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Sample records for visible light activity

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

    Indian Academy of Sciences (India)

    Mohamed Abdel Salam

    2017-09-25

    Sep 25, 2017 ... Yin D and Zhao F 2015 Visible-light-responsive sulfated vanadium-doped TS-1 with hollow structure: Enhanced photocatalytic activity in selective oxidation of cyclo- hexane J. Catal. 330 208. 11. Kim J, Ichikuni N, Hara T and Shimazu S 2016 Study on the selectivity of propane photo-oxidation reaction on.

  2. Photophysics and light-activated biocidal activity of visible-light-absorbing conjugated oligomers.

    Science.gov (United States)

    Parthasarathy, Anand; Goswami, Subhadip; Corbitt, Thomas S; Ji, Eunkyung; Dascier, Dimitri; Whitten, David G; Schanze, Kirk S

    2013-06-12

    The photophysical properties of three cationic π-conjugated oligomers were correlated with their visible light activated biocidal activity vs S. aureus. The oligomers contain three arylene units (terthiophene, 4a; thiophene-benzotriazole-thiophene, 4b; thiophene-benzothiadiazole-thiophene, 4c) capped on each end by cationic -(CH2)3NMe3(+) groups. The oligomers absorb in the visible region due to their donor-acceptor-donor electronic structure. Oligomers 4a and 4b have high intersystem crossing and singlet oxygen sensitization efficiency, but 4c has a very low intersystem crossing efficiency and it does not sensitize singlet oxygen. The biocidal activity of the oligomers under visible light varies in the order 4a > 4b ≈ 4c.

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

    Indian Academy of Sciences (India)

    SrTiO₃ and Pt/SrTiO₃ nanoparticles were characterized by XRD, XPS, TEM, BET surface area UV–Vis and PL techniques in order to explore their chemical and physical properties. The visible light irradiation photocatalyticperformances of SrTiO₃ nanoparticles and Pt/SrTiO₃ nanoparticles for photocatalytic oxidation of ...

  4. Visible-Light-Activated Bactericidal Functions of Carbon "Quantum" Dots.

    Science.gov (United States)

    Meziani, Mohammed J; Dong, Xiuli; Zhu, Lu; Jones, Les P; LeCroy, Gregory E; Yang, Fan; Wang, Shengyuan; Wang, Ping; Zhao, Yiping; Yang, Liju; Tripp, Ralph A; Sun, Ya-Ping

    2016-05-04

    Carbon dots, generally defined as small carbon nanoparticles with various surface passivation schemes, have emerged as a new class of quantum-dot-like nanomaterials, with their optical properties and photocatalytic functions resembling those typically found in conventional nanoscale semiconductors. In this work, carbon dots were evaluated for their photoinduced bactericidal functions, with the results suggesting that the dots were highly effective in bacteria-killing with visible-light illumination. In fact, the inhibition effect could be observed even simply under ambient room lighting conditions. Mechanistic implications of the results are discussed and so are opportunities in the further development of carbon dots into a new class of effective visible/natural light-responsible bactericidal agents for a variety of bacteria control applications.

  5. Visible Light Activated Photocatalytic Water Polishing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal targets development of a LED light activated photocatalytic water polishing system that enables reduction of organic impurities (TOC and...

  6. Preparation of TiO2-Fullerene Composites and Their Photocatalytic Activity under Visible Light

    Directory of Open Access Journals (Sweden)

    Ken-ichi Katsumata

    2012-01-01

    Full Text Available The development of visible light-sensitive photocatalytic materials is being investigated. In this study, the anatase and rutile-C60 composites were prepared by solution process. The characterization of the samples was conducted by using XRD, UV-vis, FT-IR, Raman, and TEM. The photocatalytic activity of the samples was evaluated by the decolorization of the methylene blue. From the results of the Raman, FT-IR, and XRD, the existence of the C60 was confirmed in the samples. The C60 was modified on the anatase or rutile particle as a cluster. The C60 didn't have the photocatalytic activity under UV and visible light. The anatase and rutile-C60 composites exhibited lower photocatalytic activity than the anatase and rutile under UV light. The anatase-C60 exhibited also lower activity than the anatase under visible light. On the other hand, the rutile-C60 exhibited higher activity than the rutile under visible light. It is considered that the photogenerated electrons can transfer from the C60 to the rutile under visible light irradiation.

  7. Visible-Light Active and Magnetically Recyclable Nanocomposites for the Degradation of Organic Dye

    Directory of Open Access Journals (Sweden)

    Helin Niu

    2014-05-01

    Full Text Available Recyclable visible-light photocatalyst Fe3O4@TiO2 with core-shell structure was prepared by a simple synthetic strategy using solvothermal crystallization of titanium precursor on preformed Fe3O4 nanopartiles. The photo-degradation reaction of neutral red aqueous solution was tested to evaluate the visible-light photocatalytic activity of the as prepared Fe3O4@TiO2 nanoparticles, which show excellent photocatalytic activity compared with commercial P25 catalyst. Moreover, the Fe3O4@TiO2 nanocomposites can be easily separated from the reaction mixture, and maintain favorable photocatalytic activity after five cycles. The high visible light absorption of the Fe3O4@TiO2 nanocomposites may originate from the absence of electronic heterojunction, excellently dispersity and the high specific surface area of the as-synthesized Fe3O4@TiO2 samples.

  8. Inactivation of bacterial biofilms using visible-light-activated unmodified ZnO nanorods

    Science.gov (United States)

    Aponiene, Kristina; Serevičius, Tomas; Luksiene, Zivile; Juršėnas, Saulius

    2017-09-01

    Various zinc oxide (ZnO) nanostructures are widely used for photocatalytic antibacterial applications. Since ZnO possesses a wide bandgap, it is believed that only UV light may efficiently assist bacterial inactivation, and diverse crystal lattice modifications should be applied in order to narrow the bandgap for efficient visible-light absorption. In this work we show that even unmodified ZnO nanorods grown by an aqueous chemical growth technique are found to possess intrinsic defects that can be activated by visible light (λ = 405 nm) and successfully applied for total inactivation of various highly resistant bacterial biofilms rather than more sensitive planktonic bacteria. Time-resolved fluorescence analysis has revealed that visible-light excitation creates long-lived charge carriers (τ > 1 μs), which might be crucial for destructive biochemical reactions achieving significant bacterial biofilm inactivation. ZnO nanorods covered with bacterial biofilms of Enterococcus faecalis MSCL 302 after illumination by visible light (λ = 405 nm) were inactivated by 2 log, and Listeria monocytogenes ATCL3C 7644 and Escherichia coli O157:H7 biofilms by 4 log. Heterogenic waste-water microbial biofilms, consisting of a mixed population of mesophilic bacteria after illumination with visible light were also completely destroyed.

  9. Enhanced visible-light activity of titania via confinement inside carbon nanotubes

    KAUST Repository

    Chen, Wei

    2011-09-28

    Titania confined inside carbon nanotubes (CNTs) was synthesized using a restrained hydrolysis method. Raman spectra and magnetic measurements using a SQUID magnetometer suggested the formation of remarkable oxygen vacancies over the encapsulated TiO 2 in comparison with nanoparticles dispersed on the outer surface of CNTs, extending the photoresponse of TiO 2 from the UV to the visible-light region. The CNT-confined TiO 2 exhibited improved visible-light activity in the degradation of methylene blue (MB) relative to the outside titania and commercial P25, which is attributed to the modification of the electronic structure of TiO 2 induced by the unique confinement inside CNTs. These results provide further insight into the effect of confinement within CNTs, and the composites are expected to be promising for applications in visible-light photocatalysis. © 2011 American Chemical Society.

  10. Visible light induced fast synthesis of protein-polymer conjugates: controllable polymerization and protein activity.

    Science.gov (United States)

    Li, Xin; Wang, Lei; Chen, Gaojian; Haddleton, David M; Chen, Hong

    2014-06-21

    Herein visible light is used to induce RAFT polymerization from protein for preparing protein-polymer conjugates at ambient temperature. Polymerization is fast and can be conveniently controlled with irradiation time. By site-specific polymerization of NIPAm to protein, the protein activity is maintained and in certain cases it presents an efficient on-off-switchable property.

  11. Oxygen deficient ZnO 1-x nanosheets with high visible light photocatalytic activity.

    Science.gov (United States)

    Guo, Hong-Li; Zhu, Qing; Wu, Xi-Lin; Jiang, Yi-Fan; Xie, Xiao; Xu, An-Wu

    2015-04-28

    Zinc oxide is one of the most important wide-band-gap (3.2 eV) materials with versatile properties, however, it can not be excited by visible light. In this work, we have developed an exquisite and simple way to prepare oxygen-deficient ZnO 1-x nanosheets with a gray-colored appearance and excellent visible light photocatalytic activity. Detailed analysis based on UV-Vis absorption spectra, X-band electron paramagnetic resonance (EPR) spectra, and photoluminescence (PL) spectra confirms the existence of oxygen vacancies in ZnO 1-x. The incorporation of oxygen defects could effectively extend the light absorption of ZnO 1-x into the visible-light region due to the fact that the energy of the localized state is located in the forbidden gap. Thus, our obtained ZnO 1-x shows a higher photodegradation of methyl orange (MO) compared to defect-free ZnO under visible light illumination. Additionally, the high content of ˙OH radicals with a strong photo-oxidation capability over the ZnO 1-x nanosheets significantly contributes to the improvement in the photocatalytic performance. Our oxygen deficient ZnO 1-x sample shows a very high photocatalytic activity for the degradation of MO even after 5 cycles without any obvious decline. The results demonstrate that defect engineering is a powerful tool to enhance the optoelectronic and photocatalytic performances of nanomaterials.

  12. Catalyst-free activation of peroxides under visible LED light irradiation through photoexcitation pathway

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yaowen [Department of Environmental Engineering, Wuhan University, Wuhan, 430079 (China); Shenzhen Research Institute of Wuhan University, Shenzhen, 518057 (China); Li, Yixi; Yao, Linyu; Li, Simiao; Liu, Jin [Department of Environmental Engineering, Wuhan University, Wuhan, 430079 (China); Zhang, Hui, E-mail: eeng@whu.edu.cn [Department of Environmental Engineering, Wuhan University, Wuhan, 430079 (China); Shenzhen Research Institute of Wuhan University, Shenzhen, 518057 (China)

    2017-05-05

    Highlights: • Persulfate could decolorize Rhodamine B (RhB) directly via non-radical reactions. • LED lamps emitting white light were utilized as the visible light source. • Dyes could activate peroxides through photoexcitation pathway. • Decolorization of dyes and production of radicals were achieved simultaneously. • The catalyst-free peroxide/dye/Vis process was effective in a broad pH range. - Abstract: Catalysts are known to activate peroxides to generate active radicals (i.e., hydroxyl radical (·OH) and sulfate radical (SO{sub 4}·{sup −})) under certain conditions, but the activation of peroxides in the absence of catalysts under visible light irradiation has been rarely reported. This work demonstrates a catalyst-free activation of peroxides for the generation of ·OH and/or SO{sub 4}·{sup −} through photoexcited electron transfer from organic dyes to peroxides under visible LED light irradiation, where Rhodamine B (RhB) and Eosin Y (EY) were selected as model dyes. The formation of ·OH and/or SO{sub 4}·{sup −} in the reactions and the electron transfer from the excited dyes to peroxides were validated via electron paramagnetic resonance (EPR), photoluminescence (PL) spectra and cyclic voltammetry (CV). The performance of the peroxide/dye/Vis process was demonstrated to be altered depending on the target substrate. Meanwhile, the peroxide/dye/Vis process was effective for simultaneous decolorization of dyes and production of active radicals under neutral even or basic conditions. The findings of this study clarified a novel photoexcitation pathway for catalyst-free activation of peroxides under visible light irradiation, which could avoid the secondary metal ion (dissolved or leached) pollution from the metal-based catalysts and expand the application range of the peroxide-based catalytic process.

  13. A versatile new method for synthesis and deposition of doped, visible light-activated TiO2 thin films

    DEFF Research Database (Denmark)

    In, Su-il; Kean, A.H.; Orlov, A.

    2009-01-01

    A flexible and widely applicable method allows the deposition of carbon-doped visible light-activated photocatalytic TiO2 thin films on a variety of substrates.......A flexible and widely applicable method allows the deposition of carbon-doped visible light-activated photocatalytic TiO2 thin films on a variety of substrates....

  14. Pseudo and true visible light photocatalytic activity of nanotube titanic acid/graphene composites

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaodong, E-mail: donguser@hotmail.com; Liu, Xiaogang; Xue, Xiaoxiao; Pan, Hui; Zhang, Min; Li, Qiuye; Yu, Laigui; Yang, Jianjun; Zhang, Zhijun [Henan University, Key Laboratory of Ministry of Education for Special Functional Materials (China)

    2013-09-15

    Nanotube titanic acid/graphene (NTA/Gr) composites were prepared by an easy hydrothermal treatment of graphene oxide (GO) and NTA in a mixed solvent of ethanol-water. As-prepared NTA/Gr composites and GO were characterized by means of Fourier transform infrared spectrometry, X-ray diffraction, diffuse-reflection spectrometry, thermal analysis, and transmission electron microscopy. Besides, the photocatalytic activities of as-prepared NTA/Gr composites were evaluated by monitoring the degradation of methyl orange (MO) under visible light irradiation. It has been found that extending hydrothermal reaction time (24 h instead of 3 h) leads to great changes in the morphology and crystal structure of as-prepared composites. Namely, the orthorhombic NTA (ca. 10 nm in diameter) in the composite transformed to anatase TiO{sub 2} particle (ca. 20-30 nm in diameter) while the Gr sheets (with micrometers-long wrinkles) in it transformed to a few Gr fragments (ca. 50 nm in diameter). Correspondingly, the NTA/Gr composite transformed to titanium dioxide/graphene (TiO{sub 2}/Gr) composite. In the meantime, pure GO only has adsorption effect but it has no photocatalytic activity in the visible light region. Nevertheless, increasing Gr ratio results in enhanced visible light absorption capability and photocatalytic activity of NTA/Gr composites as well as the TiO{sub 2}/Gr composites. This demonstrates that the true visible light photocatalytic activity of NTA/Gr composites as well as the TiO{sub 2}/Gr composites for the degradation of MO is not as excellent as expected, and their high apparent activity is attributed to the strong adsorption of MO on the composites.

  15. Pseudo and true visible light photocatalytic activity of nanotube titanic acid/graphene composites

    Science.gov (United States)

    Wang, Xiaodong; Liu, Xiaogang; Xue, Xiaoxiao; Pan, Hui; Zhang, Min; Li, Qiuye; Yu, Laigui; Yang, Jianjun; Zhang, Zhijun

    2013-09-01

    Nanotube titanic acid/graphene (NTA/Gr) composites were prepared by an easy hydrothermal treatment of graphene oxide (GO) and NTA in a mixed solvent of ethanol-water. As-prepared NTA/Gr composites and GO were characterized by means of Fourier transform infrared spectrometry, X-ray diffraction, diffuse-reflection spectrometry, thermal analysis, and transmission electron microscopy. Besides, the photocatalytic activities of as-prepared NTA/Gr composites were evaluated by monitoring the degradation of methyl orange (MO) under visible light irradiation. It has been found that extending hydrothermal reaction time (24 h instead of 3 h) leads to great changes in the morphology and crystal structure of as-prepared composites. Namely, the orthorhombic NTA (ca. 10 nm in diameter) in the composite transformed to anatase TiO2 particle (ca. 20-30 nm in diameter) while the Gr sheets (with micrometers-long wrinkles) in it transformed to a few Gr fragments (ca. 50 nm in diameter). Correspondingly, the NTA/Gr composite transformed to titanium dioxide/graphene (TiO2/Gr) composite. In the meantime, pure GO only has adsorption effect but it has no photocatalytic activity in the visible light region. Nevertheless, increasing Gr ratio results in enhanced visible light absorption capability and photocatalytic activity of NTA/Gr composites as well as the TiO2/Gr composites. This demonstrates that the true visible light photocatalytic activity of NTA/Gr composites as well as the TiO2/Gr composites for the degradation of MO is not as excellent as expected, and their high apparent activity is attributed to the strong adsorption of MO on the composites.

  16. A novel sandwich-type polyoxometalate compound with visible-light photocatalytic H2 evolution activity.

    Science.gov (United States)

    Zhang, Zhenyu; Lin, Qipu; Zheng, Shou-Tian; Bu, Xianhui; Feng, Pingyun

    2011-04-07

    A tin(II) tungstosilicate derivative K(11)H[Sn(4)(SiW(9)O(34))(2)]·25H(2)O with four sandwiched Sn(2+) cations was prepared by reaction of SnCl(2), KCl and Na(10)[α-SiW(9)O(34)]·xH(2)O. Visible-light photocatalytic H(2) evolution activity was observed with Pt nanoparticles as co-catalyst and methanol as sacrificial agent.

  17. Spiky TiO2/Au nanorod plasmonic photocatalysts with enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Sun, Hang; Zeng, Shan; He, Qinrong; She, Ping; Xu, Kongliang; Liu, Zhenning

    2017-03-21

    A facile approach for the preparation of spiky TiO2/Au nanorod (NR) plasmonic photocatalysts has been demonstrated, which is through in situ nucleation and growth of spiky TiO2 onto AuNRs. Different aspect ratios of AuNRs in 2.5, 2.7, 4.1 and 4.5 have been applied to prepare spiky TiO2/AuNR nanohybrids to achieve tunable and broad localized surface plasmon resonance (LSPR) bands. All spiky TiO2/AuNR nanohybrids exhibit enhanced light harvesting by extending visible light absorption range by both transverse and longitudinal LSPR bands and decreasing light reflectance by their unique spiky structures. Compared to the bare AuNRs, commercial TiO2 (P25) and spiky TiO2/Au nanosphere photocatalysts, the spiky TiO2/AuNR photocatalysts exhibit significantly enhanced visible light photocatalytic activity in Rhodamine B (RhB) degradation due to their simultaneous enhancement in the light harvesting, charge utilization efficiency, and substrate accessibility. In particular, the spiky TiO2/AuNR-685 photocatalysts show the best photocatalytic activity with ∼98.9% of the RhB degraded within 90 min under the irradiation of 420-780 nm, which could be ascribed to the most extended visible light absorption range and sufficient photon energy of TiO2/AuNR-685 photocatalysts within this irradiation region. The bio-inspired nanostructure, as well as the facile and scalable fabrication approach, will open a new avenue for the rational design and preparation of high-performance photocatalysts for pollutant removal and water splitting.

  18. Increased visible-light photocatalytic activity of TiO2 via band gap manipulation

    Science.gov (United States)

    Pennington, Ashley Marie

    Hydrogen gas is a clean burning fuel that has potential applications in stationary and mobile power generation and energy storage, but is commercially produced from non-renewable fossil natural gas. Using renewable biomass as the hydrocarbon feed instead could provide sustainable and carbon-neutral hydrogen. We focus on photocatalytic oxidation and reforming of methanol over modified titanium dioxide (TiO2) nanoparticles to produce hydrogen gas. Methanol is used as a model for biomass sugars. By using a photocatalyst, we aim to circumvent the high energy cost of carrying out endothermic reactions at commercial scale. TiO2 is a semiconductor metal oxide of particular interest in photocatalysis due to its photoactivity under ultraviolet illumination and its stability under catalytic reaction conditions. However, TiO2 primarily absorbs ultraviolet light, with little absorption of visible light. While an effective band gap for absorbance of photons from visible light is 1.7 eV, TiO2 polymorphs rutile and anatase, have band gaps of 3.03 eV and 3.20 eV respectively, which indicate ultraviolet light. As most of incident solar radiation is visible light, we hypothesize that decreasing the band gap of TiO2 will increase the efficiency of TiO2 as a visible-light active photocatalyst. We propose to modify the band gap of TiO2 by manipulating the catalyst structure and composition via metal nanoparticle deposition and heteroatom doping in order to more efficiently utilize solar radiation. Of the metal-modified Degussa P25 TiO2 samples (P25), the copper and nickel modified samples, 1%Cu/P25 and 1%Ni/P25 yielded the lowest band gap of 3.05 eV each. A difference of 0.22 eV from the unmodified P25. Under visible light illumination 1%Ni/P25 and 1%Pt/P25 had the highest conversion of methanol of 9.9% and 9.6%, respectively.

  19. Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

    Directory of Open Access Journals (Sweden)

    Chun-Hung Huang

    2012-01-01

    Full Text Available A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities of NOx photodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the total NOx removal under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O, which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

  20. Facile synthesis and visible-light photocatalytic activity of bismuth titanate nanorods

    Science.gov (United States)

    Hou, Jungang; Jiao, Shuqiang; Zhu, Hongmin; Kumar, R. V.

    2011-10-01

    Highly crystalline bismuth titanate (Bi12TiO20, BiT) nanorods, as visible-light photocatalysts were prepared by a template-free hydrothermal process. The as-prepared BiT nanorods fabricated in high yields by simply manipulating pH values in the absence of any capping agent, were characterized by a number of techniques, such as XRD, SEM, TEM, HRTEM, BET, and UV-Vis spectrum. In this case, hydroxide ions seem to play a pivotal role in controlling the formation of seeds and the growth of the BiT nanorods. Based on the structural analysis of nanocrystals obtained at different pH values, we proposed a plausible mechanism to account for the formation of the tunable morphologies. Most importantly, the BiT nanorods with good stability exhibited higher photocatalytic activities in the degradation of Rhodamine B under visible light irradiation (λ ≥ 420 nm) than the commercial P25 TiO2 and bulk BiT powders, demonstrating that Bi12TiO20 is a promising candidate as a visible-light photocatalyst.

  1. Visible-light photocatalytic activity of nitrided TiO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Camps, Enrique, E-mail: enrique.camps@inin.gob.mx [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, Mexico DF 11801 (Mexico); Escobar-Alarcon, L. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, Mexico DF 11801 (Mexico); Camacho-Lopez, Marco Antonio [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados, Facultad de Quimica, UAEM, km 14.5 Carretera Toluca-Atlacomulco (Mexico); Casados, Dora A. Solis [Centro de Investigacion en Quimica Sustentable, Facultad de Quimica, UAEM, km 14.5 Carretera Toluca-Atlacomulco (Mexico)

    2010-10-25

    TiO{sub 2} thin films have been applied in UV-light photocatalysis. Nevertheless visible-light photocatalytic activity would make this material more attractive for applications. In this work we present results on the modification of titanium oxide (anatase) sol-gel thin films, via a nitriding process using a microwave plasma source. After the treatment in the nitrogen plasma, the nitrogen content in the TiO{sub 2} films varied in the range from 14 up to 28 at%. The titanium oxide films and the nitrided ones were characterized by XPS, micro-Raman spectroscopy and UV-vis spectroscopy. Photocatalytic activity tests were done using a Methylene Blue dye solution, and as catalyst TiO{sub 2} and nitrided TiO{sub 2} films. The irradiation of films was carried out with a lamp with emission in the visible (without UV). The results showed that the nitrided TiO{sub 2} films had photocatalytic activity, while the unnitrided films did not.

  2. Two dimensional visible-light-active Pt-BiOI photoelectrocatalyst for efficient ethanol oxidation reaction in alkaline media

    Science.gov (United States)

    Zhai, Chunyang; Hu, Jiayue; Sun, Mingjuan; Zhu, Mingshan

    2018-02-01

    Two dimensional (2D) BiOI nanoplates were synthesized and used as support for the deposition of Pt nanoparticles. Owing to broad visible light absorption (up to 660 nm), the as-obtained Pt-BiOI electrode was used as effective photoelectrocatalyst in the application of catalytic ethanol oxidation in alkaline media under visible light irradiation. Compared to dark condition, the Pt-BiOI modified electrode displayed 3 times improved catalytic activity towards ethanol oxidation under visible light irradiation. The synergistic effect of electrocatalytic and photocatalytic, and the unique of 2D structures contribute to the improvement of catalytic activity. The mechanism of enhanced photoelectrocatalytic process is proposed. The present results suggest that 2D visible-light-activated BiOI can be served as promising support for the decoration of Pt and applied in the fields of photoelectrochemical and photo-assisted fuel cell applications

  3. Photolyase activity induction by UVC irradiation and visible light in barley root

    Energy Technology Data Exchange (ETDEWEB)

    Zukas, K.; Ambrozaitis, K. [University of Vilnius, Departement of Botany and Genetics, (Lithuania)

    1997-03-01

    Using Micrococcus luteus UV-endonuclease sensitive sites (EES) photoreactivation test, photolyase (PHL) activity has been detected in barley seedlings but not in extracts from barley roots. This lack of activity was used create a model system for the investigation of PHL activity induction. It was detected that short wave ultraviolet (UVC,{lambda}{sub max} = 254 nm, dose 1 kJ/m{sup 2}) induced PHL activity in roots after 60 min. post-irradiation incubation in a dark. Extract from roots of barley seedlings illuminated with a visible light (10 kJ/m{sup 2}) and maintained in a dark up to 90 min. cause PR of 46.7 % ESS in UV-irradiated DNA from Bacillus subtilis. (authors)

  4. Heterostructures of Ag₃PO₄/TiO₂ mesoporous spheres with highly efficient visible light photocatalytic activity.

    Science.gov (United States)

    Li, Yanjuan; Yu, Liangmin; Li, Nan; Yan, Wenfu; Li, Xiaotian

    2015-07-15

    Heterostructured Ag3PO4/m-TiO2 (mesoporous sphere) visible-light photocatalyst has been synthesized via a facile method. The resultant composite consists of numerous Ag3PO4 nanoparticles with diameter less than 10nm, and these nanoparticles deposit onto the TiO2 nanoparticles surface forming a heterostructure. N2 adsorption-desorption measurements have suggested that the composite was porous with relative high surface area. Studies of the photocatalytic activity and stability of heterostructured Ag3PO4/m-TiO2 for the degradation of methylene blue (MB) have indicated that its visible light photocatalytic performance was improved compared with pure Ag3PO4 and Ag3PO4/m-TiO2, and exhibited excellent photocatalytic stability. The performance was improved attributing to three aspects: (1) the large specific surface area enhanced the adsorption of MB; (2) numerous pores enlarged the contact area between photocatalyst and MB; (3) the most importantly, depositing Ag3PO4 onto the surface of TiO2 facilitated the separation of electron and hole pairs, which also elevates the photocatalytic performance. Furthermore, the photocatalytic mechanism also has been discussed. Compare with Ag3PO4, the Ag weight percent of Ag3PO4/m-TiO2 decreases from 77% to 20.8%, significantly reducing the cost of photocatalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Hydrothermal Synthesis of Nitrogen-Doped Titanium Dioxide and Evaluation of Its Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Junjie Qian

    2012-01-01

    Full Text Available Nitrogen-doped titanium dioxide (N-doped TiO2 photocatalyst was synthesized from nanotube titanic acid (denoted as NTA; molecular formula H2Ti2O5·H2O precursor via a hydrothermal route in ammonia solution. As-synthesized N-doped TiO2 catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffuse reflectance spectrometry, X-ray photoelectron spectroscopy, electron spin resonance spectrometry and Fourier transform infrared spectrometry. It was found that nanotube ammonium titanate (NAT was produced as an intermediate during the preparation of N-doped TiO2 from NTA, as evidenced by the N1s X-ray photoelectron spectroscopic peak of NH4 + at 401.7 eV. The catalyst showed much higher activities to the degradation of methylene blue and p-chlorophenol under visible light irradiation than Degussa P25. This could be attributed to the enhanced absorption of N-doped TiO2 in visible light region associated with the formation of single-electron-trapped oxygen vacancies and the inhibition of recombination of photo-generated electron-hole pair by doped nitrogen.

  6. The Simplest Way to Iodine-Doped Anatase for Photocatalysts Activated by Visible Light

    Directory of Open Access Journals (Sweden)

    Václav Štengl

    2011-01-01

    Full Text Available Iodine-doped TiO2 was prepared by thermal hydrolysis of aqueous solutions of the titanium peroxo-complex, which includes no organic solvents or organometallic compounds. The synthesized samples were characterized by X-ray diffraction (XRD, Raman spectroscopy (RS, infrared spectroscopy (IR, specific surface area (BET, and porosity determination (BJH. The morphology and particle size was determined by high-resolution transmission electron microscopy (HRTEM and selected area electron diffraction (SAED. All prepared samples have a red-shifted band-gap transition, well crystalline anatase structure, and porous particles with a 100–200 m2 g−1 specific surface area. The photocatalytic activity of iodine-doped titania samples was determined by decomposition of Orange II dye during irradiation at 365 nm and 400 nm. Iodine doping promotes the titania photocatalytic activity very efficiently under visible light irradiation. The titania sample with 0.32 wt.% I has the highest catalytic activity during the photocatalyzed degradation of Orange II dye in an aqueous suspension in the UV and visible regions.

  7. Simple fabrication of BiOCl/Bi/P25 composite with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Xu, Yuxian; Luo, Yongjin; Qian, Qingrong; Huang, Baoquan; Chen, Qinghua

    2017-10-01

    Visible-light-induced BiOCl/Bi/P25 composite materials were prepared via a hydrothermal method, and evaluated by degradation of methyl orange (MO) aqueous solution. It exhibits the highest photocatalytic efficiency, which is 53.6 and 23.9 times higher than that of Bi/BiOCl and P25, respectively. The superior activity is attributed to the surface plasmon resonance (SPR) of metallic Bi, and the efficient separation of the photogenerated carriers with the aid of BiOCl/P25 heterostructure. In the photodegradation process, holes (hvb+) can react with Cl- ions to form Clrad radicals, both of which can oxidize MO. Then Clrad radicals reduce to Cl- again, forming a circulation and improving the photocatalytic activity.

  8. Homogeneously embedded Pt nanoclusters on amorphous titania matrix as highly efficient visible light active photocatalyst material

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Vipul; Kumar, Suneel; Krishnan, Venkata, E-mail: vkn@iitmandi.ac.in

    2016-08-15

    A novel and facile technique, based on colloidal synthesis route, has been utilized for the preparation of homogeneously embedded Pt nanoclusters on amorphous titania matrix. The material has been thoroughly characterized using high resolution transmission electron microscopy, energy dispersive x-ray analysis, powder x-ray diffraction, optical and Raman spectroscopic techniques to understand the morphology, structure and other physical characteristics. The photocatalytic activity of the material under visible light irradiation was demonstrated by investigations on the degradation of two organic dyes (methylene blue and rhodamine B). In comparison to other Pt−TiO{sub 2} based nanomaterials (core-shell, doped nanostructures, modified nanotubes, decorated nanospheres and binary nanocomposites), the embedded Pt nanoclusters on titania was found to be highly efficient for visible light active photocatalytic applications. The enhanced catalytic performance could be attributed to the efficient charge separation and decreased recombination of the photo generated electrons and holes at the Pt-titania interface and the availability of multiple metal-metal oxide interfaces due to homogeneous embedment of Pt nanoclusters on amorphous titania. In essence, this work illustrates that homogeneous embedment of noble metal nanoparticles/nanoclusters on semiconductor metal oxide matrices can lead to tuning of the photophysical properties of the final material and eventually enhance its photocatalytic activity. - Highlights: • Homogeneously embedded Pt nanoclusters on amorphous titania matrix has been prepared. • Facile low temperature colloidal synthesis technique has been used. • Enhanced catalytic performance could be observed. • Work can pave way for tuning photocatalytic activity of composite materials.

  9. Preparation of Fe-Doped TiO2 Nanotubes and Their Photocatalytic Activities under Visible Light

    Directory of Open Access Journals (Sweden)

    Honghui Teng

    2013-01-01

    Full Text Available Fe-doped TiO2 nanotubes (Fe-TNTs have been prepared by ultrasonic-assisted hydrothermal method. The structure and composition of the as-prepared TiO2 nanotubes were characterized by transmission electron microscopy, X-ray diffraction, and UV-Visible absorption spectroscopy. Their photocatalytic activities were evaluated by the degradation of MO under visible light. The UV-visible absorption spectra of the Fe-TNT showed a red shift and an enhancement of the absorption in the visible region compared to the pure TNT. The Fe-TNTs were provided with good photocatalytic activities and photostability and under visible light irradiation, and the optimum molar ratio of Ti : Fe was found to be 100 : 1 in our experiments.

