled the utilization of nanomaterials that possess the appropriate optical properties for the manufacture of LEDs capable of producing monochromatic light at germicidal wavelengths. This report describes the testing of a commercial-off-the-shelf, high power Nichia UV-A LED (250mW A365nnJ for the excitation of titanium dioxide as a point-of-use (POD) disinfection device in a potable water system. The combination of an immobilized, high surface area photocatalyst with a UV-A LED is promising for potable water system disinfection since toxic chemicals and resupply requirements are reduced. No additional consumables like chemical biocides, absorption columns, or filters are required to disinfect and/or remove potentially toxic disinfectants from the potable water prior to use. Experiments were conducted in a static test stand consisting of a polypropylene microtiter plate containing 3mm glass balls coated with titanium dioxide. Wells filled with water were exposed to ultraviolet light from an actively-cooled UV-A LED positioned above each well and inoculated with six individual challenge microorganisms recovered from the International Space Station (ISS): Burkholderia cepacia, Cupriavidus metallidurans, Methylobacterium fujisawaense, Pseudomonas aeruginosa, Sphingomonas paucimobilis and Wautersia basilensis. Exposure to the Nichia UV-A LED with photocatalytic oxidation resulted in a complete (>7-log) reduction of each challenge bacteria population in UV-A LEDs and semi

  15. Photocatalytic Activity of Nanotubular TiO2 Films Obtained by Anodic Oxidation: A Comparison in Gas and Liquid Phase

    Directory of Open Access Journals (Sweden)

    Beatriz Eugenia Sanabria Arenas

    2018-03-01

    Full Text Available The availability of immobilized nanostructured photocatalysts is of great importance in the purification of both polluted air and liquids (e.g., industrial wastewaters. Metal-supported titanium dioxide films with nanotubular morphology and good photocatalytic efficiency in both environments can be produced by anodic oxidation, which avoids release of nanoscale materials in the environment. Here we evaluate the effect of different anodizing procedures on the photocatalytic activity of TiO2 nanostructures in gas and liquid phases, in order to identify the most efficient and robust technique for the production of TiO2 layers with different morphologies and high photocatalytic activity in both phases. Rhodamine B and toluene were used as model pollutants in the two media, respectively. It was found that the role of the anodizing electrolyte is particularly crucial, as it provides substantial differences in the oxide specific surface area: nanotubular structures show remarkably different activities, especially in gas phase degradation reactions, and within nanotubular structures, those produced by organic electrolytes lead to better photocatalytic activity in both conditions tested.

  16. Integrating porphyrin nanoparticles into a 2D graphene matrix for free-standing nanohybrid films with enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Chen, Yingzhi; Huang, Zheng-Hong; Yue, Mengbin; Kang, Feiyu

    2014-01-21

    Organic nanostructures in terms of porphyrin building blocks have shown great potential in visible-light photocatalytic applications because of their optical, electrical, and catalytic properties. Graphenes are known to provide a high-quality two-dimensional (2D) support for inorganic semiconductor nanostructures to increase the adsorption capability of the photocatalysts and an electron-transfer medium with attractive potential to enhance photogenerated charge separation. A combination of porphyrin nanostructures with graphene sheets, particularly in the form of free-standing films, is highly desirable due to its photocatalysing feasibility and convenience. Toward this aim, we demonstrate a facile method to integrate porphyrin (meso-tetra(p-hydroxyphenyl)porphyrin, p-THPP) nanoparticles (NPs) into macroscopic graphene (reduced graphene oxide, rGO) films through vacuum filtration of the co-colloids of graphene oxide (GO) and p-THPP nanoparticles (NPs) followed by gaseous reduction. The obtained p-THPP/rGO nanohybrid film exhibits enhanced visible-light photocatalytic activity compared to each moiety of the hybrid, and this photocatalyst can be easily separated and recycled for successive use with excellent stability. The results show that this facile fabrication of the p-THPP/rGO nanohybrid film makes it available for high-performance optoelectronic applications, as well as for device integration.

  17. Facile synthesis of Sm-doped BiFeO{sub 3} nanoparticles for enhanced visible light photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Zijun; Chen, Da, E-mail: dchen_80@hotmail.com; Wang, Sen; Zhang, Ning; Qin, Laishun, E-mail: qinlaishun@cjlu.edu.cn; Huang, Yuexiang

    2017-06-15

    Highlights: • Effective Sm doping into BiFeO{sub 3} nanoparticles was obtained by a facile sol-gel route. • Band gap of Sm-doped BiFeO{sub 3} nanoparticles was regulated by the dopant concentration. • Sm-doped BiFeO{sub 3} nanoparticles exhibited superior photocatalytic activities. • The possible photocatalytic mechanism of Sm-doped BiFeO{sub 3} nanospheres was discussed. - Abstract: In this work, the effect of Sm doping on the structural and photocatalytic properties of BiFeO{sub 3} (BFO) was investigated. A series of Sm doped BFO nanoparticles containing different Sm dopant contents (Bi{sub (1−x)}Sm{sub x}FeO{sub 3}, x = 0.00, 0.01, 0.03, 0.05, 0.07, 0.10) were synthesized via a simple sol-gel route. It was revealed that Sm{sup 3+} ions were successfully doped into BFO nanoparticles, and the band gap value was gradually decreased when increasing Sm dopant concentration. The photocatalytic activity of Sm-doped BFO photocatalyst was significantly affected by the Sm doping content. Compared to pure BFO, the Sm-doped BFO samples exhibited much higher photocatalytic activity. The improved photocatalytic activity of Sm-doped BFO could be attributed to the enhanced visible light absorption and the efficient separation of photogenerated electrons and holes derived from Sm dopant trapping level in the Sm-doped BFO samples. In addition, the possible photocatalytic mechanism of Sm-doped BFO photocatalyst was also proposed.

  18. Photocatalytic Pre-Oxidation of Arsenic (III) in Groundwater by a Visible-Light-Driven System with Magnetic Separating Characteristic

    Science.gov (United States)

    Cui, Y.; Liu, Y.; Peng, L.; Qin, Y.

    2017-12-01

    Arsenic was a typical toxic metalloid element and its contamination in groundwater was widely recognized as a global health problem, especially in north China, where people depended on groundwater as water resource. Arsenic was existed as As(III) in underground water, and has low affinity to the surface of various minerals and more toxic and more difficultly to be removed compared with As(V), so a pre-oxidation technology by transforming As (III) to As (V) is highly desirable. Electrochemical and oxidizing agents were traditional technology, which usually causes secondary pollution. A novel methodology is presented here, using prepared magnetic visible-light-driven nanomaterials as recyclable media to investigate As(III) pre-oxidation processing. Ag@AgCl core-shell nanowires were first synthesized by oxidation of Ag nanowires with moderate FeCl3, and exhibited excellent photocatalytic activity to As(III) with visible-light. The ratio of chloridization was proved to act as key effect on photocatalytic oxidation efficiency. Testing with simulated groundwater condition proved that pH, ionic strength and concentration of humic acid have obvious effects on Ag@AgCl photocatalytic ability. h+ and ·O2- were confirmed to be the main active species during the visible-light driven photocatalytic oxidation process for As(III) by trapping experiments with radical scavengers. Then Fe0 was introduced to prepare Fe-Ag nanowire and chloridized into Fe-Ag@AgCl to provide magnetic characteristic. The magnetic recycling and re-chloride experiments validated this visible-light-driven material has excellent stable and high reused ability as photocatalyst under visible light irradiation.

  19. Aqueous arsenite removal by simultaneous ultraviolet photocatalytic oxidation-coagulation of titanium sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuxia [Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, School of Environmental & Municipal Engineering, Xi’an University of Architecture and Technology (China); Duan, Jinming, E-mail: jinmingduan@xauat.edu.cn [Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, School of Environmental & Municipal Engineering, Xi’an University of Architecture and Technology (China); Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, Mawson Lakes Campus, South Australia (Australia); Li, Wei [Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, School of Environmental & Municipal Engineering, Xi’an University of Architecture and Technology (China); Beecham, Simon; Mulcahy, Dennis [Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, Mawson Lakes Campus, South Australia (Australia)

    2016-02-13

    Highlights: • A simultaneous UV catalysed oxidation–coagulation for As(III) removal is proposed. • As(III) was effectively oxidised to As(V) by the UV catalysed coagulation. • >99% removal for As(III) in pH 4–6 at low doses of Ti(SO{sub 4}){sub 2} was achieved. • Concurrent UV radiation in massive small crystal formation facilitate the effects. • Reaction mechanisms involve both hydroxyl radicals and superoxide radicals. - Abstract: This study explored the efficacy and efficiency of a simultaneous UV-catalyzed oxidation–coagulation process of titanium sulfate (UV/Ti(SO{sub 4}){sub 2}) for efficient removal of As(III) from water. It revealed that, As(III) could be oxidized to As(V) during the UV catalyzed coagulation of Ti(SO{sub 4}){sub 2} with highly efficient As(III) removal in the pH range 4–6{sub .} The UV catalyzed oxidation–coagulation showed surprisingly effective oxidation of As(III) to As(V) within a short time. XPS indicated that 84.7% of arsenic on the coagulated precipitate was in the oxidized form of As(V) after the UV/Ti(SO{sub 4}){sub 2} treatment of As(III) aqueous solutions at pH 5. Arsenic remaining in solution at high pH was in the oxidized form As(V). Removal efficiencies of As(III) were investigated as a function of pH, Ti(SO{sub 4}){sub 2} dosage, initial As(III) concentration and irradiation energy. As(III) could almost completely be removed (>99%) by the photocatalytic oxidation–coagulation process with a moderate dose of Ti(SO{sub 4}){sub 2} in the pH range 4–6 at an initial arsenic concentration of 200 μg/L. The mechanisms of the photocatalytic coagulation oxidation of Ti(SO{sub 4}){sub 2} are similar to those of UV/crystalline TiO{sub 2} particles, involving the formation and reactions of the hydroxyl radical OH· and superoxide HO{sub 2}·/O{sub 2}{sup ·−}.

  20. A novel reducing graphene/polyaniline/cuprous oxide composite hydrogel with unexpected photocatalytic activity for the degradation of Congo red

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Jie; Xie, Anjian; Li, Shikuo; Huang, Fangzhi; Cao, Juan; Shen, Yuhua, E-mail: yhshen@ahu.edu.cn

    2016-01-01

    Graphical abstract: Excellent photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel for CR degradation under UV–vis light irradiation. - Highlights: • The RGO/PANI/Cu{sub 2}O composite hydrogel was first synthesized via a facile method. • Photocatalytic performance was studied under UV–vis light. • The ternary composite hydrogel shows unexpected photocatalytic activity. • A possible photocatalysis mechanism was illustrated. - Abstract: In this work, a novel reducing graphene/polyaniline/cuprous oxide (RGO/PANI/Cu{sub 2}O) composite hydrogel with a 3D porous network has been successfully prepared via a one-pot method in the presence of cubic Cu{sub 2}O nanoparticles. The as-synthesized ternary composites hydrogel shows unexpected photocatalytic activity such that Congo red (CR) degradation efficiency can reaches 97.91% in 20 min under UV–vis light irradiation, which is much higher than that of either the single component (Cu{sub 2}O nanoparticles), or two component systems (RGO/Cu{sub 2}O composite hydrogel and PANI/Cu{sub 2}O nanocomposites). Furthermore, the ternary composite hydrogel exhibits high stability and do not show any significant loss after five recycles. Such outstanding photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel was ascribed to the high absorption ability of the product for CR and the synergic effect among RGO, PANI and Cu{sub 2}O in photocatalytic process. The product of this work would provide a new sight for the construction of UV–vis light responsive photocatalyst with high performance.

  1. A novel reducing graphene/polyaniline/cuprous oxide composite hydrogel with unexpected photocatalytic activity for the degradation of Congo red

    International Nuclear Information System (INIS)

    Miao, Jie; Xie, Anjian; Li, Shikuo; Huang, Fangzhi; Cao, Juan; Shen, Yuhua

    2016-01-01

    Graphical abstract: Excellent photocatalytic activity of the RGO/PANI/Cu_2O composite hydrogel for CR degradation under UV–vis light irradiation. - Highlights: • The RGO/PANI/Cu_2O composite hydrogel was first synthesized via a facile method. • Photocatalytic performance was studied under UV–vis light. • The ternary composite hydrogel shows unexpected photocatalytic activity. • A possible photocatalysis mechanism was illustrated. - Abstract: In this work, a novel reducing graphene/polyaniline/cuprous oxide (RGO/PANI/Cu_2O) composite hydrogel with a 3D porous network has been successfully prepared via a one-pot method in the presence of cubic Cu_2O nanoparticles. The as-synthesized ternary composites hydrogel shows unexpected photocatalytic activity such that Congo red (CR) degradation efficiency can reaches 97.91% in 20 min under UV–vis light irradiation, which is much higher than that of either the single component (Cu_2O nanoparticles), or two component systems (RGO/Cu_2O composite hydrogel and PANI/Cu_2O nanocomposites). Furthermore, the ternary composite hydrogel exhibits high stability and do not show any significant loss after five recycles. Such outstanding photocatalytic activity of the RGO/PANI/Cu_2O composite hydrogel was ascribed to the high absorption ability of the product for CR and the synergic effect among RGO, PANI and Cu_2O in photocatalytic process. The product of this work would provide a new sight for the construction of UV–vis light responsive photocatalyst with high performance.

  2. Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods.

    Science.gov (United States)

    Balcha, Abebe; Yadav, Om Prakash; Dey, Tania

    2016-12-01

    Zinc oxide (ZnO) nanoparticles were synthesized by precipitation and sol-gel methods. The aim of this study was to understand how different synthetic methods can affect the photocatalytic activity of ZnO nanoparticles. As-synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD) and UV-Visible spectroscopic techniques. XRD patterns of ZnO powders synthesized by precipitation and sol-gel methods revealed their hexagonal wurtzite structure with crystallite sizes of 30 and 28 nm, respectively. Their photocatalytic activities were evaluated by photocatalytic degradation of methylene blue, a common water pollutant, under UV radiation. The effects of operational parameters such as photocatalyst load and initial concentration of the dye on photocatalytic degradation of methylene blue were investigated. While the degradation of dye decreased over the studied dye concentration range of 20 to 100 mg/L, an optimum photocatalyst load of 250 mg/L was needed to achieve dye degradation as high as 81 and 92.5 % for ZnO prepared by precipitation and sol-gel methods, respectively. Assuming pseudo first-order reaction kinetics, this corresponded to rate constants of 8.4 × 10 -3 and 12.4 × 10 -3  min -1 , respectively. Hence, sol-gel method is preferred over precipitation method in order to achieve higher photocatalytic activity of ZnO nanostructures. Photocatalytic activity is further augmented by better choice of capping ligand for colloidal stabilization, starch being more effective than polyethylene glycol (PEG).

  3. Advanced Chemical Reduction of Reduced Graphene Oxide and Its Photocatalytic Activity in Degrading Reactive Black 5

    Directory of Open Access Journals (Sweden)

    Christelle Pau Ping Wong

    2015-10-01

    Full Text Available Textile industries consume large volumes of water for dye processing, leading to undesirable toxic dyes in water bodies. Dyestuffs are harmful to human health and aquatic life, and such illnesses as cholera, dysentery, hepatitis A, and hinder the photosynthetic activity of aquatic plants. To overcome this environmental problem, the advanced oxidation process is a promising technique to mineralize a wide range of dyes in water systems. In this work, reduced graphene oxide (rGO was prepared via an advanced chemical reduction route, and its photocatalytic activity was tested by photodegrading Reactive Black 5 (RB5 dye in aqueous solution. rGO was synthesized by dispersing the graphite oxide into the water to form a graphene oxide (GO solution followed by the addition of hydrazine. Graphite oxide was prepared using a modified Hummers’ method by using potassium permanganate and concentrated sulphuric acid. The resulted rGO nanoparticles were characterized using ultraviolet-visible spectrophotometry (UV-Vis, X-ray powder diffraction (XRD, Raman, and Scanning Electron Microscopy (SEM to further investigate their chemical properties. A characteristic peak of rGO-48 h (275 cm−1 was observed in the UV spectrum. Further, the appearance of a broad peak (002, centred at 2θ = 24.1°, in XRD showing that graphene oxide was reduced to rGO. Based on our results, it was found that the resulted rGO-48 h nanoparticles achieved 49% photodecolorization of RB5 under UV irradiation at pH 3 in 60 min. This was attributed to the high and efficient electron transport behaviors of rGO between aromatic regions of rGO and RB5 molecules.

  4. Enhanced Photocatalytic Activity of Vacuum-activated TiO2 Induced by Oxygen Vacancies.

    Science.gov (United States)

    Dong, Guoyan; Wang, Xin; Chen, Zhiwu; Lu, Zhenya

    2018-05-01

    TiO 2 (Degussa P25) photocatalysts harboring abundant oxygen vacancies (Vacuum P25) were manufactured using a simple and economic Vacuum deoxidation process. Control experiments showed that temperature and time of vacuum deoxidation had a significant effect on Vacuum P25 photocatalytic activity. After 240 min of visible light illumination, the optimal Vacuum P25 photocatalysts (vacuum deoxidation treated at 330 °C for 3 h) reach as high as 94% and 88% of photodegradation efficiency for rhodamine B (RhB) and tetracycline, respectively, which are around 4.5 and 4.9 times as that of pristine P25. The XPS, PL and EPR analyses indicated that the oxygen vacancies were produced in the Vacuum P25 during the vacuum deoxidation process. The oxygen vacancy states can produce vacancy energy level located below the conduction band minimum, which resulting in the bandgap narrowing, thus extending the photoresponse wavelength range of Vacuum P25. The positron annihilation analysis indicated that the concentrations ratio of bulk and surface oxygen vacancies could be adjusted by changing the vacuum deoxidation temperature and time. Decreasing the ratio of bulk and surface oxygen vacancies was shown to improve photogenerated electron-hole pair separation efficiency, which leads to an obvious enhancement of the visible photocatalytic activities of Vacuum P25. © 2017 The American Society of Photobiology.

  5. Enhanced Photocatalytic Activity of TiO2 Nanoparticles Supported on Electrically Polarized Hydroxyapatite.

    Science.gov (United States)

    Zhang, Xuefei; Yates, Matthew Z

    2018-05-23

    Fast recombination of photogenerated charge carriers in titanium dioxide (TiO 2 ) remains a challenging issue, limiting the photocatalytic activity. This study demonstrates increased photocatalytic performance of TiO 2 nanoparticles supported on electrically polarized hydroxyapatite (HA) films. Dense and thermally stable yttrium and fluorine co-doped HA films with giant internal polarization were synthesized as photocatalyst supports. TiO 2 nanoparticles deposited on the support were then used to catalyze the photochemical reduction of aqueous silver ions to produce silver nanoparticles. It was found that significantly more silver nanoparticles were produced on polarized HA supports than on depolarized HA supports. In addition, the photodegradation of methyl orange with TiO 2 nanoparticles on polarized HA supports was found to be much faster than with TiO 2 nanoparticles on depolarized HA supports. It is proposed that separation of photogenerated electrons and holes in TiO nanoparticles is promoted by the internal polarization of the HA support, and consequently, the recombination of charge carriers is mitigated. The results imply that materials with large internal polarization can be used in strategies for enhancing quantum efficiency of photocatalysts.