  10. 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

  11. Synthesis of visible light active Gd3+-substituted ZnFe2O4 nanoparticles for photocatalytic and antibacterial activities

    Science.gov (United States)

    Patil, S. B.; Bhojya Naik, H. S.; Nagaraju, G.; Viswanath, R.; Rashmi, S. K.

    2017-08-01

    In the present analysis, we study the assembly of a low-cost and visible light active ZnFe2-xGdxO4 ( x = 0 , 0.3, 0.5 and 0.7) nanoparticles (NPs) photocatalyst. The synthesized samples were characterized by several physicochemical techniques, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Visible absorption spectroscopy (UV-Vis), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The phase transition from cubic to orthorhombic was confirmed by XRD patterns. The increase in the concentration of Gd3+ substitution in ZnFe2O4 NPs enhances the redshift of absorption in the visible region of UV-Vis absorption spectra and reduces the band gap. In the photo-Fenton-type reaction, the gadolinium-substituted zinc ferrite (ZGF) NPs exhibit a significant catalytic activity for the degradation of methylene blue (99% in 90 minutes) under visible light (500W xenon lamp) with respect to bare samples (95% in 240 minutes) and they also show an excellent reusability nature. These materials were also screened for antibacterial activity against Gram-negative bacteria strains ( Pseudomonas aeruginosa and Escherichia coli).

  12. Bismuth titanate microspheres: Directed synthesis and their visible light photocatalytic activity

    Science.gov (United States)

    Lin, Xue; Lv, Peng; Guan, Qingfeng; Li, Haibo; Zhai, Hongjv; Liu, Chunbo

    2012-07-01

    Bismuth titanate, Bi4Ti3O12 (BIT), with a well-defined spherical structure, was synthesized by a facile hydrothermal process without using any surfactant or template. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) showed that BIT spheres could be fabricated in high yields by simply manipulating the concentrations of hydroxide ions. In this case, hydroxide ions seem to play a key role in controlling the formation of seeds and growth rates of BIT particles. Ultraviolet-visible (UV-vis) absorption spectra demonstrated that the band gap of BIT samples was about 2.79 eV. In addition, based on the structural analysis of samples obtained at different conditions, a possible mechanism for the formation of these distinctive morphologies was proposed. The as-prepared BIT microspheres exhibited higher photocatalytic activities in the degradation of methyl orange (MO) under visible light irradiation than that of N-TiO2. Furthermore, BIT microspheres which prepared at OH- concentration of 3 mol L-1 showed the highest photocatalytic activity.

  13. Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

    Science.gov (United States)

    Ratova, Marina; Kelly, Peter J.; West, Glen T.; Tosheva, Lubomira; Edge, Michele

    2017-01-01

    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 CO2 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 TiO2 nanoparticles was enhanced by compounding it with bismuth tungstate was studied by microwave cavity perturbation. The results of these tests confirmed that such enhancement of the photocatalytic properties is due to more efficient photogenerated charge carrier separation, as well as to the contribution of the intrinsic photocatalytic properties of Bi2WO6.

  14. Enhanced Visible Light Photocatalytic Activity for TiO2 Nanotube Array Films by Codoping with Tungsten and Nitrogen

    Directory of Open Access Journals (Sweden)

    Min Zhang

    2013-01-01

    Full Text Available A series of W, N codoped TiO2 nanotube arrays with different dopant contents were fabricated by anodizing in association with hydrothermal treatment. The samples were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet-visible light diffuse reflection spectroscopy. Moreover, the photocatalytic activity of W and N codoped TiO2 nanotube arrays was evaluated by degradation of methylene blue under visible light irradiation. It was found that N in codoped TNAs exists in the forms of Ti-N-O, while W exists as W6+ by substituting Ti in the lattice of TiO2. In the meantime, W and N codoping successfully extends the absorption of TNAs into the whole visible light region and results in remarkably enhanced photocatalytic activity under visible light irradiation. The mechanism of the enhanced photocatalytic activity could be attributed to (i increasing number of hydroxyl groups on the surface of TNAs after the hydrothermal treatment, (ii a strong W-N synergistic interaction leads to produce new states, narrow the band gap which decrease the recombination effectively, and then greatly increase the visible light absorption and photocatalytic activity; (iii W ions with changing valences in all codoped samples which are considered to act as trapping sites, effectively decrease the recombination rate of electrons and holes, and improve the photocatalytic activity.

  15. An efficient visible-light photocatalyst prepared by modifying AgBr particles with a small amount of activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Desong, E-mail: dswang06@126.com; Zhao, Mangmang; Luo, Qingzhi; Yin, Rong; An, Jing; Li, Xueyan

    2016-04-15

    Highlights: • An efficient visible-light photocatalyst was prepared by modifying AgBr particles. • A small amount of activated carbon was used to modify AgBr particles. • The modified AgBr exhibited improved visible-light photocatalytic performances. - Abstract: An efficient visible-light photocatalyst was successfully prepared by modifying AgBr particles with a small amount of activated carbon (AC) via a simple chemical precipitation approach. The AC/AgBr composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis diffuse reflection spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy. The photocatalytic performances of the AC/AgBr composite were investigated by evaluating photodegradation of methyl orange (MO) and phenol under visible light irradiation, and the effects of the AC content in the composite, concentrations of AC/AgBr composite and MO, carrier scavengers on MO photodegradation rate were systematically investigated. The results indicated that the modification of AC can hardly change the crystalline and crystal size of AgBr particles, while significantly improve their specific surface areas, visible-light absorption and separation efficiency of photogenerated electron–hole pairs. Compared with pure AgBr, the AC/AgBr composite exhibited drastically enhanced visible-light photocatalytic activity and stability. The photogenerated electrons and holes, hydroxyl radicals are responsible to the photodegradation of organic pollutants, and the photogenerated holes are the main active species. On the basis of the results and the properties of AC and AgBr, the visible-light photocatalytic mechanism of the AC/AgBr composite was discussed.

  16. Double-doped TiO{sub 2} nanoparticles as an efficient visible-light-active photocatalyst and antibacterial agent under solar simulated light

    Energy Technology Data Exchange (ETDEWEB)

    Ashkarran, Ali Akbar, E-mail: ashkarran@umz.ac.ir [Department of Physics, Faculty of Basic Sciences, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Hamidinezhad, Habib [Nano and Biotechnology Research Group, Faculty of Basic Sciences, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Haddadi, Hedayat [Department of Chemistry, Faculty of Sciences, Shahrekord University, P.O. Box 115, Shahrekord (Iran, Islamic Republic of); Mahmoudi, Morteza [Department of Nanotechnology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Nanotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2014-05-01

    Graphical abstract: Double doping introduces two different electronic states in the band gap of TiO{sub 2}, which increase the lifetime of the charge carriers and leads to narrower band gap and enhancement of the visible-light absorption. - Highlights: • Preparation of single and double doped TiO{sub 2} NPs using a simple sol–gel route. • Extension of light absorption spectrum toward the visible region. • Enhanced visible-light photo-induced activity and antibacterial property in double doped TiO{sub 2} NPs. - Abstract: Silver and nitrogen doped TiO{sub 2} nanoparticles (NPs) were synthesized via sol–gel method. The physicochemical properties of the achieved NPs were characterized by various methods including X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultra violet–visible absorption spectroscopy (UV–vis). Both visible-light photocatalytic activity and antimicrobial properties were successfully demonstrated for the degradation of Rhodamine B (Rh. B.), as a model dye, and inactivation of Escherichia coli (E. coli), as a representative of microorganisms. The concentration of the employed dopant was optimized and the results revealed that the silver and nitrogen doped TiO{sub 2} NPs extended the light absorption spectrum toward the visible region and significantly enhanced the photodegradation of model dye and inactivation of bacteria under visible-light irradiation while double-doped TiO{sub 2} NPs exhibited highest photocatalytic and antibacterial activity compared with single doping. The significant enhancement in the photocatalytic activity and antibacterial properties of the double doped TiO{sub 2} NPs, under visible-light irradiation, can be attributed to the generation of two different electronic states acting as electron traps in TiO{sub 2} and responsible for narrowing the band gap of TiO{sub 2} and shifting its optical response from UV to the

  17. Visible light photocatalytic activity induced by Rh(III) modification on the surface of BiOCl

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jinli; Wu, Xin; Huang, Caijin, E-mail: cjhuang@fzu.edu.cn; Fan, Wenjie; Qiu, Xiaoqing, E-mail: qiuxq@fzu.edu.cn

    2016-11-30

    Highlights: • Rh(III) clusters were deposited on the BiOCl microflowers as an efficient modifier. • The Rh(III)-BiOCl samples show an enhanced visible-light photocatalytic activity. • The Rh(III) clusters server as the redox reaction centers for the multi-electron reduction of O{sub 2}. - Abstract: Using impregnation technique, a small amount of Rh(III) clusters has been grafted on the BiOCl microflowers. The samples are characterized by X-ray diffraction, scanning electron microscopy coupled with high energy distribution X-ray, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activities are investigated by the decomposition of gaseous acetaldehyde under irradiation of visible light. The bare BiOCl microflowers exhibit the limited visible light photocatalytic activity because of its wide band gap. After surface modification of Rh(III) clusters, the Rh(III)-BiOCl samples show an enhanced photocatalytic activity for the decomposition gaseous acetaldehyde under visible light irradiation. It is found that the Rh(III) clusters play an important role for the visible light absorption, probably through the electron transfer between Rh(III) clusters and the BiOCl, as well as the redox reaction centers for the multi-electron reduction of O{sub 2}.

  18. Synthesis of Phase Pure Hexagonal YFeO3 Perovskite as Efficient Visible Light Active Photocatalyst

    Directory of Open Access Journals (Sweden)

    Mohammed Ismael

    2017-11-01

    Full Text Available Hexagonal perovskite YFeO3 was synthesized by a complex-assisted sol-gel technique allowing crystallization at calcination temperatures below 700 °C. As determined by diffuse reflectance spectroscopy (DRS and Tauc plots, the hexagonal YFeO3 exhibits a lower optical band gap (1.81 eV than the orthorhombic structure (about 2.1 eV or even higher being typically obtained at elevated temperatures (>700 °C, and thus enables higher visible light photocatalysis activity. Structure and morphology of the synthesized YFeO3 perovskites were analyzed by powder X-ray diffraction (XRD and nitrogen adsorption, proving that significantly smaller crystallite sizes and higher surface areas are obtained for YFeO3 with a hexagonal phase. The photocatalytic activity of the different YFeO3 phases was deduced via the degradation of the model pollutants methyl orange and 4-chlorophenol. Experiments under illumination with light of different wavelengths, in the presence of different trapping elements, as well as photoelectrochemical tests allow conclusions regarding band positions of YFeO3 and the photocatalytic degradation mechanism. X-ray photoelectron spectroscopy indicates that a very thin layer of Y2O3 might support the photocatalysis by improving the separation of photogenerated charge carriers.

  19. The behavior of active bactericidal and antifungal coating under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Gang; Zhang, Xiaodong; Zhao, Yan; Su, Haijia, E-mail: suhj@mail.buct.edu.cn; Tan, Tianwei

    2014-02-15

    In the present paper, the novel active bactericidal and antifungal coatings (ABAC) have been prepared through the immobilization of Fe-doped TiO{sub 2} (anatase) with chitosan. The characterization of ABAC using optical microscope imaging, SEM, AFM and FTIR shows that the Fe doped TiO{sub 2} is embedded into the chitosan coating with favorable dispersion through the hydrogen bonds interaction between chitosan molecules and TiO{sub 2}. The contact angle measurement demonstrated the hydrophilicity of ABAC (θ = 34.5 ± 4.1°). The bactericidal activity of ABAC has been evaluated by inactivating three different test strains: Escherichia coli, Candida albicans and Aspergillus niger which illustrates the apparently higher bactericidal ability than chitosan, Fe-TiO{sub 2} and chitosan/TiO{sub 2} (pure) under visible light irradiation and its bactericidal activity is lasting for at least 24 h. ABAC showed rapid and efficient antibacterial ability for the three tested strains and its antibacterial ratio in 2 h for E. coli, C. albicans and A. niger was 99.9%, 97.0% and 95.0%, respectively. The prepared chitosan/TiO{sub 2} composite emulsion shows favorable storage stability and can be stored up to 1 year without losing its bactericidal activity. ABAC is a low-cost and eco-friendly antibacterial coating products and promising for domestic, medical and industrial applications.

  20. Full Spectrum Visible LED Light Activated Antibacterial System Realized by Optimized Cu2O Crystals.

    Science.gov (United States)

    Shi, Xiaotong; Xue, Chaowen; Fang, Fang; Song, Xiangwei; Yu, Fen; Liu, Miaoxing; Wei, Zhipeng; Fang, Xuan; Zhao, Dongxu; Xin, Hongbo; Wang, Xiaolei

    2016-04-06

    Assisted by three-dimensional printing technology, we proposed and demonstrated a full spectrum visible light activated antibacterial system by using a combination of 500 nm sized Cu2O crystals and light-emitting diode (LED) lamps. Further improved antibacterial ratios were achieved, for the first time, with pure Cu2O for both Gram-positive bacteria and Gram-negative bacteria among all of the six different color LED lamps. For practical antibacterial applications, we revealed that the nonwoven fabric could act as excellent carrier for Cu2O crystals and provide impressive antibacterial performance. Furthermore, integrated with our self-developed app, the poly(ethylene terephthalate) film loaded with Cu2O crystals also showed significant antibacterial property, thus making it possible to be applied in field of touch screen. The present research not only provided a healthier alternative to traditional ultraviolet-based sterilization but also opened an auto-response manner to decrease the rate of microbial contamination on billions of touch screen devices.

  1. Structural analysis and visible light-activated photocatalytic activity of iron-containing soda lime aluminosilicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Yusuke; Akiyama, Kazuhiko [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachi-Oji, Tokyo 192-0397 (Japan); Kobzi, Balázs; Sinkó, Katalin; Homonnay, Zoltán [Institute of Chemistry, Eötvös Loránd University, Pázmany P. s., 1/A, Budapest 1117 (Hungary); Kuzmann, Ernő [Institute of Chemistry, Eötvös Loránd University, Pázmany P. s., 1/A, Budapest 1117 (Hungary); Laboratory of Nuclear Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Budapest 1512 (Hungary); Ristić, Mira; Krehula, Stjepko [Division of Materials Chemistry, RuđerBošković Institute, Bijenička cesta 54, Zagreb 10000 (Croatia); Nishida, Tetsuaki [Department of Biological and Environmental Chemistry, Faculty of Humanity-Oriented Science and Engineering, Kinki University, 11-6 Kayanomori, Iizuka, Fukuoka 820-8555 (Japan); Kubuki, Shiro, E-mail: kubuki@tmu.ac.jp [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachi-Oji, Tokyo 192-0397 (Japan)

    2015-10-05

    Highlights: • Hematite was precipitated by heat treatment of iron aluminosilicate glass. • The hematite phase shows visible light photocatalytic activity. • We could prepare an effective photocatalyst from ‘ubiquitous elements’. - Abstract: A relationship between structure and visible light-activated photocatalytic activity of iron-containing soda lime aluminosilicate (15Na{sub 2}O⋅15CaO⋅40Fe{sub 2}O{sub 3}⋅xAl{sub 2}O{sub 3}⋅(30−x)SiO{sub 2}) glass (xNCFAS) was investigated by means of {sup 57}Fe-Mössbauer spectroscopy, X-ray diffractometry (XRD) and UV–visible light absorption spectroscopy (UV–VIS). The {sup 57}Fe-Mössbauer spectrum of 11NCFAS glass measured after heat-treatment at 1000 °C for 100 min was composed of a paramagnetic doublet due to Fe{sup III}(T{sub d}) and two magnetic sextets due to regular hematite (α-Fe{sub 2}O{sub 3}) and hematite with larger internal magnetic field. X-ray diffraction patterns of heat-treated xNCFAS samples resulted in decrease of α-Fe{sub 2}O{sub 3} and increase of Ca{sub 2}Fe{sub 22}O{sub 33} or CaFe{sub 2}O{sub 4} with alumina content. A quick decrease in methylene blue (MB) concentration from 15.6 to 4.7 μmol L{sup −1} was observed in the photocatalytic reaction test with 40 mg of heat-treated 11NCFAS glass under visible light-exposure. The largest first-order rate constant of MB decomposition (k) was estimated to be 9.26 × 10{sup −3} min{sup −1}. Tauc’s plot yielded a band gap energy (E{sub g}) of 1.88 eV for heat-treated 11NCFAS glass, which is smaller than previously reported E{sub g} of 2.2 eV for α-Fe{sub 2}O{sub 3}. These results prove that addition of Al{sub 2}O{sub 3} into iron-containing soda lime silicate glass is favorable for the preparation of improved visible light-photocatalyst with ‘ubiquitous’ elements.

  2. Role of visible light-activated photocatalyst on the reduction of anthrax spore-induced mortality in mice.

    Directory of Open Access Journals (Sweden)

    Jyh-Hwa Kau

    Full Text Available BACKGROUND: Photocatalysis of titanium dioxide (TiO(2 substrates is primarily induced by ultraviolet light irradiation. Anion-doped TiO(2 substrates were shown to exhibit photocatalytic activities under visible-light illumination, relative environmentally-friendly materials. Their anti-spore activity against Bacillus anthracis, however, remains to be investigated. We evaluated these visible-light activated photocatalysts on the reduction of anthrax spore-induced pathogenesis. METHODOLOGY/PRINCIPAL FINDINGS: Standard plating method was used to determine the inactivation of anthrax spore by visible light-induced photocatalysis. Mouse models were further employed to investigate the suppressive effects of the photocatalysis on anthrax toxin- and spore-mediated mortality. We found that anti-spore activities of visible light illuminated nitrogen- or carbon-doped titania thin films significantly reduced viability of anthrax spores. Even though the spore-killing efficiency is only approximately 25%, our data indicate that spores from photocatalyzed groups but not untreated groups have a less survival rate after macrophage clearance. In addition, the photocatalysis could directly inactivate lethal toxin, the major virulence factor of B. anthracis. In agreement with these results, we found that the photocatalyzed spores have tenfold less potency to induce mortality in mice. These data suggest that the photocatalysis might injury the spores through inactivating spore components. CONCLUSION/SIGNIFICANCE: Photocatalysis induced injuries of the spores might be more important than direct killing of spores to reduce pathogenicity in the host.

  3. Open porous BiVO{sub 4} nanomaterials: Electronspinning fabrication and enhanced visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Mengyan; Xi, Xin [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); Gong, Cairong, E-mail: gcr@tju.edu.cn [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); Zhang, Xiao Li, E-mail: xiaolizhang.z@gmail.com [ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Engineering, The University of New South Wales, Kensington, Sydney 2052 (Australia); Fan, Guoliang [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China)

    2016-02-15

    Highlights: • BiVO{sub 4} nanofibers were successfully fabricated by electrospinning method. • PVP was used to adjust the viscosity and increase spinnability of the electrospinning sol. • BiVO{sub 4} nanofibers were used for the degradation of MB. • Compared to the submicron sized BiVO4, BiVO{sub 4} nanofibers show superior photocatalytic activity. - Abstract: Witnessed by X-ray powder diffraction (XRD), Raman, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies, BiVO{sub 4} nanofibers and porous nanostructures were successfully fabricated by electrospinning method using NH{sub 4}VO{sub 3} and Bi(NO{sub 3}){sub 3} as starting materials. Polyvinylpyrrolidinone (PVP) was used to tune the viscosity and spinnability of the electrospinning sol. The slow decomposition and combustion of PVP matrix prevented rapid crystal growth of BiVO{sub 4} nanostructures leading to considerably small crystallite size (approximately 19.1–28.3 nm) with less surface defects after two hours calcination at varying temperatures. This paid great tributes to the superior visible light photocatalytic activity when compared to the submicron sized BiVO{sub 4} prepared in the absence of PVP.

  4. I-TiO2/PVC film with highly photocatalytic antibacterial activity under visible light.

    Science.gov (United States)

    Deng, Weihua; Ning, Shangbo; Lin, Qianying; Zhang, Hualei; Zhou, Tanghua; Lin, Huaxiang; Long, Jinlin; Lin, Qun; Wang, Xuxu

    2016-08-01

    Iodine-modified TiO2(I-TiO2) film were coated on medical-grade PVC material by impregnation-deposition method and subsequently characterized by XRD, SEM, TEM, AFM, DRS and XPS. The photocatalytic anti-bacterial activity of I-TiO2/PVC was investigated both by in vitro anti-bacterial experiments and by clinical study. The results revealed that I-TiO2/PVC exhibit excellent photocatalytic antibacterial activity, which can destroy the propagation of the Escherichia coli and cause the deactivation and death of most E. coli bacteria within 30min visible light illumination. Clinical study on animals showed that I-TiO2 coated on PVC decrease the formation of biofilm on PVC surface in the mechanical ventilation. Furthermore, I-TiO2/PVC can effectively reduce inflammation of tracheal tissue of bam suckling pig and prevents the occurrence of VAP. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Origin of Visible Light Photocatalytic Activity of Ag3AsO4 from First-Principles Calculation

    OpenAIRE

    Yan Gong; Hongtao Yu; Xie Quan

    2014-01-01

    Recently a novel sliver oxide Ag3AsO4 has been found to be an excellent photocatalyst with strong oxidation capability for pollutant degradation under visible light. But the origin of its high visible light photocatalytic activity was unclear which hindered further research of Ag3AsO4. For clarifying that, the electronic structure and optical properties of Ag3AsO4 have been analyzed by the hybrid density functional method. The results reveal that the Ag3AsO4 presents a narrow band gap with st...

  6. Photoreduction preparation of Cu2O@polydopamine nanospheres with enhanced photocatalytic activity under visible light irradiation

    Science.gov (United States)

    Zhou, Xiaosong; Jin, Bei; Luo, Jin; Gu, Xingxing; Zhang, Shanqing

    2017-10-01

    Cuprous oxide (Cu2O) suffers from severe electron-hole pairs recombination, instability and low photocatalytic degradation efficiency, though it has been considered as an excellent visible light photocatalyst. The incorporation of the Cu2O with other photocatalysts can address these problems. Herein, unique Cu2O@ polydopamine (PDA) nanospheres are prepared by a simple photo-reduction approach. Due to the synergistic effects of the Cu2O and PDA semiconductors, the Cu2O@PDA nanospheres composite possesses enhanced photocatalytic activity and extended life time for the degradation of the methyl orange under visible light irradiation.

  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. Silver halide/silver iodide@silver composite with excellent visible light photocatalytic activity for methyl orange degradation.

    Science.gov (United States)

    Zeng, Cuiyun; Tian, Baozhu; Zhang, Jinlong

    2013-09-01

    AgBr/AgI@Ag composite photocatalyst was prepared by a handy multistep route, including controllable double-jet precipitation to synthesize cubic AgBr microcrystals, ion exchange to form AgI on AgBr surface, and visible light reduction to generate Ag nanoparticles. UV-Vis diffuse reflectance and electrochemical impedance spectra demonstrated that AgBr/AgI composite structure not only favors forming more silver nanoparticles to harvest visible light but also facilitates the transfer of charge carriers when compared with pure AgBr. Beneficial from the synergistic effect of highly effective visible light harvest and electron-hole separation, AgBr/AgI@Ag shows higher photocatalytic activity for the degradation of methyl orange (MO) than AgBr, AgBr@Ag, and AgBr/AgBr. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Photocatalytic Oxidation of Gaseous Isopropanol Using Visible-Light Active Silver Vanadates/SBA-15 Composite

    Directory of Open Access Journals (Sweden)

    Ting-Chung Pan

    2012-01-01

    Full Text Available An environmentally friendly visible-light-driven photocatalyst, silver vanadates/SBA-15, was prepared through an incipient wetness impregnation procedure with silver vanadates (SVO synthesized under a hydrothermal condition without a high-temperature calcination. The addition of mesoporous SBA-15 improves the formation of nanocrystalline silver vanadates. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS confirms the presence of Brønsted and Lewis acids on the SVO/SBA-15 composites. The results of photoluminescence spectra indicated that the electron-hole recombination rate have been effectively inhibited when SVO was loaded with mesoporous SBA-15. All the composites loaded with various amount of SVO inherit the higher adsorption capacity and larger mineralization yield than those of P-25 (commercial TiO2 and pure SVO. The sample loaded with 51% of SVO (51SVO/SBA-15 with mixed phases of Ag4V2O7 and α-Ag3VO4 exhibits the best photocatalytic activity. A favorable crystalline phase combined with high intensities of Brønsted and Lewis acids is considered the main cause of the enhanced adsorption capacity and outstanding photoactivity of the SVO/SBA-15 composites.

  10. Bismuth titanate pyrochlore microspheres: Directed synthesis and their visible light photocatalytic activity

    Science.gov (United States)

    Hou, Jungang; Jiao, Shuqiang; Zhu, Hongmin; Kumar, R. V.

    2011-01-01

    Bismuth titanates, Bi 2Ti 2O 7 (BIT), with well-defined spherical structures were synthesized by a facile hydrothermal process without the use of any surfactant or template. XRD and SEM studies have shown that spheres could be fabricated in high yields by simply manipulating the concentrations of hydroxide ions. In this case, hydroxide ions seem to play a pivotal role in controlling the formation of seeds and growth rates of the BIT particles. On the basis of structural analysis of samples obtained at different concentrations of OH -, we also proposed a plausible mechanism to account for the formation of these distinctive morphologies under different conditions. The as-prepared BIT microspheres with good stability exhibited higher photocatalytic activities in the degradation of Rhodamine B (RhB) under visible light irradiation than that in commercial P25 TiO 2. Furthermore, the enhanced photocatalytic performance for RhB degradation was also investigated with assistance of a small amount of H 2O 2.

  11. Immobilizing photogenerated electrons from graphitic carbon nitride for an improved visible-light photocatalytic activity

    Science.gov (United States)

    Sun, Han; Cao, Yue; Feng, Leiyu; Chen, Yinguang

    2016-01-01

    Reducing the recombination probability of photogenerated electrons and holes is pivotal in enhancing the photocatalytic ability of graphitic carbon nitride (g-C3N4). Speeding the departure of photogenerated electrons is the most commonly used method of achieving this. To the best of our knowledge, there is no report on suppressing the recombination of photogenerated electron–hole pairs by immobilizing the electrons with ester functional groups. Here, for the first time the mesoporous g-C3N4 (mpg-C3N4) was integrated with polymethyl methacrylate, a polymer abundant in ester groups, which showed a photocatalytic activity unexpectedly higher than that of the original mpg-C3N4 under visible-light irradiation. Experimental observations, along with theoretical calculations, clarified that the impressive photocatalytic ability of the as-modified mpg-C3N4 was mainly derived from the immobilization of photogenerated electrons via an electron-gripping effect imposed by the ester groups in the polymethyl methacrylate. This novel strategy might also be applied in improving the photocatalytic performance of other semiconductors. PMID:26948968

  12. A simple preparation of nitrogen doped titanium dioxide nanocrystals with exposed (001) facets with high visible light activity.

    Science.gov (United States)

    Zhou, Xiaosong; Peng, Feng; Wang, Hongjuan; Yu, Hao; Fang, Yueping

    2012-01-14

    Nanoscaled nitrogen doped anatase TiO(2) with dominant (001) facets, which exhibited high photocatalytic activity and excellent photoelectrochemical properties under visible light irradiation, was successfully synthesized by solvothermal treatment of TiN in acidic NaBF(4) solution for the first time. This journal is © The Royal Society of Chemistry 2012

  13. 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.

  14. A visible light-activated direct-bonding material: An in vivo comparative study

    OpenAIRE

    O'Brien, K. D.; Read, M. J F; Sandison, R. J.; Roberts, C. T.

    1989-01-01

    A clinical trial was carried out to evaluate and compare the clinical performance of a visible light-cured material with a chemically cured adhesive. This was used in combination with two types of bracket base. Fifty-two patients entered the trial and 542 bracket bases were placed. The incidence and site of bond failure were recorded. The overall failure rate for the light-cured material in combination with both types of bracket was 4.7% and 6% for the chemical-cured adhesive. There were no s...

  15. Facile synthesis of Bi2WO6/Bi2O3-loaded polyurethane sponge with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Zhang, Fengjun; Wang, Zhi; Wang, Tianye; Jia, Liwei; Wang, Chao; Zhang, Shengyu

    2016-03-01

    In this study, Bi2WO6/Bi2O3-loaded polyurethane sponge composite photocatalyst was successfully synthesized via a facile two-step approach. The composite was characterized by X-ray diffraction, ultraviolet-visible diffuse reflectance, and scanning electron microscopy. The Bi2WO6/Bi2O3 photocatalyst was successfully loaded on polyurethane sponge and the composite displayed enhanced absorption in the ultraviolet-to-visible light region. Furthermore, the composite exhibited enhanced photocatalytic activity and reusability towards the degradation of rhodamine B (RhB) under visible light. This work demonstrates a facile method for synthesizing Bi2WO6/Bi2O3-loaded polyurethane sponge with enhanced photocatalytic activity and easy immobilization of the photocatalyst for application in environmental purification.

  16. Dye surface coating enables visible light activation of TiO2 nanoparticles leading to degradation of neighboring biological structures.

    Science.gov (United States)

    Blatnik, Jay; Luebke, Lanette; Simonet, Stephanie; Nelson, Megan; Price, Race; Leek, Rachael; Zeng, Leyong; Wu, Aiguo; Brown, Eric

    2012-02-01

    Biologically and chemically modified nanoparticles are gaining much attention as a new tool in cancer detection and treatment. Herein, we demonstrate that an alizarin red S (ARS) dye coating on TiO2 nanoparticles enables visible light activation of the nanoparticles leading to degradation of neighboring biological structures through localized production of reactive oxygen species. Successful coating of nanoparticles with dye is demonstrated through sedimentation, spectrophotometry, and gel electrophoresis techniques. Using gel electrophoresis, we demonstrate that visible light activation of dye-TiO2 nanoparticles leads to degradation of plasmid DNA in vitro. Alterations in integrity and distribution of nuclear membrane associated proteins were detected via fluorescence confocal microscopy in HeLa cells exposed to perinuclear localized ARS-TiO2 nanoparticles that were photoactivated with visible light. This study expands upon previous studies that indicated dye coatings on TiO2 nanoparticles can serve to enhance imaging, by clearly showing that dye coatings on TiO2 nanoparticles can also enhance the photoreactivity of TiO2 nanoparticles by allowing visible light activation. The findings of our study suggest a therapeutic application of dye-coated TiO2 nanoparticles in cancer research; however, at the same time they may reveal limitations on the use of dye assisted visualization of TiO2 nanoparticles in live-cell imaging.

  17. Photocatalytic activity of polymer-modified ZnO under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Rongliang [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)], E-mail: eesqrl@mail.sysu.edu.cn; Zhang Dongdong [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Mo Yueqi [College of Material Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Song Lin [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Department of Environmental Engineering, Jinan University, Guangzhou 510630 (China); Brewer, Eric [Viridian Environmental, LLC, Arlington, VA 22207 (United States); Huang Xiongfei; Xiong Ya [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

    2008-08-15

    Photocatalytic removal of phenol, rhodamine B, and methyl orange was studied using the photocatalyst ZnO/poly-(fluorene-co-thiophene) (PFT) under visible light. After 2 h irradiation with three 1 W LED (light-emitting diode) lights, about 40% removal of both phenol and methyl orange was achieved; rhodamine B was completely degraded to rhodamine. Diffuse reflectance spectra showed that the absorbance range of PFT/ZnO was expanded from 387 nm (ZnO) to about 500 nm. Photoluminescent spectra and photoluminescent quantum efficiency indicated that electrons were transferred from PFT to the conduction band of ZnO. Electron spin resonance (ESR) signals of spin-trapped paramagnetic species with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) evidenced that the OH{center_dot} radicals were indeed formed in the PFT/ZnO system under visible light irradiation. A working mechanism involving excitation of PFT, followed by charge injection into the ZnO conduction band is proposed.

  18. Synthesis of Hollow CdS-TiO2 Microspheres with Enhanced Visible-Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Yuning Huo

    2012-01-01

    Full Text Available CdS-TiO2 composite photocatalyst in the shape of hollow microsphere was successfully synthesized via the hard-template preparation with polystyrene microspheres followed by ion-exchange approach. The hollow CdS-TiO2 microspheres significantly extended the light adsorption into visible light region, comparing to TiO2 microspheres. It led to much higher photocatalytic activities of hollow CdS-TiO2 microspheres than that of TiO2 during the photodegradation of rhodamine B under visible light irradiations. Furthermore, the well-remained hollow structure could achieve light multireflection within the interior cavities and the separation of photo-induced electrons and holes is efficient in CdS-TiO2, which were facilitated to improving the photoactivity.

  19. Quick and facile preparation of visible light-driven TiO2 photocatalyst with high absorption and photocatalytic activity.

    Science.gov (United States)

    Yang, Yucheng; Zhang, Ting; Le, Ling; Ruan, Xuefeng; Fang, Pengfei; Pan, Chunxu; Xiong, Rui; Shi, Jing; Wei, Jianhong

    2014-11-13

    Self-doping TiO2 has recently attracted considerable attention for its high photocatalytic activity under visible-light irradiation. However, the literature reported synthetic methods until now were very time-consuming. In this study, we establish a quick and facile method for obtaining self-doping TiO2 with the use of directly treated commercial P25 at a desired temperature for only 5 min through spark plasma sintering technology. With the using of this method, the modified P25 samples exhibit significantly high photoelectric and photocatalytic performance. Furthermore, the sample prepared at 600 °C exhibits the optimum catalytic activity. The photodegradation and H2 evolution rates of this samples are significantly higher than those of unmodified P25 sample under visible-light irradiation. The physical origin of the visible-light absorption for the modified P25 samples is investigated in detail according to their structural, optical, and electronic properties. This work will provide a quick and facile method for the large-scale synthesis of visible-light driven photocatalyst for practical applications.

  20. Solar Synthesis: Prospects in Visible Light Photocatalysis

    Science.gov (United States)

    Schultz, Danielle M.; Yoon, Tehshik P.

    2015-01-01

    Chemists have long aspired to synthesize molecules the way that plants do — using sunlight to facilitate the construction of complex molecular architectures. Nevertheless, the use of visible light in photochemical synthesis is fundamentally challenging because organic molecules tend not to interact with the wavelengths of visible light that are most strongly emitted in the solar spectrum. Recent research has begun to leverage the ability of visible light absorbing transition metal complexes to catalyze a broad range of synthetically valuable reactions. In this review, we highlight how an understanding of the mechanisms of photocatalytic activation available to these transition metal complexes, and of the general reactivity patterns of the intermediates accessible via visible light photocatalysis, has accelerated the development of this diverse suite of reactions. PMID:24578578

  1. Synergistic Effects of Sm and C Co-Doped Mixed Phase Crystalline TiO₂ for Visible Light Photocatalytic Activity.

    Science.gov (United States)

    Peng, Fuchang; Gao, Honglin; Zhang, Genlin; Zhu, Zhongqi; Zhang, Jin; Liu, Qingju

    2017-02-21

    Mixed phase TiO₂ nanoparticles with element doping by Sm and C were prepared via a facile sol-gel procedure. The UV-Vis light-diffuse reflectance spectroscopy analysis showed that the absorption region of co-doped TiO₂ was shifted to the visible-light region, which was attributed to incorporation of samarium and carbon into the TiO₂ lattice during high-temperature reaction. Samarium effectively decreased the anatase-rutile phase transformation. The grain size can be controlled by Sm doping to achieve a large specific surface area useful for the enhancement of photocatalytic activity. The photocatalytic activities under visible light irradiation were evaluated by photocatalytic degradation of methylene blue (MB). The degradation rate of MB over the Sm-C co-doped TiO₂ sample was the best. Additionally, first-order apparent rate constants increased by about 4.3 times compared to that of commercial Degusssa P25 under the same experimental conditions. Using different types of scavengers, the results indicated that the electrons, holes, and •OH radicals are the main active species for the MB degradation. The high visible-light photocatalytic activity was attributed to low recombination of the photo-generated electrons and holes which originated from the synergistic effect of the co-doped ions and the heterostructure.

  2. Visible-Light-Driven Photocatalytic Activation of Inert Sulfur Ylides for 3-Acyl Oxindole Synthesis.

    Science.gov (United States)

    Xia, Xu-Dong; Lu, Liang-Qiu; Liu, Wen-Qiang; Chen, Dong-Zhen; Zheng, Yu-Han; Wu, Li-Zhu; Xiao, Wen-Jing

    2016-06-13

    Bicarbonyl-substituted sulfur ylide is a useful, but inert reagent in organic synthesis. Usually, harsh reaction conditions are required for its transformation. For the first time, it was demonstrated that a new, visible-light photoredox catalytic annulation of sulfur ylides under extremely mild conditions, permits the synthesis of oxindole derivatives in high selectivities and efficiencies. The key to its success is the photocatalytic single-electron-transfer (SET) oxidation of the inert amide and acyl-stabilized sulfur ylides to reactive radical cations, which easily proceeds with intramolecular C-H functionalization to give the final products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Synthesis and Optimization of Visible Light Active BiVO4 Photocatalysts for the Degradation of RhB

    Directory of Open Access Journals (Sweden)

    Rong Ran

    2015-01-01

    Full Text Available Monoclinic BiVO4 powders were synthesized via a novel route using potassium metavanadate (KVO3 prepared by calcination of K2CO3 and V2O5 as a starting material and followed by hydrothermal treatment and were investigated for the degradation of Rhodamine B (RhB under visible light irradiation. The synthesized BiVO4 particles were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, and UV-Visible (UV-Vis light diffuse reflectance spectrophotometry. The synthesis produced pure monoclinic BiVO4 particles with multimorphological features containing flower-like, flake-ball, flake, cuboid-like, and plate-like shapes and exhibited strong absorption in the visible light range. The BiVO4 prepared via KVO3 possessed excellent photocatalytic activity for the degradation of RhB under visible light. The performance of this catalyst was found to be superior to other BiVO4 photocatalysts prepared via ammonium metavanadate (NH4VO3 using coprecipitation, combustion, and calcination methods reported in literature, respectively.

  4. In situ polymerization synthesis of Z-scheme tungsten trioxide/polyimide photocatalyst with enhanced visible-light photocatalytic activity

    Science.gov (United States)

    Meng, Pengcheng; Heng, Huimin; Sun, Yanhong; Liu, Xia

    2018-01-01

    A novel direct Z-scheme P-containing tungsten trioxide/polyimide (PWO/PI) photocatalyst was synthesized by an in-situ solid-state polymerization strategy to enhance the visible-light photocatalytic oxidation capacity of PI. The effects of polymerization temperature and PWO content on the physicochemical properties of PWO/PI composites and photocatalytic degradation efficiency of imidacloprid were investigated. The photocatalysts were characterized by X-ray powder diffraction, Fourier transformed infrared spectra, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, UV-vis diffused reflection spectra and N2 adsorption-desorption isothermals. The results showed that the photocatalysts with visible-light photocatalytic activity can already be prepared at 300 °C. The PWO/PI composites exhibited a lamellar structure and PWO was wrapped by PI. After PWO was introduced, there was a significant interaction between PWO and PI, and the visible light response of photocatalysts was also improved. The visible-light photocatalytic degradation efficiency of imidacloprid on 3% PWO/PI-300 composite was about 3.2 times of commercial P25, and the corresponding pseudo-first-order rate constant was about 2.9 times of pristine PI. The Z-scheme photocatalytic system of PWO/PI composites was confirmed by the electron spin resonance technology, terephthalic acid photoluminescence probing technique, reactive species trapping experiments, X-ray photoelectron spectroscopy and photoluminescence of PWO/PI composites and pristine photocatalysts.

  5. Oxygen vacancies confined in SnO2 nanoparticles for desirable electronic structure and enhanced visible light photocatalytic activity

    Science.gov (United States)

    Yang, Yuanjie; Wang, Yuhua; Yin, Shu

    2017-10-01

    Electronic structure in principle determines the light absorbance, charge transfer and separation, and consequently, photocatalytic property of a photocatalyst. Herein, we report rutile SnO2 with a desirable electronic structure that exhibits a narrowed bandgap and an increased valence band width resulted from the introduction of homogeneous oxygen vacancies. XPS, Raman, ESR and PL spectra demonstrate the homogeneous oxygen vacancies confined in SnO2 nanoparticles. Moreover, the first principle calculations theoretically reveal the desirable electronic structure. The narrowed bandgap further contributes to extended light absorption range and the increased valence band width leads to efficient charge transfer and separation, hence facilitating the visible light photoreactivity. As a result, the defected SnO2 exhibits a superior visible light photocatalytic activity. More strikingly, the photodegration of methyl orange (MO) is completely accomplished within only 20 min under λ ≥ 420 nm. Briefly, this work both experimentally and theoretically indicates that homogeneous oxygen vacancies confined in SnO2 nanoparticles lead to the optimized electronic structure and, consequently, the remarkable visible light photocatalytic activity. This could open up an innovative strategy for designing potentially efficient photocatalysts.

  6. Visible Light Induced Photocatalytic Activity of Polyaniline Modified TiO2 and Clay-TiO2 Composites

    Directory of Open Access Journals (Sweden)

    K.P. Sandhya

    2013-12-01

    Full Text Available Sonochemical synthesis of Titania, Titania-Polyaniline, and Clay-Titania-Polyaniline composites were car-ried out. The composite systems were characterized by various physico-chemical techniques. Photocatalytic activity was tested selecting some common dyes as substrates. Composites exhibited higher activity for the degradation of dyes under visible light in most of the cases. © 2013 BCREC UNDIP. All rights reservedReceived: 15th May 2013; Revised: 1st September 2013; Accepted: 3rd October 2013[How to Cite: Sandhya, K.P., Haridas, S., Sugunan, S. (2013. Visible Light Induced Photocatalytic Activity of Polyaniline Modified TiO2 and Clay-TiO2 Composites. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (2: 145-153. (doi:10.9767/bcrec.8.2.4949.145-153][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.2.4949.145-153

  7. Visible-Light Photocatalytic Activity of N-Doped TiO2 Nanotube Arrays on Acephate Degradation

    Directory of Open Access Journals (Sweden)

    Xinlei Zhang

    2015-01-01

    Full Text Available Highly ordered nitrogen-doped titanium dioxide (N-doped TiO2 nanotube arrays were prepared by anodic oxidation method and then annealed in a N2 atmosphere to obtain N-doped TiO2 nanotube arrays. The samples were characterized with scanning electron microscope (SEM, X-ray powder diffraction (XRD, X-ray photoelectron spectrum (XPS, and UV-visible spectrophotometry (UV-vis spectrum. Degradation of the insecticide acephate under the visible light was used as a model to examine the visible-light photocatalytic activity of N-doped TiO2 nanotube arrays. The results show that N type doping has no notable effects on the morphology and structure of TiO2 nanotube arrays. After N type doping, the N replaces a small amount of O in TiO2, forming an N–Ti–O structure. This shifts the optical absorption edge and enhances absorption of the visible light. N-doped TiO2 nanotube arrays subjected to annealing at 500°C in N2 atmosphere show the strongest photocatalytic activity and reach a degradation rate of 84% within 2 h.

  8. Bactericidal activity under UV and visible light of cotton fabrics coated with anthraquinone-sensitized TiO2

    KAUST Repository

    Rahal, Raed

    2013-06-01

    This study describes a method derived from ISO/TC 206/SC specifications to assess the bactericidal activity against a bacterial strain, Pseudomonas fluorescens, of various photocatalytic fabrics, under UVA and filtered visible light. The experimental method allowed the accurate quantification of bacteria survival on photoactive surfaces and films under UVA and UV-free visible irradiation. Cotton fabrics coated with TiO2, anthraquinone or anthraquinone-sensitized TiO2 display a significant bactericidal efficiency. TiO2-coated fabrics are very efficient against P. fluorescens after 4 h UVA irradiation (bacteria survival below the detection limit). Under UVA-free visible light, anthraquinone-sensitized TiO2 coated fabrics induced a significant bactericidal activity after 2 h irradiation, while anthraquinone alone-coated fabrics were not as efficient and TiO2 coated fabrics were almost inefficient. These results show that although exhibiting a weak n-π* band in the 350-420 nm range, anthraquinone is a good candidate as an efficient visible light photosensitizer. A synergy effect between anthraquinone and TiO2 was demonstrated. A possible reaction mechanism, involving a synergy effect for singlet oxygen formation with anthraquinone-sensitized TiO2 is proposed to account for these results. © 2012 Elsevier B.V. All rights reserved.

  9. Enhanced photocatalytic activity of ZnO/CuO nanocomposite for the degradation of textile dye on visible light illumination

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, R. [Materials science centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600 025 (India); Karthikeyan, S. [Environmental technology division, Central Leather Research Institute, Adyar, Chennai 600 020 (India); Gupta, V.K. [Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247 667 (India); King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Sekaran, G. [Environmental technology division, Central Leather Research Institute, Adyar, Chennai 600 020 (India); Narayanan, V. [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600 025 (India); Stephen, A., E-mail: stephen_arum@hotmail.com [Materials science centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2013-01-01

    The photocatalytic degradation of organic dyes such as methylene blue and methyl orange in the presence of various percentages of composite catalyst under visible light irradiation was carried out. The catalyst ZnO nanorods and ZnO/CuO nanocomposites of different weight ratios were prepared by new thermal decomposition method, which is simple and cost effective. The prepared catalysts were characterized by different techniques such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV-visible absorption spectroscopy. Further, the most photocatalytically active composite material was used for degradation of real textile waste water under visible light illumination. The irradiated samples were analysed by total organic carbon and chemical oxygen demand. The efficiency of the catalyst and their photocatalytic mechanism has been discussed in detail. Highlights: Black-Right-Pointing-Pointer Visible light active photocatalyst Black-Right-Pointing-Pointer Degradation of methylene blue and methyl orange Black-Right-Pointing-Pointer Preparation of composite materials is a simple, fast and cost effective method. Black-Right-Pointing-Pointer Nano composite materials Black-Right-Pointing-Pointer Degradation of textile waste water.

  10. ZnO:SnO nanorods and nanosheets and their enhanced photocatalytic activity under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Harish, S., E-mail: aravindharri@gmail.com, E-mail: suruponnus@gmail.com; Ponnusamy, S., E-mail: aravindharri@gmail.com, E-mail: suruponnus@gmail.com; Muthamizhchelvan, C. [Centre for Nanoscience and Nanotechnology, Department of Physics, SRM University, Kattankulathur, Chennai, 603203, Tamil Nadu (India); Silambarasan, A. [Department of Chemistry, SRM University, Ramapuram, Chennai, 600089, Tamil Nadu (India); Navaneethan, M.; Archana, J.; Hayakawa, Y. [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8011 (Japan)

    2015-06-24

    ZnO-SnO nanocomposites were synthesized by a simple hydrothermal method. It was found that Sn concentration acted as a crucial factor in determining the morphology of ZnO-SnO nanostructures, in the presence of ethylenediamine (EDA) as a stabilizing agent. XRD analysis confirmed the formation of ZnO and SnO with good crystallinity. The morphological analysis revealed tin oxide (SnO) nanoparticles coated on the surface of ZnO nanorods and nanosheets. The photocatalytic activity of synthesized samples were evaluated by methylene blue (MB) as a model pollutant under visible light irradiation. Photocatalysis studies revealed that, ZnO-SnO nanocomposites show the enhanced photocatalytic activity compared to ZnO, which could be attributed to the formation of hetero-junction between ZnO and SnO of MB degradation. Sn concentration can extend the light absorption spectra of ZnO to visible light region and enhance the visible light photocatalytic activity. This research could provide new insights to the development of excellent photocatalyst with efficient performance for pollution control.

  11. Flower-like BiVO4 Microspheres and Their Visible Light-Driven Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Arini Nuran Zulkifili

    2018-01-01

    Full Text Available A flower-like BiVO4 microsphere photocatalyst was synthesized with a simple template-free homogeneous precipitation method at 60 °C for 24 h. The purpose of this study is to explore a low-cost, simple method of synthesizing the self-assembled 3D structure in order to enhance photocatalytic performance under visible light irradiation (λ > 420 nm. In this study, the morphology, structure, and photo-absorption of flower-like BiVO4 microspheres were characterized, and the effects of photocatalysis were analyzed. The results indicate that the size of the flower-like microspheres was about 2 μm to 4 μm and they were composed of several nanosheets. The mechanism of hierarchical microsphere formation has been proposed as the Ostwald ripening process and the self-assembled process. The obtained samples were calcined under different temperatures (300 °C, 400 °C, 500 °C and 600 °C to study the effects of calcination on the structure and on photocatalysis. The photocatalytic process was then evaluated by decolorization of methylene blue dye under visible-light irradiation.

  12. TiO2 nanoparticles immobilized on carbon nanotubes for enhanced visible-light photo-induced activity

    Directory of Open Access Journals (Sweden)

    Ali Akbar Ashkarran

    2015-04-01

    Full Text Available CNT–TiO2 nanocomposites were prepared through (i simple mixing of as prepared CNTs and TiO2 nanoparticles (NPs, (ii simple mixing of as prepared CNTs and TiO2 NPs followed by heat treatment and (iii simple mixing of as prepared CNTs and TiO2 NPs followed by UV illumination. The synthesis of CNTs and TiO2 NPs were performed individually by arc discharge in water and sol–gel methods, respectively and characterized by X-ray diffraction (XRD, ultra violet and visible spectroscopy (UV–vis, Fourier transform infrared spectroscopy (FT-IR, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The visible-light photocatalytic performance of CNT–TiO2 nanocomposites was successfully demonstrated for the degradation of Rhodamine B (Rh. B as a model dye at room temperature. It is found that CNT–TiO2 nanocomposites extended the light absorption spectrum toward the visible region and considerably improved the photocatalytic efficiency under visible-light irradiation. The visible-light photocatalytic activities of CNT–TiO2 nanocomposites in which CNTs are produced by arc discharge in deionized (DI water at 40, 60 and 80 A arc currents and combined through three different protocols are also investigated. It was found that samples prepared at 80 A arc current and 5 s arc duration followed by UV illumination revealed best photocatalytic activity compared with the same samples prepared under simple mixing and simple mixing followed by heat treatment. The enhancement in the photocatalytic property of CNT–TiO2 nanocomposites prepared at 80 A arc current followed by UV illumination may be ascribed to the quality of CNTs produced at this current, as was reported before.

  13. Ethylene C-H Bond Activation by Neutral Mn2O5 Clusters under Visible Light Irradiation.

    Science.gov (United States)

    Yin, Shi; Bernstein, Elliot R

    2016-05-05

    A photo excitation fast flow reactor coupled with a single-photon ionization (118 nm, 10.5 eV) time-of-flight mass spectrometry (TOFMS) instrument is used to investigate reactions of neutral MnmOn clusters with C2H4 under visible (532 nm) light irradiation. Association products Mn2O5(C2H4) and Mn3O6,7(C2H4) are observed without irradiation. Under light irradiation, the Mn2O5(C2H4) TOFMS feature decreases, and a new species, Mn2O5H2, is observed. This light-activated reaction suggests that the visible radiation can induce the chemistry, Mn2O5 + C2H4 + hv(532 nm) → Mn2O5*(C2H4) → Mn2O5H2 + C2H2. High barriers (0.67 and 0.59 eV) are obtained on the ground-state potential energy surface (PES); the reaction is barrierless and thermodynamically favorable on the first excited-state PES, as performed by time-dependent density functional theory calculations. The calculational and experimental results suggest that Mn2O5-like structures on manganese oxide surfaces are the appropriate active catalytic sites for visible light photocatalysis of ethylene dehydrogenation.

  14. BiVO(4)/CeO(2) nanocomposites with high visible-light-induced photocatalytic activity.

    Science.gov (United States)

    Wetchakun, Natda; Chaiwichain, Saranyoo; Inceesungvorn, Burapat; Pingmuang, Kanlaya; Phanichphant, Sukon; Minett, Andrew I; Chen, Jun

    2012-07-25

    Preparation of bismuth vanadate and cerium dioxide (BiVO4/CeO2) nanocomposites as visible-light photocatalysts was successfully obtained by coupling a homogeneous precipitation method with hydrothermal techniques. The BiVO4/CeO2 nanocomposites with different mole ratios were synthesized and characterized by X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). Absorption range and band gap energy, which are responsible for the observed photocatalyst behavior, were investigated by UV-vis diffuse reflectance (UV-vis DR) spectroscopy. Photocatalytic activities of the prepared samples were examined by studying the degradation of model dyes Methylene Blue, Methyl Orange, and a mixture of Methylene Blue and Methyl Orange solutions under visible-light irradiation (>400 nm). Results clearly show that the BiVO4/CeO2 nanocomposite in a 0.6:0.4 mol ratio exhibited the highest photocatalytic activity in dye wastewater treatment.

  15. Mechanochemically synthesized sub-5 nm sized CuS quantum dots with high visible-light-driven photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shun; Ge, Zhen-Hua [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Bo-Ping, E-mail: bpzhang@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Yao, Yao [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Huan-Chun [School of Materials Science and Engineering, Tsinghua University, Beijing, 100084 (China); Yang, Jing; Li, Yan; Gao, Chao [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Lin, Yuan-Hua [School of Materials Science and Engineering, Tsinghua University, Beijing, 100084 (China)

    2016-10-30

    Highlights: • CuS quantum dots (<5 nm) were synthesized by mechanochemical ball milling. • Defects was observed in the CuS quantum dots. • They show good visible light photocatalytic activity as Fenton-like reagents. - Abstract: We report a simple mechanochemical ball milling method for synthesizing monodisperse CuS quantum dots (QDs) with sizes as small as sub-5 nm. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–vis spectroscopy. The CuS QDs exhibited excellent visible-light-driven photocatalytic activity and stability for degradation of Rodanmine B aqueous solution as Fenton-like reagents. Our study opens the opportunity to low-cost and facile synthesis of QDs in large scale for future industrial applications.

  16. Visible Light Responsive Catalyst for Air Water Purification Project

    Science.gov (United States)

    Wheeler, Raymond M.

    2014-01-01

    Investigate and develop viable approaches to render the normally UV-activated TIO2 catalyst visible light responsive (VLR) and achieve high and sustaining catalytic activity under the visible region of the solar spectrum.

  17. Antipseudomonal activity enhancement of luminescent iridium(iii) dipyridylamine complexes under visible blue light.

    Science.gov (United States)

    Sauvageot, E; Elie, M; Gaillard, S; Daniellou, R; Fechter, P; Schalk, I J; Gasser, V; Renaud, J-L; Mislin, G L A

    2017-11-22

    Cyclometallated iridium(iii) dipyridylamine complexes present antibacterial activity against P. aeruginosa, a highly resistant pathogenic bacterium. This activity is increased when the complex is conjugated to biotin, a bacterial nutrient, and a MIC of 4 μM (4 μg mL(-1)) has been observed. The irradiation of P. aeruginosa cultures with blue LED light potentiates the anti-bacterial activities of these iridium(iii) complexes when they are conjugated to a glycoside.

  18. Three-Dimensional BiOI/BiOX (X = Cl or Br) Nanohybrids for Enhanced Visible-Light Photocatalytic Activity.

    Science.gov (United States)

    Liu, Yazi; Xu, Jian; Wang, Liqiong; Zhang, Huayang; Xu, Ping; Duan, Xiaoguang; Sun, Hongqi; Wang, Shaobin

    2017-03-14

    Three-dimensional flower-like BiOI/BiOX (X = Br or Cl) hybrids were synthesized via a facile one-pot solvothermal approach. With systematic characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET)specific surface area, X-ray photoelectron spectroscopy (XPS), and the UV-Vis diffuse reflectance spectra (DRS), the BiOI/BiOCl composites showed a fluffy and porous 3-D architecture with a large specific surface area (SSA) and high capability for light absorption. Among all the BiOX (X = Cl, Br, I) and BiOI/BiOX (X = Cl or Br) composites, BiOI/BiOCl stands out as the most efficient photocatalyst under both visible and UV light irradiations for methyl orange (MO) oxidation. The reaction rate of MO degradation on BiOI/BiOCl was 2.1 times higher than that on pure BiOI under visible light. Moreover, BiOI/BiOCl exhibited enhanced water oxidation efficiency for O₂ evolution which was 1.5 times higher than BiOI. The enhancement of photocatalytic activity could be attributed to the formation of a heterojunction between BiOI and BiOCl, with a nanoporous structure, a larger SSA, and a stronger light absorbance capacity especially in the visible-light region. The in situ electron paramagnetic resonance (EPR) revealed that BiOI/BiOCl composites could effectively evolve superoxide radicals and hydroxyl radicals for photodegradation, and the superoxide radicals are the dominant reactive species. The superb photocatalytic activity of BiOI/BiOCl could be utilized for the degradation of various industrial dyes under natural sunlight irradiation which is of high significance for the remediation of industrial wastewater in the future.

  19. Three-Dimensional BiOI/BiOX (X = Cl or Br Nanohybrids for Enhanced Visible-Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Yazi Liu

    2017-03-01

    Full Text Available Three-dimensional flower-like BiOI/BiOX (X = Br or Cl hybrids were synthesized via a facile one-pot solvothermal approach. With systematic characterizations by X-ray diffraction (XRD, scanning electron microscopy (SEM, Transmission electron microscopy (TEM, the Brunauer-Emmett-Teller (BETspecific surface area, X-ray photoelectron spectroscopy (XPS, and the UV-Vis diffuse reflectance spectra (DRS, the BiOI/BiOCl composites showed a fluffy and porous 3-D architecture with a large specific surface area (SSA and high capability for light absorption. Among all the BiOX (X = Cl, Br, I and BiOI/BiOX (X = Cl or Br composites, BiOI/BiOCl stands out as the most efficient photocatalyst under both visible and UV light irradiations for methyl orange (MO oxidation. The reaction rate of MO degradation on BiOI/BiOCl was 2.1 times higher than that on pure BiOI under visible light. Moreover, BiOI/BiOCl exhibited enhanced water oxidation efficiency for O2 evolution which was 1.5 times higher than BiOI. The enhancement of photocatalytic activity could be attributed to the formation of a heterojunction between BiOI and BiOCl, with a nanoporous structure, a larger SSA, and a stronger light absorbance capacity especially in the visible-light region. The in situ electron paramagnetic resonance (EPR revealed that BiOI/BiOCl composites could effectively evolve superoxide radicals and hydroxyl radicals for photodegradation, and the superoxide radicals are the dominant reactive species. The superb photocatalytic activity of BiOI/BiOCl could be utilized for the degradation of various industrial dyes under natural sunlight irradiation which is of high significance for the remediation of industrial wastewater in the future.

  20. Three-Dimensional BiOI/BiOX (X = Cl or Br) Nanohybrids for Enhanced Visible-Light Photocatalytic Activity

    Science.gov (United States)

    Liu, Yazi; Xu, Jian; Wang, Liqiong; Zhang, Huayang; Xu, Ping; Duan, Xiaoguang; Sun, Hongqi; Wang, Shaobin

    2017-01-01

    Three-dimensional flower-like BiOI/BiOX (X = Br or Cl) hybrids were synthesized via a facile one-pot solvothermal approach. With systematic characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET)specific surface area, X-ray photoelectron spectroscopy (XPS), and the UV-Vis diffuse reflectance spectra (DRS), the BiOI/BiOCl composites showed a fluffy and porous 3-D architecture with a large specific surface area (SSA) and high capability for light absorption. Among all the BiOX (X = Cl, Br, I) and BiOI/BiOX (X = Cl or Br) composites, BiOI/BiOCl stands out as the most efficient photocatalyst under both visible and UV light irradiations for methyl orange (MO) oxidation. The reaction rate of MO degradation on BiOI/BiOCl was 2.1 times higher than that on pure BiOI under visible light. Moreover, BiOI/BiOCl exhibited enhanced water oxidation efficiency for O2 evolution which was 1.5 times higher than BiOI. The enhancement of photocatalytic activity could be attributed to the formation of a heterojunction between BiOI and BiOCl, with a nanoporous structure, a larger SSA, and a stronger light absorbance capacity especially in the visible-light region. The in situ electron paramagnetic resonance (EPR) revealed that BiOI/BiOCl composites could effectively evolve superoxide radicals and hydroxyl radicals for photodegradation, and the superoxide radicals are the dominant reactive species. The superb photocatalytic activity of BiOI/BiOCl could be utilized for the degradation of various industrial dyes under natural sunlight irradiation which is of high significance for the remediation of industrial wastewater in the future. PMID:28336897

  1. Microwave-Hydrothermal Synthesis of SnO2-CNTs Hybrid Nanocomposites with Visible Light Photocatalytic Activity.

    Science.gov (United States)

    Wu, Shuisheng; Dai, Weili

    2017-03-03

    SnO2 nanoparticles coated on carbon nanotubes (CNTs) were prepared via a simple microwave-hydrothermal route. The as-obtained SnO2-CNTs composites were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2-CNTs for degradation of Rhodamine B under visible light irradiation was investigated. The results show that SnO2-CNTs nanocomposites have a higher photocatalytic activity than pure SnO2 due to the rapid transferring of electrons and the effective separation of holes and electrons on SnO2-CNTs.

  2. Low temperature synthesis of polyaniline-crystalline TiO2-halloysite composite nanotubes with enhanced visible light photocatalytic activity.

    Science.gov (United States)

    Li, Cuiping; Wang, Jie; Guo, Hong; Ding, Shujiang

    2015-11-15

    A series of one-dimensional polyaniline-crystalline TiO2-halloysite composite nanotubes with different mass ratio of polyaniline to TiO2 are facilely prepared by employing the low-temperature synthesis of crystalline TiO2 on halloysite nanotubes. The halloysite nanotubes can adsorb TiO2/polyaniline precursors and induce TiO2 nanocrystals/polyaniline to grow on the support in situ simultaneously. By simply adjusting the acidity of reaction system, PANI-crystalline TiO2-HA composite nanotubes composed of anatase, a mixed phase TiO2 and different PANI redox state are obtained. The XRD and UV-vis results show that the surface polyaniline sensitization has no effect on the crystalline structure of halloysite and TiO2 and the light response of TiO2 is extended to visible-light regions. Photocatalysis test results reveal the photocatalytic activity will be affected by the pH value and the volume ratio of ANI to TTIP. The highest photocatalytic activity is achieved with the composite photocatalysts prepared at pH 0.5 and 1% volume ratio of ANI and TTIP owing to the sensitizing effect of polyaniline and the charge transfer from the photoexcited PANI sensitizer to TiO2. Moreover, the PANI-TiO2-HA composite nanotubes synthesized by one-step at pH 0.5 with 1% volume ratio of ANI to TTIP exhibit higher visible light photocatalytic activity than those synthesized by the two-step. Heterogeneous PANI-TiO2-HA composite nanotubes prepared at pH 0.5 exhibit a higher degradation activity than that prepared at pH 1.5. The redoped experiment proves that the PANI redox state plays the main contribution to the enhanced visible light catalytic degradation efficiency of PANI-TiO2-HA prepared at pH 0.5. Furthermore, the heterogeneous PANI-crystalline TiO2-HA nanotubes have good photocatalytic stability and can be reused four times with only gradual loss of activity under visible light irradiation. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. A Novel Technique for the Deposition of Bismuth Tungstate onto Titania Nanoparticulates for Enhancing the Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Marina Ratova

    2016-07-01

    Full Text Available A novel powder handling technique was used to allow the deposition of bismuth tungstate coatings onto commercial titanium dioxide photocatalytic nanoparticles. The coatings were deposited by reactive pulsed DC magnetron sputtering in an argon/oxygen atmosphere. The use of an oscillating bowl with rotary particle propagation, positioned beneath two closed-field planar magnetrons, provided uniform coverage of the titania particle surfaces. The bismuth/tungsten atomic ratio of the coatings was controlled by varying the power applied to each target. The resulting materials were characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX, Brunauer–Emmett–Teller (BET surface area measurements, transmission electron microscopy (TEM, and UV-visible diffuse reflectance spectroscopy. Photocatalytic properties under visible light irradiation were assessed using an acetone degradation test. It was found that deposition of bismuth tungstate onto titania nanoparticles resulted in significant increases in visible light photocatalytic activity, compared to uncoated titania. Of the coatings studied, the highest photocatalytic activity was measured for the sample with a Bi/W atomic ratio of 2/1.