  6. Enhanced Photocatalytic Performance of NiO-Decorated ZnO Nanowhiskers for Methylene Blue Degradation

    Directory of Open Access Journals (Sweden)

    I. Abdul Rahman

    2014-01-01

    Full Text Available ZnO nanowhiskers were used for photodecomposition of methylene blue in aqueous solution under UV irradiation. The rate of methylene blue degradation increased linearly with time of UV irradiation. 54% of degradation rate was observed when the ZnO nanowhiskers were used as photocatalysts for methylene blue degradation for 80 min under UV irradiation. The decoration of p-type NiO nanoparticles on n-type ZnO nanowhiskers significantly enhanced photocatalytic activity and reached 72% degradation rate of methylene blue by using the same method. NiO-decorated ZnO was recycled for second test and shows 66% degradation from maximal peak of methylene blue within the same period. The increment of photocatalytic activity of NiO-decorated ZnO nanowhiskers was explained by the extension of the electron depletion layer due to the formation of nanoscale p-n junctions between p-type NiO and n-type ZnO. Hence, these products provide new alternative proficient photocatalysts for wastewater treatment.

  7. Enhanced Photocatalytic Activity of Rare Earth Metal (Nd and Gd doped ZnO Nanostructures

    Directory of Open Access Journals (Sweden)

    P. Logamani

    2017-06-01

    Full Text Available Presence of harmful organic pollutants in wastewater effluents causes serious environmental problems and therefore purification of this contaminated water by a cost effective treatment method is one of the most important issue which is in urgent need of scientific research. One such promising treatment technique uses semiconductor photocatalyst for the reduction of recalcitrant pollutants in water. In the present work, rare earth metals (Nd and Gd doped ZnO nanostructured photocatalyst have been synthesized by wet chemical method. The prepared samples were characterized by X-ray diffraction (XRD, Field Emission Scanning Electron Microscopy (FESEM and energy dispersive X-ray spectroscopy (EDS. The XRD results showed that the prepared samples were well crystalline with hexagonal Wurtzite structure. The results of EDS revealed that rare earth elements were doped into ZnO structure. The effect of rare earth dopant on morphology and photocatalytic degradation properties of the prepared samples were studied and discussed. The results revealed that the rare earth metal doped ZnO samples showed enhanced visible light photocatalytic activity for the degradation of methylene blue dye than pure nano ZnO photocatalyst.

  8. Ultrathin g-C3N4 films supported on Attapulgite nanofibers with enhanced photocatalytic performance

    Science.gov (United States)

    Xu, Yongshuai; Zhang, Lili; Yin, Minghui; Xie, Dengyu; Chen, Jiaqi; Yin, Jingzhou; Fu, Yongsheng; Zhao, Pusu; Zhong, Hui; Zhao, Yijiang; Wang, Xin

    2018-05-01

    A novel visible-light-responsive photocatalyst is fabricated by introducing g-C3N4 ultrathin films onto the surface of attapulgite (ATP) via a simple in-situ depositing technique, in which ATP was pre-grafted using (3-Glycidyloxypropyl) trimethoxysilane (KH560) as the surfactant. A combination of XRD, FT-IR, BET, XPS, UV-vis, TEM and SEM techniques are utilized to characterize the composition, morphology and optical properties of the products. The results show that with the help of KH560, g-C3N4 presented as ultrathin layer is uniformly loaded onto the surface of ATP by forming a new chemical bond (Sisbnd Osbnd C). Comparing with g-C3N4 and ATP, ATP/g-C3N4 exhibits remarkably enhanced visible-light photocatalytic activity in degradation of methyl orange (MO) because of its high surface area, appropriate band gap and the synergistic effect between g-C3N4 and ATP. To achieve the best photocatalyst, the ratio of g-C3N4 was adjusted by controlling the mass portion between ATP-KH560 and melamine (r = m (ATP-KH560)/m (melamine)). The highest decomposition rate of methyl orange (MO) was 96.06% when r = 0.5 and this degradation efficiency remained unchanged after 4 cycles, which is 10 times as that of pure g-C3N4 particles. Possible photocatalytic mechanism is presented.

  9. Facile Br- assisted hydrothermal synthesis of Bi2MoO6 nanoplates with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Zhang, Peng; Teng, Xiaoxu; Liu, Dongsheng; Fu, Liang; Xie, Hualin; Zhang, Guoqing; Ding, Shimin

    2017-01-01

    Bi 2 MoO 6 nanoplates have been controllably synthesized via a facile hydrothermal process with the assistance of Br - containing surfactant cetyltrimethylammonium bromide (CTAB) or KBr. A remarkable enhancement in the visible-light-driven photocatalytic degradation of Rhodamine B was observed. It was found that reaction temperature and surfactant play crucial roles in the formation and properties of the Bi 2 MoO 6 nanoplates. The best results as photocatalyst were obtained with the sample hydrothermally synthesized at 150 C with the assistance of CTAB. The improved photocatalytic performance could be ascribed to the {001}-oriented nanostructure of the Bi 2 MoO 6 nanoplates. KBr-templated Bi 2 MoO 6 nanoplates also showed better photocatalytic efficiency compared with that of flower-like Bi 2 MoO 6 but inferior to that of CTAB-templated Bi 2 MoO 6 nanoplates. (orig.)

  10. Facile synthesis of core-shell Cu2O@ ZnO structure with enhanced photocatalytic H2 production

    Science.gov (United States)

    Zhang, Yong-Hui; Jiu, Bei-Bei; Gong, Fei-Long; Lu, Kuan; Jiang, Nan; Zhang, Hao-Li; Chen, Jun-Li

    2018-05-01

    Core-shell Cu2O@ZnO composites were synthesized successfully based on a one-pot hydrothermal method in the presence of dioctyl sulfosuccinate sodium salt (AOT) surfactant. The Cu2O can be converted to rough core-shell Cu2O@ZnO structure by adjusting the amount of zinc powder added. The as-synthesized Cu2O@ZnO composites exhibited excellent photocatalytic activity and the amount of H2 generated using these composites was 4.5-fold more than that produced with Cu2O cubes. A possible photocatalytic mechanism for the Cu2O@ZnO composites with enhanced photocatalytic activity could be the separation by ZnO of the effective charge carriers.

  11. Reduced graphene oxide–cuprous oxide composite via facial deposition for photocatalytic dye-degradation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, MingYan, E-mail: mingyanlyg@hotmail.com [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Huang, JunRao; Tong, ZhiWei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Li, WeiHua [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Chen, Jun, E-mail: junc@uow.edu.au [Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2013-08-15

    Highlights: •Cubic Cu{sub 2}O were effectively loaded on n-propylamine (PA) intercalated graphene oxide. •The addition of PA on the carbon sheets supports the stable structure of the composites. •Cu{sub 2}O/PA/rGO showed superior adsorption capacity and photocatalytic activity. -- Abstract: Cubic Cu{sub 2}O nanoparticles have been successfully synthesized on n-propylamine (PA) intercalated graphene oxide (GO) with uniform distribution followed with a subsequent hydrazine hydrate reduction process to generate Cu{sub 2}O/PA/rGO composite. For comparison, Cu{sub 2}O conjugated reduced graphene oxide (Cu{sub 2}O/rGO) composite was also synthesized using the same method. The as-prepared Cu{sub 2}O/PA/rGO and Cu{sub 2}O/rGO nanocomposites are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis, and Electrochemical impedance spectra (EIS) measurements. UV/vis diffuse reflectance spectroscopy was employed to estimate band gap energies of cuprous oxide composites. The results show that the intercalation of PA into the layered GO increases the surface area of the composites and provides an efficient strategy to load Cu{sub 2}O due to the large and uniform distribution of active sites for anchoring copper ions. The surface area of the Cu{sub 2}O/PA/rGO (123 m{sup 2}/g) nanocomposite was found to be almost 2.5 times higher than that of Cu{sub 2}O/rGO (55.7 m{sup 2}/g). The as-prepared Cu{sub 2}O/PA/rGO show significant improvement on both adsorption capacity and photocatalytic activity towards organic pigment pollution compared with Cu{sub 2}O/rGO under identical performance conditions.

  12. Graphitic carbon nitride: Synthesis, characterization and photocatalytic decomposition of nitrous oxide

    Energy Technology Data Exchange (ETDEWEB)

    Praus, Petr, E-mail: petr.praus@vsb.cz [Institute of Environmental Technology, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Department of Chemistry, Faculty of Metallurgy and Materials Engineering, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Svoboda, Ladislav [Institute of Environmental Technology, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Department of Chemistry, Faculty of Metallurgy and Materials Engineering, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Ritz, Michal [Department of Chemistry, Faculty of Metallurgy and Materials Engineering, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic); Troppová, Ivana; Šihor, Marcel; Kočí, Kamila [Institute of Environmental Technology, VŠB-Technical University of Ostrava, 17. Listopadu 15/2172, Ostrava 708 33 (Czech Republic)

    2017-06-01

    Graphitic carbon nitride (g-C{sub 3}N{sub 4}) was synthetized by condensation of melamine at the temperatures of 400–700 °C in air for 2 h and resulting products were characterized and finally tested for the photocatalytic decomposition of nitrous oxide. The characterization methods were elemental analysis, UV–Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), Fourier transform infrared (FTIR) and Raman spectroscopy, measurement of specific surface area (SSA), X-ray powder diffraction (XRD), scanning (SEM) and transmission (TEM) electron microscopy. The XRD patterns, FTIR and Raman spectra proved the presence of g-C{sub 3}N{sub 4} at above 550 °C but the optimal synthesis temperature of 600–650 °C was found. Under these conditions graphitic carbon nitride of the overall empirical composition of C{sub 6}N{sub 9}H{sub 2} was formed. At lower temperatures g-C{sub 3}N{sub 4} with a higher content of hydrogen was formed but at higher temperatures g-C{sub 3}N{sub 4} was decomposed. At the temperatures above 650 °C, its exfoliation was observed. The photocatalytic experiments showed that the activity of all the samples synthetized at 400–700 °C was very similar, that is, within the range of experimental error (5 %). The total conversion of N{sub 2}O reached about 43 % after 14 h. - Highlights: • Graphitic carbon nitride (g-C{sub 3}N{sub 4}) was thermally synthetized from melamine in the range of 400–700 °C. • The optimal temperature was determined at 600–650 °C. • All synthesis products were properly characterized by physico-chemical methods. • Exfoliation of g-C{sub 3}N{sub 4} at above 600 °C was observed. • g-C{sub 3}N{sub 4} was used for the photocatalytic decomposition of N{sub 2}O.

  13. A detailed study on Sn4+ doped ZnO for enhanced photocatalytic degradation

    Science.gov (United States)

    Beura, Rosalin; Pachaiappan, R.; Thangadurai, P.

    2018-03-01

    The samples of Sn4+ doped (1, 5, 10, 15, 20 & 30%) ZnO nanostructures were synthesized by a low temperature hydrothermal method. Structural analysis by XRD and Raman spectroscopy showed the hexagonal wurtzite phase of ZnO and the formation of a secondary phase Zn2SnO4 beyond 10% doping of Sn4+. Microstructural analysis by TEM also confirmed the wurtzite ZnO with rod as well as particle like structure. Presence of various functional groups (sbnd OH, sbnd CH, Znsbnd O) were confirmed by FTIR. Optical properties were studied by UV-vis absorption, photoluminescence emission spectroscopies and lifetime measurement. Band gap of the undoped and Sn4+ doped ZnO were analyzed by Tauc plot and it was observed that the band gap of the materials had slightly decreased from 3.2 to 3.16 eV and again increased to 3.23 eV with respect to the increase in the doping concentration from 1 to 30%. A significant change was also noticed in the photoluminescence emission properties of ZnO i.e. increase in the intensity of NBE emission and decrease in DLE, on subject to Sn4+ doping. Average PL lifetime had increased from 29.45 ns for ZnO to 30.62 ns upon 1% Sn ion doping in ZnO. Electrical properties studied by solid state impedance spectroscopy showed that the conductivity had increased by one order of magnitude (from 7.48×10-8 to 2.21×10-7 S/cm) on Sn4+ doping. Photocatalytic experiments were performed on methyl orange (MO) as a model industrial dye under UV light irradiation for different irradiation times. The optimum Sn4+ content in order to achieve highest photocatalytic activity was found to be 1% Sn 4+ doping. The enhancement was achieved due to a decrease in the band gap favoring the generation of electron-hole pairs and the enhanced PL life time that delays the recombination of these charge carrier formation. The third reason was that the increased electrical conductivity that indicated the faster charge transfer in this material to enhance the photocatalytic activity. The Sn

  14. Enhanced photocatalytic ozonation of organics by g-C3N4 under visible light irradiation

    International Nuclear Information System (INIS)

    Liao, Gaozu; Zhu, Dongyun; Li, Laisheng; Lan, Bingyan

    2014-01-01

    Highlights: • g-C 3 N 4 is employed as active catalyst in the photocatalytic ozonation system. • The more negative conduction band of g-C 3 N 4 benefits the transfer of electrons. • The synergistic effect between photocatalysis and ozonation is promoted by g-C 3 N 4 . • Enhanced degradation of oxalic acid and biphenol A is achieved via g-C 3 N 4 /Vis/O 3 . - Abstract: Graphitic carbon nitride (g-C 3 N 4 ) was employed as the active photocatalyst in the photocatalytic ozonation coupling system in the present study. g-C 3 N 4 was prepared by directly heating thiourea in air at 550 °C. XRD, FT-IR, UV–vis was used to characterize the structure and optical property. Oxalic acid and bisphenol A were selected as model substances for photocatalytic ozonation reactions to evaluate the catalytic ability of g-C 3 N 4 (g-C 3 N 4 /Vis/O 3 ). The results showed that the degradation ratio of oxalic acid with g-C 3 N 4 /Vis/O 3 was 65.2% higher than the sum of ratio when it was individually decomposed by g-C 3 N 4 /Vis and O 3 . The TOC removal of biphenol A with g-C 3 N 4 /Vis/O 3 was 2.17 times as great as the sum of the ratio when using g-C 3 N 4 /Vis and O 3 . This improvement was attributed to the enhanced synergistic effect between photocatalysis and ozonation by g-C 3 N 4 . Under visible light irradiation, the photo-generated electrons produced on g-C 3 N 4 facilitated the electrons transfer owing to the more negative conduction band potential (−1.3 V versus NHE). It meant that the photo-generated electrons could be trapped by ozone and reaction with it more easily. Subsequently, the yield of hydroxyl radicals was improved so as to enhance the organics degradation efficiency. This work indicated that metal-free g-C 3 N 4 could be an excellent catalyst for mineralization of organic compounds in waste control

  15. Building novel Ag/CeO2 heterostructure for enhancing photocatalytic activity

    International Nuclear Information System (INIS)

    Leng, Qiang; Yang, Dezhi; Yang, Qi; Hu, Chenguo; Kang, Yue; Wang, Mingjun; Hashim, Muhammad

    2015-01-01

    Highlights: • Ag nanoparticle is designed to building Schottky heterojunction on CeO 2 nanocube. • The photocatalytic activity of Ag/CeO 2 heterostructure is much enhanced. • 95.33% of MB can be effectively degraded within half an hour. • Ag as acceptor of photoelectrons blocks the recombination of electron–hole pairs. - Abstract: Stable and recyclable photocatalysts with high efficiency to degrade organic contamination are important and widely demanded under the threat of the environment pollution. Ag/CeO 2 heterostructure is designed as a photocatalyst to degrade organic dye under the simulated sunlight. The catalytic activity of CeO 2 nanocubes (NCs) to degrade methylene blue (MB) is obviously enhanced when Ag nanoparticles (NPs) are deposited on the surface of them. The weight ratio of Ag and CeO 2 in forming high efficiency catalyst, the amount of Ag/CeO 2 catalyst used in degradation process, and the dye concentration and pH value of the initial MB solution are examined systematically. 95.33% of MB can be effectively degraded within half an hour when 50 mg of Ag/CeO 2 catalyst in an optimal weight ratio of 1:3, is added to the 100 mL of MB solution (c 0 = 1 × 10 −5 mol L −1 , pH 6.2). The mechanism of the enhanced catalytic activity of Ag/CeO 2 heterostructure is discussed. The photocatalytic degradation rate is found to obey pseudo-first-order kinetics equations according to Langmuir–Hinshelwood model. The intermediate products in different stages during the degradation of MB are analyzed

  16. Building novel Ag/CeO{sub 2} heterostructure for enhancing photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Leng, Qiang; Yang, Dezhi; Yang, Qi [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Hu, Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Kang, Yue; Wang, Mingjun [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Hashim, Muhammad [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Applied Physics Department, Federal Urdu University of Arts Science and Technology, Islamabad (Pakistan)

    2015-05-15

    Highlights: • Ag nanoparticle is designed to building Schottky heterojunction on CeO{sub 2} nanocube. • The photocatalytic activity of Ag/CeO{sub 2} heterostructure is much enhanced. • 95.33% of MB can be effectively degraded within half an hour. • Ag as acceptor of photoelectrons blocks the recombination of electron–hole pairs. - Abstract: Stable and recyclable photocatalysts with high efficiency to degrade organic contamination are important and widely demanded under the threat of the environment pollution. Ag/CeO{sub 2} heterostructure is designed as a photocatalyst to degrade organic dye under the simulated sunlight. The catalytic activity of CeO{sub 2} nanocubes (NCs) to degrade methylene blue (MB) is obviously enhanced when Ag nanoparticles (NPs) are deposited on the surface of them. The weight ratio of Ag and CeO{sub 2} in forming high efficiency catalyst, the amount of Ag/CeO{sub 2} catalyst used in degradation process, and the dye concentration and pH value of the initial MB solution are examined systematically. 95.33% of MB can be effectively degraded within half an hour when 50 mg of Ag/CeO{sub 2} catalyst in an optimal weight ratio of 1:3, is added to the 100 mL of MB solution (c{sub 0} = 1 × 10{sup −5} mol L{sup −1}, pH 6.2). The mechanism of the enhanced catalytic activity of Ag/CeO{sub 2} heterostructure is discussed. The photocatalytic degradation rate is found to obey pseudo-first-order kinetics equations according to Langmuir–Hinshelwood model. The intermediate products in different stages during the degradation of MB are analyzed.

  17. The decisive effect of interface states on the photocatalytic activity of the silver(I) oxide/titanium dioxide heterojunction.