  4. 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.

  5. Synthesis and characterization of graphene oxide modified AgBr nanocomposites with enhanced photocatalytic activity and stability under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Du [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Tang, Hua, E-mail: tanghua@mail.ujs.edu.cn [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Wang, Yuqi; Wu, Kongqiang; Huang, Hong [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Tang, Guogang [Department of Chemical Engineering, Zhenjiang College, Zhenjiang, Jiangsu 212003 (China); Yang, Jin [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013 (China)

    2014-11-15

    Highlights: • GO/AgBr nanocomposites were prepared successfully. • There exists some synergistic effect between components in the composites. • The composites show high photocatalytic activity toward RhB, MB and MO degradation under visible light. - Abstract: Novel visible-light-driven graphene oxide (GO)/AgBr nanocomposites were synthesized by a facile solution method. The GO/AgBr nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoemission spectroscopy (XPS) analysis, UV–vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectra (FTIR), and Raman spectra. The results indicated that AgBr nanoparticles were evenly distributed on the surface of GO and the heterostructures were formed. The photocatalytic activity of the as-prepared nanocomposites was evaluated by using Rhodamine B (RhB), Methylene blue (MB) and Methyl orange (MO) as target organic pollutants. The nanocomposites exhibit excellent photocatalytic activity for all of three dyes. Compared with bare AgBr particles, the GO/AgBr nanocomposites show better photocatalytic properties toward RhB pollutants. Additionally, the radical scavengers experiment indicated that O{sub 2}·{sup −} radicals was the main reactive species for the RhB degradation under visible light. The increased photocatalytic activity of the GO/AgBr nanocomposites was attributed to the strong coupling between GO and AgBr, which facilitated interfacial charge transfer and inhibited electron-hole recombination. A photocatalytic mechanism of GO/AgBr nanocomposites was also proposed.

  6. Synthesis, Characterization and Photocatalytic Activity of New Photocatalyst ZnBiSbO4 under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Jingfei Luan

    2014-05-01

    Full Text Available In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2 and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO42− and NO3−, and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC wastewater was detected by examining its effect on seed germination and growth.

  7. Synthesis, Characterization and Photocatalytic Activity of New Photocatalyst ZnBiSbO4 under Visible Light Irradiation

    Science.gov (United States)

    Luan, Jingfei; Chen, Mengjing; Hu, Wenhua

    2014-01-01

    In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2) and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO42− and NO3−, and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth. PMID:24879521

  8. 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.

  9. The {0 0 1} facets-dependent superior photocatalytic activities of BiOCl nanosheets under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingjun [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Wang, Qin, E-mail: qinwang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Liu, Baocang [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China); Zhang, Jun, E-mail: cejzhang@imu.edu.cn [College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021 (China); Inner Mongolia Key Lab of Nanoscience and Nanotechnology, Inner Mongolia University, Hohhot 010021 (China)

    2015-09-15

    Graphical abstract: - Highlights: • BiOCl nanosheets were selectively synthesized via a facile hydrothermal method. • The percentage of {0 0 1} facets over BiOCl nanosheets were well controlled. • These samples manifest superior catalytic activity for the degradation of RhB dyes. - Abstract: BiOCl nanosheets with tunable lamella thickness and dominantly exposed {0 0 1} facets were selectively synthesized via a facile hydrothermal method. By modifying the synthetic parameters, such as the amount of P123 and mannitol, the reaction time, types of surfactants, the size, thickness, morphologies, and percentage of {0 0 1} facets over BiOCl nanosheets were well controlled. The exposed {0 0 1} facets with high surface energy and high density of oxygen atoms are not only conducive to the adsorption of the rhodamine B (RhB) dye but also can accumulate the photo-generated electrons, which can be captured by O{sub 2} and converted into reactive oxygen species O{sub 2}{sup −}·. Therefore, the resultant ultrathin BiOCl nanosheets with exposed {0 0 1} facets exhibit superior catalytic activity for dye photosensitization degradation under visible light irradiation. Impressively, the ultrathin BiOCl nanosheets prepared with P123 and mannitol manifest superior catalytic activity and RhB was completely degraded within 20 min. Our current work is expected to offer a new insight into photocatalytic theory for better understanding of visible light photocatalytic reactions and rational design of highly active photocatalysts.

  10. Micro and nano hierachical structures of BiOI/activated carbon for efficient visible-light-photocatalytic reactions.

    Science.gov (United States)

    Hou, Jianhua; Jiang, Kun; Shen, Ming; Wei, Rui; Wu, Xiaoge; Idrees, Faryal; Cao, Chuanbao

    2017-09-15

    Constructing the heterojunctions or designing the novel nanostructures are thought as effective methods to improve photocatalytic activities of semiconductors. Herein, a one-step green route was developed to fabricate bismuth oxyiodide/activated carbon (BiOI/C) composite. The prepared BiOI/C exhibit obviously red shifts and increased absorption range of visible light. The presence of Bi-C bonds confirms the heterojunction, on account of which the BiOI nanosheets tightly grew on the surface of carbon and subsequently provided the hierarchical structure, sufficient interfacial interaction and high specific surface area. Significantly, the sufficient interracial interaction is beneficial to the detachment of electrons (e(-))-holes (h(+)) pairs and the Bi-C bonds work like a bridge to rapidly transmit the e(-) from BiOI to carbon. What's more, the hierarchical structure of BiOI/C efficiently shortened the diffusion pathways of pollutants and the high SBET provided more exposed reaction sites. Benefiting from multiple synergistic effects, the as-prepared BiOI/C exhibited enhanced photocatalytic activities in degrading Rhodamine B (RhB) solution under visible light irradiation. The degradation rate of optimized BiOI/C reaches up to 95% in 120 min, and the efficiency is 3.36 times higher than pure BiOI. This study provides a promising strategy that activated carbon can be utilized in highly-efficiency photocatalysts.

  11. Quick and Facile Preparation of Visible light-Driven TiO2 Photocatalyst with High Absorption and Photocatalytic Activity

    OpenAIRE

    Yucheng Yang; Ting Zhang; Ling Le; Xuefeng Ruan; Pengfei Fang; Chunxu Pan; Rui Xiong; Jing Shi; Jianhong Wei

    2014-01-01

    Self-doping TiO2 has recently attracted considerable attention for its high photocatalytic activity under visible-light irradiation. However, the literature reported synthetic methods until now were very time-consuming. In this study, we establish a quick and facile method for obtaining self-doping TiO2 with the use of directly treated commercial P25 at a desired temperature for only 5 min through spark plasma sintering technology. With the using of this method, the modified P25 samples exhib...

  12. Graphitic C3N4 Sensitized TiO2 Nanotube Layers: A Visible Light Activated Efficient Antimicrobial Platform

    CERN Document Server

    Xu, Jingwen; Zhou, Xuemei; Li, Yuzhen; Gao, Zhi-Da; Song, Yan-Yan; Schmuki, Patrik

    2016-01-01

    In this work, we introduce a facile procedure to graft a thin graphitic C3N4 (g-C3N4) layer on aligned TiO2 nanotube arrays (TiNT) by one-step chemical vapor deposition (CVD) approach. This provides a platform to enhance the visible-light response of TiO2 nanotubes for antimicrobial applications. The formed g- C3N4/TiNT binary nanocomposite exhibits excellent bactericidal efficiency against E. coli as a visiblelight activated antibacterial coating.

  13. Mechanochemically synthesized sub-5 nm sized CuS quantum dots with high visible-light-driven photocatalytic activity

    Science.gov (United States)

    Li, Shun; Ge, Zhen-Hua; Zhang, Bo-Ping; Yao, Yao; Wang, Huan-Chun; Yang, Jing; Li, Yan; Gao, Chao; Lin, Yuan-Hua

    2016-10-01

    We report a simple mechanochemical ball milling method for synthesizing monodisperse CuS quantum dots (QDs) with sizes as small as sub-5 nm. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. The CuS QDs exhibited excellent visible-light-driven photocatalytic activity and stability for degradation of Rodanmine B aqueous solution as Fenton-like reagents. Our study opens the opportunity to low-cost and facile synthesis of QDs in large scale for future industrial applications.

  14. Preparation of titanium dioxide/tungsten disulfide composite photocatalysts with enhanced photocatalytic activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Lili; Zhang, Weiping; Xiao, Xinyan [South China University of Technology, Guangzhou (China)

    2016-01-15

    Titanium dioxide/tungsten disulfide (TiO{sub 2}/WS{sub 2}) composite photocatalysts were fabricated via a one-step hydrothermal synthesis process, using TiCl{sub 4} as titanium source and bulk WS{sub 2} as sensitizer. The morphology, structure, specific surface area and optical absorption properties of the composite photocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), specific surface area analyzer and ultraviolet-visible diffuse reflection spectrum (UV-vis DRS), respectively. The photocatalytic activity of as-prepared photocatalysts was evaluated by the degradation of methyl orange (MO) under illumination of 500W Xenon lamp. The results indicated that TiO2/WS2 composite photocatalysts possessed excellent photocatalytic activity, and -95% of the degradation rate for MO was reached when molar ratio of WS{sub 2} to TiO{sub 2} was 0.004 and the irradiation time was 60 min. Moreover, the carrier trapping experiment and fluorescence spectra showed that •O{sup -}{sub 2} was the key component in the photocatalytic degradation process and O{sub 2} was reduced to be •O{sup -}{sub 2} by the electrons from the conduction band of TiO{sub 2} and WS{sub 2} for the degradation of MO.

  15. CdSe nanorod/TiO2 nanoparticle heterojunctions with enhanced solar- and visible-light photocatalytic activity

    Directory of Open Access Journals (Sweden)

    Fakher Laatar

    2017-12-01

    Full Text Available CdSe nanorods (NRs with an average length of ≈120 nm were prepared by a solvothermal process and associated to TiO2 nanoparticles (Aeroxide® P25 by annealing at 300 °C for 1 h. The content of CdSe NRs in CdSe/TiO2 composites was varied from 0.5 to 5 wt %. The CdSe/TiO2 heterostructured materials were characterized by XRD, TEM, SEM, XPS, UV–visible spectroscopy and Raman spectroscopy. TEM images and XRD patterns show that CdSe NRs with wurtzite structure are associated to TiO2 particles. The UV–visible spectra demonstrate that the narrow bandgap of CdSe NRs serves to increase the photoresponse of CdSe/TiO2 composites until ≈725 nm. The CdSe (2 wt %/TiO2 composite exhibits the highest photocatalytic activity for the degradation of rhodamine B in aqueous solution under simulated sunlight or visible light irradiation. The enhancement in photocatalytic activity likely originates from CdSe sensitization of TiO2 and the heterojunction between these materials which facilitates electron transfer from CdSe to TiO2. Due to its high stability (up to ten reuses without any significant loss in activity, the CdSe/TiO2 heterostructured catalysts show high potential for real water decontamination.

  16. Effects of bismuth addition and photo-deposition of platinum on (surface) composition, morphology and visible light photocatalytic activity of sol-gel derived TiO2

    NARCIS (Netherlands)

    Yi, Wentao; Yan, Chunyan; Hamdy, Mohamed S.; Baltrusaitis, Jonas; Mul, Guido

    2014-01-01

    Several remarkable observations regarding structure, (surface) composition and visible light induced photocatalytic activity of Bi-promoted Anatase photocatalysts are reported. First, XPS characterization data show that compositions of mixed Bi-Ti-oxide phases obtained by hydrothermal treatment at

  17. Mussel-inspired green synthesis of polydopamine-Ag-AgCl composites with efficient visible-light-driven photocatalytic activity.

    Science.gov (United States)

    Cai, Aijun; Wang, Xiuping; Guo, Aiying; Chang, Yongfang

    2016-09-01

    Polydopamine-Ag-AgCl composites (PDA-Ag-AgCl) were synthesized using a mussel-inspired method at room temperature, where PDA acts as a reducing agent to obtain the noble Ag nanoparticles from a precursor. The morphologies and structures of the as-prepared PDA-Ag-AgCl were characterized by several techniques including field emission scanning electron microscopy (FESEM), transmission electron microscopy (SEM), Raman spectra, and X-Ray photoelectron spectrum (XPS). The morphological observation depicts formation of nanoparticles with various micrometer size diameters and surface XPS analysis shows presence of various elements including Ag, N, Cl, and O. The enhanced absorbance of the PDA-Ag-AgCl particles in the visible light region is confirmed through UV-Vis diffuse reflectance spectra (DRS), and the charge transfer is demonstrated by photoluminescence (PL) and photocurrent response. The synthesized PDA-Ag-AgCl composites could be used as visible-light-driven photocatalysts for the degradation of Rhodamine B. The elevated photocatalytic activity is ascribed to the effective charge transfer from plasmon-excited Ag to AgCl that can improve the efficiency of the charge separation during the photocatalytic reaction. Furthermore, differences in the photocatalytic performance among the different PDA-Ag-AgCl composites are noticed that could be attributed to the Brunauer-Emmett-Teller (BET) specific surface area, which benefits to capture the visible light efficiently. The PDA-Ag-AgCl exhibits excellent stability without a significant loss in activity after 5cycles. The proposed method is low-cost and environmentally friendly, hence a promising new way to fabricate plasmon photocatalysts. Copyright © 2016. Published by Elsevier B.V.

  18. Controlled synthesis of T-shaped BiVO{sub 4} and enhanced visible light responsive photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Shuying; Yu, Chongfei; Li, Yukun [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China); Li, Yihui [School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007 (China); Sun, Jianhui, E-mail: sunjh@htu.cn [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China); Geng, Xiaofei [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China)

    2014-03-15

    A novel T-shaped BiVO{sub 4} microcrystal photocatalyst was successfully synthesized by the hydrothermal method with the aid of a structure-directing surfactant SDBS in the present study. Having received well characterization with the aid of various techniques and the results showed that the SDBS greatly changed the microstructure of BiVO{sub 4}, which had a unique T shape and belonged to the monoclinic family. The fast exchange dynamics between the surfactants bound to the Bi{sup 3+} seed surface and the free VO{sub 3}{sup −} in the solution significantly increase the rate of heterogeneous nucleation. In addition, the photocatalytic activity of the prepared T-shaped BiVO{sub 4} was evaluated by the degradation of Methylene Blue solution under visible light irradiation, 17% and 47% higher decolorization rates than the commercial P25 and BiVO{sub 4} synthesized without SDBS, respectively. Meanwhile, it has been found that the degradation kinetics of MB fitted the pseudo-first-order kinetics and the T-shaped BiVO{sub 4} also displayed high photocatalytic performance for metronidazole degradation. -- Graphical abstract: H{sub 2}O{sub 2} molecules function as electron trapping reagent to react with e{sup −} to enhance the photocatalytic degradation efficiency of MB in the BiVO{sub 4}/H{sub 2}O{sub 2} system under visible light irradiation. Highlights: • T-shaped BiVO{sub 4} was synthesized using SDBS as a structure-directing surfactant. • SDBS greatly changed the microstructure of BiVO{sub 4}. • The T-shaped BiVO{sub 4} had a better visible-light photocatalytic activity. • Degradation kinetics of MB by BiVO{sub 4} fitted the pseudo-first-order kinetics.

  19. Hydrothermal synthesis of FeWO{sub 4}-graphene composites and their photocatalytic activities under visible light

    Energy Technology Data Exchange (ETDEWEB)

    He, Gang-Ling; Chen, Ming-Jie; Liu, You-Qin; Li, Xin; Liu, Ying-Ju; Xu, Yue-Hua, E-mail: xuyuehua@scau.edu.cn

    2015-10-01

    Graphical abstract: - Highlights: • FeWO{sub 4}-RGO composites were hydrothermally fabricated by facile one-step method. • FeWO{sub 4}-RGO and FeWO{sub 4} had a similar particle size, in the range of 30–50 nm. • High efficiency for photocatalytic degradation of RhB was exhibited by FeWO{sub 4}-RGO. • FeWO{sub 4}-xRGO showed higher photocatalytic activities than pure FeWO{sub 4}. • The electron–hole pairs can be effectively separated due to RGO coupling. - Abstract: Monoclinic ferberite FeWO{sub 4}-reduced graphene oxide (FeWO{sub 4}-RGO) composites were hydrothermally fabricated by facile one-pot method in situ reduction of graphene oxide. As-prepared FeWO{sub 4}-RGO photocatalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, and diffuse reflectance spectra (DRS). The FeWO{sub 4}-RGO photocatalysts and pure FeWO{sub 4} photocatalyst had a similar particle size, which was in the range of 30–50 nm. FeWO{sub 4} and FeWO{sub 4}-RGO photocatalysts showed absorption in the visible region, and the band gap energy of FeWO{sub 4} decreased slightly after RGO coupling. FeWO{sub 4}-RGO photocatalysts exhibited high efficiencies in photocatalytic degradation of dye pollutant Rhodamine B (RhB) in solution under visible light irradiation (a 4 W Light Emitting Diode lamp). All FeWO{sub 4}-RGO photocatalysts under visible light showed higher photocatalytic activities than pure FeWO{sub 4} photocatalyst, and FeWO{sub 4}-0.3RGO showed the best photocatalytic activity. The FeWO{sub 4}-RGO composites were formed through the chemical contact between nanometer FeWO{sub 4} particles and RGO, and RGO could act as a good electron acceptor. The enhancement in visible-light photocatalytic performance may be mainly attributed to the effective separation of the photogenerated electron–hole pairs.

  20. Quantum dots in photocatalytic applications: efficiently enhancing visible light photocatalytic activity by integrating CdO quantum dots as sensitizers.

    Science.gov (United States)

    Reshak, A H

    2017-09-20

    The amalgamation of a wide optical band gap photocatalyst with visible-light-active CdO quantum dots (QDs) as sensitizers is one of the most efficient ways to improve photocatalytic performance under visible light irradiation. The photocatalytic performance of cadmium benzoate ((Cd(C 7 H 5 O 2 ) 2 ) 3 (CH 3 CN) 1 ) is comprehensively investigated. The estimated optical band gap of cadmium benzoate is 2.64 eV and the EPc and EPv are about -0.09 V (vs. NHE) and +2.55 V (vs. NHE), respectively, which implies that cadmium benzoate possesses a high negative reduction potential of excited electrons due to its higher conduction band position, and hence, the locations of the conduction band minimum and the valence band maximum meet the redox capacity. Thus, this composite photocatalyst exhibits superior activity in visible-light-driven photocatalytic H 2 evolution. We found that introducing the QDs enhance the photocatalytic performance towards the visible light region. The electronic band structure shows high k-dispersion bands around the Fermi level, which implies low effective masses, and hence, the high mobility carriers favor the enhancement of the charge transfer process. The mobility of the photogenerated carriers significantly influences the photocatalytic efficiency and the higher photogenerated carriers' mobility enhances the photocatalytic performance. Moreover, the result shows a great effective mass difference between electrons (e - ) and holes (h + ), which can facilitate the e - and h + migration and separation, and finally improve the photocatalytic performance. The large mobility difference is useful for the separation of e - and h + , the reduction of the e - and h + recombination rate, and the improvement of the photocatalytic activity. Thus, cadmium benzoate exhibits rapid generation of e - -h + pairs with photoexcitation and a high negative reduction potential of excited electrons due to its higher CB position. Based on these results one can conclude

  1. A Novel Heterostructure of BiOI Nanosheets Anchored onto MWCNTs with Excellent Visible-Light Photocatalytic Activity

    Science.gov (United States)

    Li, Shijie; Hu, Shiwei; Xu, Kaibing; Jiang, Wei; Liu, Jianshe; Wang, Zhaohui

    2017-01-01

    Developing efficient visible-light-driven (VLD) photocatalysts for environmental decontamination has drawn significant attention in recent years. Herein, we have reported a novel heterostructure of multiwalled carbon nanotubes (MWCNTs) coated with BiOI nanosheets as an efficient VLD photocatalyst, which was prepared via a simple solvothermal method. The morphology and structure were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and specific surface area measurements. The results showed that BiOI nanosheets were well deposited on MWCNTs. The MWCNTs/BiOI composites exhibited remarkably enhanced photocatalytic activity for the degradation of rhodamine B (RhB), methyl orange (MO), and para-chlorophenol (4-CP) under visible-light, compared with pure BiOI. When the MWCNTs content is 3 wt %, the MWCNTs/BiOI composite (3%M-Bi) achieves the highest activity, which is even higher than that of a mechanical mixture (3 wt % MWCNTs + 97 wt % BiOI). The superior photocatalytic activity is predominantly due to the strong coupling interface between MWCNTs and BiOI, which significantly promotes the efficient electron-hole separation. The photo-induced holes (h+) and superoxide radicals (O2−) mainly contribute to the photocatalytic degradation of RhB over 3%M-Bi. Therefore, the MWCNTs/BiOI composite is expected to be an efficient VLD photocatalyst for environmental purification. PMID:28336856

  2. A Novel Heterostructure of BiOI Nanosheets Anchored onto MWCNTs with Excellent Visible-Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Shijie Li

    2017-01-01

    Full Text Available Developing efficient visible-light-driven (VLD photocatalysts for environmental decontamination has drawn significant attention in recent years. Herein, we have reported a novel heterostructure of multiwalled carbon nanotubes (MWCNTs coated with BiOI nanosheets as an efficient VLD photocatalyst, which was prepared via a simple solvothermal method. The morphology and structure were characterized by powder X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, UV-Vis diffuse reflectance spectroscopy (DRS, and specific surface area measurements. The results showed that BiOI nanosheets were well deposited on MWCNTs. The MWCNTs/BiOI composites exhibited remarkably enhanced photocatalytic activity for the degradation of rhodamine B (RhB, methyl orange (MO, and para-chlorophenol (4-CP under visible-light, compared with pure BiOI. When the MWCNTs content is 3 wt %, the MWCNTs/BiOI composite (3%M-Bi achieves the highest activity, which is even higher than that of a mechanical mixture (3 wt % MWCNTs + 97 wt % BiOI. The superior photocatalytic activity is predominantly due to the strong coupling interface between MWCNTs and BiOI, which significantly promotes the efficient electron-hole separation. The photo-induced holes (h+ and superoxide radicals (O2− mainly contribute to the photocatalytic degradation of RhB over 3%M-Bi. Therefore, the MWCNTs/BiOI composite is expected to be an efficient VLD photocatalyst for environmental purification.

  3. One-step fabrication of BiOCl/CuS heterojunction photocatalysts with enhanced visible-light responsive activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiufang, E-mail: wxfxbs159@sohu.com [Key Laboratory of Functional Molecule Design and Interface Process, Anhui Jianzhu University, Hefei, Anhui 230601 (China); Hu, Hanmei; Chen, Shaohua; Zhang, Kehua; Zhang, Jun; Zou, Wensheng [Key Laboratory of Functional Molecule Design and Interface Process, Anhui Jianzhu University, Hefei, Anhui 230601 (China); Wang, Runxia [Pharmacy Department, Anhui Medical College, Hefei, Anhui 230601 (China)

    2015-05-05

    Fore the first time, a novel BiOCl/CuS nanocomposite with a heterojunction structure was prepared by a one-step hydrothermal method. The BiOCl/CuS heterojunctions were used as photocatalyst for degradation of organic pollutants, such as rhodamine B (RhB), under visible light irradiation (λ > 420 nm). The results reveal that the heterojunction structure composite exhibits markedly improved efficiency and high photostability for the RhB photodegradation in comparison with pure BiOCl and pure CuS. This is ascribed to the heterojunction structure with an efficient charge separation and transfer across the BiOCl/CuS junction. Moreover, the catalytic activity is related to the ratio of CuS to BiOCl in the nanocomposite, and the BiOCl/CuS heterojunction in a 0.5:1 mol ratio exhibits the highest photocatalytic activity. According to experimental results, the photocatalytic mechanism of BiOCl/CuS photocatalyst is proposed to explain the improvement of the photocatalytic activity. - Highlights: • Novel BiOCl/CuS heterojunctions have been prepared firstly. • The heterojunction structure has with an efficient charge separation and transfer across the BiOCl/CuS junction. • The improved efficiency and high photostability for the dye photodegradation under visible light irradiation.

  4. One-Step Cohydrothermal Synthesis of Nitrogen-Doped Titanium Oxide Nanotubes with Enhanced Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Cheng-Ching Hu

    2012-01-01

    Full Text Available Nitrogen-doped TiO2 nanotubes with enhanced visible light photocatalytic activity have been synthesized using commercial titania P25 as raw material by a facile P25/urea cohydrothermal method. Morphological and microstructural characteristics were conducted by transmission electron microscopy, powder X-ray diffraction, and nitrogen adsorption/desorption isotherms; chemical identifications were performed using X-ray photoelectron spectroscopy, and the interstitial nitrogen linkage to the TiO2 nanotubes is identified. The photocatalytic activity of nitrogen-doped TiO2 nanotubes, evaluated by the decomposition of rhodamine B dye solution under visible light using UV-vis absorption spectroscopy, is found to exhibit ~ four times higher than that of P25 and undoped titanate nanotubes. Factors affecting the photocatalytic activity are analyzed; it is found that the nitrogen content and surface area, rather than the crystallinity, are more crucial in affecting the photocatalytic efficiency of the nitrogen-doped TiO2 nanotubes.

  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. Significant improvement in visible light photocatalytic activity of Fe doped TiO2 using an acid treatment process

    Science.gov (United States)

    Moradi, Vahid; Jun, Martin B. G.; Blackburn, Arthur; Herring, Rodney A.

    2018-01-01

    Transition metal dopants have been used to decrease the band gap energy of TiO2 for visible light photocatalytic purposes. Fe3+ is a good dopant candidate owing to its capability to decrease the band gap energy and enhance the electron/hole trapping. However, in previous studies the photocatalytic activity of Fe-TiO2 was around 40-50% for a reaction time of ∼300 min. Herein, using HRTEM it was found out that the photocatalytic activity of Fe-TiO2 is limited by an amorphous contamination layer on the surface of the Fe-TiO2 nanoparticles. The contamination layer was determined to be composed of iron oxide by XPS surface analysis. The contamination layer was successfully removed using an acid treatment process comprising of HCl solution. Using the cleaned Fe-TiO2 nanoparticles, the photocatalytic activity measured utilizing a solution of 20 mg L-1 methyl orange (MO) was significantly increased from 24% to 98% within 60 min of reaction time under visible light illumination.

  7. Designing Visible Light-Cured Thiol-Acrylate Hydrogels for Studying the HIPPO Pathway Activation in Hepatocellular Carcinoma Cells.

    Science.gov (United States)

    Lin, Tsai-Yu; Bragg, John C; Lin, Chien-Chi

    2016-04-01

    Various polymerization mechanisms have been developed to prepare peptide-immobilized poly(ethylene glycol) (PEG) hydrogels, a class of biomaterials suitable for studying cell biology in vitro. Here, a visible light mediated thiol-acrylate photopolymerization scheme is reported to synthesize dually degradable PEG-peptide hydrogels with controllable crosslinking and degradability. The influence of immobilized monothiol pendant peptide is systematically evaluated on the crosslinking of these hydrogels. Further, methods are proposed to modulate hydrogel crosslinking, including adjusting concentration of comonomer or altering the design of multifunctional peptide crosslinker. Due to the formation of thioether ester bonds, these hydrogels are hydrolytically degradable. If the dithiol peptide linkers used are susceptible to protease cleavage, these thiol-acrylate hydrogels can be designed to undergo partial proteolysis. The differences between linear and multiarm PEG-acrylate (i.e., PEGDA vs PEG4A) are also evaluated. Finally, the use of the mixed-mode thiol-acrylate PEG4A-peptide hydrogels is explored for in situ encapsulation of hepatocellular carcinoma cells (Huh7). The effects of matrix stiffness and integrin binding motif (e.g., RGDS) on Huh7 cell growth and HIPPO pathway activation are studied using PEG4A-peptide hydrogels. This visible light poly-merized thiol-acrylate hydrogel system represents an alternative to existing light-cured hydrogel platforms and shall be useful in many biomedical applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Active modulation of visible light with graphene-loaded ultrathin metal plasmonic antennas

    National Research Council Canada - National Science Library

    Yu, Renwen; Pruneri, Valerio; García de Abajo, F Javier

    2016-01-01

    ... by microelectronic drivers. Here we show that planar nanostructures patterned in ultrathin metal-graphene hybrid films sustain highly tunable plasmons in the visible and near-infrared spectral regions...

  9. Enhanced photocatalytic activity of Bi2WO6/TiO2 composite coated polyester fabric under visible light irradiation

    Science.gov (United States)

    Du, Zoufei; Cheng, Cheng; Tan, Lin; Lan, Jianwu; Jiang, Shouxiang; Zhao, Ludan; Guo, Ronghui

    2018-03-01

    In this study, a visible-light-driven photocatalyst Bi2WO6/TiO2 composite was reported using one-step hydrothermal method and then coated on the polyester fabric. The samples were systematically characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, UV-vis diffuse reflection spectroscopy and photoluminescence spectroscopy (PL). The photocatalytic activity of Bi2WO6/TiO2 coated polyester fabric was evaluated by degradation of Rhodamine B (RhB) and Methylene blue (MB) under visible light irradiation. The self-cleaning property of the fabrics was assessed through removing red wine stain. The results reveal that the Bi2WO6/TiO2 composites with irregular shape are coated on the polyester fabric successfully. The UV-vis absorption spectra show a broad absorption band in the visible region, which extends the scope of absorption spectrum and helps to improve the photocatalytic degradation efficiency. Photocatalytic activities of the Bi2WO6/TiO2 composite polyester fabric are associated with the content of TiO2. Bi2WO6/15%TiO2 coated polyester fabric exhibits the degradation efficiency for RhB and MB up to 98% and 95.1%, respectively, which is much higher than that of pure Bi2WO6 and TiO2 coated polyester fabric. Moreover, Bi2WO6/15%TiO2 coated polyester fabric shows good cycle stability toward continuous three cycles of photocatalytic experiment for dyes degradation. In addition, the Bi2WO6/TiO2 coated polyester fabric shows good self-cleaning property. This work could be extended to design of other composite photocatalyst coating on the fabric for enhancing activity by coupling suitable wide and narrow band-gap semiconductors.

  10. Dendritic α-Fe2O3/TiO2 nanocomposites with improved visible light photocatalytic activity.

    Science.gov (United States)

    Li, Xin; Lin, Huiming; Chen, Xiang; Niu, Hao; Liu, Jiuyu; Zhang, Ting; Qu, Fengyu

    2016-04-07

    The design and synthesis of unique novel heterostructures for high-performance photocatalytic activity has exerted a tremendous fascination and has recently attracted intensive attention. In this work, a branch-like α-Fe2O3/TiO2 heterostructure has been synthesized controllably through an electrospinning method combined with a hydrothermal approach. The backbone of the heterostructure is composed of a 3D porous TiO2 nanofiber (∼70 nm in diameter) network with plenty of α-Fe2O3 nanorods (100-200 nm in length) deposited on them. The novel branch-like nanocomposites have an abundantly porous structure as well as large surface areas (up to 42.8 m(2) g(-1)). In addition, their visible light photodegradation behaviour towards organic dyes, including Congo red (CR), methylene blue (MB), eosin red (ER) and methyl orange (MO), was investigated. Their excellent photocatalytic performances are attributed to their large surfaces, improved visible light absorption and high separation efficiency of the photogenerated electrons/holes. Furthermore, the degradation process was further studied by varying the amount of α-Fe2O3 deposited. The sample α-Fe2O3/TiO2-3 possessed the best performance to efficiently decolor CR solution even at a high concentration of 50 mg L(-1) (160 min, 94 mg g(-1)), ascribed to the high adsorption capacity derived from the large surface, strong electrostatic interaction and structural match between α-Fe2O3/TiO2-3 and CR. These α-Fe2O3/TiO2 heterostructures exhibit great potential for decontamination of organic pollutants in waste water under visible light.

  11. Hydrogen-terminated mesoporous silicon monoliths with huge surface area as alternative Si-based visible light-active photocatalysts

    KAUST Repository

    Li, Ting

    2016-07-21

    Silicon-based nanostructures and their related composites have drawn tremendous research interest in solar energy storage and conversion. Mesoporous silicon with a huge surface area of 400-900 m2 g-1 developed by electrochemical etching exhibits excellent photocatalytic ability and stability after 10 cycles in degrading methyl orange under visible light irradiation, owing to its unique mesoporous network, abundant surface hydrides and efficient light harvesting. This work showcases the profound effects of surface area, crystallinity, pore topology on charge migration/recombination and mass transportation. Therein the ordered 1D channel array has outperformed the interconnected 3D porous network by greatly accelerating the mass diffusion and enhancing the accessibility of the active sites on the extensive surfaces. © 2016 The Royal Society of Chemistry.

  12. Composites of Laminar Nanostructured ZnO and VOx-Nanotubes Hybrid as Visible Light Active Photocatalysts

    Directory of Open Access Journals (Sweden)

    Eglantina Benavente

    2018-02-01

    Full Text Available A series of hybrid heterostructured nanocomposites of ZnO with V2O5 nanotubes (VOx-NTs in different mixing ratios were synthesized, with the aim of reducing the recombination of photoinduced charge carriers and to optimize the absorption of visible light. The study was focused on the use of heterostructured semiconductors that can extend light absorption to the visible range and enhance the photocatalytic performance of ZnO in the degradation of methylene blue as a model pollutant. The addition of VOx-NTs in the synthesis mixture led to a remarkable performance in the degradation of the model dye, with hybrid ZnO (stearic acid/VOx-NTs at a ratio of 1:0.06 possessing the highest photocatalytic activity, about seven times faster than pristine zinc oxide. Diffuse reflectance spectroscopic measurements and experiments in the presence of different trapping elements allowed us to draw conclusions regarding the band positions and photocatalytic degradation mechanism. The photocatalytic activity measured in three subsequent cycles showed good reusability as no significant loss in efficiency of dye degradation was observed.

  13. Biomimetic synthesis of TiO₂-SiO₂-Ag nanocomposites with enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Liu, Chuang; Yang, Dong; Jiao, Yang; Tian, Yao; Wang, Yuangui; Jiang, Zhongyi

    2013-05-01

    Ternary TiO2-SiO2-Ag nanocomposites with enhanced visible-light photocatalytic activity have been synthesized through a facile biomimetic approach by utilizing lysozyme as both inducing agent of TiO2 and reducing agent of Ag(+). TiO2 nanoparticles (∼280 nm) are at first fabricated by the inducing of lysozyme. Afterward, SiO2 layers are formed as "pancakes" stuck out of TiO2 nanoparticles through a sol-gel process. Finally, Ag nanocrystals (∼24.5 nm) are deposited onto the surface of TiO2-SiO2 composites via the reduction of lysozyme, forming TiO2-SiO2-Ag nanocomposites. The resultant nanocomposites display a high photocatalytic activity for the degradation of Rhodamine B under the visible-light irradiation, which can be attributed to the synergistic effect of enhanced photon absorption from the surface plasma resonance of Ag nanocrystals and the elevated adsorption capacity for Rhodamine B from the high specific surface area of SiO2. This study may provide some inspiration for the rational design and the facile synthesis of composite catalysts with a high and tunable catalytic property through a green, efficient pathway.

  14. Improved Visible Light Photocatalytic Activity for TiO2 Nanomaterials by Codoping with Zinc and Sulfur

    Directory of Open Access Journals (Sweden)

    Qianzhi Xu

    2015-01-01

    Full Text Available S/Zn codoped TiO2 nanomaterials were synthesized by a sol-gel method. X-ray diffraction, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy, photoluminescence spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the morphology, structure, and optical properties of the prepared samples. The introduction of Zn and S resulted in significant red shift of absorption edge for TiO2-based nanomaterials. The photocatalytic activity was evaluated by degrading reactive brilliant red X-3B solution under simulated sunlight irradiation. The results showed S/Zn codoped TiO2 exhibited higher photocatalytic activity than pure TiO2 and commercial P25, due to the photosynergistic effect of obvious visible light absorption, efficient separation of photoinduced charge carriers, and large surface area. Moreover, the content of Zn and S in the composites played important roles in photocatalytic activity of TiO2-based nanomaterials.

  15. Synthesis and characterization of chitosan-TiO2:Cu nanocomposite and their enhanced antimicrobial activity with visible light.

    Science.gov (United States)

    Raut, A V; Yadav, H M; Gnanamani, A; Pushpavanam, S; Pawar, S H

    2016-12-01

    In the present investigation, novel strategy for the preparation of hybrid nanocomposite containing organic polymer (Chitosan) and inorganic (TiO2:Cu) nanoparticles (NPs) has been developed and demonstrated its biomedical application. The sol-gel and ultra-sonication method assisted for the preparation of uniformly distributed Chitosan-TiO2:Cu (CS-CT) nanocomposite. The structural properties of prepared CS-CT nanocomposite were studied by XRD and FTIR techniques. The XPS was used to estimate elemental composition of the nanocomposite. Thermal properties were studied using TGA. TEM and SEM analysis showed the non-spherical nature of NPs with the average mean diameter 16nm. The optical properties were analyzed with UV-vis diffuse reflectance spectroscopy to confirm optical absorption in the visible region of light. Where CS-CT showed 200% enhanced light mediated photocatalytic antimicrobial activity against microorganism (Escherichia coli and Staphylococcus aureus) as compared with control. The antimicrobial activity of CS-CT nanocomposite in presence of light is found to be enhanced than that of its components, this is due to synergistic effect of organic and inorganic material complimenting each other's activity. The OH radicals release studied by PL spectroscopy on the surface of nanocomposite was used to examine antibacterial activity. Cytotoxicity assessment of CS-CT on human fibroblast cells was performed by MTT assay. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Visible-light activate Ag/WO3 films based on wood with enhanced negative oxygen ions production properties

    Science.gov (United States)

    Gao, Likun; Gan, Wentao; Cao, Guoliang; Zhan, Xianxu; Qiang, Tiangang; Li, Jian

    2017-12-01

    The Ag/WO3-wood was fabricated through a hydrothermal method and a silver mirror reaction. The system of visible-light activate Ag/WO3-wood was used to produce negative oxygen ions, and the effect of Ag nanoparticles on negative oxygen ions production was investigated. From the results of negative oxygen ions production tests, it can be observed that the sample doped with Ag nanoparticles, the concentration of negative oxygen ions is up to 1660 ions/cm3 after 60 min visible light irradiation. Moreover, for the Ag/WO3-wood, even after 60 min without irradiation, the concentration of negative oxygen ions could keep more than 1000 ions/cm3, which is up to the standard of the fresh air. Moreover, due to the porous structure of wood, the wood acted as substrate could promote the nucleation of nanoparticles, prevent the agglomeration of the particles, and thus lead the improvement of photocatalytic properties. And such wood-based functional materials with the property of negative oxygen ions production could be one of the most promising materials in the application of indoor decoration materials, which would meet people's pursuit of healthy, environment-friendly life.

  17. One-pot synthesis of hierarchical Cu2O/Cu hollow microspheres with enhanced visible-light photocatalytic activity

    Science.gov (United States)

    Hong, Tianjie; Tao, Feifei; Lin, Jiudong; Ding, Wei; Lan, Mingxuan

    2015-08-01

    The hierarchical Cu2O/Cu hollow microspheres have been fabricated by the one-pot solvothermal redox method, which is one-step approach without any surfactant and template. By using the HRTEM, XRD, XPS and UV-vis spectroscopy, the as-prepared product is composed of Cu2O and Cu with energy band gap of 1.72 eV. Based on the time-dependent experiments, the content of Cu2O and Cu compositions can be effectively controlled by adjusting the reaction time and a possible mechanism is proposed. In addition, using various dye molecules to stimulate pollutants, the hierarchical Cu2O/Cu hollow microspheres reacted for 8 h exhibit excellent visible-light photocatalytic activities, which is much higher than those of the Cu2O/Cu catalysts formed at the shorter reaction time, commercial Cu2O powder and the mixture of alone Cu2O and Cu. This enhanced photocatalytic performance makes these hierarchical Cu2O/Cu hollow microspheres a kind of efficient visible-light photocatalyst in removing some organic compounds in wastewater.

  18. Synthesis and characterization of LaFeO3/TiO2 nanocomposites for visible light photocatalytic activity

    Science.gov (United States)

    Dhinesh Kumar, R.; Thangappan, R.; Jayavel, R.

    2017-02-01

    LaFeO3/TiO2 nanocomposites were successfully synthesized by hydrothermal method. The as-prepared nanoparticles were characterized by TGA, XRD, HRSEM, EDS, TEM, VSM and UV-Vis techniques. Thermal stability of the material was studied by thermal analysis. XRD studies confirm the orthorhombic and rutile phase for pure LaFeO3 and TiO2 nanoparticles. The LaFeO3/TiO2 composite shows the coexistence of LaFeO3 and TiO2 phases with no extra peaks. Morphological analysis shows the spherical nanoparticles and the average particle size of LaFeO3, TiO2 and LaFeO3/TiO2 was around 60 nm. The LaFeO3/TiO2 nanocomposites show a significant shift in the UV-vis absorption spectra in comparison with both TiO2 and LaFeO3 nanoparticles. The photocatalytic activity of the samples were tested for the degradation of methyl orange (MO) in aqueous solutions under visible light irradiations for 180 min. The LaFeO3/TiO2 composite exhibits enhanced visible light photocatalytic properties in comparison with that of LaFeO3 nanoparticles.

  19. Solvothermal synthesis of graphene-Sb{sub 2}S{sub 3} composite and the degradation activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Wenguang; Chang, Jiuli; Wu, Dapeng [College of Chemistry and Chemical Engineering, Henan Normal University, Henan, Xinxiang 453007 (China); Gao, Zhiyong, E-mail: zygao512@163.com [College of Chemistry and Chemical Engineering, Henan Normal University, Henan, Xinxiang 453007 (China); Duan, Xiaoli [Engineering Technology Research Center of Motive Power and Key Materials, Henan, 453007 (China); Xu, Fang [College of Chemistry and Chemical Engineering, Henan Normal University, Henan, Xinxiang 453007 (China); Engineering Technology Research Center of Motive Power and Key Materials, Henan, 453007 (China); Jiang, Kai, E-mail: jiangkai6898@126.com [College of Chemistry and Chemical Engineering, Henan Normal University, Henan, Xinxiang 453007 (China); Engineering Technology Research Center of Motive Power and Key Materials, Henan, 453007 (China)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Graphene-Sb{sub 2}S{sub 3} composites were synthesized through a facile solvothermal method. ► Hydroxyl radicals are the main species responsible for the photodegradation activity. ► Graphene-Sb{sub 2}S{sub 3} demonstrated dramatically improved visible light degradation activity. -- Abstract: Novel graphene-Sb{sub 2}S{sub 3} (G-Sb{sub 2}S{sub 3}) composites were synthesized via a facile solvothermal method with graphene oxide (GO), SbCl{sub 3} and thiourea as the reactants. GO played an important role in controlling the size and the distribution of the formed Sb{sub 2}S{sub 3} nanoparticles on the graphene sheets with different density. Due to the negative surface charge, smaller Sb{sub 2}S{sub 3} particles size and efficient electrons transfer from Sb{sub 2}S{sub 3} to graphene, the composites demonstrated improved photodegradation activity on rhodamine B (RhB). Among these composites, the product G-Sb{sub 2}S{sub 3} 0.1, which was synthesized with the GO concentration of 0.1 mg/mL, exhibited the highest photodegradation activity owing to the considerable density of Sb{sub 2}S{sub 3} nanoparticles onto graphene sheet free of aggregation. Hydroxyl radicals (·OH) derived from conduction band (CB) electrons of Sb{sub 2}S{sub 3} is suggested to be responsible for the photodegradation of RhB. The high visible light degradation activity and the satisfactory cycling stability made the as-prepared G-Sb{sub 2}S{sub 3} 0.1 an applicable photocatalyst.

  20. Highly exposed surface area of {001} facets dominated BiOBr nanosheets with enhanced visible light photocatalytic activity.

    Science.gov (United States)

    Duan, Fang; Wang, Xiaofeng; Tan, Tingting; Chen, Mingqing

    2016-02-17

    Two groups of BiOBr nanosheets with different sizes and similar exposure percentages of {001} facets were selectively synthesized by simple hydrothermal methods. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity was estimated from the degradation of organic pollutants under visible-light irradiation. The results indicated that BiOBr nanosheets with similar exposure percentages of {001} facets but smaller sizes exhibited higher photocatalytic activity. Furthermore, the effects of the size, including the thickness and length, of BiOBr nanosheets were also studied. The results showed that the impact of thickness was more significant than that of length. It was found that reducing the thickness of BiOBr nanosheets can significantly increase the exposed surface areas of {001} facets (S{001}), but not necessarily the exposure percentage of {001} facets. Moreover, in our experiment, the photocatalytic activity of BiOBr nanosheets increased linearly with an increase in S{001} in the range of 0.022 to 0.111 nm(-1). Therefore, the photocatalytic activity of BiOBr nanosheets depended on the exposed surface areas of {001} facets rather than the exposure percentage of {001} facets. The enhancement of the photocatalytic activity of ultrathin BiOBr nanosheets with large exposed surface areas of {001} facets can be mainly ascribed to their enhanced absorption of visible light and improved separation efficiency of charge carriers.

  1. Bi(1-x)Ni(x)VO(4-y) Solid Solution with a High Visible-Light Photocatalytic Activity for Degradation Methyl Orange.

    Science.gov (United States)

    Wang Jing; Wei, Yuelin; Huang, Yunfang; Wu, Jihuai; Dong, Qiang; Yin, Shu; Sato, Tsugio

    2015-09-01

    Particulate solid solutions Bi(1-x)Ni(x)VO(4-y) were synthesized by solid-state reaction at high temperature. The samples were characterized by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectrometer (EDS), Brunauer-Emmett-Teller (BET) surface area and Ultraviolet-Visible spectroscopy (UV-Vis). The photocatalytic activity of BiVO4 for photocatalytic degradation of organic contaminants ability in visible light region could be improved by doping of Ni(2+). The high visible light photocatalytic activity of Bi(1-x)Ni(x)VO(4-y) solid solution might be due to the generation of a new band gap and expanding the range of visible light response. It was suggested that the Ni(2+) doping was beneficial to effective charge separation of Bi(1-x)Ni(x)VO(4-y) solid solution, thus improved the photocatalytic activity.

  2. Nanotechnology in environmental remediation: degradation of volatile organic compounds (VOCs) over visible-light-active nanostructured materials.

    Science.gov (United States)

    Selvaraj, Rengaraj; Al-Kindy, Salma M Z; Silanpaa, Mika; Kim, Younghun

    2014-01-01

    Volatile organic compounds (VOCs) are major pollutants and are considered to be one of the most important contaminants generated by human beings living in urban and industrial areas. Methyl tert-butyl ether (MTBE) is a VOC that has been widely used as a gasoline additive to reduce VOC emissions from motor vehicles. However, new gasoline additives like MTBE are having negative environmental impacts. Recent survey reports clearly show that groundwater is often polluted owing to leakage of petroleum products from underground storage tanks. MTBE is highly soluble in water (e.g., 0.35-0.71 M) and has been detected at high concentrations in groundwater. The presence of MTBE in groundwater poses a potential health problem. The documented effects of MTBE exposure are headaches, vomiting, diarrhea, fever, cough, muscle aches, sleepiness, disorientation, dizziness, and skin and eye irritation. To address these problems, photocatalytic treatment is the preferred treatment for polluted water. In the present work, a simple and template-free solution phase synthesis method has been developed for the preparation of novel cadmium sulfide (CdS) hollow microspheres using cadmium nitrate and thioacetamide precursors. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction, high-resolution scanning electron microscopy (HR-SEM), X-ray photoelectron spectroscopy, and UV-visible diffused reflectance spectroscopy. The HR-SEM measurements revealed the spherical morphology of the CdS microspheres, which evolved by the oriented aggregation of the primary CdS nanocrystals. Furthermore, studies of photocatalytic activity revealed that the synthesized CdS hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading MTBE in aqueous solution under visible light illumination. These results suggest that CdS microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light

  3. Preparation of g-C3N4/Ta2O5 Composites with Enhanced Visible-Light Photocatalytic Activity

    Science.gov (United States)

    Vo, Vien; Van Kim, Nguyen; Nga, Nguyen Thi Viet; Trung, Nguyen Tien; Giang, Le Truong; Van Hanh, Pham; Hoang, Luc Huy; Kim, Sung-Jin

    2016-05-01

    g-C3N4/Ta2O5 composites have been synthesized by a facile route in which mixtures of Ta2O5 and urea are heated at various temperatures of 450°C, 500°C, and 550°C. The obtained materials (denoted as CN/TaO- T, where T is the heating temperature) were characterized using x-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, diffuse-reflectance ultraviolet-visible (UV-Vis) spectroscopy, thermogravimetric analysis, and x-ray photoelectron spectroscopy. The results show that the as-prepared composites are in orthorhombic Ta2O5 phase coated by g-C3N4. The photocatalytic activity of the composites was evaluated by photodegradation of methylene blue under visible light. Among the three materials, CN/TaO-500 exhibited the highest photocatalytic activity. The improved photocatalytic activity of the g-C3N4/Ta2O5 composites is attributed to the presence of g-C3N4 in the materials.

  4. Significantly enhanced photocatalytic activity of visible light responsive AgBr/Bi2Sn2O7 heterostructured composites

    Science.gov (United States)

    Hu, Chaohao; Zhuang, Jing; Zhong, Liansheng; Zhong, Yan; Wang, Dianhui; Zhou, Huaiying

    2017-12-01

    Heterostructured AgBr/Bi2Sn2O7 photocatalysts were synthesized successfully via the ultrasonic-assisted chemical precipitation method. XRD, FT-IR, FE-SEM, TEM, XPS, UV-vis-DRS and PL spectroscopy were used to characterize the phase structure, morphology, chemical composition, oxidation state, and optical properties of AgBr/Bi2Sn2O7 heterojunction. The photocatalytic activity of as-prepared catalysts was evaluated by the degradation of RhB under visible light irradiation. The obtained AgBr/Bi2Sn2O7 composite with the 1:1 molar ratio exhibited significantly enhanced photocatalytic performance. Further first-principles calculations indicated that the hybridization interaction between Ag and O atoms at AgBr/Bi2Sn2O7 interface is expected to be beneficial for enhancing the charge transfer and improving the photocatalytic activity of heterostructured composites.

  5. Antibacterial Activity of Hydrophobic Composite Materials Containing a Visible-Light-Sensitive Photocatalyst

    Directory of Open Access Journals (Sweden)

    Kentaro Yamauchi

    2011-01-01

    Full Text Available The conventional superhydrophobic surface offered by PTFE provides no sterilization performance and is not sufficiently repellent against organic liquids. These limit PTFE's application in the field of disinfection and result a lack of durability. N-doped TiO2 photocatalyst added PTFE composite material was developed to remedy these shortcomings. This paper reports the surface characteristics, and the bactericidal and self-cleaning performance of the newly-developed composite material. The material exhibited a contact angle exceeding 150 degrees consistent with its hydrophobicity despite the inclusion of the hydrophilic N-doped TiO2. The surface free energy obtained for this composite was 5.8 mN/m. Even when exposed to a weak fluorescent light intensity (100 lx for 24 hours, the viable cells of gram-negative E. coli on the 12% N-doped TiO2-PTFE film were reduced 5 logs. The higher bactericidal activity was also confirmed on the gram-positive MRSA. Compared with the N-doped TiO2 coating only, the inactivation rate of the composite material was significantly enhanced. Utilizing the N-doped TiO2 with the PTFE composite coating could successfully remove, by UV illumination, oleic acid adsorbed on its surface. These results demonstrate the potential applicability of the novel N-doped TiO2 photocatalyst hydrophobic composite material for both indoor antibacterial action and outdoor contamination prevention.

  6. 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.

  7. Facile preparation of C, N co-modified Nb2O5 nanoneedles with enhanced visible light photocatalytic activity

    KAUST Repository

    Xue, Jiao

    2016-09-28

    C, N co-modified niobium pentoxide (Nb2O5) nanoneedles have been successfully synthesized via a facile hydrothermal method with Niobium Chloride (NbCl5) as a precursor and triethylamine as both the carbon and nitrogen source. The formation process of Nb2O5 nanoneedles has been presented in detail by investigating the effect of the crystallization temperature, the amount of triethylamine and the calcination temperature. The as-prepared Nb2O5 nanoneedles exhibit more efficient photocatalytic activity than commercial Degussa P25 and commercial Nb2O5 towards photodegradation of Rhodamine B (RhB) at a concentration of 10 mg L−1 under visible light. Special chemical species, such as carbonate species and NOX species, that exist on the surface of the as-prepared catalyst could extend the absorption into the visible region and thus enhance the photocatalytic activity of the Nb2O5 nanoneedles. At the same time, the obtained Nb2O5 nanoneedles exhibit excellent stability even after three successive cycles. A possible photodegradation mechanism was proposed and the corresponding photodecomposition process of RhB over the Nb2O5 nanoneedles was elucidated by a reactive species trapping experiment, suggesting that h+ and O2˙− play a major role in the photodegradation of RhB in aqueous solution.

  8. Synthesis and characterization of Cu2O-modified Bi2O3 nanospheres with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Luo, Yidan; Huang, Qingqing; Li, Bin; Dong, Lihui; Fan, Minguang; Zhang, Feiyue

    2015-12-01

    In this work, a series of Cu2O-modified Bi2O3 nanospheres with perfect visible-light catalytic activity were successfully synthesized via the two-step method. The obtained products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, UV-visible diffuse reflectance spectroscopy (UV-vis DRS), and X-ray photoelectron spectroscopy (XPS). In the catalysts of Cu2O-modified Bi2O3 nanospheres, Cu2O was dispersed on the surface of Bi2O3 nanospheres. All of Cu2O-modified Bi2O3 nanospheres showed uniformly nanospheres with the size of 80-150 nm, and exhibited enhanced photocatalytic activity in the degradation of Rhodamine B. The higher BET surface area, the band gap narrowing, and the interfacial charge transfer effect were considered to cause the excellent photocatalysis of Cu2O loading Bi2O3 samples. Furthermore, the possible photocatalysis mechanism was proposed.

  9. Preparation of visible-light-activated metal complexes and their use in photoredox/nickel dual catalysis.

    Science.gov (United States)

    Kelly, Christopher B; Patel, Niki R; Primer, David N; Jouffroy, Matthieu; Tellis, John C; Molander, Gary A

    2017-03-01

    Visible-light-activated photoredox catalysts provide synthetic chemists with the unprecedented capability to harness reactive radicals through discrete, single-electron transfer (SET) events. This protocol describes the synthesis of two transition metal complexes, [Ir{dF(CF3)2ppy}2(bpy)]PF6 (1a) and [Ru(bpy)3](PF6)2 (2a), that are activated by visible light. These photoredox catalysts are SET agents that can be used to facilitate transformations ranging from proton-coupled electron-transfer-mediated cyclizations to C-C bond constructions, dehalogenations, and H-atom abstractions. These photocatalysts have been used in the synthesis of medicinally relevant compounds for drug discovery, as well as the degradation of biological polymers to access fine chemicals. These catalysts are prepared from IrCl3 and RuCl3, respectively, in three chemical steps. These steps can be described as a series of two ligand modifications followed by an anion metathesis. Using the cost-effective, scalable procedures described here, the ruthenium-based photocatalyst 2a can be synthesized in a 78% overall yield (∼8.1 g), and the iridium-based photocatalyst 1a can be prepared in a 56% overall yield (∼4.4 g). The total time necessary for the complete protocols ranges from ∼2 d for 2a to 5-7 d for 1a. Procedures for applying each catalyst in representative photoredox/Ni cross-coupling to form Csp3-Csp2 bonds using the appropriate radical precursor-organotrifluoroborates with 1a and bis(catecholato)alkylsilicates with 2a-are described. In addition, more traditional photoredox-mediated transformations are included as diagnostic tests for catalytic activity.

  10. An ion exchange strategy to BiOI/CH3COO(BiO) heterojunction with enhanced visible-light photocatalytic activity

    Science.gov (United States)

    Han, Qiaofeng; Yang, Zhen; Wang, Li; Shen, Zichen; Wang, Xin; Zhu, Junwu; Jiang, Xiaohong

    2017-05-01

    It is very significant to develop CH3COO(BiO) (denoted as BiOAc) based photocatalysts for the removal of pollutants due to its non-toxicity and availability. We previously reported that BiOAc exhibited excellent photocatalytic activity for rhodamine B (RhB) degradation under UV light irradiation. Herein, by an ion exchange approach, BiOI/BiOAc heterojunction could be easily obtained. The as-prepared heterojunction possessed enhanced photodegradation activity for multiple dyes including RhB and methyl orange (MO) under visible light illumination in comparison with individual materials. Good visible-light photocatalytic activity of the heterojunction could be attributed to the increased visible light response, effective charge transfer from the modified band position and close interfacial contact due to partial ion exchange method.

  11. Ag/Bi2WO6 prepared by photo-reduction method and its visible-light photocatalytic activity

    Directory of Open Access Journals (Sweden)

    PAN Gaifang

    2016-12-01

    Full Text Available In this paper,an ionic liquid assisted solvothermal process has been developed to synthesize the Bi2WO6 photocatalyst.Furthermore,Ag/Bi2WO6 was prepared by aphoto-reduction method.The relationships between catalyst structure and catalysis performance were discussed in detail.Ag nanoparticles deposited on the surface of Bi2WO6 enhanced the absorption of visible light and improved the separation efficiency of the carrier via plasma resonance effect.Ag/Bi2WO6 catalyst with 0.75% (mole fraction Ag/Bi and photo-reduction time of 20 min has been confirmed to have the best photocatalytic activity.

  12. Improving the visible light photocatalytic activity of TiO{sub 2} by combining sulfur doping and rectorite carrier

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Xianzhong, E-mail: buxianzhongsx@163.com [College of Materials and Mineral Resources, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Wang, Yang [College of Materials and Mineral Resources, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Li, Ji [Shaanxi Yanchang Petroleum Mining Industry Co., Ltd., Xi’an 710075 (China); Zhang, Chonghui [College of Materials and Mineral Resources, Xi’an University of Architecture and Technology, Xi’an 710055 (China)

    2015-04-15

    Highlights: • Dimethyl sulfoxide was used as the sources of S to prepare sulfur-doped TiO{sub 2}. • Combination of S-doping and clay carrier enhanced the photocatalytic performance of TiO{sub 2}. • Sulfur-doped TiO{sub 2}/rectorite catalysts showed high performance for photocatalytic degradation of metronidazolein under visible light irradiation. • The photocatalytic activity improvement was ascribed to the increased specific surface area, the narrowed band gap and the reduced electron–hole recombination. - Abstract: Sulfur-doped TiO{sub 2}/rectorite (STC) was prepared by an intercalation method using tetra-n-butyl titanate and dimethyl sulfoxide as the sources of Ti and S, respectively. A number of characterization methods including X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption/desorption measurements, X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (UV–vis DRS) and photoluminescence spectroscopy (PL) were used to understand the properties of STC. It was found that the layer structure of rectorite was partly destroyed by intercalation, and the STC showed a looser porous lamellar structure with a large specific surface area (187.5 m{sup 2}/g). By doping S into TiO{sub 2} lattice as Ti–O–S bond, the band gap of TiO{sub 2} was reduced from 3.2 to 2.8 eV. The removal of metronidazole by the STC under visible light irradiation for 240 min reached 93.8%, which was 71.8% higher than that of P25 TiO{sub 2}. The improved photocatalytic activity was ascribed to the increased specific surface area, the narrowed band gap and the reduced electron–hole recombination.

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

    Science.gov (United States)

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

    2015-10-01

    In this work, Ag nanoparticles were loaded by chemical reduction onto TiO2 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 TiO2/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). TiO2/Ag/rGO coupled nanocomposite presented significantly enhanced photocatalytic activity compared to the TiO2/Ag, TiO2/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 TiO2/Ag/rGO nanocatalyst, while the respective removal efficiency was 92% for TiO2/Ag, 93% for TiO2/rGO and only 80% for the bare TiO2 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.

  14. 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.

  15. Active tracking system for visible light communication using a GaN-based micro-LED and NRZ-OOK.

    Science.gov (United States)

    Lu, Zhijian; Tian, Pengfei; Chen, Hong; Baranowski, Izak; Fu, Houqiang; Huang, Xuanqi; Montes, Jossue; Fan, Youyou; Wang, Hongyi; Liu, Xiaoyan; Liu, Ran; Zhao, Yuji

    2017-07-24

    Visible light communication (VLC) holds the promise of a high-speed wireless network for indoor applications and competes with 5G radio frequency (RF) system. Although the breakthrough of gallium nitride (GaN) based micro-light-emitting-diodes (micro-LEDs) increases the -3dB modulation bandwidth exceptionally from tens of MHz to hundreds of MHz, the light collected onto a fast photo receiver drops dramatically, which determines the signal to noise ratio (SNR) of VLC. To fully implement the practical high data-rate VLC link enabled by a GaN-based micro-LED, it requires focusing optics and a tracking system. In this paper, we demonstrate an active on-chip tracking system for VLC using a GaN-based micro-LED and none-return-to-zero on-off keying (NRZ-OOK). Using this novel technique, the field of view (FOV) was enlarged to 120° and data rates up to 600 Mbps at a bit error rate (BER) of 2.1×10(-4) were achieved without manual focusing. This paper demonstrates the establishment of a VLC physical link that shows enhanced communication quality by orders of magnitude, making it optimized for practical communication applications.

  16. Reduced graphene oxides loaded-ZnS/CuS heteronanostructures as high-activity visible-light-driven photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Bin [College of Materials Science and Engineering, Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082 (China); College of Mechanical Engineering, Hunan University of Arts and Science, Changde 415000 (China); Chen, Xiaohua, E-mail: 240939138@qq.com [College of Materials Science and Engineering, Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082 (China); Chen, Chuansheng; Ning, Xutao; Deng, Weina [College of Materials Science and Engineering, Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082 (China)

    2014-01-05

    Highlights: • The nanocomposite of ZnS/CuS heterostructures decorated rGO is prepared. • Electrons in rGO have efficient oxygen reduction power. • Holes in the ZnS have high oxidation power. • The charge transfers between ZnS, CuS and rGO are proposed. -- Abstract: The reduced graphene oxides (rGO) loaded-ZnS/CuS heteronanostructures have been successfully prepared for the first time. Scanning electron microscopy and transmission electron microscopy observations confirm that ZnS/CuS heteronanostructures are decorated on the rGO. The experimental results reveal that these novel nanostructures exhibit a visible-light photocatalytic activities for methyl orange (MO) dye degradation. The high visible photocatalytic performances are attributed to photoinduced interfacial charge transfer in the heteronanostructures and their further separation and transfer by rGO. This new nanostructure is expected to show considerable potential applications in water purification as well as optoelectronic fields at a large scale.

  17. The composite of nitrogen-doped anatase titania plates with exposed {001} facets/graphene nanosheets for enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Shi, Jian-Wen; Ai, Hui-Ying; Chen, Jian-Wei; Cui, Hao-Jie; Fu, Ming-Lai

    2014-09-15

    Composite photocatalysts composed of nitrogen-doped anatase TiO2 plates with exposed {001} facets (NTS) and graphene nanosheets (G) were firstly synthesized by a facile one-pot hydrothermal process. The morphologies, structural properties, and photocatalytic activities of the resultant NTS/G composites were investigated in detail. Graphene nanosheets were demonstrated play three important roles in the NTS/G composites, as transporter of photo-excited electrons, extender of light absorption range and enhancer of adsorptive capacity, respectively. Due to the effective charge anti-recombination, the efficient utilization of the visible light and the high adsorptive capacity to target pollutants, the composites exhibited significant improvement in photocatalytic degradation of methylene blue under visible light irradiation. Based on the results, the mechanism of enhanced visible-light photocatalytic activity on NTS/G composites was proposed. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Mutagenesis by near-visible light.