    Science.gov (United States)

    Lei, Yanqiang; Lu, Xiaoqing

    2017-04-15

    A one-step hydrothermal method was adopted to synthesize the Ag 2 O/TiO 2 nanoheterojunction. Its photocatalytic activity was evaluated by degrading methylene blue (MB) aqueous solution under UV and visible light. The MB degradation results showed that the Ag 2 O/TiO 2 nanoheterojunction enhances the photocatalytic activity under UV irradiation rather than visible light. X-ray photoelectron spectroscopy (XPS) was performed to detect the electronic structure at the interface of Ag 2 O and TiO 2 . The XPS results confirmed that the electronic band structure of the nanoheterojunction was determined by the interface states between the Ag 2 O and TiO 2 interface. Thus, the photocatalytic enhancement mechanism can be ascribed to the creation of an additional potential barrier in the conduction band between Ag 2 O and TiO 2 , which facilitates the transport of holes from TiO 2 to Ag 2 O but inhibits the flow of electrons in the reverse direction unless sufficient potential energy is provided to overcome the additional barrier. Our results have provided a new insight on the role of interface states between the p-n nanojunction in the photocatalytic activity. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Preparation and characterization of graphene oxide/Ag{sub 2}CO{sub 3} photocatalyst and its visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiade; Wei, Longfu [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province (China); Yu, Changlin, E-mail: yuchanglinjx@163.com [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province (China); School of Environment Engineering and Biology Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, Guangdong Province (China); Fang, Wen [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province (China); State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350002 (China); Xie, Yu, E-mail: xieyu_121@163.com [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province (China); College of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063, Jiangxi (China); Zhou, Wanqin; Zhu, Lihua [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi Province (China)

    2015-12-15

    Graphical abstract: - Highlights: • GO/Ag{sub 2}CO{sub 3} photocatalyst was prepared by liquid deposition process. • GO increase e{sup −}/h{sup +} pairs separation. • The production of ·OH and O{sub 2}·{sup −} radicals was promoted. • High photocatalytic activity and stability were obtained over GO/Ag{sub 2}CO{sub 3}. - Abstract: Graphene oxide (GO) was firstly fabricated from graphite powder by Hummers method. Then a series of GO/Ag{sub 2}CO{sub 3} composite photocatalysts (0.1% GO/Ag{sub 2}CO{sub 3}, 0.5%GO/Ag{sub 2}CO{sub 3}, 1%GO/Ag{sub 2}CO{sub 3}, 4%GO/Ag{sub 2}CO{sub 3}) were synthesized by a facile liquid deposition process. The produced products were characterized by powder X-ray diffraction (XRD), N{sub 2} physical adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscope (FT-IR), Raman spectra and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation. The influence of GO concentration on the photocatalytic activity of GO/Ag{sub 2}CO{sub 3} was investigated. The results showed that GO can be easily dispersed into Ag{sub 2}CO{sub 3}, producing well contacted GO/Ag{sub 2}CO{sub 3} composite. Coupling of trace GO largely enhanced the visible light absorption. Moreover, GO could suppress the growth of Ag{sub 2}CO{sub 3} grain crystals. With optimum GO content (0.5%), the degradation rate of MO is 85.37% after 120 min light irradiation, which Exhibits 1.53 times activity of that of pure Ag{sub 2}CO{sub 3}. More importantly, a large improvement in stability was obtained over the composite. The increase in photocatalytic activity and stability could be mainly attributed to the coupling of GO which increased the surface area and suppressed the recombination rate of e{sup −}/h{sup +} pairs.

  19. Preparation of Ni Doped ZnO-TiO2 Composites and Their Enhanced Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Xiaowen Zou

    2014-01-01

    Full Text Available Herein, Ni doped ZnO-TiO2 composites were prepared by facile sol-gel approach and were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, UV-visible diffuse reflectance spectroscopy (UV-Vis DRS, X-ray photoelectron spectroscopy (XPS, and photoluminescence spectroscopy (PL. The results indicated that the Ni ions can be incorporated into the lattice of TiO2 structure and replace Ti. The introduction of Ni expanded light absorption of TiO2 to visible region, increased amount of surface hydroxyl groups and physically adsorbed oxygen (as the electronic scavenges, and then enhanced separation rate of photogenerated carriers. The photodegradation test of reactive brilliant blue (KN-R under simulated solar light indicated that Ni doped ZnO-TiO2 composites have better photocatalytic activities, as compared to those of TiO2 and ZnO-TiO2.

  20. Constructing MnO{sub 2}/single crystalline ZnO nanorod hybrids with enhanced photocatalytic and antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Weiwei [College of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Liu, Tiangui, E-mail: tianguiliu@gmail.com [College of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Cao, Shiyi; Wang, Chen [College of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Chen, Chuansheng, E-mail: 1666423158@qq.com [College of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China)

    2016-07-15

    In order to improve the photocatalytic and antibacterial activity of ZnO nanorods, ZnO nanorods decorated with MnO{sub 2} nanoparticles (MnO{sub 2}/ZnO nanorod hybrids) were prepared by using microwave assisted coprecipitation method under the influence of hydrogen peroxide, and the structure, photocatalytic activity and antibacterial property of the products were studied. Experimental results indicated that MnO{sub 2} nanoparticles are decorated on the surface of single crystalline ZnO nanorods. Moreover, the resultant MnO{sub 2}/ZnO nanorod hybrids have been proven to possess good photocatalytic and antibacterial activity, which their degradated efficiency for Rhodamin B (RhB) is twice as the pure ZnO nanorods. Enhancement for photocatalytic and antibacterial activity is mainly attributed to the low band gap energy and excellent electrochemical properties of MnO{sub 2} nanoparticles. - Graphical abstract: The MnO{sub 2}/single crystalline ZnO nanorods hybrids, which MnO{sub 2} nanoparticles are loaded on the surface of ZnO nanorods, were prepared by the step-by-step precipitation method under the assistance of ammonia and hydrogen peroxide. Display Omitted - Highlights: • MnO{sub 2}/ZnO nanorod hybrids were prepared by the step-by-step assembly method. • Single crystalline ZnO nanorods can be decorated by MnO{sub 2} nanoparticles. • MnO{sub 2}/ZnO nanorod hybrids possess good photocatalytic and antibacterial activity. • MnO{sub 2} can improve the photocatalytic activity of ZnO nanorods under visible light.

  1. A novel Ni{sup 2+}-doped Ag{sub 3}PO{sub 4} photocatalyst with high photocatalytic activity and enhancement mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Song, Limin, E-mail: songlmnk@sohu.com [College of Environment and Chemical Engineering, State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Chen, Zewen; Li, Tongtong [College of Environment and Chemical Engineering, State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Zhang, Shujuan, E-mail: zhangshujuan@tust.edu.cn [College of Science, Tianjin University of Science & Technology, Tianjin, 300457 (China)

    2017-01-15

    Ni{sup 2+}-doped Ag{sub 3}PO{sub 4} (Ni{sup 2+}-Ag{sub 3}PO{sub 4}) photocatalysts with superhigh activity for photodegradation of organic pollutants were prepared by a simple hydrothermal method. The photocatalysts were characterized with X-ray powder diffractometry, transmission electron microscopy, ultraviolet–visible absorption spectroscopy, X-ray photoelectron spectroscopy, measurement of total organic carbon, and electron paramagnetic resonance spectrometry. The photocatalysts were evaluated by methyl orange (MO) photodegradation experiments under visible light irradiation (λ > 420 nm). Comparative analysis showed the optimal doping dosage was 0.05 mol/L Ni{sup 2+}. The optimal Ni{sup 2+}-Ag{sub 3}PO{sub 4} has an MO photodegradation rate constant four times larger than pure Ag{sub 3}PO{sub 4}. The photocatalytic ratio of 40 mg/L MO over the optimal Ni{sup 2+}-Ag{sub 3}PO{sub 4} after 10 min is 89%, which indicates excellent photocatalytic ability in high-concentration MO solutions. The Ni{sup 2+} doping into Ag{sub 3}PO{sub 4} can increase the level of band gap, and accelerate the utilization of photons and the separation of photo-generated charges. Therefore, the Ni{sup 2+} doping into Ag{sub 3}PO{sub 4} is responsible for the enhancement of photocatalytic ability. - Highlights: • Ni{sup 2+}-modified with higher photodegradation ability was synthesized. • ·OH radicals were the main active species in the oxidation of MO. • The doping of Ni{sup 2+} in Ag{sub 3}PO{sub 4} is responsible for the enhanced activity.

  2. Ionic liquid-assisted photochemical synthesis of ZnO/Ag_2O heterostructures with enhanced visible light photocatalytic activity

    International Nuclear Information System (INIS)

    Zhao, Shuo; Zhang, Yiwei; Zhou, Yuming; Zhang, Chao; Fang, Jiasheng; Sheng, Xiaoli

    2017-01-01

    Highlights: • ZnO/Ag_2O heterostructures have been successfully fabricated by a photochemical route. • Ionic liquids were used as template for shape-controllable ZnO nanomaterials. • The type of ionic liquid played an important role in the growth of ZnO nanoparticles. • ZnO/Ag_2O heterostructures had the enhanced photocatalytic ability. • Photocatalytic activity is a result of the combination of various factors. - Abstract: ZnO/Ag_2O heterostructures have been successfully fabricated using ionic liquids (ILs) as templates by a simple photochemical route. The influence of the type of ionic liquid and synthetic method on the morphology of ZnO, as well as the photocatalytic activity for the degradation of Rhodamine B (RhB), tetracycline (TC) and ciprofloxacin (CIP) under ultraviolet and visible light irradiation was studied. The samples were characterized by XRD, SEM, TEM, PL and UV–vis DRS. The results established that the type of ionic liquid and synthetic method played an important role in the growth of ZnO nanoparticles. And as-fabricated ZnO/Ag_2O materials exhibited self-assembled flower-like architecture whose size was about 3 μm. Moreover, as-prepared ZnO/Ag_2O exhibited the enhanced photocatalytic activity than ZnO sample, which may be due to the special structure, heterojunction, enhanced adsorption capability of dye, the improved separation rate of photogenerated electron–hole pairs. According to the results of radical trapping experiments, it can be found that • OH and h"+ were the main active species for the photocatalytic degradation of RhB. It is valuable to develop this facile route preparing the highly dispersive flower-like ZnO/Ag_2O materials, which can be beneficial for environmental protection.

  3. Electrospun cerium-based TiO2 nanofibers for photocatalytic oxidation of elemental mercury in coal combustion flue gas.

    Science.gov (United States)

    Wang, Lulu; Zhao, Yongchun; Zhang, Junying

    2017-10-01

    Photocatalytic oxidation is an attractive method for Hg-rich flue gas treatment. In the present study, a novel cerium-based TiO 2 nanofibers was prepared and selected as the catalyst to remove mercury in flue gas. Accordingly, physical/chemical properties of those nanofibers were clarified. The effects of some important parameters, such as calcination temperature, cerium dopant content and different illumination conditions on the removal of Hg 0 using the photocatalysis process were investigated. In addition, the removal mechanism of Hg 0 over cerium-based TiO 2 nanofibers focused on UV irradiation was proposed. The results show that catalyst which was calcined at 400 °C exhibited better performance. The addition of 0.3 wt% Ce into TiO 2 led to the highest removal efficiency at 91% under UV irradiation. As-prepared samples showed promising stability for long-term use in the test. However, the photoluminescence intensity of nanofibers incorporating ceria was significantly lower than TiO 2 , which was attributed to better photoelectron-hole separation. Although UV and O 2 are essential factors, the enhancement of Hg 0 removal is more obviously related to the participation of catalyst. The coexistence of Ce 3+ and Ce 4+ , which leads to the efficient oxidation of Hg 0 , was detected on samples. Hg 2+ is the final product in the reaction of Hg 0 removal. As a consequence, the emissions of Hg 0 from flue gas can be significantly suppressed. These indicate that combining photocatalysis technology with cerium-based TiO 2 nanofibers is a promising strategy for reducing Hg 0 efficiently. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Integrating high electrical conductivity and photocatalytic activity in cotton fabric by cationizing for enriched coating of negatively charged graphene oxide.

    Science.gov (United States)

    Sahito, Iftikhar Ali; Sun, Kyung Chul; Arbab, Alvira Ayoub; Qadir, Muhammad Bilal; Jeong, Sung Hoon

    2015-10-05

    Electroconductive textiles have attended tremendous focus recently and researchers are making efforts to increase conductivity of e-textiles, in order to increase the use of such flexible and low cost textile materials. In this study, surface conductivity and photo catalytic activity of standard cotton fabric (SCF) was enhanced by modifying its surface charge, from negative to positive, using Bovine Serum Albumin (BSA) as a cationic agent, to convert it into cationised cotton fabric (CCF). Then, both types of fabrics were dip coated with a simple dip and dry technique for the adsorption of negatively charged graphene oxide (GO) sheets onto its surface. This resulted in 67.74% higher loading amount of GO on the CCF making self-assembly. Finally, this coating was chemically converted by vapor reduction using hydrazine hydrate to reduced graphene oxide (rGO) for restoration of a high electrical conductivity at the fabric surface. Our results revealed that with such high loading of GO, the surface resistance of CCF was only 40Ω/sq as compared to 510Ω/sq of the SCF and a 66% higher photo catalytic activity was also achieved through cationization for improved GO coating. Graphene coated SCF and CCF were characterized using FE-SEM, FTIR, Raman, UV-vis, WAXD, EDX and XPS spectroscopy to ascertain successful reduction of GO to rGO. The effect of BSA treatment on adsorption of cotton fabric was studied using drop shape analyzer to measure contact angle and for thermal and mechanical resistance, the fabric was tested for TGA and tensile strength, respectively. rGO coated fabric also showed slightly improved thermal stability yet a minor loss of strength was observed. The high flexibility, photocatalytic activity and excellent conductivity of this fabric suggests that it can be used as an electrode material for various applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    Science.gov (United States)

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-12-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

  6. Synthesis of Br-doped TiO{sub 2} hollow spheres with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qianqian; Zhu, Shengli, E-mail: slzhu@tju.edu.cn; Liang, Yanqin; Cui, Zhenduo; Yang, Xianjin [Tianjin University, School of Materials Science and Engineering (China); Liang, Chunyong [Hebei University of Technology, Research Institute for Energy Equipment Materials (China); Inoue, Akihisa [Tianjin University, School of Materials Science and Engineering (China)

    2017-02-15

    The Br-doped hollow TiO{sub 2} photocatalysts were prepared by a simple hydrothermal process on the carbon sphere template following with calcination at 400 °C. The structure and properties of photocatalysts were characterized by X-ray diffraction, Raman spectrum, scanning electron microscope, transmission electron microscopy, N{sub 2} desorption–adsorption, UV–Vis spectroscopy, and X-ray photoelectron spectroscopy. The TiO{sub 2} hollow spheres are in diameter of 500 nm with shell thickness of 50 nm. The shell is composed of small anatase nanoparticles with size of about 10 nm. The TiO{sub 2} hollow spheres exhibit high crystalline and high surface area of 89.208 m{sup 2}/g. With increasing content of Br doping, the band gap of TiO{sub 2} hollow spheres decreased from 2.85 to 1.75 eV. The formation of impurity band in the band gap would narrow the band gap and result in the red shift of absorption edge from 395 to 517 nm, which further enhances the photocatalytic activity. The appropriate Br doping improves the photocatlytic activity significantly. The TiO{sub 2} hollow spheres with 1.55% Br doping (0.5Br-TiO{sub 2}) exhibit the highest photocatalytic activity under full light. More than 98% of RhB, MO, and MB can be photodegraded using 0.5Br-TiO{sub 2} with concentration of 10 mg/L in 40, 30, and 30 min, respectively. The degradation rate of Br-doped photocatalysts was 40% faster than undoped ones.

  7. Novel Z-scheme BiOBr/reduced graphene oxide/protonated g-C3N4 photocatalyst: Synthesis, characterization, visible light photocatalytic activity and mechanism

    Science.gov (United States)

    Bao, Yongchao; Chen, Kezheng

    2018-04-01

    The novel BiOBr/reduced graphene oxide/protonated g-C3N4 (BiOBr/RGO/pg-C3N4) composites were successfully synthesized by using a facile solvothermal synthesis method. The structure, morphology, optical and electronic properties were explored by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoelectrochemical measurement. The photocatalytic activities of as-synthesized samples were evaluated by the degradation of Rhodamine B (Rh B) and tetracycline hydrochloride (TC) aqueous solution under visible light irradiation (λ > 420nm). Compared with BiOBr, protonated g-C3N4 (pg-C3N4), BiOBr/pg-C3N4 and RGO/pg-C3N4, BiOBr/RGO/pg-C3N4 composites exhibited higher photocatalytic activity. The total organic carbon (TOC) removal ratios of Rh B and TC over 10% BiOBr/RGO/pg-C3N4 were 88% and 59%, respectively. The excellent photcatalytic performance was investigated by photoluminescence spectroscopy (PL), the radical quenching and electron spin resonance experiments. A Z-scheme charge transfer mechanism was proposed, in which RGO acted as an electron transfer mediator. It was worth pointing out that the closely contacted two-dimensional interface among the BiOBr, the RGO and pg-C3N4 promoted the separation and transfer of photo-generated charge carriers, and thus enhanced the photocatalytic efficiency.

  8. Synthesis of C@Bi{sub 2}MoO{sub 6} nanocomposites with enhanced visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yuying; Wu, Juan; Ma, Tianjin; Wang, Pengchao; Cui, Chunyue; Ma, Dong, E-mail: madong8088@126.com

    2017-05-01

    Highlights: • C@BM composites were obtained by two–step hydrothermal method. • The properties of Bi{sub 2}MoO{sub 6} were deeply influenced by carbon layer. • Carbon could reduce recombination of electrons and holes in C@BM composites. • The holes and ·O{sub 2}{sup −} are the two main reactive species for Rh B degradation. - Abstract: Carbon–coated Bi{sub 2}MoO{sub 6} (C@BM) composites have been successfully synthesized via two–step hydrothermal method. The morphology, structure and photocatalytic performance of the composites in the degradation of Rhodamine B (Rh B) are characterized. The results show that the C@BM composites exhibit enhanced photocatalytic performance in the degradation of Rh B with maximum degradation rates of 90% (210 min) under visible light irradiation. 1.0%C@BM sample shows the highest photocatalytic activity, and the improved photocatalytic performance is mainly ascribed to the formation of Mo−O−C and Bi−O−C bonds. The bonds could promote electron transfer from Bi{sub 2}MoO{sub 6} to carbon layer and inhibit the recombination of electron–hole pairs with the presence of carbon layer in the composites. Moreover, the carbon layer on Bi{sub 2}MoO{sub 6} could enhance the absorption in the visible light region. In the photocatalytic degradation process, ·O{sub 2}{sup −}and holes are the predominant active species for the decomposition of Rh B.

  9. Application of Ni-Oxide@TiO2 Core-Shell Structures to Photocatalytic Mixed Dye Degradation, CO Oxidation, and Supercapacitors

    Directory of Open Access Journals (Sweden)

    Seungwon Lee

    2016-12-01

    Full Text Available Performing diverse application tests on synthesized metal oxides is critical for identifying suitable application areas based on the material performances. In the present study, Ni-oxide@TiO2 core-shell materials were synthesized and applied to photocatalytic mixed dye (methyl orange + rhodamine + methylene blue degradation under ultraviolet (UV and visible lights, CO oxidation, and supercapacitors. Their physicochemical properties were examined by field-emission scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and UV-visible absorption spectroscopy. It was shown that their performances were highly dependent on the morphology, thermal treatment procedure, and TiO2 overlayer coating.

  10. Poly(vinyl alcohol)/poly(acrylic acid)/TiO2/graphene oxide nanocomposite hydrogels for pH-sensitive photocatalytic degradation of organic pollutants

    International Nuclear Information System (INIS)

    Moon, Young-E; Jung, Gowun; Yun, Jumi; Kim, Hyung-Il

    2013-01-01

    Graphical abstract: The photocatalytic removal of pollutants was improved by the two-step mechanism based on the adsorption of pollutants by hydrogel and the effective decomposition by combination of TiO 2 and graphene oxide. -- Highlights: • pH sensitive PVA/PAAc hydrogels were prepared by radical polymerization and condensation reaction. • PVA/PAAc/TiO 2 /graphene oxide nanocomposite hydrogels were used for treatment of basic waste water. • Photocatalytic acitivity of TiO 2 was improved by incorporation of graphene oxide. • Photocatalytic decomposition by nanocomposite hydrogel was improved by increasing pH. -- Abstract: Poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were prepared using radical polymerization and condensation reaction for the photocatalytic treatment of waste water. Graphene oxide was used as an additive to improve the photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 nanocomposite hydrogels. Both TiO 2 and graphene oxide were immobilized in poly(vinyl alcohol)/poly(acrylic acid) hydrogel matrix for an easier recovery after the waste water treatment. The photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels was evaluated on the base of the degradation of pollutants by using UV spectrometer. The improved removal of pollutants was due to the two-step mechanism based on the adsorption of pollutants by nanocomposite hydrogel and the effective decomposition of pollutants by TiO 2 and graphene oxide. The highest swelling of nanocomposite hydrogel was observed at pH 10 indicating that poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were suitable as a promising system for the treatment of basic waste water

  11. Hierarchical Ag/AgCl-TiO{sub 2} hollow spheres with enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xu Long; Yin, Hao Yong [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Nie, Qiu Lin, E-mail: nieqiulin@hdu.edu.cn [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Wei Wei [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhang, Yang; LiYuan, Qiu [College of Science, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2017-01-01

    The hierarchical Ag/AgCl-TiO{sub 2} hollow spheres were synthesized by depositing Ag/AgCl nanoparticles on TiO{sub 2} hollow spheres via a precipitation photoreduction method, and they were further characterized using TGA, SEM, TEM, XRD, XPS, UV–vis DRS and photoelectric chemical analysis. The analysis showed that the hierarchical Ag/AgCl-TiO{sub 2} hollow spheres exhibited the highest photocatalytic activity, which was approximately 13 times higher than that of TiO{sub 2} hollow spheres. The high photocatalytic activity of the composites is due to efficient electron-hole pairs separation at the photocatalyst interfaces, and localized surface plasmon resonance of Ag nanoparticles formed on AgCl particles in the degradation reaction. - Highlights: • TiO{sub 2} hollow spheres were prepared by a sacrificial template method. • The hollow spheres were modified with Ag/AgCl to form the heterojunctions. • The modification may produce synergistic effect of LSPR and hollow structure. • Visible light photocatalytic activity was enhanced on this hollow catalyst. • The mechanism of the improved photocatalytic performance was discussed.

  12. Enhanced photocatalytic activity of Bi{sub 2}O{sub 3}–Ag{sub 2}O hybrid photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinjuan, E-mail: lxj669635@126.com [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Junying [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Chu, Haipeng [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Li, Jinliang; Yu, Wei [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Zhu, Guang [Anhui Key Laboratory of Spin Electron and Nanomaterials, Suzhou University, Suzhou 234000 (China); Niu, Lengyuan [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Sun, Zhuo [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Sun, Chang Q. [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China)

    2015-08-30

    Graphical abstract: Bi{sub 2}O{sub 3}–Ag{sub 2}O composites were fabricated for visible light photocatalytic degradation of phenol with a high degradation rate of 92% for 60 min. - Highlights: • Bi{sub 2}O{sub 3}–Ag{sub 2}O composites were synthesized via a co-precipitation method. • The photocatalytic activity for the degradation of phenol is investigated. • A high degradation rate of 92% for 60 min is achieved under visible light irradiation. - Abstract: Bi{sub 2}O{sub 3}–Ag{sub 2}O hybrid photocatalysts were successfully synthesized via a co-precipitation method. The morphology, structure and photocatalytic performance in the degradation of phenol were characterized by using scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, electrochemical impedance spectra and UV–vis absorption spectroscopy, respectively. The results show that Bi{sub 2}O{sub 3}–Ag{sub 2}O hybrid photocatalysts exhibit enhanced photocatalytic performance in the degradation of phenol with a maximum degradation rate of 92% for 60 min under visible light irradiation compared with pure Bi{sub 2}O{sub 3} (57%), which is ascribed to the increase in light adsorption and the reduction in electron–hole pair recombination with the introduction of Ag{sub 2}O.

  13. One pot synthesis of Ag nanoparticle modified ZnO microspheres in ethylene glycol medium and their enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Tian Chungui; Li Wei; Pan Kai; Zhang Qi; Tian Guohui; Zhou Wei; Fu Honggang

    2010-01-01

    Ag nanoparticles (NPs) modified ZnO microspheres (Ag/ZnO microspheres) were prepared by a facile one pot strategy in ethylene glycol (EG) medium. The EG played two important roles in the synthesis: it could act as a reaction media for the formation of ZnO and reduce Ag + to Ag 0 . A series of the characterizations indicated the successful combination of Ag NPs with ZnO microspheres. It was shown that Ag modification could greatly enhance the photocatalytic efficiency of ZnO microspheres by taking the photodegradation of Rhodamine B as a model reaction. With appropriate ratio of Ag and ZnO, Ag/ZnO microspheres showed the better photocatalytic performance than commercial Degussa P-25 TiO 2 . Photoluminescence and surface photovoltage spectra demonstrated that Ag modification could effectively inhibit the recombination of the photoinduced electron and holes of ZnO. This is responsible for the higher photocatalytic activity of Ag/ZnO composites. -- Graphical abstract: A 'one-pot' strategy was developed for preparing the Ag/ZnO microspheres in ethylene glycol. The composites exhibited superior photocatalytic performance for photodegradation of Rhodamine B dye in water. Display Omitted

  14. Hierarchical ZnO/S,N:GQD composites: Biotemplated synthesis and enhanced visible-light-driven photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Aijun, E-mail: caiaijun80@163.com [College of Life Science and Technology, Hebei Normal University of Science & Technology, Qinhuangdao 066600 (China); College of Chemistry and Material Sciences, Hebei Normal University, Shijiazhuang 050016 (China); Wang, Xiuping, E-mail: wangxiuping0721@163.com [College of Life Science and Technology, Hebei Normal University of Science & Technology, Qinhuangdao 066600 (China); Qi, Yanling, E-mail: qyl6790@126.com [College of Life Science and Technology, Hebei Normal University of Science & Technology, Qinhuangdao 066600 (China); Ma, Zichuan, E-mail: mazc@vip.163.com [College of Chemistry and Material Sciences, Hebei Normal University, Shijiazhuang 050016 (China)

    2017-01-01

    Highlights: • ZnO/S,N:GQD composites were synthesized by using poplar leaves as biotemplates. • The composites have enhanced visible-light-driven photocatalytic activity. • The highly efficient charge separation of electron-hole pairs is achieved. • High surface areas play an important role in the photocatalysis. - Abstract: Graphene quantum dots co-doped with sulfur and nitrogen (S,N:GQDs) are successfully combined with leaf-templated ZnO nanoparticles (L-ZnO) to obtain hierarchical L-ZnO/S,N:GQD composites exhibiting highly surface area. The morphology, structure, and the visible-light-driven photocatalytic activity are investigated. Compared with non-templated ZnO/S,N:GQDs, L-ZnO/S,N:GQD composites exhibit higher photocatalytic activity for the degradation of rhodamine B under visible light irradiation. Such elevated photocatalytic activity results from two main effects: one is the highly effective charge separation in L-ZnO/S,N:GQD composites; the other is the high surface area, allowing for efficient capture of the visible light.

  15. Enhanced selective photocatalytic CO{sub 2} reduction into CO over Ag/CdS nanocomposites under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zezhou; Qin, Jiani; Jiang, Min; Ding, Zhengxin; Hou, Yidong, E-mail: ydhou@fzu.edu.cn

    2017-01-01

    Highlights: • Ag/CdS nanocomposites were prepared by a facile photodeposition method. • Ag/CdS was more effective as a photocatalyst for CO{sub 2} reduction than CdS. • Ag as cocatalyst served as electron trap as well as active site for CO{sub 2} reduction reaction. - Abstract: Photocatalytic reduction of carbon dioxide can convert chemically inert carbon dioxide into useful chemical fuel in a mild manner. Herein, Ag-CdS nanocomposites were prepared by photodeposition method and examined for photocatalytic CO{sub 2} reduction under visible light. Meanwhile, the nanocomposites were characterized by XRD, SEM, TEM, XPS, DRS and PL in detail. The results show that, the deposition of Ag improves the photocatalytic performance of CdS, especially in the selectivity of CO{sub 2}-to-CO. The highest photocatalytic activity is achieved over 1.0 wt.% Ag/CdS, with an increase by 3 times in comparison to CdS. In this reaction system, Ag can serve as electron trap as well as active site for CO{sub 2} reduction, which is probably responsible for the enhanced activity and selectivity of CO{sub 2} to CO over Ag/CdS. The possible mechanism of CO{sub 2} photoreduction over Ag/CdS was proposed in view of the abovementioned analysis.

  16. Fabrication of CaFe2O4 nanofibers via electrospinning method with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Wang, Jianmin; Wang, Yunan; Liu, Yinglei; Li, Song; Cao, Feng; Qin, Gaowu

    CaFe2O4 nanofibers with diameters of about 130nm have been fabricated via a facile electrospinning method. The structures, morphologies and optical properties of the obtained CaF2O4 nanofibers have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-Visible UV-Vis diffuse reflectance spectrum. The photocatalytic activities of the CaFe2O4 nanofibers are evaluated by the photo-degradation of Methyl orange (MO). The results show that the CaFe2O4 nanofibers (72%) exhibit much higher photocatalytic performance than the CaFe2O4 powders (27%) prepared by conventional method under visible light irradiation. The enhanced photocatalytic performance of CaFe2O4 nanofibers could be attributed to the large surface area, high photogenerated charge carriers density and low charge transfer resistance, as revealed by photoelectrochemical measurement. And fundamentally, it could be attributed to the decreased particle size and the fibrous nanostructure. This work not only provides an efficient way to improve the photocatalytic activity of CaFe2O4, but also provides a new method for preparing materials with nanofibrous structure.

  17. Photocatalytic growth of Ag nanocrystals on hydrothermally synthesized multiphasic TiO2/reduced graphene oxide (rGO) nanocomposites and their SERS performance

    Science.gov (United States)

    Guo, Tian-Long; Li, Ji-Guang; Sun, Xudong; Sakka, Yoshio

    2017-11-01

    TiO2/reduced graphene oxide (rGO) nanocomposites were prepared via a facile one-step hydrothermal method using TiCl3 as the TiO2 precursor. Cetyltrimethyl ammonium bromide (CTAB) was introduced as a stabilizer for GO in solution. The effects of GO content, Ti3+ concentration and urea additive on phase constituent and morphology of the TiO2 crystallites in the nanocomposites were systematically investigated. UV-vis absorption ability of the as-made composites was further tested and discussed. Ag nanocrystals (NCs) were photocatalytically grown on the surfaces of biphasic (anatase + brookite) and triphasic (anatase + brookite + rutile) TiO2/rGO nanocomposites to evaluate their surface-enhanced Raman scattering (SERS) performances. Morphology evolution of the Ag NCs in response to different photocatalytic ability of the TiO2/rGO nanocomposite was also investigated in detail. The nanocomposite with triphasic TiO2 of proper phase constituents was confirmed to favor the growth of Ag particles of two distinctly different sizes and to produce SERS substrates of substantially better performance.

  18. Synthesis of Nb doped TiO2 nanotube/reduced graphene oxide heterostructure photocatalyst with high visible light photocatalytic activity

    Science.gov (United States)

    Niu, Xiaoyou; Yan, Weijing; Zhao, Hongli; Yang, Jingkai

    2018-05-01

    Limited by the narrowed photoresponse range and unsatisfactory recombination of photoinduced electron-hole pairs, the photocatalytic efficiency of TiO2 is still far below what is expected. Here, we initially doped TiO2 nanotubes (TNTS) by transition metal ion Nb, then it is coupled with reduced graphene oxide (rGO) to construct a heterostructure photocatalyst. The defect state presented in TiO2 leading to the formation of localized midgap states (MS) in the bandgap, which regulating the band structure of TiO2 and extending the optical absorption to visible light region. The internal charge transport and transfer behavior analyzed by electrochemical impedance spectroscopy (EIS) reveal that the coupling of rGO with TNTS results in the formation of electron transport channel in the heterostructure, which makes a great contribution to the photoinduced charge separation. As expected, the Nb-TNTS/rGO exhibits a stable and remarkably enhanced photocatalytic activity in the visible-light irradiation degradation of methylene blue (MB), up to ∼5 times with respect to TNTS, which is attributed to the effective inhibition of charge recombination, the reduction of bandgap and higher redox potential, as well as the great adsorptivity.

  19. The role of calcium ions in the photocatalytic oxidation of humic acid at neutral pH.

    Science.gov (United States)

    Mariquit, Eden G; Salim, Chris; Hinode, Hirofumi

    2008-10-01

    Humic acids (HAs) are natural organic matter derived from the decomposition of plant, algal, and microbial materials. They belong to the group of the most predominant type of natural organic matter present in ground and surface waters. HAs affect the mobility and bioavailability of aquatic contaminants. However, if they are left unremoved from the water before water treatment processes, they can form carcinogenic disinfection by-products, such as trihalomethanes, haloacetic acids, and other halogenated disinfection by-products, that can pose a threat to human beings. An advanced oxidation process using UV light and a commercially available titanium dioxide was used to oxidize HA at a pH that is similar to that of natural water. The effect of adding calcium ions to the adsorption and the photocatalytic oxidation of HAs was studied. The effect of varying the TiO(2) load was also investigated. The experiment was done using a photochemical batch reactor equipped with a mercury lamp emitting light with wavelengths of 310-580 nm. The absorbances by the samples were determined at wavelengths of 254 nm and 436 nm, which represent the aromatic-compound content of and the color of the solution, respectively. Results indicated calcium ions have an effect on both the adsorption and the photocatalytic oxidation of HA at a pH within 8.0 +/- 0.5. Calcium ions facilitated adsorption of HA onto the surface of TiO(2) and resulted to faster photocatalytic oxidation. The data were plotted with respect to the normalized absorbances and irradiation time.

  20. Fabrication, characterization, and photocatalytic property of α-Fe2O3/graphene oxide composite

    International Nuclear Information System (INIS)

    Li Hong; Zhao Qidong; Li Xinyong; Zhu Zhengru; Tade, Moses; Liu Shaomin

    2013-01-01

    Spindle-shaped microstructure of α-Fe 2 O 3 was successfully synthesized by a simple hydrothermal method. The α-Fe 2 O 3 /graphene oxide (GO) composites was prepared using a modified Hummers’ strategy. The properties of the samples were systematically investigated by X-ray powder diffraction (XRD), UV–Vis diffuse reflectance spectrophotometer, transmission electron microscope, atomic force microscope, X-ray photoelectron spectroscopy, and Raman spectroscopy (Raman) techniques. GO nanosheets act as supporting materials for anchoring the α-Fe 2 O 3 particles. The average crystallite sizes of the α-Fe 2 O 3 and α-Fe 2 O 3 /GO samples are ca. 27 and 24 nm, respectively. The possible growth of α-Fe 2 O 3 onto GO layers led to a higher absorbance capacity for visible light by α-Fe 2 O 3 /GO than α-Fe 2 O 3 composite. The photocatalytic degradation of toluene over the α-Fe 2 O 3 and α-Fe 2 O 3 /GO samples under xenon-lamp irradiation was comparatively studied by in situ FTIR technique. The results indicate that the α-Fe 2 O 3 /GO sample synthesized exhibited a higher capacity for the degradation of toluene. The composite of α-Fe 2 O 3 /GO could be promisingly applied in photo-driven air purification.

  1. Fabrication, characterization, and photocatalytic property of α-Fe2O3/graphene oxide composite

    Science.gov (United States)

    Li, Hong; Zhao, Qidong; Li, Xinyong; Zhu, Zhengru; Tade, Moses; Liu, Shaomin

    2013-06-01

    Spindle-shaped microstructure of α-Fe2O3 was successfully synthesized by a simple hydrothermal method. The α-Fe2O3/graphene oxide (GO) composites was prepared using a modified Hummers' strategy. The properties of the samples were systematically investigated by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectrophotometer, transmission electron microscope, atomic force microscope, X-ray photoelectron spectroscopy, and Raman spectroscopy (Raman) techniques. GO nanosheets act as supporting materials for anchoring the α-Fe2O3 particles. The average crystallite sizes of the α-Fe2O3 and α-Fe2O3/GO samples are ca. 27 and 24 nm, respectively. The possible growth of α-Fe2O3 onto GO layers led to a higher absorbance capacity for visible light by α-Fe2O3/GO than α-Fe2O3 composite. The photocatalytic degradation of toluene over the α-Fe2O3 and α-Fe2O3/GO samples under xenon-lamp irradiation was comparatively studied by in situ FTIR technique. The results indicate that the α-Fe2O3/GO sample synthesized exhibited a higher capacity for the degradation of toluene. The composite of α-Fe2O3/GO could be promisingly applied in photo-driven air purification.

  2. Comparative study of photocatalytic oxidation on the degradation of formaldehyde and fuzzy mathematics evaluation of filters

    Science.gov (United States)

    Yu, Huili; Zhang, Jieting

    2012-04-01

    In this study, formaldehyde, one of the major volatile organic compounds, is chosen as the target pollutant. The polytetrafluoroethylene (PTFE) filter, a low cost and commonly used material in industry, is employed as the substrate for nano TiO2 photocatalyst coating at room temperature, which has been scarcely used compared to ceramics or glass beads. Furthermore, a specific experimental set-up that is similar to actual air purification system is developed for the testing. The degradation mechanisms of photolysis reaction, adsorption and photocatalytic oxidation reaction on volatile organic compounds are present respectively. The influences of three aspects mentioned above are compared by a serial of experimental data. The high efficiency of volatile organic compounds on the degradation of formaldehyde is assured. Furthermore, the purification characteristics of three kinds of activated carbon filters and PTFE filter with nano TiO2 are evaluated with the method of fuzzy mathematics. In the end, the result shows that the filter with nano TiO2 has the optimal comprehensive performances.

  3. pH-regulated antimony oxychloride nanoparticle formation on titanium oxide nanostructures: a photocatalytically active heterojunction

    KAUST Repository

    Buchholcz, Balázs

    2017-02-06

    Improving the catalytic activity of heterogeneous photocatalysts has become a hot topic recently. To this end, considerable progress has been made in the efficient separation of photogenerated charge carriers by e.g. the realization of heterojunction photocatalysts. V-VI-VII compound semiconductors, namely, bismuth oxyhalides, are popular photocatalysts. However, results on antimony oxyhalides [SbOX (X = Br, Cl, I)], the very promising alternatives to the well-known BiOX photomodifiers, are scarce. Here, we report the successful decoration of titanium oxide nanostructures with 8-11 nm diameter SbOX nanoparticles for the first time ever. The product size and stoichiometry could be controlled by the pH of the reactant mixture, while subsequent calcination could transform the structure of the titanate nanotube (TiONT) support and the prepared antimony oxychloride particles. In contrast to the ease of composite formation in the SbOX/TiONT case, anatase TiO could not facilitate the formation of antimony oxychloride nanoparticles on its surface. The titanate nanotube-based composites showed activity in a generally accepted quasi-standard photocatalytic test reaction (methyl orange dye decolorization). We found that the SbOCl/TiONT synthesized at pH = 1 is the most active sample in a broad temperature range.

  4. Zinc oxide nanostructures and its nano-compounds for efficient visible light photo-catalytic processes

    Science.gov (United States)

    Adam, Rania E.; Alnoor, Hatim; Elhag, Sami; Nur, Omer; Willander, Magnus

    2017-02-01

    Zinc oxide (ZnO) in its nanostructure form is a promising material for visible light emission/absorption and utilization in different energy efficient photocatalytic processes. We will first present our recent results on the effect of varying the molar ratio of the synthesis nutrients on visible light emission. Further we will use the optimized conditions from the molar ration experiments to vary the synthesis processing parameters like stirring time etc. and the effect of all these parameters in order to optimize the efficiency and control the emission spectrum are investigated using different complementary techniques. Cathodoluminescence (CL) is combined with photoluminescence (PL) and electroluminescence (EL) as the techniques to investigate and optimizes visible light emission from ZnO/GaN light emitting diodes. We will then show and discuss our recent finding of the use of high quality ZnO nanoparticles (NPs) for efficient photo-degradation of toxic dyes using the visible spectra, namely with a wavelength up to 800 nm. In the end, we show how ZnO nanorods (NRs) are used as the first template to be transferred to bismuth zinc vanadate (BiZn2VO6). The BiZn2VO6 is then used to demonstrate efficient and cost effective hydrogen production through photoelectrochemical water splitting using solar radiation.