    Science.gov (United States)

    Kubitschek, H E

    1967-03-24

    Mutants resistant to bacter iophage T5 were produced both in continuous and in stationary cultures of Escherichia coli by near-visible light, 320 to 400 millimicrons, at rates greatly exceeding spontaneous rates in the ab sence of light. Aerobic mutation rates were about twice anaerobic rates, which shows that mutations were induced in either of at least two different proces ses. Mutations induced by near-visible light involve different photochemical processes than those induced by ul traviolet light.

  19. In vitro and in vivo antimicrobial activity of combined therapy of silver nanoparticles and visible blue light against Pseudomonas aeruginosa.

    Science.gov (United States)

    Nour El Din, Suzanne; El-Tayeb, Tarek A; Abou-Aisha, Khaled; El-Azizi, Mohamed

    2016-01-01

    Silver nanoparticles (AgNPs) have been used as potential antimicrobial agents against resistant pathogens. We investigated the possible therapeutic use of AgNPs in combination with visible blue light against a multidrug resistant clinical isolate of Pseudomonas aeruginosa in vitro and in vivo. The antibacterial activity of AgNPs against P. aeruginosa (1×10(5) colony forming unit/mL) was investigated at its minimal inhibitory concentration (MIC) and sub-MIC, alone and in combination with blue light at 460 nm and 250 mW for 2 hours. The effect of this combined therapy on the treated bacteria was then visualized using transmission electron microscope. The therapy was also assessed in the prevention of biofilm formation by P. aeruginosa on AgNP-impregnated gelatin biopolymer discs. Further, in vivo investigations were performed to evaluate the efficacy of the combined therapy to prevent burn-wound colonization and sepsis in mice and, finally, to treat a real infected horse with antibiotic-unresponsive chronic wound. The antimicrobial activity of AgNPs and visible blue light was significantly enhanced (P<0.001) when both agents were combined compared to each agent alone when AgNPs were tested at MIC, 1/2, or 1/4 MIC. Transmission electron microscope showed significant damage to the cells that were treated with the combined therapy compared to other cells that received either the AgNPs or blue light. In addition, the combined treatment significantly (P<0.001) inhibited biofilm formation by P. aeruginosa on gelatin discs compared to each agent individually. Finally, the combined therapy effectively treated a horse suffering from a chronic wound caused by mixed infection, where signs of improvement were observed after 1 week, and the wound completely healed after 4 weeks. To our knowledge, this combinatorial therapy has not been investigated before. It was proved efficient and promising in managing infections caused by multidrug resistant bacteria and could be used as an

  20. Preparation of chitosan-TiO2 composite film with efficient antimicrobial activities under visible light for food packaging applications.

    Science.gov (United States)

    Zhang, Xiaodong; Xiao, Gang; Wang, Yaoqiang; Zhao, Yan; Su, Haijia; Tan, Tianwei

    2017-08-01

    By incorporation of TiO2 nano-powder in chitosan, a chitosan-TiO2 composite film was prepared with efficient antimicrobial activity against food-borne pathogenic microbes and expected to be a promising food packaging material. Scanning electron microscopy analysis showed that the TiO2 nano-powder was successfully and uniformly dispersed into the chitosan matrix. TiO2 addition led to enhanced hydrophilicity, to better mechanical properties, and to decreased light transmittance in visible light region of the composite film. The chitosan-TiO2 film possessed efficient antimicrobial activity against four tested strains, i.e. Escherichia coli, Staphylococcus aureus, Candida albicans, and Aspergillus niger with 100% sterilization in 12h. It moreover provoked the leakage of cellular substances through damaged membrane. The prepared chitosan-TiO2 film was tested for packaging red grapes to prevent microbial infection and extend their shelf life. Results were positive, stressing the potential of the novel bio-nano composite film for food packaging applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Photocatalytic activity of attapulgite–BiOCl–TiO{sub 2} toward degradation of methyl orange under UV and visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lili, E-mail: zll@hytc.edu.cn; Zhang, Jiahui; Zhang, Weiguang; Liu, Jianquan; Zhong, Hui; Zhao, Yijiang

    2015-06-15

    Highlights: • Excellent photocatalyst was obtained by introducing BiOCl–TiO{sub 2} onto attapulgite. • 100 mg L{sup −1} methyl orange (MO) was totally decomposed under UV light within 70 min. • 92.6% of 10 mg L{sup −1} MO was decomposed within 120 min under visible light. • ATT–BiOCl–TiO{sub 2} show better activity than P{sub 25} especially under visible light. • Mechanism of photocatalytic activity enhancement was identified. - Abstract: An environmental friendly composite photocatalyst with efficient UV and visible light activity has been synthesized by introducing BiOCl–TiO{sub 2} hybrid oxide onto the surface of attapulgite (ATT) (denoted as ATT–BiOCl–TiO{sub 2}), using a simple in situ depositing technique. The obtained products were characterized by XRD, TEM, BET and UV–vis diffuse reflectance spectra measurements. Results showed that BiOCl–TiO{sub 2} composite particles were successfully loaded onto attapulgite fibers' surface without obvious aggregation. The photocatalytic activity of ATT–BiOCl–TiO{sub 2} was investigated by degradation of methyl orange under UV and visible light irradiation. It was found that 100 mg L{sup −1} methyl orange was totally decomposed under UV light within 70 min and 92.57% of 10 mg L{sup −1} methyl orange was decomposed under visible light within 120 min using ATT–BiOCl–TiO{sub 2} as photocatalyst. These results were quite better than that of P{sub 25}, especially under visible light irradiation. Possible mechanism for the enhancement was proposed.

  2. Effect of FeWO{sub 4} doping on the photocatalytic activity of ZnO under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Buvaneswari, K. [P.G. Department of Chemistry, Sir S. Ramasamy Naidu Memorial College, Sattur 626203, Tamilnadu (India); Karthiga, R.; Kavitha, B. [P.G. & Research Department of Chemistry, C.P.A. College, Bodinayakanur 625513, Tamilnadu (India); Rajarajan, M., E-mail: rajarajan_1962@yahoo.com [P.G. & Research Department of Chemistry, C.P.A. College, Bodinayakanur 625513, Tamilnadu (India); Suganthi, A. [P.G. & Research Department of Chemistry, Thiagarajar College, Madurai 625009, Tamilnadu (India)

    2015-11-30

    Highlights: • Novel FeWO{sub 4}/ZnO nanocomposites synthesized by co-precipitation method. • Nanocomposites were characterized by UV–vis-DRS, FT-IR, XRD, SEM, EDX, TEM and BET techniques. • FeWO{sub 4}/ZnO shows good photocatalytic activity towards degradation of FeWO{sub 4}/ZnO. - Abstract: FeWO{sub 4}/ZnO photocatalyst has been prepared by simple co-precipitation method and characterized using UV–vis diffuse reflectance spectroscopy (UV–vis-DRS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) techniques and Brunauer–Emmett–Teller (BET) techniques. The XRD results showed that the average particle size of ZnO, FeWO{sub 4} and FeWO{sub 4}/ZnO were found to be 31.17 nm, 63.53 nm and 22.59 nm respectively. The prepared photocatalyst composed of rod and plate with little agglomeration is seen from SEM result. The specific surface area of the as prepared FeWO{sub 4}/ZnO photocatalyst was estimated to be 31.3379 m{sup 2}/g. The photocatalyst can degrade methylene blue (MB), an azo dye extensively used in textile and paper industries in water under visible light irradiation. The effect of various parameters such as irradiation time, initial dye concentration, pH and catalyst concentration has been investigated in detail. FeWO{sub 4}/ZnO photocatalyst (0.04 g/L) in the molar ratio of 1:0.5 calcination at 500 °C can effectively degrade about 96% of (20 μm) MB at a pH of about 10 by 180 min illumination in visible light. In all the degradation studies the reaction follows first order kinetics.

  3. Composite multi-lobe descriptor for cross spectral face recognition: matching active IR to visible light images

    Science.gov (United States)

    Cao, Zhicheng; Schmid, Natalia A.

    2015-05-01

    Matching facial images across electromagnetic spectrum presents a challenging problem in the field of biometrics and identity management. An example of this problem includes cross spectral matching of active infrared (IR) face images or thermal IR face images against a dataset of visible light images. This paper describes a new operator named Composite Multi-Lobe Descriptor (CMLD) for facial feature extraction in cross spectral matching of near-infrared (NIR) or short-wave infrared (SWIR) against visible light images. The new operator is inspired by the design of ordinal measures. The operator combines Gaussian-based multi-lobe kernel functions, Local Binary Pattern (LBP), generalized LBP (GLBP) and Weber Local Descriptor (WLD) and modifies them into multi-lobe functions with smoothed neighborhoods. The new operator encodes both the magnitude and phase responses of Gabor filters. The combining of LBP and WLD utilizes both the orientation and intensity information of edges. Introduction of multi-lobe functions with smoothed neighborhoods further makes the proposed operator robust against noise and poor image quality. Output templates are transformed into histograms and then compared by means of a symmetric Kullback-Leibler metric resulting in a matching score. The performance of the multi-lobe descriptor is compared with that of other operators such as LBP, Histogram of Oriented Gradients (HOG), ordinal measures, and their combinations. The experimental results show that in many cases the proposed method, CMLD, outperforms the other operators and their combinations. In addition to different infrared spectra, various standoff distances from close-up (1.5 m) to intermediate (50 m) and long (106 m) are also investigated in this paper. Performance of CMLD is evaluated for of each of the three cases of distances.

  4. White LED visible light communication technology research

    Science.gov (United States)

    Yang, Chao

    2017-03-01

    Visible light communication is a new type of wireless optical communication technology. White LED to the success of development, the LED lighting technology is facing a new revolution. Because the LED has high sensitivity, modulation, the advantages of good performance, large transmission power, can make it in light transmission light signal at the same time. Use white LED light-emitting characteristics, on the modulation signals to the visible light transmission, can constitute a LED visible light communication system. We built a small visible optical communication system. The system composition and structure has certain value in the field of practical application, and we also research the key technology of transmitters and receivers, the key problem has been resolved. By studying on the optical and LED the characteristics of a high speed modulation driving circuit and a high sensitive receiving circuit was designed. And information transmission through the single chip microcomputer test, a preliminary verification has realized the data transmission function.

  5. Visible light photocatalytic H2-production activity of wide band gap ZnS nanoparticles based on the photosensitization of grapheme.

    Science.gov (United States)

    Wang, Faze; Zheng, Maojun; Zhu, Changqing; Zhang, Bin; Chen, Wen; Ma, Li; Shen, Wenzhong

    2015-08-28

    Visible light photocatalytic H(2) production from water splitting is considered an attractive way to solve the increasing global energy crisis in modern life. In this study, a series of zinc sulfide nanoparticles and graphene (GR) sheet composites were synthesized by a two-step hydrothermal method, which used zinc chloride, sodium sulfide, and graphite oxide (GO) as the starting materials. The as-prepared ZnS-GR showed highly efficient visible light photocatalytic activity in hydrogen generation. The morphology and structure of the composites obtained by transmission electron microscope and x-ray diffraction exhibited a small crystallite size and a good interfacial contact between the ZnS nanoparticles and the two-dimensional (2D) GR sheet,which were beneficial for the photocatalysis. When the content of the GR in the catalyst was 0.1%, the ZG0.1 sample exhibited the highest H(2)-production rate of 7.42 μmol h(−1) g(−1), eight times more than the pure ZnS sample. This high visible-light photocatalytic H(2) production activity is attributed to the photosensitization of GR. Irradiated by visible light, the electrons photogenerated from GR transfer to the conduction band of ZnS to participate in the photocatalytic process. This study presents the visible-light photocatalytic activity of wide bandgap ZnS and its application in H(2) evolution.

  6. Cationic (V, Y)-codoped TiO2 with enhanced visible light induced photocatalytic activity: A combined experimental and theoretical study

    Science.gov (United States)

    Khan, Matiullah; Cao, Wenbin

    2013-11-01

    To employ TiO2 as an efficient photocatalyst, high reactivity under visible light and improved separation of photoexcited carriers are required. An effective co-doping approach is applied to modify the photocatalytic properties of TiO2 by doping vanadium (transition metal) and yttrium (rare earth element). V and/or Y codoped TiO2 was prepared using hydrothermal method without any post calcination for crystallization. Based on density functional theory, compensated and noncompensated V, Y codoped TiO2 models were constructed and their structural, electronic, and optical properties were calculated. Through combined experimental characterization and theoretical modeling, V, Y codoped TiO2 exhibited high absorption coefficient with enhanced visible light absorption. All the prepared samples showed pure anatase phase and spherical morphology with uniform particle distribution. Electronic band structure demonstrates that V, Y codoping drastically reduced the band gap of TiO2. It is found that both the doped V and Y exist in the form of substitutional point defects replacing Ti atom in the lattice. The photocatalytic activity, evaluated by the degradation of methyl orange, displays that the codoped TiO2 sample exhibits enhanced visible light photocatalytic activity. The synergistic effects of V and Y drastically improved the Brunauer-Emmett-Teller specific surface area, visible light absorption, and electron-hole pair's separation leading to the enhanced visible light catalytic activity.

  7. Nanostructured composite material graphite/TiO2 and its antibacterial activity under visible light irradiation.

    Science.gov (United States)

    Dědková, Kateřina; Lang, Jaroslav; Matějová, Kateřina; Peikertová, Pavlína; Holešinský, Jan; Vodárek, Vlastimil; Kukutschová, Jana

    2015-08-01

    The paper addresses laboratory preparation, characterization and in vitro evaluation of antibacterial activity of graphite/TiO2 nanocomposites. Composites graphite/TiO2 with various ratio of TiO2 nanoparticles (30wt.%, and 50wt.%) to graphite were prepared using a thermal hydrolysis of titanylsulfate in the presence of graphite particles, and subsequently dried at 80°C. X-ray powder diffraction, transmission electron microscopy and Raman microspectroscopy served as phase-analytical methods distinguishing anatase and rutile phases in the prepared composites. Scanning and transmission electron microscopy techniques were used for characterization of morphology of the prepared samples. A developed modification of the standard microdilution test was used for in vitro evaluation of daylight induced antibacterial activity, using four common human pathogenic bacterial strains (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa). Antibacterial activity of the graphite/TiO2 nanocomposites could be based mainly on photocatalytic reaction with subsequent potential interaction of reactive oxygen species with bacterial cells. During the antibacterial activity experiments, the graphite/TiO2 nanocomposites exhibited antibacterial activity, where differences in the onset of activity and activity against bacterial strains were observed. The highest antibacterial activity evaluated as minimum inhibitory concentration was observed against P. aeruginosa after 180min of irradiation. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Controllable Fabrication of Ordered Mesoporous Bi2WO6 and Its High Photocatalytic Activity under Visible Light

    National Research Council Canada - National Science Library

    Xueming Dang; Xiaoli Dong; Hua Wang; Xiufang Zhang; Hongchao Ma; Mang Xue

    2014-01-01

    .... It was confirmed that the ordered mesoporous structure was obtained as the dosage of SBA-15 was 0.3 g. It was found that, compared to Bi2WO6, the RhB degradation rate with ordered mesoporous Bi2WO6 was enhanced under visible light...

  9. Integrated Bi2O3 nanostructure modified with Au nanoparticles for enhanced photocatalytic activity under visible light irradiation

    Directory of Open Access Journals (Sweden)

    Hankwon Lim

    2017-06-01

    Full Text Available An integrated Bi2O3 (i-Bi2O3 nanostructure with a particle size 10 nm inducing agglomerated structure were synthesized by dissolving bismuth nitrate pentahydrate in diethylene glycol at 180 °C with post heat treatment. The prepared i-Bi2O3 nanostructures were employed for the construction of Au/i-Bi2O3 composite system and characterized by X-ray diffraction pattern, UV–visible diffuse reflectance spectroscopy (DRS, and transmission electron microscopy, X-ray photoemission spectroscopy (XPS and Energy dispersive X-ray spectroscopy (EDS. The i-Bi2O3 nanostructure and Au/i-Bi2O3 composite system were found to exhibit high photocatalytic activity than commercial Bi2O3 in decomposing salicylic acid under visible light irradiation. The high catalytic activity of i-Bi2O3 nanostructure was deduced to be caused by charge separation facilitated by electron hopping between the particles within the integrated structure and space-charge separation between i-Bi2O3 and Au. The charge separation behavior in i-Bi2O3 nanostructure was further bolstered by comparing the measured. OH radical produced in the solution with i-Bi2O3 nanostructure, commercial Bi2O3 and Au/i-Bi2O3 composite which readily react with 1,4-terephthalic acid (TA inducing 2-hydroxy terephthalic acid (TAOH that shows unique fluorescence peak at 426 nm. The space-charge separation between i-Bi2O3 and Au was confirmed by measuring the electron spin resonance (ESR spectra.

  10. 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.

  11. Enhanced photocatalytic activity of calcined natural sphalerite under visible light irradiation

    Directory of Open Access Journals (Sweden)

    Abdulhamid Hamza

    2017-01-01

    Full Text Available The photocatalytic activity of natural sphalerite (the main mineral ore of ZnS is relatively low in the absence of sacrificial donors. Present work focuses on the improvement of the photocatalytic activity of a natural sphalerite obtained from Abuni deposit, Nigeria, via calcination at 600 °C, 700 °C and 800 °C. The raw and calcined natural sphalerite samples were characterized using X-ray diffraction (XRD, scanning electron microscopy (SEM, and specific surface area analysis. The activity of the raw and calcined samples was evaluated using photocatalytic decolorization of methyl orange (MO as the model reaction. The kinetics of photocatalytic decolorization of MO on the raw and calcined natural sphalerite samples was fitted to the pseudo-first order approximation of the Langmuir–Hinshelwood model. The photocatalytic activity of the natural sphalerite was doubled upon calcination at 700 °C. The natural sphalerite calcined at 700 °C is also more active than the ones calcined at 600 °C and 800 °C due to the combined effects of chemical composition, crystallite size, specific surface area and oxygen vacancies.

  12. Synthesis and visible-light-driven photocatalytic activity of p–n heterojunction Ag{sub 2}O/NaTaO{sub 3} nanocubes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Songbo [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Xu, Dongbo [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013 (China); Chen, Biyi; Luo, Bifu [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yan, Xu [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013 (China); Xiao, Lisong, E-mail: xiaolisong123@sina.com [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Shi, Weidong, E-mail: swd1978@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2016-10-15

    Highlights: • We firstly report a facile way to prepare the visible-light-driven Ag{sub 2}O/NaTaO{sub 3}p–n heterojunction by chemical precipitation method. • The Ag{sub 2}O/NaTaO{sub 3} heterojunction shows the highest photocatalytic activity than the pure NaTaO{sub 3} and Ag{sub 2}O nanoparticles under visible light. • The enhancement of the heterojunction photocatalytic activity was discussed and the photocatalytic mechanism was tested in our paper. • In summary, we think that the Ag{sub 2}O/NaTaO{sub 3} heterojunction with the strong visible light absorption and efficient photocatalytic activity have been extended application in photocatalysis for organic dyes pollutants degradation and purification of water. - Abstract: The constructing of p–n heterojunction photocatalytic system has received much attention in environmental purification and hydrogen generation from water. In this study, an efficient visible-light-driven p–n heterojunction Ag{sub 2}O/NaTaO{sub 3} was successfully prepared by chemical precipitation method at room temperature. It showed an enhanced photocatalytic activity for the degradation of rhodamine B (RhB) under visible-light irradiation, much higher than those of either individual Ag{sub 2}O or NaTaO{sub 3}. The reactive species scavenger results indicated the superoxide anion radicals (·O{sup 2−}) played key roles in RhB decoloration. From the experimental results and the relative band gap position of these semiconductors, a detailed possible photocatalytic mechanism of the Ag{sub 2}O/NaTaO{sub 3} heterojunction under visible light was proposed. The enhancement of the photocatalytic activity was attributed to the interfacial electronic interaction between NaTaO{sub 3} and Ag{sub 2}O and the high migration efficiency of photogenerated carriers.

  13. 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.

  14. In₂S₃/carbon nanofibers/Au ternary synergetic system: hierarchical assembly and enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Zhang, Xin; Shao, Changlu; Li, Xinghua; Lu, Na; Wang, Kexin; Miao, Fujun; Liu, Yichun

    2015-01-01

    In this paper, carbon nanofibers (CNFs) were successfully synthesized by electrospinning technique. Next, Au nanoparticles (NPs) were assembled on the electrospun CNFs through in situ reduction method. By using the obtained Au NPs modified CNFs (CNFs/Au) as hard template, the In2S3/CNFs/Au composites were synthesized through hydrothermal technique. The results showed that the super long one-dimensional (1D) CNFs (about 306 nm in average diameter) were well connected to form a nanofibrous network; and, the Au NPs with 18 nm in average diameter and In2S3 nanosheets with 5-10nm in thickness were uniformly grown onto the surface of CNFs. Photocatalytic studies revealed that the In2S3/CNFs/Au composites exhibited highest visible-light photocatalytic activities for the degradation of Rhodamine B (RB) compared with pure In2S3 and In2S3/CNFs. The enhanced photocatalytic activity might arise from the high separation efficiency of photogenerated electron-hole pairs based on the positive synergetic effect between In2S3, CNFs and Au components in this ternary photocatalytic system. Meanwhile, the In2S3/CNFs/Au composites with hierarchical structure possess a strong adsorption ability towards organic dyes, which also contributed to the enhancement of photocatalytic activity. Moreover, the In2S3/CNFs/Au composites could be recycled easily by sedimentation due to their nanofibrous network structure. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Ionic liquid-assisted photochemical synthesis of ZnO/Ag2O heterostructures with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Zhao, Shuo; Zhang, Yiwei; Zhou, Yuming; Zhang, Chao; Fang, Jiasheng; Sheng, Xiaoli

    2017-07-01

    ZnO/Ag2O 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/Ag2O materials exhibited self-assembled flower-like architecture whose size was about 3 μm. Moreover, as-prepared ZnO/Ag2O 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/Ag2O materials, which can be beneficial for environmental protection.

  16. Activation of arene-heteroatom bonds by photoredox catalysis with visible light

    OpenAIRE

    Majek, Michal

    2016-01-01

    Aim of this thesis is the use of photo-redox catalysis for the activation of Ar-X bonds, and development of new synthetic methods based on this approach. In the beginning, the evolution that led to the development of modern photo-redox catalysis is discussed. Explanation of basic theories and definitions, which are encountered in the field of photo-redox catalysis is given. This is followed by a short overview of common photocatalysts, and the most important photocatalytic reactions discov...

  17. An ion exchange strategy to BiOI/CH{sub 3}COO(BiO) heterojunction with enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Han, Qiaofeng, E-mail: hanqiaofeng@njust.edu.cn; Yang, Zhen; Wang, Li; Shen, Zichen; Wang, Xin; Zhu, Junwu; Jiang, Xiaohong

    2017-05-01

    Highlights: • BiOI/BiOAc heterojunction was firstly synthesized by an ion exchange route. • BiOI/BiOAc exhibited enhanced visible-light-driven photoreactivity for the dyes degradation in comparison with individuals. • Photocatalytic activity of the as-prepared BiOI/BiOAc is better than that prepared by precipitation-deposition method. • Photosensitization effect of BiOI to BiOAc was superior to that of Bi{sub 2}S{sub 3} due to suitable solubility constant. - Abstract: It is very significant to develop CH{sub 3}COO(BiO) (denoted as BiOAc) based photocatalysts for the removal of pollutants due to its non-toxicity and availability. We previously reported that BiOAc exhibited excellent photocatalytic activity for rhodamine B (RhB) degradation under UV light irradiation. Herein, by an ion exchange approach, BiOI/BiOAc heterojunction could be easily obtained. The as-prepared heterojunction possessed enhanced photodegradation activity for multiple dyes including RhB and methyl orange (MO) under visible light illumination in comparison with individual materials. Good visible-light photocatalytic activity of the heterojunction could be attributed to the increased visible light response, effective charge transfer from the modified band position and close interfacial contact due to partial ion exchange method.

  18. TiO2 Nanotubes with Different Ag Loading to Enhance Visible-Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Thi Ngoc Tu Le

    2017-01-01

    Full Text Available An improved photocatalytic activity of semiconductor materials using incorporation of the noble metals such as Ag, Au, and Pt is a promising technology. In this study, Ag nanoparticle-TiO2 nanotube structures (Ag-TNTs have been investigated as a photocatalyst in different irradiation conditions using different characterization techniques. The results indicate that Ag nanoparticles dispersed uniformly on the TNTs’ surface without any change in TNTs’ morphology. In addition, Ag-TNTs exhibited lower photoactivity than the TNTs under UV irradiation. In contrast, Ag-TNTs increased the photoactivity in comparison with TNTs and the photocatalytic performance under sunlight irradiation. These phenomena could be contributed to the appearance of Ag nanoparticles on the nanotube surface.

  19. 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.

  20. Photocatalytic activity of novel AgBr/WO3 composite photocatalyst under visible light irradiation for methyl orange degradation.

    Science.gov (United States)

    Cao, Jing; Luo, Bangde; Lin, Haili; Chen, Shifu

    2011-06-15

    A novel AgBr/WO(3) composite photocatalyst was synthesized by loading AgBr on WO(3) substrate via deposition-precipitation method and characterized by XRD, SEM and DRS. The as-prepared AgBr/WO(3) was composed of monoclinic WO(3) substrate and face-centered cubic AgBr nanoparticles with crystalline sizes less than 56.8 nm. AgBr/WO(3) had absorption edge at about 470 nm in the visible light region. The optical AgBr content in AgBr/WO(3) was 0.30:1 (Ag/W) at the corresponding apparent rate, k(app), of 0.0160 min(-1) for MO degradation. The highest k(app) was 0.0216 min(-1) for 4 g/L catalyst. The OH acted as active species. Addition of H(2)O(2) within 0.020 mmol/L can efficiently trap electrons to generate more OH and further improved photocatalytic activity of AgBr/WO(3). Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Conversion of Carbon Dioxide by Methane Reforming under Visible-Light Irradiation: Surface-Plasmon-Mediated Nonpolar Molecule Activation.

    Science.gov (United States)

    Liu, Huimin; Meng, Xianguang; Dao, Thang Duy; Zhang, Huabin; Li, Peng; Chang, Kun; Wang, Tao; Li, Mu; Nagao, Tadaaki; Ye, Jinhua

    2015-09-21

    A novel CO2 photoreduction method, CO2 conversion through methane reforming into syngas (DRM) was adopted as an efficient approach to not only reduce the environmental concentration of the greenhouse gas CO2 but also realize the net energy storage from solar energy to chemical energy. For the first time it is reported that gold, which was generally regarded to be inactive in improving the performance of a catalyst in DRM under thermal conditions, enhanced the catalytic performance of Rh/SBA-15 in DRM under visible-light irradiation (1.7 times, CO2 conversion increased from 2100 to 3600 μmol g(-1) s(-1)). UV/Vis spectra and electromagnetic field simulation results revealed that the highly energetic electrons excited by local surface plasmon resonances of Au facilitated the polarization and activation of CO2 and CH4 with thermal assistance. This work provides a new route for CO2 photoreduction and offers a distinctive method to photocatalytically activate nonpolar molecules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Facile synthesis of graphitic C3N4 nanoporous-tube with high enhancement of visible-light photocatalytic activity

    Science.gov (United States)

    Zhao, Ruiru; Gao, Jianping; Mei, Shunkang; Wu, Yongli; Wang, Xiaoxue; Zhai, Xiangang; Yang, Jiangbing; Hao, Chaoyue; Yan, Jing

    2017-12-01

    A simple and convenient method was used to synthesize a graphitic carbon nitride (g-C3N4) nanoporous-tube by using SiO2 nanoparticles as pore formers. The structure of the g-C3N4 nanoporous-tube was characterized by the SEM and TEM images. Taking photodegradation of RhB as an example, the photocatalytic activity of the as-prepared g-C3N4 nanoporous-tube was investigated. It can photodegrade 90% RhB in 40 min under visible-light irradiation and obtain a k value of 0.04491 min‑1, which is 8.16 times that of bulk g-C3N4, 3.09 times that of tubular g-C3N4 and 1.48 times that of tubular g-C3N4-SiO2. The significant enhancement in photocatalytic efficiency is due to the edge effect of the pores and the special structure of the tubes. In addition, the possible mechanism of photocatalytic degradation of RhB was also proposed based on the trapping experiment of active species, which indicated that the superoxide radicals ({{{{O}}}2}\\bullet -) and the holes (h +) were the main reactive species in this photocatalyst. This work may open up a new idea of innovation in g-C3N4 structure and inspire its follow-up study.

  3. Visible Light-Photocatalytic Activity of Sulfate-Doped Titanium Dioxide Prepared by the Sol−Gel Method

    Directory of Open Access Journals (Sweden)

    Tsuneo Fujii

    2013-04-01

    Full Text Available Sulfate-doped TiO2 was prepared from sol−gel systems containing titaniumalkoxide and sulfuric acid. The time needed for gelation of the systems was significantlyreduced by ultrasonic irradiation. The doped sulfate was observed by FTIR and XPSmeasurements. Some sulfate ions remained in the TiO2 even after heating at 300−600 °C.The UV and visible photocatalytic activities of the samples were confirmed by thedegradation of trichloroethylene (TCE. The activity of the photocatalyst samples duringthe UV irradiation strongly depended on their crystallinities rather than their specificsurface areas, i.e., adsorption ability. The degradation rate during the visible irradiationdepended on both the adsorption ability and visible absorption of the photocatalystsamples. The visible absorption induced by the sulfate-doping was effective for theTCE degradation.

  4. Synthesis and Characterization of Fe-N-S-tri-Doped TiO2 Photocatalyst and Its Enhanced Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Biying Li

    2012-01-01

    Full Text Available Fe-N-S-tri-doped TiO2 photocatalysts were synthesized by one step in the presence of ammonium ferrous sulfate. The resulting materials were characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and ultraviolet-visible diffuse reflection spectrum (UV-Vis DRS. XPS analysis indicated that Fe (III and S6+ were incorporated into the lattice of TiO2 through substituting titanium atoms, and N might coexist in the forms of substitutional N (O-Ti-N and interstitial N (Ti-O-N in tridoped TiO2. XRD results showed that tri-doping with Fe, N, and S elements could effectively retard the phase transformation of TiO2 from anatase to rutile and growth of crystallite size. DRS results revealed that the light absorbance edge of TiO2 in visible region was greatly improved by tri-doping with Fe, N, and S elements. Further, the photocatalytic activity of the as-synthesized samples was evaluated by the degradation of phenol under visible light irradiation. It was found that Fe-N-S-tri-doped TiO2 catalyst exhibited higher visible light photocatalytic activity than that of pure TiO2 and P25 TiO2, which was mainly attributed to the small crystallite size, intense light absorbance in visible region, and narrow bandgap energy.

  5. Fabrication and characterization of brookite-rich, visible light-active TiO2 films for water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Hui [ORNL; Qiu, Xiaofeng [ORNL; Ivanov, Ilia N [ORNL; Meyer III, Harry M [ORNL; Wang, Wei [ORNL; Zhu, Wenguang [ORNL; Paranthaman, Mariappan Parans [ORNL; Zhang, Zhenyu [ORNL; Eres, Gyula [ORNL; Gu, Baohua [ORNL

    2009-01-01

    We report that mild oxidation of Ti foils in air results in brookite-rich titanium oxide (TiO2) films with similar spectral response to that of dye-sensitized TiO2. X-ray powder diffraction and Raman spectroscopy show that the onset of brookite formation occurs at 500 8C, and the material is characterized by a strong absorption band in the visible spectral range. The first-principle calculations show that enhanced visible light absorption correlates with the presence of Ti interstitials. Photocurrent density measurements of water splitting reveal that the brookite-rich TiO2 exhibits the highest photocatalytic performance among the different forms of TiO2 produced by oxidation of Ti foils. With increasing oxidation temperature transformation to the rutile phase accompanied by declining visible range photoactivity is observed.

  6. Visible light-induced photocatalytic activity of Bi2O3 prepared via microwave-assisted method.

    Science.gov (United States)

    Liu, Xinjuan; Pan, Likun; Li, Jinliang; Yu, Kai; Sun, Zhuo

    2013-07-01

    Bi2O3 was successfully synthesized via microwave-assisted reaction of Bi2O3 precursor in aqueous solution using a microwave system. Their morphologies, structures and photocatalytic performances in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, photoluminescence spectroscopy and UV-vis absorption spectroscopy, respectively. The results show that Bi2O3 synthesized at pH value of 7 exhibits an optimal photocatalytic performance with the MB degradation rate of 76% at 240 min under visible light irradiation due to its higher visible light absorption and comparatively low electron-hole pair recombination.