  5. Enhancement of photocatalytic property on ZnS/MoS2 composite under visible light irradiation

    Directory of Open Access Journals (Sweden)

    Cheng Jiushan

    2017-01-01

    Full Text Available In this paper, the composite ZnS/MoS2 was obtained via two steps including solvothermal methods. The as-synthesized sample was characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM and UV-Vis. diffuse reflectance spectra (DRS. The photocatalytic activity of the product was evaluated through photocatalytic degradation of Rhodamine B (Rh B under UV-Vis. light irradiation; the electrical conductivity of ZnS/MoS2 composites was significantly improved compared to ZnS, MoS2, respectively. The results showed that the ZnS/MoS2 composite photocatalyst possesses better photocatalytic activity in degrading Rh B than the single ZnS or the single MoS2. The better photocatalytic properties may be due to the synergetic effect of two semiconductors, because of which electrons and holes were separated effectively. And its specific microstructure played an active role in evaluating photocatalytic performance.

  6. A facile preparation of immobilized BiOCl nanosheets/TiO{sub 2} arrays on FTO with enhanced photocatalytic activity and reusability

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yinghua [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Yu, Xiang [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Analytical & Testing Center, Jinan University, Guangzhou 510632 (China); Lin, Weitian; Zhu, Yi [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Zhang, Yuanming, E-mail: tzhangym@jnu.edu.cn [Department of Chemistry, Jinan University, Guangzhou 510632 (China)

    2017-03-31

    Highlights: • Immobilized BiOCl nanosheets/TiO{sub 2} arrays hybrid photocatalyst were fabricated. • The degradation efficiency of BCTO-3 can still reach 91.7% after eight cycles. • The immobilized BCTO-3 can be recycled for removal of organic pollutants in water. - Abstract: Forming a hybrid structure is considered as an efficient strategy toward improving the photocatalytic activity of TiO{sub 2}-based photocatalyst. In this work, we report a facile impregnation method to prepare BiOCl nanosheets on rutile TiO{sub 2} nanorod arrays on transparent conductive fluorine-doped tin oxide (FTO) substrate. According to RhB photocatalytic degradation experiments, the degradation efficiency of the immobilized BiOCl/TiO{sub 2} (denoted as BCTO-3) hybrid photocatalyst can reach 99.1% after visible light irradiation for 3 h, and its efficiency is higher than that of pure BiOCl (42.7%) and TiO{sub 2} (44.8%), respectively. The enhancement is demonstrated to be the match of energy level between BiOCl and TiO{sub 2}. Hence, the separation and transfer of photogenerated electron-hole pairs are obviously improved, which have been illustrated by the result of the photoluminescence spectra analysis and photoelectrochemical performance. Moreover, the degradation efficiency of BCTO-3 can still reach 91.7% after eight times photodegradation cycle experiments. Due to the easy recycling and excellent durability, the immobilized BCTO-3 photocatalyst is considered as a promising photocatalytic material for the removal of organic pollutants in aqueous eco-environments.

  7. Synthesis of surface oxygen-deficient BiPO{sub 4} nanocubes with enhanced visible light induced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Bingtao; Yin, Haoyong; Li, Tao; Gong, Jianying; Lv, Shumei; Nie, Qiulin, E-mail: yhy@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou (China)

    2017-05-15

    The visible light driven BiPO{sub 4} nanocubes with sufficient surface oxygen deficiency were fabricated by a hydrothermal process and subsequently ultrasonic assistant Fe reduction process. The products were characterized by XRD, DRS, XPS, SEM and TEM which showed that the BiPO{sub 4} had cuboid-like shape with a smooth surface and clear edges and the oxygen vacancies were successfully introduced on the surface of the BiPO{sub 4} nanocubes. The as prepared oxygen-deficient BiPO{sub 4} nanocubes showed greatly enhanced visible light induced photocatalytic activity in degradation of Rhodamine B. The enhanced photocatalytic performance and expanded visible light response of BiPO{sub 4} may be due to the introduction of surface oxygen vacancies which can generate the oxygen vacancies mid-gap states lower to the conduction band of BiPO{sub 4}. (author)

  8. Direct evidence of charge separation in a metal-organic framework: efficient and selective photocatalytic oxidative coupling of amines via charge and energy transfer.

    Science.gov (United States)

    Xu, Caiyun; Liu, Hang; Li, Dandan; Su, Ji-Hu; Jiang, Hai-Long

    2018-03-28

    The selective aerobic oxidative coupling of amines under mild conditions is an important laboratory and commercial procedure yet a great challenge. In this work, a porphyrinic metal-organic framework, PCN-222, was employed to catalyze the reaction. Upon visible light irradiation, the semiconductor-like behavior of PCN-222 initiates charge separation, evidently generating oxygen-centered active sites in Zr-oxo clusters indicated by enhanced porphyrin π-cation radical signals. The photogenerated electrons and holes further activate oxygen and amines, respectively, to give the corresponding redox products, both of which have been detected for the first time. The porphyrin motifs generate singlet oxygen based on energy transfer to further promote the reaction. As a result, PCN-222 exhibits excellent photocatalytic activity, selectivity and recyclability, far superior to its organic counterpart, for the reaction under ambient conditions via combined energy and charge transfer.

  9. Synthesis of Cu{sub 2}O/graphene/rutile TiO{sub 2} nanorod ternary composites with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Mingxuan, E-mail: mingxuansun@sues.edu.cn; Fang, Yalin; Wang, Ying; Sun, Shanfu; He, Jia; Yan, Zhi

    2015-11-25

    A ternary composite of Cu{sub 2}O, graphene and rutile TiO{sub 2} nanorods was prepared using Cu(CH{sub 3}COO){sub 2}·H{sub 2}O, graphene oxide and TiCl{sub 4} as the starting materials and its enhanced photocatalytic performance was demonstrated. Graphene/TiO{sub 2} nanorod composites (GT) were obtained by a simple hydrothermal method and then, Cu{sub 2}O was coupled onto the surface of graphene/rutile TiO{sub 2} to form Cu{sub 2}O/graphene/rutile TiO{sub 2} nanorod (CGT) composites via a chemical bath deposition process. The as-prepared sample was characterized by X-ray diffraction (XRD), emission field scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), specific surface area analyzer (BET), Raman spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS). It is found that the introduction of graphene and Cu{sub 2}O has little effect on the morphology of TiO{sub 2} nanorods with average dimensions of 140 nm (length) × 30 nm (diameter) (L/D ratio ≈5). A red shift of light absorption edge and more absorption in the visible light region were observed for the resulted ternary samples compared with TiO{sub 2} and graphene/TiO{sub 2} composites. The photocatalytic activity was evaluated by the photodegradation of methylene blue under visible light irradiation, which showed 2.8 times corresponding enhancement of the degradation efficiency for the ternary composites compared with TiO{sub 2}. This work provides a new strategy to improve the visible light response of TiO{sub 2} and facilitate its application in environmental remediation. - Highlights: • A ternary composite of Cu{sub 2}O/graphene/rutile TiO{sub 2} nanorods were successfully fabricated. • Red shift and more absorption in the visible light region were observed for the ternary composites. • Improved photocatalytic degradation was detected with the introduction of Cu{sub 2}O and graphene. • Both Cu{sub 2}O and graphene played an important role

  10. Facile synthesis and enhanced visible-light photocatalytic activity of micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jin [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); The Key Laboratory of Rare Earth Functional Materials and Applications, Zhoukou Normal University, Zhoukou 466001 (China); Zhang, Gaoke, E-mail: gkzhang@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China)

    2015-03-15

    Graphical abstract: - Highlights: • Micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres were synthesized by a facile method. • The formation mechanism for the Ag{sub 2}ZnGeO{sub 4} hollow spheres was investigated. • The catalyst exhibited an enhanced visible-light photocatalytic activity. • The reactive species in the photocatalytic process were studied. - Abstract: Micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres were successfully synthesized by a one-step and low-temperature route under ambient pressure. The micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres have a diameter of 1–2 μm and their shells are composed of numerous nanoparticles and nanorods. The growth process of the micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres was investigated in detail. The results indicated that the morphologies and composition of Ag{sub 2}ZnGeO{sub 4} samples were strongly dependent on the dose of the AgNO{sub 3} and reaction time. Excessive AgNO{sub 3} was favorable for the nucleation and growth rate of Ag{sub 2}ZnGeO{sub 4} crystals and the formation of pure Ag{sub 2}ZnGeO{sub 4}. Moreover, the formation mechanism of the micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres is related to the Ostwald ripening. Under the same conditions, the photocatalytic activity of micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres is about 1.7 times and 11 times higher than that of bulk Ag{sub 2}ZnGeO{sub 4} and Degussa P25, respectively. These interesting findings could provide new insight on the synthesis of micro/nanostructured ternary-metal oxides with enhanced photocatalytic activity.

  11. SrTiO3 Nanocube-Doped Polyaniline Nanocomposites with Enhanced Photocatalytic Degradation of Methylene Blue under Visible Light

    Directory of Open Access Journals (Sweden)

    Syed Shahabuddin

    2016-02-01

    Full Text Available The present study highlights the facile synthesis of polyaniline (PANI-based nanocomposites doped with SrTiO3 nanocubes synthesized via the in situ oxidative polymerization technique using ammonium persulfate (APS as an oxidant in acidic medium for the photocatalytic degradation of methylene blue dye. Field emission scanning electron microscopy (FESEM, transmission electron microscopy (TEM, thermogravimetric analysis (TGA, X-ray diffraction (XRD, UV–Vis spectroscopy, Brunauer–Emmett–Teller analysis (BET and Fourier transform infrared spectroscopy (FTIR measurements were used to characterize the prepared nanocomposite photocatalysts. The photocatalytic efficiencies of the photocatalysts were examined by degrading methylene blue (MB under visible light irradiation. The results showed that the degradation efficiency of the composite photocatalysts that were doped with SrTiO3 nanocubes was higher than that of the undoped polyaniline. In this study, the effects of the weight ratio of polyaniline to SrTiO3 on the photocatalytic activities were investigated. The results revealed that the nanocomposite P-Sr500 was found to be an optimum photocatalyst, with a 97% degradation efficiency after 90 min of irradiation under solar light.

  12. Core-shell SrTiO3/graphene structure by chemical vapor deposition for enhanced photocatalytic performance

    Science.gov (United States)

    He, Chenye; Bu, Xiuming; Yang, Siwei; He, Peng; Ding, Guqiao; Xie, Xiaoming

    2018-04-01

    Direct growth of high quality graphene on the surface of SrTiO3 (STO) was realized through chemical vapor deposition (CVD), to construct few-layer 'graphene shell' on every STO nanoparticle. The STO/graphene composite shows significantly enhanced UV light photocatalytic activity compared with the STO/rGO reference. Mechanism analysis confirms the role of special core-shell structure and chemical bond (Tisbnd C) for rapid interfacial electron transfer and effective electron-hole separation.

  13. Size dependence of photocatalytic oxidation reactions of Rh nanoparticles dispersed on (Ga1-xZnx)(N1-xOx) support

    NARCIS (Netherlands)

    Zhang, Y.; Ligthart, D.A.J.M.; Liu, P.; Gao, L.; Verhoeven, M.W.G.M.; Hensen, E.J.M.

    2014-01-01

    Mixed Ga–Zn oxynitrides were synthesized using coprecipitation, wet-precipitation, and solid-solution methods. The oxynitrides were used as supports for Rh nanoparticle catalysts in photocatalytic water splitting, CO oxidation, and H2 oxidation. Mixed Ga–Zn oxynitrides produced by wet precipitation

  14. Remarkably enhanced photocatalytic hydrogen evolution over MoS2 nanosheets loaded on uniform CdS nanospheres

    Science.gov (United States)

    Chai, Bo; Xu, Mengqiu; Yan, Juntao; Ren, Zhandong

    2018-02-01

    The MoS2/CdS composites with layered MoS2 loaded on uniform CdS nanospheres were synthesized by a two-step process combination hydrothermal and solvothermal treatments, and then applied in photocatalytic hydrogen evolution under visible light irradiation. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectra, UV-vis diffuse reflectance absorption spectra (UV-DRS), nitrogen adsorption-desorption measurement, photoluminescence spectra (PL) and photoelectrochemical tests. The effects of loading contents of MoS2 in the composites on the photocatalytic H2 evolution activity were comparatively investigated with 0.45 mol L-1 Na2S and 0.55 mol L-1 Na2SO3 as sacrificial agents. The results showed that the 5 wt% MoS2/CdS composite could achieve the highest photocatalytic H2 evolution rate of 372 μmol h-1 and apparent quantum efficiency (AQE) about 7.31% under 420 nm monochromatic light irradiation. The remarkably enhanced photocatalytic activity of MoS2/CdS composite could be attributed to the effective transfer and separation of photogenerated charge carriers, and MoS2 being as a cocatalyst to facilitating photocatalytic H2 evolution reaction. A tentative mechanism of MoS2/CdS composites as photocatalysts for H2 evolution was proposed.

  15. Synergistically enhanced photocatalytic hydrogen evolution performance of ZnCdS by co-loading graphene quantum dots and PdS dual cocatalysts under visible light

    Science.gov (United States)

    Wang, Fang; Su, Yanhong; Min, Shixiong; Li, Yanan; Lei, Yonggang; Hou, Jianhua

    2018-04-01

    Here, we report that the co-loading of graphene quantum dots (GQDs) and PdS dual cocatalysts on ZnCdS surface achieves a high efficiency photocatalytic H2 evolution under visible light (≥420 nm). The GQDs/ZnCdS/PdS photocatalyst was prepared by a facile two steps: hydrothermal coupling of GQDs on ZnCdS surface followed by an in-situ chemical deposition of PdS. The resulted GQDs/ZnCdS/PdS exhibits a H2 evolution rate of 517 μmol h-1, which is 15, 7, and 1.7 times higher than that of pure ZnCdS, GQDs/ZnCdS, and ZnCdS/PdS, respectively, demonstrating the synergistic effects of GQDs and PdS dual cocatalysts. A high apparent quantum efficiency (AQE) up to 22.4% can be achieved over GQDs/ZnCdS/PdS at 420 nm. GQDs/ZnCdS/PdS also has a relatively good stability. Such a considerable enhancement of photocatalytic activity was attributable to the co-loading of the GQDs and PdS as respective reduction and oxidation cocatalysts, leading to an efficient charge separation and surface reactions.

  16. Microwave-assisted synthesis of NiS2 nanostructures for supercapacitors and cocatalytic enhancing photocatalytic H2 production

    Science.gov (United States)

    Pang, Huan; Wei, Chengzhen; Li, Xuexue; Li, Guochang; Ma, Yahui; Li, Sujuan; Chen, Jing; Zhang, Jiangshan

    2014-01-01

    Uniform NiS2 nanocubes are successfully synthesized with a microwave-assisted method. Interestingly, NiS2 nanocubes, nanospheres and nanoparticles are obtained by controlling microwave reaction time. NiS2 nanomaterials are primarily applied to supercapacitors and cocatalytic enhancing photocatalytic H2 production. Different morphologies of NiS2 nanostructures show different electrochemical and cocatalytic enhancing H2 production activities. Benefited novel nanostructures, NiS2 nanocube electrodes show a large specific capacitance (695 F g−1 at 1.25 A g−1) and excellent cycling performance (the retention 93.4% of initial specific capacitance after 3000 cycles). More importantly, NiS2 nanospheres show highly cocatalytic enhancing photocatalytic for H2 evolution, in which the photocatalytic H2 production is up to 3400 μmol during 12 hours under irradiation of visible light (λ>420 nm) with an average H2 production rate of 283 μmol h−1. PMID:24389929

  17. CNTs threaded (001) exposed TiO2 with high activity in photocatalytic NO oxidation.

    Science.gov (United States)

    Xiao, Shuning; Zhu, Wei; Liu, Peijue; Liu, Fanfan; Dai, Wenrui; Zhang, Dieqing; Chen, Wei; Li, Hexing

    2016-02-07

    A microwave-ionothermal strategy was developed for in situ synthesis of CNTs threaded TiO2 single crystal with a tunable percentage of surface exposed (001) active facets. The CNTs were used as microwave antennas to create local "super hot" dots to induce Ti(3+) adsorption and hydrolysis, thereby leading to a good assembly of (001) facets exposed single crystalline TiO2 threaded by the CNTs in the presence of Hmim[BF4] ionic liquid. Due to the high percentage of the active (001) facets of single crystal TiO2 and the direct electron transfer property of the CNTs, the as-prepared CNTs-TiO2 composite showed a photocatalytic NO removal ratio of up to 76.8% under UV irradiation. In addition, with self-doped Ti(3+), the CNTs-TiO2 composite also exhibited an enhanced activity under irradiation with either solar lights or visible lights, showing good potential in practical applications for environmental remediation.

  18. Temperature dependence of electrocatalytic and photocatalytic oxygen evolution reaction rates using NiFe oxide

    KAUST Repository

    Nurlaela, Ela; Shinagawa, Tatsuya; Qureshi, Muhammad; Dhawale, Dattatray Sadashiv; Takanabe, Kazuhiro

    2016-01-01

    The present work compares oxygen evolution reaction (OER) in electrocatalysis and photocatalysis in aqueous solutions using nanostructured NiFeOx as catalysts. The impacts of pH and reaction temperature on the electrocatalytic and photocatalytic OER

  19. The effect of natural iron oxide and oxalic acid on the photocatalytic degradation of isoproturon: a kinetics and analytical study.

    Science.gov (United States)

    Boucheloukh, H; Remache, W; Parrino, F; Sehili, T; Mechakra, H

    2017-05-17

    The photocatalytic degradation of isoproturon, a persistent toxic herbicide, was investigated in the presence of natural iron oxide and oxalic acid and under UV irradiation. The influence of the relevant parameters such as the pH and the iron oxide and oxalic acid concentrations has been studied. The presence of natural iron oxide and oxalic acid in the system effectively allow the degradation of isoproturon, whereas the presence of t-butyl alcohol adversely affects the phototransformation of the target pollutant, thus indicating that an OH radical initiated the degradation mechanism. The degradation mechanism of isoproturon was investigated by means of GC-MS analysis. Oxidation of both the terminal N-(CH 3 ) 2 and isopropyl groups is the initial process leading to N-monodemethylated (NHCH 3 ), N-formyl (N(CH 3 )CHO), and CHCH 3 OH as the main intermediates. The substitution of the isopropyl group by an OH group is also observed as a side process.