  7. Modified Sol-Gel Synthesis of Carbon Nanotubes Supported Titania Composites with Enhanced Visible Light Induced Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Quanjie Wang

    2016-01-01

    Full Text Available Multiwalled carbon nanotube (MWCNT enhanced MWCNT/TiO2 nanocomposites were synthesized by surface coating of carbon nanotube with mixed phase of anatase and rutile TiO2 through a modified sol-gel approach using tetrabutyl titanate as raw material. The morphological structures and physicochemical properties of the nanocomposites were characterized by FT-IR, XRD, DTA-TG, TEM, and UV-Vis spectra. The results show that TiO2 nanoparticles with size of around 15 nm are closely attached on the sidewall of MWCNT. The nanocomposites possess good absorption properties not only in the ultraviolet but also in the visible light region. Under irradiation of ultraviolet lamp, the prepared composites have the highest photodegradation efficiency of 83% within 4 hours towards the degradation of Methyl Orange (MO aqueous solution. The results indicate that the carbon nanotubes supported TiO2 nanocomposites exhibit high photocatalytic activity and stability, showing great potentials in the treatment of wastewater.

  8. Facile Low-Temperature Synthesis of Carbon Nanotube/ Nanohybrids with Enhanced Visible-Light-Driven Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Yunlong Xie

    2012-01-01

    Full Text Available We demonstrate a facile and novel chemical precipitation strategy for the accurate coating of TiO2 nanoparticles on the surface of carbon nanotubes (CNTs to form CNT/TiO2 nanohybrids, which only requires titanium sulfate and CNTs as starting materials and reacts in the alkaline solution at 60°C for 6 h. Using this process, the as-prepared hybrid structures preserved the good dispersity and uniformity of initial CNTs. Furthermore, the CNT/TiO2 nanohybrids show a broad blue luminescence at 469 nm and exhibit significantly enhanced photocatalytic activity for the degradation of rhodamine B (RhB under visible-light irradiation, which is about 1.5 times greater than that of commercial Degussa P25 TiO2 nanoparticles. It is believed that this facile chemical precipitation strategy is scalable and its application can be extended to synthesize other CNT/oxide nanohybrids for various applications.

  9. A facile chemical conversion synthesis of Sb2S3 nanotubes and the visible light-driven photocatalytic activities

    Science.gov (United States)

    2012-01-01

    We report a simple chemical conversion and cation exchange technique to realize the synthesis of Sb2S3 nanotubes at a low temperature of 90°C. The successful chemical conversion from ZnS nanotubes to Sb2S3 ones benefits from the large difference in solubility between ZnS and Sb2S3. The as-grown Sb2S3 nanotubes have been transformed from a weak crystallization to a polycrystalline structure via successive annealing. In addition to the detailed structural, morphological, and optical investigation of the yielded Sb2S3 nanotubes before and after annealing, we have shown high photocatalytic activities of Sb2S3 nanotubes for methyl orange degradation under visible light irradiation. This approach offers an effective control of the composition and structure of Sb2S3 nanomaterials, facilitates the production at a relatively low reaction temperature without the need of organics, templates, or crystal seeds, and can be extended to the synthesis of hollow structures with various compositions and shapes for unique properties. PMID:22448960

  10. Visible Light Dye-Sensitized Photosensititve Systems

    National Research Council Canada - National Science Library

    Fang Gao; Yong-yuan Yang

    2000-01-01

      The visible light dyes were employed to sensitized o-Cl-Hexaarylbiimidazole (o-Cl-HABI). The obtained results suggested that o-Cl-HABI displayed a efficient sensitized photocleavage when exposed to Xenon lamp...

  11. Preparation and characterization of Cobalt Sulfophthalocyanine/TiO 2/fly-ash cenospheres photocatalyst and study on degradation activity under visible light

    Science.gov (United States)

    Huo, Pengwei; Yan, Yongsheng; Li, Songtian; Li, Huaming; Huang, Weihong

    2009-05-01

    Cobalt Sulfophthalocyanine (CoSPc) sensitized TiO 2 sol samples were prepared through a Sol-Gel method using Cobalt Sulfophthalocyanine as a sensitizer. Loading and modified floating photocatalyst was prepared by hydrothermal method using fly-ash cenospheres as a carrier. The properties of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance spectrum (DRS). Photocatalytic activity was studied by degrading wastewater of methylene blue under visible light. The results indicate that the fly-ash cenospheres are covered by modified TiO 2 film which composed of the anatase, brookite and rutile misch crystal phase. CoSPc/TiO 2/fly-ash cenospheres samples have good catalytic activity under visible light, and have strong absorbency during 600-700 nm. The sensitization of CoSPc can enhance visible light catalytic activity of TiO 2/fly-ash cenospheres. The degradation rate of methylene blue reaches 73.36% in 180 min under the visible light illumination. But too much CoSPc can decrease its catalytic activity.

  12. Preparation and characterization of Cobalt Sulfophthalocyanine/TiO{sub 2}/fly-ash cenospheres photocatalyst and study on degradation activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Huo Pengwei [School of Chemistry and Chemical Engineering, Jiangsu University, Jiangsu, Xuefu Road 301, Zhenjiang 212013 (China); Yan Yongsheng, E-mail: henanhuo@yahoo.com [School of Chemistry and Chemical Engineering, Jiangsu University, Jiangsu, Xuefu Road 301, Zhenjiang 212013 (China); Li Songtian; Li Huaming; Huang Weihong [School of Chemistry and Chemical Engineering, Jiangsu University, Jiangsu, Xuefu Road 301, Zhenjiang 212013 (China)

    2009-05-15

    Cobalt Sulfophthalocyanine (CoSPc) sensitized TiO{sub 2} sol samples were prepared through a Sol-Gel method using Cobalt Sulfophthalocyanine as a sensitizer. Loading and modified floating photocatalyst was prepared by hydrothermal method using fly-ash cenospheres as a carrier. The properties of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance spectrum (DRS). Photocatalytic activity was studied by degrading wastewater of methylene blue under visible light. The results indicate that the fly-ash cenospheres are covered by modified TiO{sub 2} film which composed of the anatase, brookite and rutile misch crystal phase. CoSPc/TiO{sub 2}/fly-ash cenospheres samples have good catalytic activity under visible light, and have strong absorbency during 600-700 nm. The sensitization of CoSPc can enhance visible light catalytic activity of TiO{sub 2}/fly-ash cenospheres. The degradation rate of methylene blue reaches 73.36% in 180 min under the visible light illumination. But too much CoSPc can decrease its catalytic activity.

  13. VERUCLAY – a new type of photo-adsorbent active in the visible light range: modification of montmorillonite surface with organic surfactant

    Science.gov (United States)

    Montmorillonite K10 was treated with VeruSOL-3, a biodegradable and food-grade surfactant mixture of coconut oil, castor oil and citrus extracts, to manufacture a benign catalytic adsorbent that is active in the visible light. Veruclay was characterized by SEM, XRD, TGA, UVDRS, a...

  14. Controllable assembly of well-defined monodisperse Au nanoparticles on hierarchical ZnO microspheres for enhanced visible-light-driven photocatalytic and antibacterial activity.

    Science.gov (United States)

    Wang, Yuan; Fang, Hua-Bin; Zheng, Yan-Zhen; Ye, Rongqin; Tao, Xia; Chen, Jian-Feng

    2015-12-07

    A high-efficiency visible-light-driven photocatalyst composed of homogeneously distributed Au nanoparticles (AuNPs) well-defined on hierarchical ZnO microspheres (ZMS) via a controllable layer-by-layer self-assembly technique is demonstrated. The gradual growth of the characteristic absorption bands of Au loaded on ZnO in the visible light region with an increasing number of assemblies indicates the enhancement of the light harvesting ability of the ZMS/Au composites as well as the reproducibility and controllability of the entire assembly process. Results on the photoelectrochemical performance characterized by EIS and transient photocurrent response spectra indicate that the ZMS/Au composites possess increased photoinduced charge separation and transfer efficiency compared to the pure ZMS film. As a result, the hybrid composites exhibited enhanced decomposition activity for methylene blue and salicylic acid as well as antibacterial activity in killing S. aureus and E. coli under visible light irradiation. It can be noted that well-distributed Au components even at a rather low Au/ZnO weight ratio of ∼1.2% also exhibited extraordinary photocatalysis. Such a facile and controllable self-assembly approach may be viable for preparing high-performance visible-light-driven ZMS/Au photocatalysts in a simple and controllable way, and consequently, the technology may extend to other plasmon-enhanced heterostructures made of nanostructured semiconductors and noble metals for great potential application in environmental protection.

  15. Photocatalytic activity of Pt-TiO2 films supported on hydroxylated fly ash cenospheres under visible light

    Science.gov (United States)

    Wang, Bing; Yang, Zewei; An, Hao; Zhai, Jianping; Li, Qin; Cui, Hao

    2015-01-01

    TiO2 was coated on the surface of hydroxylated fly ash cenospheres (FACs) by the sol-gel method. Platinum (Pt) was then deposited on these TiO2/FAC particles by a photoreduction method to form PTF photocatalyst. The photocatalytic activity of PTF for the degradation of methylene blue (MB) under visible-light irradiation was determined. The PTF sample that was calcined at 450 °C and had a Pt/TiO2 mass ratio of 1.5% exhibited the optimal photocatalytic activity for degradation of MB with a catalyst concentration of 3 g L-1. MB was photodecomposed by PTF in aqueous solution more effectively at alkali pH than at acidic pH, because more MB molecules were adsorbed on the surface of PTF under alkaline conditions than that under acidic. The effect of various inorganic anions (HCO3-, F-, SO42-, NO3-, and Cl-) on the photodegradation of MB by PTF was also investigated. Addition of anions with a concentration of 5 mM enhanced the photocatalytic efficiency of PTF because of the improved adsorption of MB. This effect weakened as the anion concentration was increased, which was attributed to the ability of the anions to scavenge hydroxyl radicals and holes. Our results indicated that the photodegradation of MB took place mainly on the catalyst surface. The generation of hydroxyl radicals in the photocatalytic reaction was measured by the fluorescence method. KI was used to determine the participation of holes in the photocatalytic reaction. Both hydroxyl radicals and valence-band holes were detected in the PTF system. Recycling tests revealed that calcination of the used PTF helped to regain its photocatalytic activity.

  16. Preparation and enhanced visible-light photocatalytic H2-production activity of CdS-sensitized Pt/TiO2 nanosheets with exposed (001) facets.

    Science.gov (United States)

    Qi, Lifang; Yu, Jiaguo; Jaroniec, Mietek

    2011-05-21

    CdS-sensitized Pt/TiO(2) nanosheets with exposed (001) facets were prepared by hydrothermal treatment of a Ti(OC(4)H(9))(4)-HF-H(2)O mixed solution followed by photochemical reduction deposition of Pt nanoparticles (NPs) on TiO(2) nanosheets (TiO(2) NSs) and chemical bath deposition of CdS NPs on Pt/TiO(2) NSs, successively. The UV and visible-light driven photocatalytic activity of the as-prepared samples was evaluated by photocatalytic H(2) production from lactic acid aqueous solution under UV and visible-light (λ ≥ 420 nm) irradiation. It was shown that no photocatalytic H(2)-production activity was observed on the pure TiO(2) NSs under UV and/or visible-light irradiation. Deposition of CdS NPs on Pt/TiO(2) NSs caused significant enhancement of the UV and visible-light photocatalytic H(2)-production rates. The morphology of TiO(2) particles had also significant influence on the visible-light H(2)-production activity. Among TiO(2) NSs, P25 and the NPs studied, the CdS-sensitized Pt/TiO(2) NSs show the highest photocatalytic activity (13.9% apparent quantum efficiency obtained at 420 nm), exceeding that of CdS-sensitized Pt/P25 by 10.3% and that of Pt/NPs by 1.21%, which can be attributed to the combined effect of several factors including the presence of exposed (001) facets, surface fluorination and high specific surface area. After many replication experiments of the photocatalytic hydrogen production in the presence of lactic acid, the CdS-sensitized Pt/TiO(2) NSs did not show great loss in the photocatalytic activity, confirming that the CdS/Pt/TiO(2) NSs system is stable and not photocorroded. © The Owner Societies 2011

  17. One-Pot Template-Free Hydrothermal Synthesis of Monoclinic Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Bei Cheng

    2012-01-01

    Full Text Available Monoclinic-phase BiVO4 hollow microspheres with diameters of about 2–4 μm have been successfully fabricated in high yield by a one-pot template-free hydrothermal route. The reaction duration and urea concentration are shown to play important roles in the formation of the BiVO4 hollow microspheres. X-ray diffraction, scanning electron microscopy, nitrogen adsorption-desorption isotherms, fourier transform infrared spectrometry, and UV-visible diffuse reflectance spectroscopy are used to characterize the products. The results show that all the as-prepared BiVO4 samples have monoclinic phase structure and exhibit good crystallinity. A formation mechanism for the BiVO4 hollow spherical structure via a localized Ostwald ripening is proposed based on the experimental observations. In addition, studies of the photocatalytic properties by exposure to visible light irradiation demonstrate that the as-obtained BiVO4 hollow spheres show potential photocatalytic application. Hydroxyl radicals (•OH are not detected on the surface of visible-light-illuminated BiVO4 by the photoluminescence technique, suggesting that •OH is not the dominant photooxidant and photogenerated hole could directly take part in photocatalytic reaction. The prepared BiVO4 hollow spheres are also of great interest in pigment, catalysis, separation technology, biomedical engineering, and nanotechnology.

  18. AgI/TiO2 nanocomposites: ultrasound-assisted preparation, visible-light induced photocatalytic degradation of methyl orange and antibacterial activity.

    Science.gov (United States)

    Xue, Bin; Sun, Tao; Wu, Ji-Kui; Mao, Fang; Yang, Wei

    2015-01-01

    AgI/TiO2 nanocomposites were prepared by an ultrasound-assisted precipitation process and subsequent low-temperature (350°C) calcination. The crystal phase, morphology and optical properties of the AgI/TiO2 nanocomposites were characterized by X-ray diffraction, transmission electron microscopy and UV-vis absorption spectroscopy. After calcination, the crystallite size of AgI nanoparticles in the AgI/TiO2 nanocomposites decreased, and visible light absorption intensity of the AgI/TiO2 nanocomposites was significantly enhanced. The AgI/TiO2 nanocomposites after calcination exhibited the superior photocatalytic activity for methyl orange degradation and killing of Escherichia coli under visible light irradiation. The improvement of photocatalytic activity could be attributed to two reasons, namely, reduced crystallite size and enhanced visible light absorption of AgI nanoparticles in calcined AgI/TiO2 nanocomposites. The trapping experiments demonstrated that superoxide radical (O2(-)) and holes (h(+)) were the main reactive species for the photodegradation of methyl orange under visible light irradiation. The ultrasound-assisted preparation approach is efficient and facile, which promotes large-scale production and application of AgI/TiO2 nanocomposites in photocatalytic degradation of organic pollutants, disinfection and other fields. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Effective visible light-active boron and europium co-doped BiVO4 synthesized by sol-gel method for photodegradion of methyl orange.

    Science.gov (United States)

    Wang, Min; Che, Yinsheng; Niu, Chao; Dang, Mingyan; Dong, Duo

    2013-11-15

    Eu-B co-doped BiVO4 visible-light-driven photocatalysts have been synthesized using the sol-gel method. The resulting materials were characterized by a series of joint techniques, including XPS, XRD, SEM, BET, and UV-vis DRS analyses. Compared with BiVO4 and B-BiVO4 photocatalysts, the Eu-B-BiVO4 photocatalysts exhibited much higher photocatalytic activity for methyl orange (MO) degradation under visible light irradiation. The optimal Eu doping content is 0.8 mol%. It was revealed that boron and europium were doped into the lattice of BiVO4 and this led to more surface oxygen vacancies, high specific surface areas, small crystallite size, a narrower band gap and intense light absorbance in the visible region. The doped Eu(III) cations can help in the separation of photogenerated electrons. The synergistic effects of boron and europium in doped BiVO4 were the main reason for improving visible light photocatalytic activity. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Effect of Different Activated Carbon as Carrier on the Photocatalytic Activity of Ag-N-ZnO Photocatalyst for Methyl Orange Degradation under Visible Light Irradiation.

    Science.gov (United States)

    Chen, Xiaoqing; Wu, Zhansheng; Gao, Zhenzhen; Ye, Bang-Ce

    2017-09-05

    In order to enhance the photodegradation of methyl orange (MO) by ZnO under visible light irradiation, ZnO nanoparticles co-doped with Ag and N and supported on activated carbon (AC) with different properties were synthesized through the sol-gel method. The prepared photocatalysts were characterized in terms of the structure and properties through X-ray diffraction, N₂ adsorption-desorption, ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence, and electron spin resonance. The photocatalytic activities of these photocatalysts followed the order: Ag-N-ZnO/ACs > Ag-N-ZnO > N, or Ag single-doped ZnO > commercial ZnO. This result was attributed to the small particle size, large surface area, narrow band gap, and high charge separation of Ag-N-ZnO/ACs. The Ag-N-ZnO/coconut husk activated carbon (Ag-N-ZnO/CHAC) exhibited the highest degradation efficiency of 98.82% for MO under visible light irradiation. This outcome was due to the abundant pore structure of Ag-N-ZnO/CHAC, resulting in stronger adsorption than that of other Ag-N-ZnO/ACs. Moreover, the degradation of MO on photocatalysis followed first order kinetics. The reactive species ·OH and ·O₂ - played more important roles in the photocatalytic degradation of MO over composite photocatalyst. Ag-N-ZnO/CHAC photocatalyst exhibited higher photocatalytic activity than unsupported Ag-N-ZnO after five recycling runs.

  1. 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.

  2. Photocatalytic activity of Pt–TiO{sub 2} films supported on hydroxylated fly ash cenospheres under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bing; Yang, Zewei; An, Hao; Zhai, Jianping; Li, Qin; Cui, Hao, E-mail: cuihao@nju.edu.cn

    2015-01-01

    Graphical abstract: - Highlights: • Buoyant Pt–TiO{sub 2}/FAC (PTF) photocatalysts are synthesized. • Photocatalytic activity of PTF is discussed in details. • PTF is favor of taking advantage of sunlight in practical application. • The concept is expected to be applicable to fabricate other buoyant materials. - Abstract: TiO{sub 2} was coated on the surface of hydroxylated fly ash cenospheres (FACs) by the sol–gel method. Platinum (Pt) was then deposited on these TiO{sub 2}/FAC particles by a photoreduction method to form PTF photocatalyst. The photocatalytic activity of PTF for the degradation of methylene blue (MB) under visible-light irradiation was determined. The PTF sample that was calcined at 450 °C and had a Pt/TiO{sub 2} mass ratio of 1.5% exhibited the optimal photocatalytic activity for degradation of MB with a catalyst concentration of 3 g L{sup −1}. MB was photodecomposed by PTF in aqueous solution more effectively at alkali pH than at acidic pH, because more MB molecules were adsorbed on the surface of PTF under alkaline conditions than that under acidic. The effect of various inorganic anions (HCO{sub 3}{sup −}, F{sup −}, SO{sub 4}{sup 2−}, NO{sub 3}{sup −}, and Cl{sup −}) on the photodegradation of MB by PTF was also investigated. Addition of anions with a concentration of 5 mM enhanced the photocatalytic efficiency of PTF because of the improved adsorption of MB. This effect weakened as the anion concentration was increased, which was attributed to the ability of the anions to scavenge hydroxyl radicals and holes. Our results indicated that the photodegradation of MB took place mainly on the catalyst surface. The generation of hydroxyl radicals in the photocatalytic reaction was measured by the fluorescence method. KI was used to determine the participation of holes in the photocatalytic reaction. Both hydroxyl radicals and valence-band holes were detected in the PTF system. Recycling tests revealed that calcination of the

  3. pH-dependent synthesis of iodine-deficient bismuth oxyiodide microstructures: Visible-light photocatalytic activity.

    Science.gov (United States)

    Wu, Gongjuan; Zhao, Yan; Li, Yawen; Ma, Hongmei; Zhao, Jingzhe

    2017-09-14

    Bismuth oxyiodides have exhibited high potential for applications in visible-light photocatalytic environmental remediation and solar energy conversion. In this work, a series of iodine-deficient bismuth oxyiodides (Bi4O5I2, Bi7O9I3, Bi5O7I) can be simply prepared through a pH-dependent aqueous procedure with feeding Bi/I ratio of 2:1. The compositions of the Bi-based oxyiodides are closely related to acid-base circumstances, with Bi4O5I2 formed in weakly acidic medium (pH = 5) and Bi7O9I3, Bi5O7I in basic medium (pH = 8 and 11). Morphology differences of nanosheet-assembled Bi4O5I2, Bi7O9I3 architectures and rod-like Bi5O7I microstructures demonstrate different crystalline characters and construction of Bi-based oxyiodide crystals. UV-vis DRS results revealed good visible-light absorptions of Bi4O5I2 and Bi7O9I3 architectures and appropriate band structures for photocatalytic reactions, on comparison to Bi5O7I microrods. Low electrochemical impedance of Bi7O9I3 microflowers with sheet-like units further facilitated the separation of e(-)-h(+) carriers in the degradation process. Accordingly, among the bismuth oxyiodide samples, Bi7O9I3 displayed prominent visible-light degradation performance for colorless bisphenol-A (BPA) due to the direct photoexcitation process. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Synergistic Effects of Sm and C Co-Doped Mixed Phase Crystalline TiO2 for Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Fuchang Peng

    2017-02-01

    Full Text Available Mixed phase TiO2 nanoparticles with element doping by Sm and C were prepared via a facile sol-gel procedure. The UV-Vis light-diffuse reflectance spectroscopy analysis showed that the absorption region of co-doped TiO2 was shifted to the visible-light region, which was attributed to incorporation of samarium and carbon into the TiO2 lattice during high-temperature reaction. Samarium effectively decreased the anatase-rutile phase transformation. The grain size can be controlled by Sm doping to achieve a large specific surface area useful for the enhancement of photocatalytic activity. The photocatalytic activities under visible light irradiation were evaluated by photocatalytic degradation of methylene blue (MB. The degradation rate of MB over the Sm-C co-doped TiO2 sample was the best. Additionally, first-order apparent rate constants increased by about 4.3 times compared to that of commercial Degusssa P25 under the same experimental conditions. Using different types of scavengers, the results indicated that the electrons, holes, and •OH radicals are the main active species for the MB degradation. The high visible-light photocatalytic activity was attributed to low recombination of the photo-generated electrons and holes which originated from the synergistic effect of the co-doped ions and the heterostructure.

  5. Ag3PO4/graphene-oxide composite with remarkably enhanced visible-light-driven photocatalytic activity toward dyes in water.

    Science.gov (United States)

    Chen, Guodong; Sun, Meng; Wei, Qin; Zhang, Yongfang; Zhu, Baocun; Du, Bin

    2013-01-15

    Ag(3)PO(4)/graphene-oxide (Ag(3)PO(4)/GO) composite has been synthesized by a liquid phase deposition method, and used for the photodegradation of organic dyes in water under visible light. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscope, N(2) sorption-desorption, and UV-vis diffuse reflectance spectra. The SEM image indicated that Ag(3)PO(4) particles were mainly distributed on the surface of GO sheets uniformly. DRS analysis revealed that the samples had good visible light response. The photocatalytic activity of Ag(3)PO(4)/GO composite was evaluated by decomposing of dyes (such as methyl orange, rhodamine B) in water under visible or UV-vis light irradiation. The degradation results indicated that the photocatalytic performance of Ag(3)PO(4)/GO was greatly enhanced due to the improved adsorption performance and separation efficiency of photo-generated carriers. The Ag(3)PO(4)/GO composite with GO content of 15 wt.% exhibited superior activity under visible light irradiation. After 50 min of reaction, the degradation ratio of MO was about 86.7%, while RhB solution could be completely degraded within 30 min of reaction. Further study proved that the direct oxidation of pollutants by holes has played a major role in the degradation process. The results of this work would provide a new sight for the construction of visible light-responsive photocatalysts with high performance. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. CeVO4 nanofibers hybridized with g-C3N4 nanosheets with enhanced visible-light-driven photocatalytic activity

    Science.gov (United States)

    Li, Li; Wang, Haoran; Wang, Xiong

    2018-01-01

    The g-C3N4/CeVO4 composites were successfully synthesized by hybridizing CeVO4 nanofibers with g-C3N4 nanosheets. The photocatalytic activity of g-C3N4/CeVO4 composites was evaluated for the photodegradation of methylene blue under visible light irradiation. Among them, the 50 wt% g-C3N4/CeVO4 composites presented the highest photocatalytic activity, about 2 and 3.2 times higher than those of CeVO4 and g-C3N4, respectively. The improved catalytic activity was owed to the hybridization, which facilitated the rapid separation of photoinduced carriers and enhanced the visible light harvesting. A possible photocatalytic mechanism was proposed.

  7. Effect of Electronegativity and Charge Balance on the Visible-Light-Responsive Photocatalytic Activity of Nonmetal Doped Anatase TiO2

    Directory of Open Access Journals (Sweden)

    Jibao Lu

    2012-01-01

    Full Text Available The origin of visible light absorption and photocatalytic activity of nonmetal doped anatase TiO2 were investigated in details in this work based on density functional theory calculations. Our results indicate that the electronegativity is of great significance in the band structures, which determines the relative positions of impurity states induced by the doping species, and further influences the optical absorption and photocatalytic activities of doped TiO2. The effect of charge balance on the electronic structure was also discussed, and it was found that the charge-balance structures may be more efficient for visible light photocatalytic activities. In addition, the edge positions of conduction band and valence band, which determine the ability of a semiconductor to transfer photoexcited electrons to species adsorbed on its surface, were predicted as well. The results may provide a reference to further experimental studies.

  8. Synthesis, characterization and photocatalytic activity of WO{sub 3}/TiO{sub 2} for NO removal under UV and visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luévano-Hipólito, E. [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Martínez-de la Cruz, A., E-mail: azael.martinezdl@uanl.edu.mx [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); López-Cuellar, E. [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Yu, Q.L.; Brouwers, H.J.H. [Department of the Built Environment, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2014-11-14

    Samples with different proportions WO{sub 3}/TiO{sub 2} were prepared by co-precipitation method followed by a heat treatment. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and adsorption–desorption N{sub 2} isotherms (BET). The photocatalytic properties of WO{sub 3}/TiO{sub 2} samples were evaluated in the photo-oxidation reaction of nitric oxide (NO) under UV and visible light irradiation. The highest photocatalytic activity was observed in the WO{sub 3}/TiO{sub 2} sample with a composition of 80% mole of TiO{sub 2}. Among the different substrates used for supporting the photocatalyst, the best results were reached over concrete and glass when it was exposed to UV and visible light irradiation, respectively. In overall, the photocatalytic efficiency of the synthesized materials was higher under UV than visible light irradiation. - Highlights: • WO{sub 3}/TiO{sub 2} prepared in simple way show high photocatalytic activity for NO removal. • The concrete was the best substrate to the performance of WO{sub 3}/TiO{sub 2} with UV radiation. • The glass was the best substrate to the performance of WO{sub 3}/TiO{sub 2} with visible radiation.

  9. Photodeposition-assisted synthesis of novel nanoparticulate In, S-codoped TiO2 powders with high visible light-driven photocatalytic activity

    Science.gov (United States)

    Hamadanian, M.; Reisi-Vanani, A.; Razi, P.; Hoseinifard, S.; Jabbari, V.

    2013-11-01

    In order to search for an efficient photocatalysts working under visible light illumination, we have investigated the effect of metal and nonmetal ions (In, S) codoping on the photocatalytic activity of TiO2 nanoparticles (TiO2 NPs) prepared by combining of sol-gel (SG) and photodeposition (PD) methods using titanium tetra isopropoxide (TTIP), indium nitrate (In(NO3)3) and thiourea as precursors. In this regard, at first three different percentage of S (0.05, 0.2 and 0.5) doped into the TiO2 by SG method, and then different amount of In(III) loaded on the surface of the prepared samples by PD technique. The results showed that the In, S-codoped TiO2 (In, S-TiO2) with a spheroidal shape demonstrates a smaller grain size than the pure TiO2. Meanwhile, the UV-vis DRS of In, S-TiO2 showed a considerable red shift to the visible region. Finally, the photocatalytic activity of In, S-TiO2 photocatalysts were evaluated by photooxidative degradation of methyl orange (MO) solution under UV and visible light illumination. As a result, it was found that 0.05%S-0.5%In/TiO2, 0.2%S-1.5%In/TiO2 and 0.5%S-0.5%In/TiO2 had the highest catalytic activity under visible light in each group and among these samples 0.2%S-1.5%In/TiO2 showed the best photocatalytic performance under visible light and decomposes more than 95% MO in only 90 min.

  10. A Carpet Cloak Device for Visible Light

    CERN Document Server

    Gharghi, Majid; Zentgraf, Thomas; Liu, Yongmin; Yin, Xiaobo; Valentine, Jason; Zhang, Xiang

    2011-01-01

    We report an invisibility carpet cloak device, which is capable of making an object undetectable by visible light. The cloak is designed using quasi conformal mapping and is fabricated in a silicon nitride waveguide on a specially developed nano-porous silicon oxide substrate with a very low refractive index. The spatial index variation is realized by etching holes of various sizes in the nitride layer at deep subwavelength scale creating a local effective medium index. The fabricated device demonstrates wideband invisibility throughout the visible spectrum with low loss. This silicon nitride on low index substrate can also be a general scheme for implementation of transformation optical devices at visible frequency.

  11. Room-temperature synthesis of Zn(0.80)Cd(0.20)S solid solution with a high visible-light photocatalytic activity for hydrogen evolution.

    Science.gov (United States)

    Wang, Dong-Hong; Wang, Lei; Xu, An-Wu

    2012-03-21

    Visible light photocatalytic H(2) production from water splitting is of great significance for its potential applications in converting solar energy into chemical energy. In this study, a series of Zn(1-x)Cd(x)S solid solutions with a nanoporous structure were successfully synthesized via a facile template-free method at room temperature. The obtained solid solutions were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and N(2) adsorption-desorption analysis. The solid solutions show efficient photocatalytic activity for H(2) evolution from aqueous solutions containing sacrificial reagents S(2-) and SO(3)(2-) under visible-light irradiation without a Pt cocatalyst, and loading of the Pt cocatalyst further improves the visible-light photocatalytic activity. The optimal photocatalyst with x = 0.20 prepared at pH = 7.3 displays the highest activity for H(2) evolution. The bare and 0.25 wt% Pt loaded Zn(0.80)Cd(0.20)S nanoparticles exhibit a high H(2) evolution rate of 193 μmol h(-1) and 458 μmol h(-1) under visible-light irradiation (λ ≥ 420 nm), respectively. In addition, the bare and 0.25 wt% Pt loaded Zn(0.80)Cd(0.20)S catalysts show a high H(2) evolution rate of 252 and 640 μmol h(-1) under simulated solar light irradiation, respectively. Moreover, the Zn(0.80)Cd(0.20)S catalyst displays a high photocatalytic stability for H(2) evolution under long-term light irradiation. The incorporation of Cd in the solid solution leads to the visible light absorption, and the high content of Zn in the solid solution results in a relatively negative conduction band, a modulated band gap and a rather wide valence bandwidth, which are responsible for the excellent photocatalytic performance of H(2) production and for the high photostability

  12. Preparation of visible-light-responsive TiO{sub 2} coatings using molten KNO{sub 3} treatment and their photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Liang [Tianjin Key Lab of Integrated Design and On-line Monitoring for Light Industry & Food Machinery and Equipment, Tianjin (China); College of Mechanical Engineering, Tianjin University of Science & Technology, No. 1038 Dagu Nanlu, Hexi District, Tianjin 300222 (China); College of Mechanical Engineering & Graduate School, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Guan, Sujun; Takaya, Shunsuke [College of Mechanical Engineering & Graduate School, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Yoshida, Hiroyuki [Chiba Industrial Technology Research Institute, 6-13-1, Tendai, Inage-ku, Chiba 263-0016 (Japan); Tochihara, Misako [JFE Techno-Research Corporation, No. 1 Kawasaki-cho, Chuo-ku, Chiba 260-0835 (Japan); Lu, Yun, E-mail: luyun@faculty.chiba-u.jp [College of Mechanical Engineering & Graduate School, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)

    2017-06-15

    Highlights: • Molten KNO{sub 3} treatment are used to prepare K-doped TiO{sub 2} photocatalyst coatings. • The coatings show good antibacterial activity even in absence of light. • The photocatalytic activity is increased with the amount increase of K-doping. • The good antibacterial activity should come from the doping and release of K ions. - Abstract: In this work, the process of mechanical coating followed by molten KNO{sub 3} treatment is given to prepare visible-light-responsive K{sup +}-doped TiO{sub 2}. X-ray diffraction (XRD), scanning electron spectroscopy (SEM), Energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) were conducted to characterize these TiO{sub 2} coatings. The results showed that K{sup +}-doped anatase TiO{sub 2}/Ti composite coatings formed after molten KNO{sub 3} treatment at elevated temperatures. Meanwhile, their photocatalytic degradation of methylene blue (MB) and the antibacterial activity against Escherichia coli (E. coli) was also studied. The visible-light-responsive photocatalytic activity of the coatings in MB degradation increased with increase of K{sup +} ions when holding temperature was raised from 673 to 773 K. An excellent antibacterial activity of the K{sup +}-doped TiO{sub 2}/Ti coatings against E. coli was also obtained even in absence of light. The antibacterial activity in dark should attribute to the release of K{sup +} ions from the coatings. The photocatalytic activity under visible-light irradiation should result from the absorption spectrum extension due to the doping of K{sup +} ions into the lattice of TiO{sub 2}.