  20. Low-temperature growth of well-aligned zinc oxide nanorod arrays on silicon substrate and their photocatalytic application

    Directory of Open Access Journals (Sweden)

    Azam A

    2014-04-01

    Full Text Available Ameer Azam,1 Saeed Salem Babkair21Center of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia; 2Center of Nanotechnology, Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi ArabiaAbstract: Well-aligned and single-crystalline zinc oxide (ZnO nanorod arrays were grown on silicon (Si substrate using a wet chemical route for the photodegradation of organic dyes. Structural analysis using X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction confirmed the formation of ZnO nanorods grown preferentially oriented in the (001 direction and with a single phase nature with a wurtzite structure. Field emission scanning electron microscopy and transmission electron microscopy micrographs showed that the length and diameter of the well-aligned rods were about ~350–400 nm and ~80–90 nm, respectively. Raman scattering spectra of ZnO nanorod arrays revealed the characteristic E2 (high mode that is related to the vibration of oxygen atoms in the wurtzite ZnO. The photodegradation of methylene blue (MB using ZnO nanorod arrays was performed under ultraviolet light irradiation. The results of photodegradation showed that ZnO nanorod arrays were capable of degrading ~80% of MB within 60 minutes of irradiation, whereas ~92% of degradation was achieved in 120 minutes. Complete degradation of MB was observed after 270 minutes of irradiation time. Owing to enhanced photocatalytic degradation efficiency and low-temperature growth method, prepared ZnO nanorod arrays may open up the possibility for the successful utilization of ZnO nanorod arrays as a future photocatalyst for environmental remediation.Keywords: ZnO, nanorods, XRD, photodegradation

  1. In situ growth of lamellar ZnTiO3 nanosheets on TiO2 tubular array with enhanced photocatalytic activity.

    Science.gov (United States)

    Cai, Yunyu; Ye, Yixing; Tian, Zhenfei; Liu, Jun; Liu, Yishu; Liang, Changhao

    2013-12-14

    We report a self-sacrificed in situ growth design toward preparation of ZnTiO3-TiO2 heterojunction structure. Highly reactive zinc oxide colloidal particles derived by laser ablation in liquids can react with TiO2 nanotubes to form a lamellar ZnTiO3 nanosheet structure in a hydrothermal-treatment process. Such hybrid structural product was characterized by X-ray diffraction, scanning and transmission electron microscopy, UV-vis diffuse reflection spectroscopy and X-ray photoelectron spectroscopy. The enhanced photocatalytic activity of the hybrid structure toward degradation of methyl orange (MO) and pentachlorophenol (PCP) molecules was demonstrated and compared with single phase TiO2, as a result of the efficient separation of light excited electrons and holes at the hetero-interfaces in the two semiconductors.

  2. Influence of inlet concentration and light intensity on the photocatalytic oxidation of nitrogen(II) oxide at the surface of Aeroxide{sup Registered-Sign} TiO{sub 2} P25

    Energy Technology Data Exchange (ETDEWEB)

    Dillert, Ralf, E-mail: dillert@iftc.uni-hannover.de [Institut fuer Technische Chemie, Leibniz Universitaet Hannover, Callinstr. 3, 30167 Hannover (Germany); Laboratorium fuer Nano- und Quantenengineering, Leibniz Universitaet Hannover, Schneiderberg 39, 30167 Hannover (Germany); Stoetzner, Julia [Institut fuer Technische Chemie, Leibniz Universitaet Hannover, Callinstr. 3, 30167 Hannover (Germany); Engel, Astrid [Institut fuer Technische Chemie, Leibniz Universitaet Hannover, Callinstr. 3, 30167 Hannover (Germany); Laboratorium fuer Nano- und Quantenengineering, Leibniz Universitaet Hannover, Schneiderberg 39, 30167 Hannover (Germany); Bahnemann, Detlef W. [Institut fuer Technische Chemie, Leibniz Universitaet Hannover, Callinstr. 3, 30167 Hannover (Germany)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer The photocatalytic oxidation of nitrogen(II) oxide at the TiO{sub 2} surface was studied. Black-Right-Pointing-Pointer The effect of the UV(A) light intensity on the reaction rate was evaluated. Black-Right-Pointing-Pointer The effect of the NO concentration on the reaction rate was evaluated. Black-Right-Pointing-Pointer A mechanistic model for the heterogeneous NO oxidation is presented. Black-Right-Pointing-Pointer A rate law describing the influence of NO concentration and light intensity is given. - Abstract: Air pollution by nitrogen oxides represents a serious environmental problem in urban areas where numerous sources of these pollutants are concentrated. One approach to reduce the concentration of these air pollutants is the light-induced oxidation in the presence of molecular oxygen and a photocatalytically active building material, e.g., paints, roof tiles, or pavement stones. Herein, results of an investigation concerning the photocatalytic oxidation of nitrogen(II) oxide (NO) in the presence of molecular oxygen and UV(A) irradiated TiO{sub 2} powder are presented. The standard operating procedure described in ISO 22197-1 which was developed to characterize the photocatalytic activity of air-cleaning products was successfully applied to determine the photocatalytic activity of a bare TiO{sub 2} powder. The experimental data reveal that at the light intensity stipulated by the operation procedure the amount of NO removed from the gas phase by photocatalytic oxidation is strongly affected by small changes of this light intensity as well as of the NO concentration in the gas stream in the photoreactor. Therefore, these parameters have to be controlled very carefully. Based upon the experimental data obtained in this study a rate law for the photocatalytic NO oxidation inside the photoreactor is derived.

  3. Influence of inlet concentration and light intensity on the photocatalytic oxidation of nitrogen(II) oxide at the surface of Aeroxide® TiO2 P25

    International Nuclear Information System (INIS)

    Dillert, Ralf; Stötzner, Julia; Engel, Astrid; Bahnemann, Detlef W.

    2012-01-01

    Highlights: ► The photocatalytic oxidation of nitrogen(II) oxide at the TiO 2 surface was studied. ► The effect of the UV(A) light intensity on the reaction rate was evaluated. ► The effect of the NO concentration on the reaction rate was evaluated. ► A mechanistic model for the heterogeneous NO oxidation is presented. ► A rate law describing the influence of NO concentration and light intensity is given. - Abstract: Air pollution by nitrogen oxides represents a serious environmental problem in urban areas where numerous sources of these pollutants are concentrated. One approach to reduce the concentration of these air pollutants is the light-induced oxidation in the presence of molecular oxygen and a photocatalytically active building material, e.g., paints, roof tiles, or pavement stones. Herein, results of an investigation concerning the photocatalytic oxidation of nitrogen(II) oxide (NO) in the presence of molecular oxygen and UV(A) irradiated TiO 2 powder are presented. The standard operating procedure described in ISO 22197-1 which was developed to characterize the photocatalytic activity of air-cleaning products was successfully applied to determine the photocatalytic activity of a bare TiO 2 powder. The experimental data reveal that at the light intensity stipulated by the operation procedure the amount of NO removed from the gas phase by photocatalytic oxidation is strongly affected by small changes of this light intensity as well as of the NO concentration in the gas stream in the photoreactor. Therefore, these parameters have to be controlled very carefully. Based upon the experimental data obtained in this study a rate law for the photocatalytic NO oxidation inside the photoreactor is derived.

  4. Properties of photocatalytically generated oxygen species produced by Ag2Se-graphene oxide heterojunction and its application for the visible-light degradation of ammonia

    Science.gov (United States)

    Meng, Ze-Da; Zhao, Wei; Kim, Sukyoung

    2017-11-01

    Reactive oxygen species (ROS) can be produced by the interactions between sunlight and light-absorbing substances in aqueous environments, and these ROS are capable of destroying various organic pollutants in wastewater. In this study, the photocatalytic degradation of ammonia in petrochemical wastewater was investigated by solar light photocatalysis. We used graphene oxide modified Ag2Se nanoparticles to enhance the activity of photochemically generated oxygen (PGO) species. There was a catastrophic decrease in the surface area and pore volume of the Ag2Se-graphene oxide (Ag2Se-G) samples because of the deposition of Ag2Se. The generation of ROS was detected by the oxidation of 1,5- diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It was revealed that the photocurrent density and PGO effect increased with the graphene oxide modified. The experimental results indicate that this heterogeneous catalyst achieved a degradation of 88.43% under visiblelight irradiation. The NH3 degradation product was N2 and neither NO2- nor NO3- were detected.[Figure not available: see fulltext.

  5. The influence of narrow optical gap silver oxide on zinc oxide nanoparticles produced by microwave-assisted colloidal synthesis: photocatalytic studies

    Science.gov (United States)

    Prakoso, S. P.; Paramarta, V.; Tju, H.; Taufik, A.; Saleh, R.

    2016-11-01

    This paper reports a photocatalytic study on wide band gap zinc oxide (ZnO) incorporated by narrow band gap silver oxide (Ag2O), namely Ag2O/ZnO nanocomposites, which were prepared by colloidal synthesis with microwave supports. The Ag2O/ZnO nanocomposites were prepared with three different molar ratios (MR) of Ag2O to ZnO (MR: 0.25, 0.5 and 0.75). In order to confirm qualitatively the concentration ratio of Ag2O in ZnO, crystal phase intensity ratio was executed by peak indexing from x-ray diffraction. The Ag2O/ZnO nanocomposites properties were further investigated using diffuse reflectance spectroscopy. The nanocomposites were tested for the degradation of organic dyes solutions under visible and UV light irradiations. The photocatalytic activity of Ag2O/ZnO nanocomposites under visible light increased with increasing molar ratio of Ag2O to ZnO, while the opposite trends observed under UV light irradiation. The improvement of photoabsorption together with photocatalytic activities might be suspected due to the p-n heterojunction structure in Ag2O/ZnO nanocomposites. The corresponding mechanism will be discussed in detail.

  6. The transformation to cadmium oxide through annealing of cadmium oxide hydroxide deposited by ammonia-free SILAR method and the photocatalytic properties

    International Nuclear Information System (INIS)

    Chávez Urbiola, I.R.; Ramírez Bon, R.; Vorobiev, Y.V.

    2015-01-01

    Cadmium oxide-hydroxide films were prepared on glass substrates from aqueous alkaline solution at room temperature which was prepared by a more simple and economic version of chemical bath deposition — SILAR (successive ionic layer adsorption and reaction) method. The films obtained were converted to polycrystalline cadmium oxide by annealing treatment at different temperatures. It was found that the annealing temperature affects the grain size and films' density. The morphology, crystallinity, optical and electrical properties of the material obtained confirms its high quality. Finally its photocatalytical effect on methylene blue colorant was observed and analyzed. We expect that this method of CdO films preparation might be of interest for applications in solar energy converter and photocatalytical reactors. - Highlights: • Original SILAR production of Cd(O_2)_0_._8_8(OH)_0_._2_4 and its conversion to CdO were found. • Crystalline structure of CdO obtained is not different from that in bulk crystals. • The thickness of the film is controlled with the number of cycles. • The CdO and Cd(O_2)_0_._8_8(OH)_0_._2_4 has a similar photocatalytic effect • The properties of the CdO films are influenced by annealing process.

  7. The transformation to cadmium oxide through annealing of cadmium oxide hydroxide deposited by ammonia-free SILAR method and the photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Chávez Urbiola, I.R., E-mail: ichavez@qro.cinvestav.mx; Ramírez Bon, R.; Vorobiev, Y.V.

    2015-10-01

    Cadmium oxide-hydroxide films were prepared on glass substrates from aqueous alkaline solution at room temperature which was prepared by a more simple and economic version of chemical bath deposition — SILAR (successive ionic layer adsorption and reaction) method. The films obtained were converted to polycrystalline cadmium oxide by annealing treatment at different temperatures. It was found that the annealing temperature affects the grain size and films' density. The morphology, crystallinity, optical and electrical properties of the material obtained confirms its high quality. Finally its photocatalytical effect on methylene blue colorant was observed and analyzed. We expect that this method of CdO films preparation might be of interest for applications in solar energy converter and photocatalytical reactors. - Highlights: • Original SILAR production of Cd(O{sub 2}){sub 0.88}(OH){sub 0.24} and its conversion to CdO were found. • Crystalline structure of CdO obtained is not different from that in bulk crystals. • The thickness of the film is controlled with the number of cycles. • The CdO and Cd(O{sub 2}){sub 0.88}(OH){sub 0.24} has a similar photocatalytic effect • The properties of the CdO films are influenced by annealing process.

  8. The influence of narrow optical gap silver oxide on zinc oxide nanoparticles produced by microwave-assisted colloidal synthesis: photocatalytic studies

    International Nuclear Information System (INIS)

    Prakoso, S. P.; Paramarta, V.; Tju, H.; Taufik, A.; Saleh, R.

    2016-01-01

    This paper reports a photocatalytic study on wide band gap zinc oxide (ZnO) incorporated by narrow band gap silver oxide (Ag 2 O), namely Ag 2 O/ZnO nanocomposites, which were prepared by colloidal synthesis with microwave supports. The Ag 2 O/ZnO nanocomposites were prepared with three different molar ratios (MR) of Ag 2 O to ZnO (MR: 0.25, 0.5 and 0.75). In order to confirm qualitatively the concentration ratio of Ag 2 O in ZnO, crystal phase intensity ratio was executed by peak indexing from x-ray diffraction. The Ag 2 O/ZnO nanocomposites properties were further investigated using diffuse reflectance spectroscopy. The nanocomposites were tested for the degradation of organic dyes solutions under visible and UV light irradiations. The photocatalytic activity of Ag 2 O/ZnO nanocomposites under visible light increased with increasing molar ratio of Ag 2 O to ZnO, while the opposite trends observed under UV light irradiation. The improvement of photoabsorption together with photocatalytic activities might be suspected due to the p-n heterojunction structure in Ag 2 O/ZnO nanocomposites. The corresponding mechanism will be discussed in detail. (paper)

  9. Enhanced photocatalytic performance of BiVO_4 in aqueous AgNO_3 solution under visible light irradiation

    International Nuclear Information System (INIS)

    Huang, Chien-Kai; Wu, Tsunghsueh; Huang, Chang-Wei; Lai, Chi-Yung; Wu, Mei-Yao; Lin, Yang-Wei

    2017-01-01

    Graphical abstract: Ag"+ ions enhanced photocatalytic activity of BiVO_4 under visible light irradiation. - Highlights: • The presence of Ag"+ ions enhanced the photodegradation activity of BiVO_4. • Photoreduction of Ag deposited on the BiVO_4 surface was obtained. • Luminescence and electrochemical results elucidated the photocatalytic mechanism. • Holes and oxygen radicals were the main reactive species generated by BiVO_4/Ag"+. • Used BiVO_4/Ag"+ exhibited photocatalytic antibacterial activity toward E. coli. - Abstract: Monoclinic-phase bismuth vanadate (BiVO_4) with a 2.468 eV band gap exhibited enhanced synergic photodegradation activity toward methylene blue (MB) when combined with silver ions (Ag"+) in an aqueous solution under visible light irradiation. The mass ratio of AgNO_3 to BiVO_4 and the calcination temperature were discovered to considerably affect the degradation activity of BiVO_4/Ag"+. Superior photocatalytic performance was obtained when BiVO_4 was mixed with 0.01%(w/v) AgNO_3 solution, and complete degradation of MB was achieved after 25 min visible light irradiation, outperforming BiVO_4 or AgNO_3 solution alone. The enhanced photodegradation was investigated using systematic luminescence measurements, electrochemical impedance spectroscopy, and scavenger addition, after which a photocatalytic mechanism for MB degradation under visible light irradiation was identified that involved oxygen radicals and holes. This study also discovered the two dominating processes involved in enhancing the electron–hole separation efficiency and reducing their recombination rate, namely photoreduction of Ag"+ and the formation of a BiVO_4/Ag heterojunction. The synergic effect between BiVO_4 and Ag"+ was discovered to be unique. BiVO_4/Ag"+ was successfully used to degrade two other dyes and disinfect Escherichia Coli. A unique fluorescent technique using BiVO_4 and a R6G solution to detect Ag"+ ions in water was discovered.

  10. Photocatalytic production of 1O2 and ·OH mediated by silver oxidation during the photoinactivation of Escherichia coli with TiO2

    International Nuclear Information System (INIS)

    Castro, Camilo A.; Osorio, Paula; Sienkiewicz, Andrzej; Pulgarin, Cesar; Centeno, Aristóbulo; Giraldo, Sonia A.

    2012-01-01

    Highlights: ► Metallic silver enhances the Ag–TiO 2 photoinactivation of Escherichia coli under Vis irradiation. ► 1 O 2 and ·OH were identified in Vis irradiated Ag–TiO 2 suspensions. ► UV oxidized the Ag metallic species in the material decreasing photoactivity. ► Dark contact of the UV oxidized material with E. coli regenerates the photocatalyst. - Abstract: Ag loaded TiO 2 was applied in the photocatalytic inactivation of Escherichia coli under ultraviolet (UV) and visible (Vis) light irradiations. Ag enhanced the TiO 2 photodisinfecting effect under Vis irradiation promoting the formation of singlet oxygen and hydroxyl radicals as identified by EPR analyses. Ag nanoparticles, determined on TEM analyses, undergo an oxidation process on the TiO 2 's surface under UV or Vis irradiation as observed by XPS. In particular, UV pre-irradiation of the material totally diminished its photodisinfection activity under a subsequent Vis irradiation test. Under UV, photodegradation of dichloroacetic acid (DCA), attributed to photoproduced holes in TiO 2 , was inhibited by the presence of Ag suggesting that oxidation of Ag 0 to Ag + and Ag 2+ is faster than the oxidative path of the TiO 2 's holes on DCA molecules. Furthermore, photoassisted increased of Ag + concentration on TiO 2 's surface enhances the bacteriostatic activity of the material in dark periods. Indeed, this latter dark contact of Ag + –TiO 2 and E. coli seems to induce recovering of the Vis light photoactivity promoted by the surface Ag photoactive species.

  11. Enhanced visible light-responsive photocatalytic activity of LnFeO3 (Ln = La, Sm) nanoparticles by synergistic catalysis

    International Nuclear Information System (INIS)

    Li, Li; Wang, Xiong; Zhang, Yange

    2014-01-01

    Highlights: • LnFeO 3 (Ln = La, Sm) nanoparticles were prepared by a facile sol–gel method. • The samples exhibit superior visible-light-responsive photocatalytic activity. • Synergistic effect will enhance the photodegradation of RhB under visible light. - Abstract: LnFeO 3 (Ln = La, Sm) nanoparticles were prepared by a facile sol–gel method with assistance of glycol at different calcination temperatures. The as-synthesized LnFeO 3 was characterized by X-ray diffraction, transmission electron microscopy, differential scanning calorimeter and thermogravimetric analysis, and UV–vis absorption spectroscopy. The photocatalytic behaviors of LnFeO 3 nanoparticles were evaluated by photodegradation of rhodamine B under visible light irradiation. The results indicate that the visible light-responsive photocatalytic activity of LnFeO 3 nanoparticles was enhanced remarkably by the synergistic effect between the semiconductor photocatalysis and Fenton-like reaction. And a possible catalytic mechanism was also proposed based on the experimental results

  12. Intercorrelated Ag3PO4 nanoparticles decorated with graphic carbon nitride: Enhanced stability and photocatalytic activities for water treatment

    Science.gov (United States)

    Ren, Jia; Chai, Yuanyuan; Liu, Qianqian; Zhang, Lu; Dai, Wei-Lin

    2017-05-01

    The method of decorating Ag3PO4 nanoparticles with carbon nitride material (g-C3N4) is demonstrated as an efficient pathway to remarkably improve the stability and photocatalytic performance of Ag3PO4 nanoparticles which have been widely used in photocatalysis, but limited by the instability. The improved material herein results in the largely enhanced photocatalytic performance for water purification under visible light irradiation, which was nearly 7 times as high as that of pure Ag3PO4. Meanwhile, the as-obtained materials show the unique stable property, mainly contributed by the protection effect of decorated g-C3N4 sheet. Additionally, the radical trapping experiments revealed that the introduction of g-C3N4 transformed the photocatalytic mechanism to some degree, where rad O2- played a more important role. The tremendous enhancement in catalytic performance may be attributed to the larger surface area, controllable particle size and the synergistic effect between Ag3PO4 and g-C3N4, promoting the separation efficiency of the photogenerated electron-hole pairs. The decorating system can in principle be broadly put into use for unstable photocatalysts.

  13. Enhanced visible light photocatalytic properties of Fe-doped TiO2 nanorod clusters and monodispersed nanoparticles

    International Nuclear Information System (INIS)

    Liu, Y.; Wei, J.H.; Xiong, R.; Pan, C.X.; Shi, J.

    2011-01-01

    In order to get photocatalysts with desired morphologies and enhanced visible light responses, the Fe-doped TiO 2 nanorod clusters and monodispersed nanoparticles were prepared by modified hydrothermal and solvothermal method, respectively. The microstructures and morphologies of TiO 2 crystals can be controlled by restraining the hydrolytic reaction rates. The Fe-doped photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy (UV-vis), N 2 adsorption-desorption measurement (BET), and photoluminescence spectroscopy (PL). The refinements of the microstructures and morphologies result in the enhancement of the specific surface areas. The Fe 3+ -dopants in TiO 2 lattices not only lead to the significantly extending of the optical responses from UV to visible region but also diminish the recombination rates of the electrons and holes. The photocatalytic activities were evaluated by photocatalytic decomposition of formaldehyde in air under visible light illumination. Compared with P25 (TiO 2 ) and N-doped TiO 2 nanoparticles, the Fe-doped photocatalysts show high photocatalytic activities under visible light.

  14. Fabrication, structure, and enhanced photocatalytic properties of hierarchical CeO2 nanostructures/TiO2 nanofibers heterostructures

    International Nuclear Information System (INIS)

    Cao, Tieping; Li, Yuejun; Wang, Changhua; Wei, Liming; Shao, Changlu; Liu, Yichun

    2010-01-01

    Combining the versatility of electrospinning technique and hydrothermal growth of nanostructures enabled the fabrication of hierarchical CeO 2 /TiO 2 nanofibrous mat. The as-prepared hierarchical heterostructure consisted of CeO 2 nanostructures growing on the primary TiO 2 nanofibers. Interestingly, not only were secondary CeO 2 nanostructures successfully grown on TiO 2 nanofibers substrates, but also the CeO 2 nanostructures were uniformly distributed without aggregation on TiO 2 nanofibers. By selecting different alkaline source, CeO 2 /TiO 2 heterostructures with CeO 2 nanowalls or nanoparticles were facilely fabricated. The photocatalytic studies suggested that the CeO 2 /TiO 2 heterostructures showed enhanced photocatalytic efficiency of photodegradation of dye pollutants compared with bare TiO 2 nanofibers under UV light irradiation.

  15. Enhanced photocatalytic activity induced by sp 3 to sp 2 transition of carbon dopants in BiOCl crystals

    KAUST Repository

    Sun, Jianguo

    2017-09-19

    The insufficient light absorption and low quantum efficiency limit the photocatalytic performance of wide bandgap semiconductors. Here, we report a facile strategy to engineer the surface disordered defects of BiOCl nanosheets via carbon doping. The surface defects boost the light absorption and also the quantum yields, as the doped carbon atoms exhibit a transition from sp3 to sp2 hybridization at elevated temperature, corresponding to a change of assembly state from 3D cluster to 2D graphite-like structure. This transition results in an effective charge separation and thus one order of enhancement in photocatalytic activity toward phenol degradation under visible light. The current study opens an avenue to introduce sp3 to sp2 transition of carbon dopants for simultaneous increment of light absorption and quantum efficiency for application in photocatalysis and energy conversion.

  16. Facile synthesis of silver/silver thiocyanate (Ag@AgSCN plasmonic nanostructures with enhanced photocatalytic performance

    Directory of Open Access Journals (Sweden)

    Xinfu Zhao

    2017-12-01

    Full Text Available A nanostructured plasmonic photocatalyst, silver/silver thiocyanate (Ag@AgSCN, has been prepared by a simple precipitation method followed by UV-light-induced reduction. The ratio of Ag to silver thiocyanate (AgSCN can be controlled by simply adjusting the photo-induced reduction time. The formation mechanism of the product was investigated based on the time-dependent experiments. Further experiments indicated that the prepared Ag@AgSCN nanostructures with an atomic ratio of Ag/AgSCN = 0.0463 exhibited high photocatalytic activity and long-term stability for the degradation of oxytetracycline (84% under visible-light irradiation. In addition to the microstructure and high specific surface area, the enhanced photocatalytic activity was mainly caused by the surface plasmon resonance of Ag nanoparticles, and the high stability of AgSCN resulted in the long-term stability of the photocatalyst product.

  17. Enhanced visible light-induced photocatalytic activity of surface-modified BiOBr with Pd nanoparticles

    Science.gov (United States)

    Meng, Xiangchao; Li, Zizhen; Chen, Jie; Xie, Hongwei; Zhang, Zisheng

    2018-03-01

    Palladium nanoparticles well-dispersed on BiOBr surfaces were successfully prepared via a two-step process, namely hydrothermal synthesis of BiOBr followed by photodeposition of palladium. Surface-exposed palladium nanoparticles may improve the harvesting capacity of visible light photons via the surface plasmonic resonance effect to produce extra electrons. Palladium is an excellent electron acceptor, and therefore favours the separation of photogenerated electron/hole pairs. As a result, palladium significantly improves the photocatalytic activity of BiOBr in the removal of organic pollutants (phenol) under visible light irradiation. In addition to as-prepared samples which were comprehensively characterized, the mechanism for the enhancement via the deposition of palladium nanoparticles was also proposed based on results. This work may serve as solid evidence to confirm that surface-deposited palladium nanoparticles are capable of improving photocatalytic activity, and that photodeposition may be an effective approach to load metal nanoparticles onto a surface.

  18. One-pot engineering TiO2/graphene interface for enhanced adsorption and photocatalytic degradation of multiple organics.

    Science.gov (United States)

    Song, Jianhua; Ling, Yun; Xie, Yu; Liu, Lianjun; Zhu, Huihua

    2018-06-13

    It is challenging to design a multifunctional structure or composite for simultaneously adsorb and photocatalytic degrade organic pollutants in water. Towards this goal, this work innovatively engineered interfacial sites between TiO2 particles and reduced graphene oxide (RGO) sheets by employing in situ one-pot one-step solvothermal method. The interface was associated with the content of RGO, solvothermal time and solvent ratio of n-pentanol to n-hexane. It was found that when at a moderate amount of RGO (25%), TiO2 nanoparticles were well dispersed on the surface of RGO or wrapped by RGO, thus leading to a fully contact and strong interaction to form Ti - O - C interfacial structure. But when at a low content of RGO (6%), TiO2 aggregates were mixture of nanosheets, nanoparticles and nanorods. 25%RGO/TiO2 also had 175% higher surface area (146m2/g), 95% larger volume (0.339 cm3/g) and smaller band gap than 6%RGO/TiO2. More importantly, 25%RGO/TiO2 demonstrated higher adsorption efficiency (25%) and 4 times faster degradation rate than TiO2 (0%). It also exhibited good capability to eliminate multiple organics and stable long-term cycle performance (up to 93% retention after 30 cycles). Its superiority was attributed to the large surface area and unique interface between TiO2 and RGO, which not only provided more active sites to capture pollutants but also enhanced charge transfer (3 µA/cm2, 5 times higher than TiO2). This work offered a promising way to purify water through engineering new materials structure and integrating adsorption and photodegradation technologies. © 2018 IOP Publishing Ltd.

  19. Enhanced photoelectrochemical activity in all-oxide heterojunction devices based on correlated "metallic" oxides.

    Science.gov (United States)

    Apgar, Brent A; Lee, Sungki; Schroeder, Lauren E; Martin, Lane W

    2013-11-20

    n-n Schottky, n-n ohmic, and p-n Schottky heterojunctions based on TiO2 /correlated "metallic" oxide couples exhibit strong solar-light absorption driven by the unique electronic structure of the "metallic" oxides. Photovoltaic and photocatalytic responses are driven by hot electron injection from the "metallic" oxide into the TiO2 , enabling new modalities of operation for energy systems. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Efficient silver modification of TiO2 nanotubes with enhanced photocatalytic activity

    Science.gov (United States)

    Huang, Jing; Ding, Lei; Xi, Yaoning; Shi, Liang; Su, Ge; Gao, Rongjie; Wang, Wei; Dong, Bohua; Cao, Lixin

    2018-06-01

    In this paper, Ag(CH3NH2)2+, Ag(NH3)2+ and Ag+ with different radii have been used as silver sources to find out the distribution of Ag ions on the H-TNT surface, which is critical to the final performance. The influence of this distribution on visible photocatalytic activity is further studied. The results indicate that, when Ag+ used as silver source with low concentration, these small sized silver ions mainly distribute on interlayer spacing of H-TNT. After heat-treatment and photo-reduction, the generated silver nanoparticles uniformly embed in the anatase TiO2 nanotube walls, and bring large interfacial area between Ag particles and TiO2 nanotubes. The separation effect of photogenerated electron-hole pair in TiO2 is enhanced by Ag particles, and achieves the best at 0.15 g/L, much higher than P25, TiO2/0, Ag-N@TiO2 and Ag-C-N@TiO2. This paper provides new ideas for the modification of TiO2 nanotubes.

  1. Controllable synthesis of Au@SnO2 core-shell nanohybrids with enhanced photocatalytic activities

    Science.gov (United States)

    Zhang, Shaofeng; Hao, Jinggang; Ren, Feng; Wu, Wei; Xiao, Xiangheng

    2017-05-01

    Combination of semiconductors with plasmonic nanostructures is an effective route to promote the solar light harvesting as well as the efficiency of photocatalysis. In the present work, the Au@SnO2 hybrid nanostructures with Au nanorods as the cores and highly crystallized SnO2 nanoparticles as the shells were fabricated by a facile hydrothermal method. A critical factor, which influences the coating state of the SnO2 shells over Au NRs, was found to be the concentration of CTAB agent in the system and the corresponding mechanism was also proposed. The photocatalytic activities of the Au@SnO2 nanohybrids were examined by degradation of rhodamine B (RhB) dyes at room temperature. The Au@SnO2 nanohybrids exhibited much higher catalytic activities than that of the commercial SnO2 NPs, which could be attributed to the localized electric field enhancement effect of Au nanorods plasmon and charges transfer between the Au nanorods and SnO2.

  2. Fabrication of doped TiO2 nanotube array films with enhanced photo-catalytic activity

    Science.gov (United States)

    Peighambardoust, Naeimeh-Sadat; Khameneh-asl, Shahin; Khademi, Adib

    2018-01-01

    In the present work, we investigate the N and Fe-doped TiO2 nanotube array film prepared by treating TiO2 nanotube array film with ammonia solution and anodizing in Fe(NO3)3 solution respectively. This method avoided the use of hazardous ammonia gas, or laborious ion implantation process. N and Fe-doped TiO2 nanotube arrays (TiO2 NTs) were prepared by electrochemical anodization process in 0.5 wt % HF aqueous solution. The anodization was performed at the conditions of 20 V and 20 min, Followed by a wet immersion in NH3.H2O (1M) for N-doping for 2 hr and annealing post-treatment at 450 °C. The morphology and structure of the nanotube films were characterized by field emission scanning electron microscope (FESEM) and EDX. UV-vis. illumination test were done to observe photo-enhanced catalysis. The effect of different annealing temperature on the structure and photo-absorption property of the TiO2-TNTs was investigated. The results showed that N-TNTs nanotubes exhibited higher photocatalytic activity compared whit the Fe-doped and pure TNTs, because doping N promoted the separation of the photogenerated electrons and holes.

  3. Enhanced photocatalytic degradation of methylene blue on carbon nanotube-TiO{sub 2}-Pd composites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Hye; Choi, Hyun Chul [Dept. of Chemistry, Chonnam National University, Gwangju (Korea, Republic of)

    2016-11-15

    Semiconductor-based photocatalysis is recognized as a promising technique for addressing energy and environmental issues. Among various semiconductors, the use of titanium dioxide (TiO-2) as a photocatalyst in solar energy conversion and pollutant degradation has been widely investigated because of its high efficiency, photostability, and low toxicity. However, its practical application is restricted by the intrinsic wide band gap of TiO-2 and the rapid recombination of photogenerated electron–hole pairs. Therefore, several remedial methods have been proposed, such as the doping of TiO{sub 2} with metallic or non-metallic elements, increasing its surface area, sensitization with dyes, and the generation of defect structures. We have successfully prepared CNT–TiO{sub 2}–Pd composites with a simple two-step sol–gel method. We characterized the composites with TEM and XRD, and demonstrated that anatase TiO{sub 2} and metallic Pd nanoparticles were deposited onto the surfaces of the CNTs. The average particle size of these nanoparticles was approximately 3.4 nm. The prepared catalyst was found to exhibit a higher activity in MB photodegradation than the reference systems. The synergy of the combination of CNTs and Pd nanoparticles with TiO{sub 2} provides superior MB degradation. More comprehensive studies of the mechanism for this synergy between the metal nanoparticles and TiO{sub 2} that enhances the photocatalytic activity of CNT–TiO{sub 2} are underway in our laboratory.

  4. Effect of post-treatment on photocatalytic oxidation activity of (111 oriented NaNbO3 film

    Directory of Open Access Journals (Sweden)

    Feng Zhang

    2015-10-01

    Full Text Available We investigate the impact of post-treatment on photocatalytic oxidation activity of (111 oriented NaNbO3 film prepared by pulse laser deposition. Some impurities such as Na2Nb4O11 and bigger particles appear in the treated samples. The activity of rhodamine B degradation with N2 purge increases with the amount of ⋅OH, the sample treated under H2/Ar(7% being the highest activity, followed by under air and untreated one; the opposite trend is observed when the system was without N2 purge.

  5. Performance of ultraviolet photocatalytic oxidation for indoor air applications: Systematic experimental evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Lexuan [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8 (Canada); Haghighat, Fariborz, E-mail: fariborz.haghighat@concordia.ca [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8 (Canada); Lee, Chang-Seo [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8 (Canada); Lakdawala, Ness [DECTRON International Inc., Montreal, Quebec (Canada)

    2013-10-15

    Highlights: • An innovative experimental set-up was designed and constructed for testing UV-PCO. • Test methodologies were developed to examine UV-PCO air cleaners for VOCs removal. • VOCs type, inlet concentration, flow rate, irradiance, and RH have influence on PCO. • Gas-phase ozonation with a variety of compounds was examined in a duct system. • Formation of by-products generated from incomplete conversion was investigated. -- Abstract: Photocatalytic oxidation (PCO) is a promising technology that has potential to be applied in mechanically ventilated buildings to improve indoor air quality (IAQ). However, the major research studies were done in bench-top scale reactors under ideal reaction conditions. In addition, no study has been carried out on the investigation of the ozonation and photolysis effect using a pilot duct system. The objective of this study is the development of methodologies to evaluate the performance of PCO systems. A systematic parametric evaluation of the effects of various kinetic parameters, such as compound's type, inlet concentration, airflow rate, light intensity, and relative humidity, was conducted, and new interpretations were provided from a fundamental analysis. In addition, the photolysis effect under vacuum ultraviolet (VUV) irradiation for a variety of volatile organic compounds (VOCs) was examined for the first time in a pilot duct system. The performance comparison of ultraviolet C (UVC)-PCO and VUV-PCO was also discussed due to the presence of ozone. Moreover, the formation of by-products generated with or without ozone generation was fully compared to evaluate the PCO technology.

  6. Performance of ultraviolet photocatalytic oxidation for indoor air applications: Systematic experimental evaluation

    International Nuclear Information System (INIS)

    Zhong, Lexuan; Haghighat, Fariborz; Lee, Chang-Seo; Lakdawala, Ness

    2013-01-01

    Highlights: • An innovative experimental set-up was designed and constructed for testing UV-PCO. • Test methodologies were developed to examine UV-PCO air cleaners for VOCs removal. • VOCs type, inlet concentration, flow rate, irradiance, and RH have influence on PCO. • Gas-phase ozonation with a variety of compounds was examined in a duct system. • Formation of by-products generated from incomplete conversion was investigated. -- Abstract: Photocatalytic oxidation (PCO) is a promising technology that has potential to be applied in mechanically ventilated buildings to improve indoor air quality (IAQ). However, the major research studies were done in bench-top scale reactors under ideal reaction conditions. In addition, no study has been carried out on the investigation of the ozonation and photolysis effect using a pilot duct system. The objective of this study is the development of methodologies to evaluate the performance of PCO systems. A systematic parametric evaluation of the effects of various kinetic parameters, such as compound's type, inlet concentration, airflow rate, light intensity, and relative humidity, was conducted, and new interpretations were provided from a fundamental analysis. In addition, the photolysis effect under vacuum ultraviolet (VUV) irradiation for a variety of volatile organic compounds (VOCs) was examined for the first time in a pilot duct system. The performance comparison of ultraviolet C (UVC)-PCO and VUV-PCO was also discussed due to the presence of ozone. Moreover, the formation of by-products generated with or without ozone generation was fully compared to evaluate the PCO technology

  7. Photocatalytic degradation and photo-Fenton oxidation of Congo red dye pollutants in water using natural chromite—response surface optimization

    Science.gov (United States)

    Shaban, Mohamed; Abukhadra, Mostafa R.; Ibrahim, Suzan S.; Shahien, Mohamed. G.

    2017-12-01

    Refined natural Fe-chromite was characterized by XRD, FT-IR, reflected polarized microscope, XRF and UV spectrophotometer. Photocatalytic degradation and photo-Fenton oxidation of Congo red dye by Fe-chromite was investigated using 1 mL H2O2. The degradation of dye was studied as a function of illumination time, chromite mass, initial dye concentration, and pH. Fe-chromite acts as binary oxide system from chromium oxide and ferrous oxide. Thus, it exhibits photocatalytic properties under UV illumination and photo-Fenton oxidation after addition of H2O2. The degradation in the presence of H2O2 reached the equilibrium stage after 8 h (59.4%) but in the absence of H2O2 continued to 12 h (54.6%). Photocatalytic degradation results fitted well with zero, first order and second order kinetic model but it represented by second order rather than by the other models. While the photo-Fenton oxidation show medium fitting with the second order kinetic model only. The values of kinetic rate constants for the photo-Fenton oxidation were greater than those for the photocatalytic degradation. Thus, degradation of Congo red dye using chromite as catalyst is more efficient by photo-Fenton oxidation. Based on the response surface analysis, the predicted optimal conditions for maximum removal of Congo red dye by photocatalytic degradation (100%) were 12 mg/l, 0.14 g, 3, and 11 h for dye concentration, chromite mass, pH, and illumination time, respectively. Moreover, the optimum condition for photo-Fenton oxidation of dye (100%) is 13.5 mg/l, 0.10 g, 4, and 10 h, respectively.

  8. A three-dimensional BiOBr/RGO heterostructural aerogel with enhanced and selective photocatalytic properties under visible light

    International Nuclear Information System (INIS)

    Yu, Xue; Shi, Junjie; Feng, Lijuan; Li, Chunhu; Wang, Liang

    2017-01-01

    Highlights: • A BiOBr/RGO aerogel photocatalyst was synthesized using dopamine as reducing agent. • BiOBr/RGO aerogel can be easily controlled morphology by a simple two-step method. • BiOBr/RGO aerogel photocatalyst exhibited superior performance in MO decoloration. - Abstract: A series of BiOBr/reduced graphene oxide (RGO) aerogel was fabricated using a two steps hydrothermal method. Various methods such as SEM, TEM, DRS and Raman spectroscopy were employed to fully characterize the as-obtained BiOBr/RGO. Their photocatalytic degradation of methyl orange (MO) were studied under visible light irradiation. The combination of BiOBr and RGO result in an improved activity. The sample with 10 wt% RGO abbreviated as BiOBr-G10 shows the highest activity. Moreover, this sample exhibits a selective visible-light photocatalytic behavior as the degradation rate over MO (80%) is much higher than that over Rhodamin B (50%) and phenol (35%) in 60 min. The XRD and photoluminescence emission spectroscopy characterization of the BiOBr-G10 samples indicates an increased crystallization of BiOBr and efficient quenching of photo-excited electrons and holes contributes to the improved photocatalytic activities.

  9. A three-dimensional BiOBr/RGO heterostructural aerogel with enhanced and selective photocatalytic properties under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xue [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qing dao 266100 (China); Shi, Junjie, E-mail: junjieshiding@gmail.com [Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology, University Bremen, Leobener Str. UFT, 28359 Bremen (Germany); Feng, Lijuan; Li, Chunhu [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qing dao 266100 (China); Wang, Liang, E-mail: wangliangouc@ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qing dao 266100 (China)

    2017-02-28

    Highlights: • A BiOBr/RGO aerogel photocatalyst was synthesized using dopamine as reducing agent. • BiOBr/RGO aerogel can be easily controlled morphology by a simple two-step method. • BiOBr/RGO aerogel photocatalyst exhibited superior performance in MO decoloration. - Abstract: A series of BiOBr/reduced graphene oxide (RGO) aerogel was fabricated using a two steps hydrothermal method. Various methods such as SEM, TEM, DRS and Raman spectroscopy were employed to fully characterize the as-obtained BiOBr/RGO. Their photocatalytic degradation of methyl orange (MO) were studied under visible light irradiation. The combination of BiOBr and RGO result in an improved activity. The sample with 10 wt% RGO abbreviated as BiOBr-G10 shows the highest activity. Moreover, this sample exhibits a selective visible-light photocatalytic behavior as the degradation rate over MO (80%) is much higher than that over Rhodamin B (50%) and phenol (35%) in 60 min. The XRD and photoluminescence emission spectroscopy characterization of the BiOBr-G10 samples indicates an increased crystallization of BiOBr and efficient quenching of photo-excited electrons and holes contributes to the improved photocatalytic activities.

  10. Photocatalytic activity of ferric oxide/titanium dioxide nanocomposite films on stainless steel fabricated by anodization and ion implantation

    Science.gov (United States)

    Zhan, Wei-ting; Ni, Hong-wei; Chen, Rong-sheng; Yue, Gao; Tai, Jun-kai; Wang, Zi-yang

    2013-08-01

    A simple surface treatment was used to develop photocatalytic activity for stainless steel. AISI 304 stainless steel specimens after anodization were implanted by Ti ions at an extracting voltage of 50 kV with an implantation dose of 3 × 1015 atoms·cm-2 and then annealed in air at 450°C for 2 h. The morphology was observed by scanning electron microscopy. The microstructure was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The photocatalytic degradation of methylene blue solution was carried out under ultraviolet light. The corrosion resistance of the stainless steel was evaluated in NaCl solution (3.5 wt%) by electrochemical polarization curves. It is found that the Ti ions depth profile resembles a Gaussian distribution in the implanted layer. The nanostructured Fe2O3/TiO2 composite film exhibits a remarkable enhancement in photocatalytic activity referenced to the mechanically polished specimen and anodized specimen. Meanwhile, the annealed Ti-implanted specimen remains good corrosion resistance.

  11. Enhanced surface area, high Zn interstitial defects and band gap reduction in N-doped ZnO nanosheets coupled with BiVO{sub 4} leads to improved photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sonal [Deen Dayal Upadhyaya College, Dwarka, University of Delhi, New Delhi 110078 (India); Sharma, Rishabh, E-mail: rishabh.rammstien@gmail.com [Thin Film Laboratory, Department of Physics, Indian Institute of Technology, New Delhi 110016 (India); Mehta, Bodh Raj [Thin Film Laboratory, Department of Physics, Indian Institute of Technology, New Delhi 110016 (India)

    2017-07-31

    Highlights: • In this study, we report novel nitrogen doped ZnO (nanosheet)/BiVO{sub 4} nanocomposite with enhanced visible light photocatalytic activity tested on methylene blue dye. • In a typical composite synthesis process, individual metal oxides synthesized by chemical route were mixed through ultrasonication followed by annealing at the temperature of 400 °C. • To understand mechanism of action we carried out XRD, TEM, UV–vis spectroscopy, XPS, BET & PL of the samples. • Enhancement in photocatalytic performance of the composite was due to increased light absorption due to band gap reduction and formation intermediate band. • Also, charge exchange as per Z-scheme at the hetrojunction between N-ZnO and BiVO{sub 4} resulted in reduced charge recombination rate which is further responsible for enhancement in photocatalytic activity. - Abstract: For the first time, a series of Nitrogen-doped-ZnO nanosheet coupled with BiVO{sub 4} (N-ZnO/BiVO{sub 4}) heterojunctioned photocatalysts have been synthesized. The new N-ZnO/BiVO{sub 4} material has been prepared via a simple and effective method of precipitation followed by high temperature annealing process. The photocatalytic activities of the N-ZnO/BiVO{sub 4} composites were evaluated for the degradation of methylene blue (MB) a common organic pollutant under visible-light irradiation. The results revealed that photocatalytic activity of the coupled system was directly influenced by the percentage amount of BiVO{sub 4} in N-ZnO which affected the available exposed surface area for photoreactions. 30% N-ZnO/BiVO{sub 4} system exhibited remarkable performance than 10%N-ZnO/BiVO{sub 4}, 50%N-ZnO/BiVO{sub 4}, and also to their pristine counterparts. The composite demonstrated the degradation efficiency of 90% in 90 min which is 1.76 times the efficiency of pure ZnO for same time duration. This pronounced photocatalytic effect is ascribed to the reduced band gap and lowered recombination rate of ZnO due to

  12. A Hierarchical Z-Scheme α-Fe2 O3 /g-C3 N4 Hybrid for Enhanced Photocatalytic CO2 Reduction.

    Science.gov (United States)

    Jiang, Zhifeng; Wan, Weiming; Li, Huaming; Yuan, Shouqi; Zhao, Huijun; Wong, Po Keung

    2018-03-01

    The challenge in the artificial photosynthesis of fossil resources from CO 2 by utilizing solar energy is to achieve stable photocatalysts with effective CO 2 adsorption capacity and high charge-separation efficiency. A hierarchical direct Z-scheme system consisting of urchin-like hematite and carbon nitride provides an enhanced photocatalytic activity of reduction of CO 2 to CO, yielding a CO evolution rate of 27.2 µmol g -1 h -1 without cocatalyst and sacrifice reagent, which is >2.2 times higher than that produced by g-C 3 N 4 alone (10.3 µmol g -1 h -1 ). The enhanced photocatalytic activity of the Z-scheme hybrid material can be ascribed to its unique characteristics to accelerate the reduction process, including: (i) 3D hierarchical structure of urchin-like hematite and preferable basic sites which promotes the CO 2 adsorption, and (ii) the unique Z-scheme feature efficiently promotes the separation of the electron-hole pairs and enhances the reducibility of electrons in the conduction band of the g-C 3 N 4 . The origin of such an obvious advantage of the hierarchical Z-scheme is not only explained based on the experimental data but also investigated by modeling CO 2 adsorption and CO adsorption on the three different atomic-scale surfaces via density functional theory calculation. The study creates new opportunities for hierarchical hematite and other metal-oxide-based Z-scheme system for solar fuel generation. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Synthesize of Graphene-Tin Oxide Nanocomposite and Its Photocatalytic Properties for the Degradation of Organic Pollutants Under Visible Light.

    Science.gov (United States)

    Shanmugam, M; Jayavel, R

    2015-09-01

    Graphene-tinoxide nanocomposite has been synthesised by coating SnO2 nanoparticles on graphene sheets by the redox reaction between graphene oxide (GO) and tin chloride. Graphene oxide was reduced to graphene and Sn2+ was oxidized to SnO2 during the redox reaction, resulting in the uniform distribution of SnO2 nanoparticles on graphene sheets. The synthesised material was characterized by XRD, SEM, AFM, FT-IR, UV-vis, TGA and Raman spectroscopic studies. SEM and AFM studies reveal the formation of wrinkled paper like structure of graphene sheets with uniform coating of SnO2 nanoparticles on either side. The strong photocatalytic degradation of Methylene orange (MO) dye was analysed using G-SnO2 nanocomposite under the visible light irradiation.

  14. Oxidation reactions catalyzed by cobalt ions in a photocatalytic system based on solutions of lecit hin vesicles

    International Nuclear Information System (INIS)

    Tsvetkov, I.M.; Lymar, S.V.; Parmon, V.N.; Zamaraev, V.I.

    1986-01-01

    The features of the light-induced transfer of electrons through the membranes of lecithin vesicles with an electron carrier, viz., cetyl viologen, incorporated in the lipid bilayer have been studied with the use of the water-soluble trisbipyridyl complex of ruthenium (II) as a photocatalyst. It has been shown that additions of cobalt ions to the systems just indicated are capable of catalyzing the oxidation processes of organic compounds (most probably, of lecithin), the role of the oxidizing agent being played by Ru(bpy) 3 3+ , which forms upon the transfer of an electron to the acceptor Fe(CN) 6 3- through the lipid membrane The possibility of the utilization of the photocatalytic oxidation of water to oxygen under the action of visible light has been discussed

  15. A comprehensive investigation of tetragonal Gd-doped BiVO{sub 4} with enhanced photocatalytic performance under sun-light

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Yangyang; Tan, Guoqiang, E-mail: tan3114@163.com; Dong, Guohua; Ren, Huijun; Xia, Ao

    2016-02-28

    Graphical abstract: - Highlights: • Tetragonal Gd-BiVO{sub 4} with enhanced photocatalytic activity was synthesized. • Gd doping can induce the phase transition from monoclinic to tetragonal BiVO{sub 4}. • GdVO{sub 4} seeds as crystal nucleus dominate the formation of tetragonal Gd-BiVO{sub 4}. • Tetragonal Gd-BiVO{sub 4} exhibits the excellent separation of electrons and holes. • The contribution of high photocatalytic activity under sun-light is from UV-light. - Abstract: Tetragonal Gd-doped BiVO{sub 4} having enhanced photocatalytic activity have been synthesized by a facile microwave hydrothermal method. The structural analysis indicates that Gd doping can induce the phase transition from monoclinic to tetragonal BiVO{sub 4}. The reaction results in precursor solutions imply that tetragonal GdVO{sub 4} seeds as crystal nucleus are the original and determined incentives to force the formation of tetragonal Gd-BiVO{sub 4}. The influences of the surface defect, band structure, and BET surface area on the improved photocatalytic activities of tetragonal Gd-doped BiVO{sub 4} are investigated systematically. The results demonstrate that the more surface oxygen deficiencies as active sites and the excellent mobility and separation of photogenerated electrons and holes are beneficial to the enhancement of the photocatalytic performance of tetragonal Gd-BiVO{sub 4}. The RhB photodegradation experiments indicate that the contribution of high photocatalytic activities under simulated sun-light is mainly from UV-light region due to the tetragonal structure feature. The best photocatalytic performance is obtained for tetragonal 10 at% Gd-BiVO{sub 4}, of which the RhB degradation rate can reach to 96% after 120 min simulated sun-light irradiation. The stable tetragonal Gd-BiVO{sub 4} with efficient mineralization will be a promising photocatalytic material applied in water purification.

  16. Hierarchical Bi{sub 2}WO{sub 6} architectures decorated with Pd nanoparticles for enhanced visible-light-driven photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jinniu; Chen, Tianhua [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710062 (China); Lu, Hongbing, E-mail: hblu@snnu.edu.cn [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710062 (China); Yang, Zhibo; Yin, Feng; Gao, Jianzhi; Liu, Qianru [School of Physics and Information Technology, Shaanxi Normal University, Xi’an, 710062 (China); Tu, Yafang [Department of Physics, Institute for Interdisciplinary Research, Jianghan University, Wuhan, 430056 (China)

    2017-05-15

    Highlights: • A new kind of Pd decorated Bi{sub 2}WO{sub 6} hierarchical microarchitecture was synthesized. • Pd nanoparticles remarkably improved the photocatalytic activity of Bi{sub 2}WO{sub 6}. • The photo-generated holes and ·O{sub 2}{sup −} played a crucial role in the degradation of RhB. • The photocatalytic enhancement mechanism of the Pd-Bi{sub 2}WO{sub 6} composites was proposed. - Abstract: A new kind of hierarchical Pd-Bi{sub 2}WO{sub 6} architecture decorated with different molar ratios of Pd to Bi, has been fabricated by a hydrothermal process, followed by a chemical deposition method. The photocatalytic activities of the pure Bi{sub 2}WO{sub 6} and Pd-Bi{sub 2}WO{sub 6} nanocatalyst were examined in the degradation of Rhodamine B (RhB) dyes and phenol under visible light. The photocatalytic results showed that the Pd-Bi{sub 2}WO{sub 6} nanocomposites possessed observably enhanced photocatalytic activities. Particularly, the 2.0% Pd loaded Bi{sub 2}WO{sub 6} had the highest photocatalytic activity, exhibiting a nearly complete degradation of 30 mg/L RhB and 10 mg/L phenol within only 50 and 60 min, respectively. In addition, the trapping experiment results indicated that the photo-generated holes (h{sup +}) and ·O{sub 2}{sup −} played a crucial role in the degradation of RhB. According to the experimental results, the photocatalytic degradation mechanism of Pd-Bi{sub 2}WO{sub 6} was also proposed. The enhanced photocatalytic activities were ascribed to the combined effects of the highly efficient separation of electrons and holes, improved visible light utilization and increased BET specific surface areas of the Pd-Bi{sub 2}WO{sub 6} nanocomposites.

  17. Preparation of flower-like TiO{sub 2} sphere/reduced graphene oxide composites for photocatalytic degradation of organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Woong [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of); Park, Mira [Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Kim, Hak Yong [Department of BIN Convergence technology, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of)

    2016-07-15

    In this study, novel flower-like TiO{sub 2} sphere (FTS)/reduced graphene oxide (rGO) composites (FTS-G) were synthesized via a hydrothermal method. The photocatalytic performance of the FTS-G composites was evaluated through the photodegradation of rhodamine B (Rh B) and trichloroethylene (TCE) under simulated solar light irradiation. The rGO to FTS ratio in the composites significantly affected photocatalytic activity. The photocatalytic activities of FTS-Gs in the degradation of Rh B and TCE were superior to that of pure FTS. Of all the FTS-G composites tested, FTS-G with 1 wt% rGO (FTS-G-1) had the greatest photocatalytic activity, while FTS-G composites with rGO contents over 1 wt% had lower photocatalytic activities. Additionally, it is expected that the synthesis of FTS with a high specific surface area and well-developed pore structure and simultaneous conversion of GO to graphene-like rGO without the use of strong reducing agents could be a promising strategy to prepare other carbon-based flower-like TiO{sub 2} sphere composite photocatalysts. - Graphical abstract: Schematic illustration of high photocatalytic activity for FTS-G composites. Display Omitted.

  18. Facile synthesis of Ag nanoparticles supported on TiO2 inverse opal with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Zhao Yongxun; Yang Beifang; Xu Jiao; Fu Zhengping; Wu Min; Li Feng

    2012-01-01

    TiO 2 inverse opal films loaded with silver nanoparticles (ATIO) were synthesized on glass substrates. TiO 2 inverse opal (TIO) films were prepared via a sol–gel process using self-assembly of SiO 2 colloidal crystal template and a facile wet chemical route featuring an AgNO 3 precursor solution to fabricate silver nanoparticles on the TIO films. The inverse opal structure and Ag deposition physically and chemically modify titania, respectively. The catalysts were characterized by Raman spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), UV–vis absorption spectra, X-ray photoelectron spectroscopy and photoluminescence spectroscopy. The HRTEM results show that Ag nanoparticles measuring 5–10 nm were evenly distributed on TIO. Both the UV- and visible-light photocatalytic activities of the samples were evaluated by analyzing the degradation of methylene blue (MB) in aqueous solution. The results reveal that the apparent reaction rate constant (k app ) of MB degradation of the sample ATIO under UV-light irradiation is approximately 1.5 times that of the conventional Ag-loaded TiO 2 film (ATF) without an ordered porous structure at an AgNO 3 concentration of 5 mM in the precursor solution. At an AgNO 3 concentration of 10 mM, the sample exhibits a k app value approximately 4.2 times that of ATF under visible-light irradiation. This enhanced visible-light photocatalytic performance can be attributed to the synergistic effect of optimized Ag nanoparticle deposition and an ordered macroporous TIO structure. Repeated cycling tests revealed that the samples showed stable photocatalytic activity, even after six repeated cycles. - Highlights: ►TiO 2 inverse opal films loaded with silver nanoparticles were synthesized. ►Physical and chemical modifications of TiO 2 were achieved simultaneously. ►The catalysts exhibited enhanced visible-light photocatalytic activity. ►The mechanism for enhanced

  19. Enhanced photocatalytic activity of anatase-TiO{sub 2} nanoparticles by fullerene modification: A theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Kezhen [Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang, 110034 (China); Selvaraj, Rengaraj, E-mail: srengaraj1971@yahoo.com [Department of Chemistry, College of Science, Sultan Qaboos University, Muscat (Oman); Al Fahdi, Tharaya; Al-Kindy, Salma [Department of Chemistry, College of Science, Sultan Qaboos University, Muscat (Oman); Kim, Younghun [Department of Chemical Engineering, Kwangwoon University, Seoul 139-701 (Korea, Republic of); Wang, Gui-Chang [Department of Chemistry and the Tianjin Key Lab of Metal and Molecule-based Material Chemistry, Nankai University, Tianjin 300071 (China); Tai, Cheuk-Wai [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm (Sweden); Sillanpää, Mika [Laboratory of Green Chemistry, LUT Savo Sustainable Technologies, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland)

    2016-11-30

    Highlights: • C{sub 60}-modified a-TiO{sub 2} nanocomposites was successfully synthesized by a simple solvothermal method. • The C{sub 60}/a-TiO{sub 2} shows remarkably enhanced organic dyes degradation activity. • C{sub 60} modification enables a-TiO{sub 2} visible light absorption. • The photocatalytic mechanism has been proposed based on DFT calculation and experiments. - Abstract: A series of fullerene (C{sub 60})-modified anatase TiO{sub 2} (a-TiO{sub 2}) nanocomposites with different weight loadings of C{sub 60} were successfully synthesized by a simple solution phase method. The as-prepared C{sub 60}@a-TiO{sub 2} nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET), UV–vis diffuse reflectance absorption spectra (DRS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The photocatalytic degradation of methylene blue (MB) by the neat a-TiO{sub 2} and C{sub 60}@a-TiO{sub 2} nanocomposites was investigated under UV-A light irradiation, demonstrating that C{sub 60} effectively enhances the photocatalytic activity of a-TiO{sub 2} nanoparticles with an optimal amount of 2.0 wt%. By combining with the density functional theory (DFT) calculations, we investigated the electronic structures of C{sub 60}@a-TiO{sub 2} hetero-interfaces to reveal the underlying principle of the C{sub 60} loading on the photocatalytic activity. It was found that the incorporation of C{sub 60} on the a-TiO{sub 2} surface not only narrowed the band gap, but also introduced an additional doping state between the valance and conduction band. Therefore, the presence of intermediate electronic state will in turn contribute to the efficient charge separation and enhanced light adsorption for the C{sub 60}@a-TiO{sub 2} nanocomposites, resulting in an improved photocatalytic performance.

  20. Efficient visible-light photocatalytic