  13. CdS nanoparticles/CeO{sub 2} nanorods composite with high-efficiency visible-light-driven photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    You, Daotong; Pan, Bao; Jiang, Fan; Zhou, Yangen; Su, Wenyue, E-mail: suweny@fzu.edu.cn

    2016-02-15

    Graphical abstract: Coupling CdS with CeO{sub 2} can effectively improve the light-harvesting ability of wide-band gap CeO{sub 2} NRs as the photoinduced electrons on the conduction band of CdS are transfered to the conduction band of CeO{sub 2}. - Highlights: • Coupling CdS can effectively improve the light-harvesting ability of wide-band gap CeO{sub 2}. • CdS/CeO{sub 2} composites show high photocatalytic activity under visible light irradiation. • The mechanism of photocatalytic H{sub 2} evolution over CdS/CeO{sub 2} was proposed. - Abstract: Different mole ratios of CdS nanoparticles (NPs)/CeO{sub 2} nanorods (NRs) composites with effective contacts were synthesized through a two-step hydrothermal method. The crystal phase, microstructure, optical absorption properties, electrochemical properties and photocatalytic H{sub 2} production activity of these composites were investigated. It was concluded that the photogenerated charge carriers in the CdS NPs/CeO{sub 2} NRs composite with a proper mole ratio (1:1) exhibited the longest lifetime and highest separation efficiency, which was responsible for the highest H{sub 2}-production rate of 8.4 mmol h{sup −1} g{sup −1} under visible-light irradiation (λ > 420 nm). The superior photocatalytic H{sub 2} evolution properties are attributed to the transfer of visible-excited electrons of CdS NPs to CeO{sub 2} NRs, which can effectively extend the light absorption range of wide-band gap CeO{sub 2} NRs. This work provides feasible routes to develop visible-light responsive CeO{sub 2}-based nanomaterial for efficient solar utilization.

  14. Alkaline hydrogen peroxide treatment for TiO{sub 2} nanoparticles with superior water-dispersibility and visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chung-Yi; Tu, Kuan-Ju; Lo, Yu-Shiu [Department of Biomedical Engineering and Environmental Sciences, College of Nuclear Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Pang, Yean Ling [Department of Chemical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, 43000 Kajang, Selangor (Malaysia); Wu, Chien-Hou, E-mail: chwu@mx.nthu.edu.tw [Department of Biomedical Engineering and Environmental Sciences, College of Nuclear Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2016-09-15

    Alkaline hydrogen peroxide treatment was proposed as a simple and green way to improve the performance of commercial TiO{sub 2} powder for water-dispersibility and visible-light photocatalytic activity on the degradation of dye pollutants. The performance of treated TiO{sub 2} was evaluated as a function of NaOH concentration, H{sub 2}O{sub 2} concentration, and treatment time. The optimal conditions were determined to be 24 h in 100 mM H{sub 2}O{sub 2} and 8 M NaOH. The treated samples were characterized by Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible spectrophotometry. The analysis revealed that the crystal structure, morphology, and absorption band gap were retained, but the surface of the treated TiO{sub 2} was dramatically changed. The treated TiO{sub 2} was highly dispersible with a uniform hydrodynamic size of 41 ± 12 nm and stable over months in water at pH 3 without any stabilizing ligand and could significantly enhance the visible-light photodegradation of dye pollutants. The superior performance might be attributed to the formation of abundant surface hydroxyl groups. This treatment paves the way for developing water-dispersible TiO{sub 2} with superior visible-light induced photocatalytic degradation of dye pollutants without any complicated and expensive surface modification. - Highlights: • Alkaline hydrogen peroxide is proposed to treat commercial TiO{sub 2} powder. • The treated TiO{sub 2} powder exhibits superior water-dispersibility with a uniform size distribution. • The treated TiO{sub 2} powder can significantly enhance the visible-light photodegradation of dyes.

  15. Efficient visible-light photocatalytic oxidation of gaseous NO with graphitic carbon nitride (g-C3N4) activated by the alkaline hydrothermal treatment and mechanism analysis.

    Science.gov (United States)

    Nie, Haoyu; Ou, Man; Zhong, Qin; Zhang, Shule; Yu, Lemeng

    2015-12-30

    In this paper, an enhanced visible-light photocatalytic oxidation (PCO) of NO (∼ 400 ppm) in the presence of the graphitic carbon nitride (g-C3N4) treated by the alkaline hydrothermal treatment is evaluated. Various g-C3N4 samples were treated in different concentrations of NaOH solutions and the sample treated in 0.12 mol L(-1) of NaOH solution possesses the largest BET specific surface area as well as the optimal ability of the PCO of NO. UV-vis diffuse reflection spectra (DRS) and photoluminescence (PL) spectra were also conducted, and the highly improved photocatalytic performance is ascribed to the large specific surface area and high pore volume, which provides more adsorption and active sites, the wide visible-light adsorption edge and the narrow band gap, which is favorable for visible-light activation, as well as the decreased recombination rate of photo-generated electrons and holes, which could contribute to the production of active species. Fluorescence spectra and a trapping experiment were conducted to further the mechanism analysis of the PCO of NO, illustrating that superoxide radicals (O2(-)) play the dominant role among active species in the PCO of NO. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Enhanced visible-light-driven photocatalytic activity of mesoporous TiO(2-x)N(x) derived from the ethylenediamine-based complex.

    Science.gov (United States)

    Jiang, Zheng; Kong, Liang; Alenazey, Feraih Sh; Qian, Yangdong; France, Liam; Xiao, Tiancun; Edwards, Peter P

    2013-06-21

    A facile solvent evaporation induced self-assembly (SEISA) strategy was developed to synthesize mesoporous N-doped anatase TiO2 (SE-meso-TON) using a single organic complex precursor derived in situ from titanium butoxide and ethylenediamine in ethanol solution. After the evaporation of ethanol in a fume hood and subsequent calcinations at 450 °C, the obtained N-doped TiO2 (meso-TON) anatase was of finite crystallite size, developed porosity, large surface area (101 m(2) g(-1)) and extended light absorption in the visible region. This SE-meso-TON also showed superior photocatalytic activity to the SG-meso-TON anatase prepared via sol-gel synthesis. On the basis of characterization results from XRD, XPS, N2 adsorption-desorption and ESR, the enhanced visible-light-responsive photocatalytic activity of SE-meso-TON was assigned to its developed mesoporosity and reduced oxygen vacancies.

  17. Fabrication of efficient visible light activated Cu-P25-graphene ternary composite for photocatalytic degradation of methyl blue

    Science.gov (United States)

    Jin, Zheng; Duan, Wubiao; Liu, Bo; Chen, Xidong; Yang, Feihua; Guo, Jianping

    2015-11-01

    Cu-P25-graphene nanocomposite was fabricated through hydrothermal method at relatively low temperature. The technique used is P25-graphene (PG) binary composite was firstly prepared by P25 and graphite oxide (GO), and then Cu2+ ions were impregnated into PG composite. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectrum respectively. As the results showed, the Cu-P25-graphene (CPG) nanocomposites possessed the extended light absorption in visible light and better charge separation capability as compared to the pure P25 and PG system. Moreover, CPG-4 (4 mM Cu(NO3)2) showed the highest degradation rate of methyl blue (MB) under the visible light, which the removal efficiency can reach 98% after 100 min. The corresponding hydrogen evolution rate of CPG-4 was 7.9 times than pure P25. It was concluded that the synergistic effects of Cu2+ ions and graphene narrowed the band gap of TiO2 and promoted charge separation, which played significant roles for the enhancement of photoactivity of CPG composite catalysts. In addition, it was observed that the photodegradation of MB followed the first order reaction kinetics. The effects of pH values of MB solution for photocatalysts had also been investigated. The result confirmed that the optimum values of pH were found to be 7. Finally, the stability test of photocatalysts was carried out and the photocatalytic mechanism was explained concretely.

  18. A Review of Solar and Visible Light Active TiO2 Photocatalysis for Treating Bacteria, Cyanotoxins and Contaminants of Emerging Concern

    OpenAIRE

    Fagan, Rachel; McCormack, Declan; Pillai, Suresh; Dionysiou, Dionysios

    2015-01-01

    Research into the development of solar and visible light active photocatalysts has been significantly increased in recent years due to its wide range of applications in treating contaminants of emerging concern (CECs), endocrine disrupting compounds (EDCs), bacteria and cyanotoxins. Solar photocatalysis is found to be highly effective in treating a wide range of CECs from sources such as pharmaceuticals, steroids, antibiotics, phthalates, disinfectants, pesticides, fragrances (musk), preserva...

  19. Visible Light-Photocatalytic Activity of Sulfate-Doped Titanium Dioxide Prepared by the Sol-Gel Method

    OpenAIRE

    Tsuneo Fujii; Hiromasa Nishikiori; Maki Hayashibe

    2013-01-01

    Sulfate-doped TiO2 was prepared from sol−gel systems containing titaniumalkoxide and sulfuric acid. The time needed for gelation of the systems was significantlyreduced by ultrasonic irradiation. The doped sulfate was observed by FTIR and XPSmeasurements. Some sulfate ions remained in the TiO2 even after heating at 300−600 °C.The UV and visible photocatalytic activities of the samples were confirmed by thedegradation of trichloroethylene (TCE). The activity of the photocatalyst samples during...

  20. Core-shell structured α-Fe2O3@TiO2 nanocomposites with improved photocatalytic activity in the visible light region.

    Science.gov (United States)

    Xia, Yubing; Yin, Longwei

    2013-11-14

    The core-shell structured Fe2O3@TiO2 nanocomposites prepared via a heteroepitaxial growth route using the Fe2O3 spindle as a hard template display improved photocatalytic degradation activity for Rhodamine B dye under visible light irradiation. The ratio of α-Fe2O3 : TiO2 in the α-Fe2O3@TiO2 core-shell nanocomposites can be tuned by etching the α-Fe2O3 core via controlling the concentration of HCl and etching time. An appropriate concentration of the Fe2O3 core could effectively induce a transition of the optical response from the UV to the visible region and decrease the recombination rate of photogenerated electrons and the holes of the core-shell structured catalyst, greatly contributing to the enhancement of visible light response and visible light photocatalytic activity of the Fe2O3@TiO2 catalysts. It is revealed that the optical response and photocatalytic performance of the core-shell α-Fe2O3@TiO2 nanocomposites can be tuned by adjusting the molar ratio of Fe2O3 : TiO2 of the α-Fe2O3@TiO2 nanocomposites. The α-Fe2O3@TiO2 core-shell nanocomposite with an optimal molar ratio of 7% for Fe2O3 : TiO2 exhibits the best photocatalytic performance under visible light irradiation. It is shown that the Fe2O3/TiO2 heterojunction structure is responsible for the efficient visible-light photocatalytic activity. As the concentration of Fe2O3 is high, Fe(3+) ions will act as recombination centres of the photogenerated electrons and holes. The present core-shell Fe2O3@TiO2 nanoparticles displaying enhanced photodegradation activity could find potential applications as photocatalysts for the abatement of various organic pollutants.

  1. Enhanced Photocatalytic Activity of Nanoparticle-Aggregated Ag-AgX(X = Cl, Br)@TiO2 Microspheres Under Visible Light

    Science.gov (United States)

    Zhang, Cuiling; Hua, Hao; Liu, Jianlin; Han, Xiangyu; Liu, Qipeng; Wei, Zidong; Shao, Chengbin; Hu, Chenguo

    2017-10-01

    Ag-AgX(X = Cl, Br)@TiO2 nanoparticle-aggregated spheres with different mass ratio of R = TiO2/Ag(X) from 35:1 to 5:1 were synthesized by a facile sol-gel technique with post-photoreduction. The photocatalytic activities of both Ag-AgCl@TiO2 and Ag-AgBr@TiO2 under visible light are effectively improved by 3 times relative to TiO2 NPAS under the simulated sunlight for the decomposition of methyl orange (MO). Ag-AgBr@TiO2 showed 30% improvement and less stable in photocatalytic activity than that of AgCl@TiO2. The role of Ag and AgX nanoparticles on the surface of Ag-AgX(X = Cl, Br)@TiO2 was discussed. Ag on these samples not only can efficiently harvest visible light especially for AgCl, but also efficiently separate excited electrons and holes via the fast electron transfer from AgX(X = Cl, Br) to metal Ag nanoparticles and then to TiO2-aggregated spheres on the surface of heterostructure. On the basis of their efficient and stable photocatalytic activities under visible-light irradiation, these photocatalysts could be widely used for degradation of organic pollutants in aqueous solution.

  2. Enhancing the visible-light-induced photocatalytic activity of the self-cleaning TiO{sub 2}-coated cotton by loading Ag/AgCl nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Deyong, E-mail: wdy001815@126.com; Wang, Lianzhi; Song, Xinjian, E-mail: whxjsong@163.com; Tan, Yuanbin

    2013-07-01

    TiO{sub 2}-coated cotton possesses excellent self-cleaning properties but requires ultraviolet irradiation for effective photocatalysis. It is highly desirable to develop self-cleaning cotton fabrics that can use visible light in high efficiency under sunlight irradiation. In this work, Ag/AgCl-TiO{sub 2}-cotton was prepared by coating TiO{sub 2} films at low temperature and then loading Ag/AgCl nanoparticles via an impregnating precipitation photoreduction method. It was characterized by meanings of scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-visible diffuse reflectance spectrophotometer. In comparison with TiO{sub 2}-cotton, Ag/AgCl-TiO{sub 2}-cotton exhibits a highly visible-light-induced photocatalytic activity for degradation of methyl orange in water. The mechanism for the degradation of methyl orange over the Ag/AgCl-TiO{sub 2}-cotton was discussed. Under visible light irradiation, Ag NPs are photoexcited due to surface plasmon resonance, and then the photoexcited electrons from Ag NPs inject into the TiO{sub 2} conduction band and the holes transfer to the surface of the AgCl particles. The produced radical groups, such as O{sub 2}• {sup −}, H{sub 2}O{sub 2}, • OH and Cl{sup 0}, can cause the photocatalytic degradation of organic pollutants. - Highlights: • TiO{sub 2} was coated on the substrates with low thermal resistance. • Ag/AgCl-TiO{sub 2}-cotton shows visible-light-induced self-cleaning property. • Silver nanoparticles lead to surface plasmon resonance absorption.

  3. Catadioptric lenses in Visible Light Communications

    Science.gov (United States)

    Garcia-Marquez, J.; Valencia, J. C.; Perez, H.; Topsu, S.

    2015-04-01

    Since few years ago, visible light communications (VLC) have experience an accelerated interest from a research point of view. The beginning of this decade has seen many improvements in VLC at an electronic level. High rates of transmission at low bit error ratios (BER) have been reported. A few numbers of start-ups have initiated activities to offer a variety of applications ranging from indoor geo-localization to internet, but in spite of these advancements, some other problems arise. Long-range transmissions mean a high BER which reduce the number of applications. In this sense, new redesigned optical collectors or in some cases, optical reflectors must be considered to ensure a low BER at higher distance transmissions. Here we also expose a preliminary design of a catadioptric and monolithical lens for a LI-FI receiver with two rotationally symmetrical main piecewise surfaces za and zb. These surfaces are represented in a system of cylindrical coordinates with an anterior surface za with a central and refractive sector surrounded by a peripheral reflective sector and a back piecewise surface zb with a central refractive sector and a reflective sector, both characterized as ideal for capturing light within large acceptance angles.

  4. Porous TiO{sub 2} nanofibers decorated CdS nanoparticles by SILAR method for enhanced visible-light-driven photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Fengyu; Hou, Dongfang, E-mail: dfhouok@126.com; Hu, Fuchao; Xie, Kui; Qiao, Xiuqing; Li, Dongsheng, E-mail: lidongsheng1@126.com

    2017-01-01

    Graphical abstract: A heterojunction photocatalyst with CdS Nanoparticles self-assembled via SILAR Method at surfaces of electrospun TiO2 nanofibers shows enhanced visible-light photocatalytic activities. - Highlights: • Combined electrospinning and successive ionic layer adsorption and reaction process. • Pouous TiO{sub 2} nanofibers decorated CdS nanoparticles. • Synergetic effect of photosensitization and heterojunction. - Abstract: 1D porous CdS nanoparticles/TiO{sub 2} nanofibers heterostructure has been fabricated via simple electrospinning and a successive ionic layer adsorption and reaction (SILAR) process. The morphology, composition, and optical properties of the resulting CdS/TiO{sub 2} heterostructures can be rationally tailored through changing the SILAR cycles. The photocatalytic hydrogen evolution and decomposition of rhodamine B (RhB) of the as-synthesized heterostructured photocatalysts were investigated under visible light irradiation. Compared to TiO{sub 2} nanofibers,the as-obtained CdS/TiO{sub 2} heterostructures exhibit enhanced photocatalytic activity for hydrogen production and decomposition of RhB under visible-light irradiation. The heterojunction system performs best with H{sub 2} generation rates of 678.61 μmol h{sup −1} g{sup −1} under visible light irradiation which benefits from the two effects: (a) the 1D porous nanofibrous morphology contributes to not only more active sites but also more efficient transfer of the photogenerated charges (b) the synergetic effect of heterojunction and photosensitization reducing the recombination of photogenerated electrons and holes.

  5. Preparation of novel Sb{sub 2}O{sub 3}/WO{sub 3} photocatalysts and their activities under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    He, Guo-Hua; Liang, Can-Jian; Ou, Yu-Da; Liu, Dan-Ni; Fang, Yue-Ping [Institute of Biomaterial, College of Science, South China Agricultural University, Guangzhou 510642 (China); Xu, Yue-Hua, E-mail: xuyuehua@scau.edu.cn [Institute of Biomaterial, College of Science, South China Agricultural University, Guangzhou 510642 (China)

    2013-06-01

    Highlights: ► Visible-light-driven Sb{sub 2}O{sub 3}/WO{sub 3} photocatalysts were synthesized. ► Results showed that RhB can be decomposed using a 4 W LED lamp as visible light. ► The coupling of Sb{sub 2}O{sub 3} and WO{sub 3} enhanced the photocatalytic activity of WO{sub 3}. - Abstract: Novel visible-light-driven Sb{sub 2}O{sub 3}/WO{sub 3} photocatalysts were prepared by a hydrothermal synthesis followed by heat treatment, and characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET surface area, Fourier transform infrared spectroscopy (FT-IR) and photoluminescence spectra (PL). The photocatalytic activities of Sb{sub 2}O{sub 3}/WO{sub 3} photocatalysts were evaluated by the rhodamine B degradation using a LED lamp as visible light irradiation. Compared with pure WO{sub 3} and Sb{sub 2}O{sub 3}, the significantly enhanced photocatalytic activities of the Sb{sub 2}O{sub 3}/WO{sub 3} composite particles are attributed to the decrease of the recombination rate of photoinduced electron–hole pairs due to the coupling of Sb{sub 2}O{sub 3} and WO{sub 3} within the composite nanoparticles. Studies of Sb{sub 2}O{sub 3}/WO{sub 3} composites indicate that one approach to design composite materials with enhanced photocatalytic performance is through coupling Sb{sub 2}O{sub 3} with WO{sub 3}, which the lowest energy states for electrons and holes are in different semiconductors.

  6. One-pot synthesis of hierarchical Cu{sub 2}O/Cu hollow microspheres with enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Tianjie; Tao, Feifei, E-mail: feifeitao@usx.edu.cn; Lin, Jiudong; Ding, Wei; Lan, Mingxuan

    2015-08-15

    The hierarchical Cu{sub 2}O/Cu hollow microspheres have been fabricated by the one-pot solvothermal redox method, which is one-step approach without any surfactant and template. By using the HRTEM, XRD, XPS and UV–vis spectroscopy, the as-prepared product is composed of Cu{sub 2}O and Cu with energy band gap of 1.72 eV. Based on the time-dependent experiments, the content of Cu{sub 2}O and Cu compositions can be effectively controlled by adjusting the reaction time and a possible mechanism is proposed. In addition, using various dye molecules to stimulate pollutants, the hierarchical Cu{sub 2}O/Cu hollow microspheres reacted for 8 h exhibit excellent visible-light photocatalytic activities, which is much higher than those of the Cu{sub 2}O/Cu catalysts formed at the shorter reaction time, commercial Cu{sub 2}O powder and the mixture of alone Cu{sub 2}O and Cu. This enhanced photocatalytic performance makes these hierarchical Cu{sub 2}O/Cu hollow microspheres a kind of efficient visible-light photocatalyst in removing some organic compounds in wastewater. - Graphical abstract: The hierarchical Cu{sub 2}O/Cu hollow microspheres with adjustable components have been synthesized by one-step solvothermal redox approach. The special structures and composition lead to the excellent visible-light photocatalytic activity. - Highlights: • The hierarchical Cu{sub 2}O/Cu hollow microspheres are fabricated by one-step approach. • The content of Cu{sub 2}O and Cu can be controlled by adjusting the reaction time. • The material exhibits a better visible-light photocatalytic activity and stability. • Degradation kinetics of MO by Cu{sub 2}O/Cu fits the pseudo first-order model.

  7. One-Pot Synthesis of Cu2ZnSnSe4 Nanoplates and their Visible-Light-Driven Photocatalytic Activity

    Science.gov (United States)

    Han, Zhenzhen; Li, Nan; Shi, Aihua; Wang, Haohua; Ma, Feng; Lv, Yi; Wu, Rongqian

    2018-01-01

    A SeO2 ethanol solution as the facile precursor has been used for the preparation of quaternary Cu2ZnSnSe4 (CZTSe) nanoplates. Monodispersed single-phase CZTSe nanoplates have been prepared successfully by a facile one-pot thermal chemical method. The as-prepared CZTSe nanoplates show uniform morphology with a bandgap of 1.4 eV. As a proof of concept, the CZTSe nanoplates have been used as a visible-light-driven photocatalyst for Rhodamine B dye degradation and show high photocatalytic activity and stability. The excellent dye removal is mainly ascribed to the efficient light utilization of CZTSe nanoplates.

  8. One-Pot Solid-State Reaction Approach to Synthesize Ag-Cu2O/GO Ternary Nanocomposites with Enhanced Visible-Light-Responsive Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Longfeng Li

    2017-01-01

    Full Text Available A facile ball milling-assisted solid-state reaction method was developed to synthesize Ag-Cu2O/graphene oxide (GO nanocomposites. In the resultant complex heterostructures, Ag nanocrystals were mainly deposited on the surface of Cu2O, while Ag-Cu2O composites were anchored onto GO sheets. The resultant Ag-Cu2O/GO nanocomposites exhibited excellent photocatalytic activity with 90% of methyl orange (MO dye degradation efficiency after 60 min of visible-light irradiation, which was much higher than that of either Cu2O or Ag-Cu2O. This study opens a new avenue to fabricate visible-light-responsive photocatalyst with high performance for environmental pollution purification.

  9. Preparation of TiO2/Ag binary nanocomposite as high-activity visible-light-driven photocatalyst via graft polymerization

    Science.gov (United States)

    Tae Park, Jung; Soo Lee, Chang; Hun Park, Cheol; Hak Kim, Jong

    2017-10-01

    We report the synthesis of a TiO2/Ag binary nanocomposite with high activity for visible-light-driven photocatalysts using graft copolymerization: (1) conversion of terminal OH groups on the surface of TiO2 nanoparticles to Cl groups, (2) graft polymerization from TiO2-Cl via ATRP with ionically charged poly(styrene sulfonic acid), (3) ion exchange process with an AgNO3 solution following sintering. TiO2/Ag binary nanocomposite showed enhanced photocatalytic performance for the degradation of methyl orange under visible light illumination. The improved photocatalytic performance of the TiO2/Ag binary nanocomposite was due to the plasmonic effect, recombination rate of electron-hole pairs that was suppressed by Ag nanoparticles.

  10. Mechanochemical Synthesis of Visible Light Sensitive Titanium Dioxide Photocatalyst

    Directory of Open Access Journals (Sweden)

    Jan Šubrt

    2011-01-01

    Full Text Available Phase transition of anatase nanoparticles into the phases TiO2-II and rutile under grinding was studied. The addition of ammonium carbamate to the reaction mixture inhibits the phase conversion and the cold welding of particles. The UV-visible absorption spectrum showed narrowing the band gap width after grinding with an ammonium carbamate additive resulting in shift of the light absorption of the ground sample towards the visible region. By EPR, intensive formation of OH• radical at irradiation of the sample with both UV (λ > 300 nm and visible (λ > 435 nm light was observed. High photocatalytic activity of the ground sample in visible light region was demonstrated also by measurement of kinetics of the photocatalytic decomposition of 4-chlorophenol.

  11. Improving the visible light photocatalytic activity of TiO{sub 2} nanotubes upon decoration with Sb{sub 2}S{sub 3} microcrystalline

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, J.S. [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wang, Q.Y., E-mail: wangqingyao0532@163.com [School of Chemistry and Materials Science, Ludong University, Yantai 264025 (China); Liang, H. [Aladdin Chemical Reagent Co., Ltd., Shanghai 201206 (China); Chen, D.Q., E-mail: dqchen@hdu.edu.cn [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Ji, Z.G. [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2015-11-15

    TiO{sub 2} nanotube arrays sensitized with Sb{sub 2}S{sub 3} microcrystalline were successfully fabricated by a two-step process of photodeposition method followed by annealing treatment. The structural investigation by X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicated that the Sb{sub 2}S{sub 3} microparticles grew uniformly on the walls of TiO{sub 2} nanotubes. The amorphous Sb{sub 2}S{sub 3} microspheres could be transformed into octahedral microcrystals after annealing treatment. The Sb{sub 2}S{sub 3} modification of the TiO{sub 2} nanotube arrays resulted in an increase in visible light adsorption and photocatalytic activities toward degradation of methyl orange (MO) and rhodamine B (RhB) dyes under visible light irradiation. - Highlights: • TiO{sub 2} nanotube arrays sensitized with Sb{sub 2}S{sub 3} microcrystalline were prepared. • The amorphous Sb{sub 2}S{sub 3} microspheres transformed into octahedral microcrystals after the annealing treatment. • The TiO{sub 2} NTs/Sb{sub 2}S{sub 3} exhibits excellent visible light photocatalytic activities.

  12. Synthesis and visible-light-driven photocatalytic activity of p-n heterojunction Ag2O/NaTaO3 nanocubes

    Science.gov (United States)

    Yang, Songbo; Xu, Dongbo; Chen, Biyi; Luo, Bifu; Yan, Xu; Xiao, Lisong; Shi, Weidong

    2016-10-01

    The constructing of p-n heterojunction photocatalytic system has received much attention in environmental purification and hydrogen generation from water. In this study, an efficient visible-light-driven p-n heterojunction Ag2O/NaTaO3 was successfully prepared by chemical precipitation method at room temperature. It showed an enhanced photocatalytic activity for the degradation of rhodamine B (RhB) under visible-light irradiation, much higher than those of either individual Ag2O or NaTaO3. The reactive species scavenger results indicated the superoxide anion radicals (rad O2-) played key roles in RhB decoloration. From the experimental results and the relative band gap position of these semiconductors, a detailed possible photocatalytic mechanism of the Ag2O/NaTaO3 heterojunction under visible light was proposed. The enhancement of the photocatalytic activity was attributed to the interfacial electronic interaction between NaTaO3 and Ag2O and the high migration efficiency of photogenerated carriers.

  13. Ag3PO4/rectorite nanocomposites: Ultrasound-assisted preparation, characterization and enhancement of stability and visible-light photocatalytic activity.

    Science.gov (United States)

    Guo, Yadan; Yu, Wenchao; Chen, Jinquan; Wang, Xuegang; Gao, Bai; Wang, Guanghui

    2017-01-01

    To overcome the drawback of low stable brought by the transformation of Ag(+) into Ag, a highly efficient and stable photocatalyst Ag3PO4/rectorite composite was successfully synthesized by ultrasound-assisted precipitation method. The as-prepared samples were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption-desorption, room-temperature photoluminescence spectra, Fourier transform infrared spectrum measurements and UV-vis diffuse reflectance spectra. The absorption edges of the Ag3PO4/rectorite display a noticeable shift to the visible light region as compared to that of the Ag3PO4. Compared with bare Ag3PO4, the Ag3PO4/rectorite composite by ultrasound-assisted precipitation process exhibits significantly enhanced photocatalytic activity and stable for methyl orange (MO) degradation under visible light irradiation. The improved activity of the Ag3PO4/rectorite photocatalyst could be attributed to the expanded visible light absorption, the enhanced interfacial charge transfer and the inhibited recombination of electron-hole pairs. Therefore, the facile ultrasound-assisted preparation process provides some insight into the application of Ag3PO4/rectorite nanocomposites in photocatalytic degradation of organic pollutants. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. In situ formed Bi/BiOBrxI1-x heterojunction of hierarchical microspheres for efficient visible-light photocatalytic activity.

    Science.gov (United States)

    Zheng, Chunrui; Cao, Chuanbao; Ali, Zulfiqar

    2015-05-28

    Bi nanoparticles deposited in situ in BiOBrxI1-x hierarchical microspheres (Bi/BiOBrxI1-x heterojunction) were synthesized by a facile one-step solvothermal method. The as-prepared samples were characterized via XRD, SEM, TEM, XPS, UV-vis absorption spectroscopy and N2 adsorption-desorption. The hierarchical microspheres were composed of numerous nanosheets aggregated together compactly to form a spherical geometry. Results indicated that Bi nanoparticles were generated on the surface of BiOBrxI1-x microspheres via the in situ reduction of Bi(3+) by ethylene glycol. BiOBrxI1-x microspheres with deposited Bi nanoparticles were employed for the degradation of RhB under visible-light irradiation and the samples exhibited exceptionally enhanced photocatalytic activity. This immense enhancement in photocatalytic activity was attributed to the contribution of Bi nanoparticles to the efficient separation of electron-hole pairs and prolongation of the lifetime of charge carriers. The behavior of Bi nanoparticles as a cocatalyst for enhancing photocatalytic activity is similar to that of noble metals in photocatalysis. The as-prepared Bi/BiOBr0.266I0.734 sample exhibited highest photocatalytic activity, which exceeded those of other types of visible-light photocatalysts such as N-TiO2, Eu(3+)-BiOI, BiOBr, BiOBr0.2I0.8/graphene and even Ag/AgBr/BiOBr. The Bi/BiOBr0.266I0.734 sample displayed high photochemical stability under repeated visible-light irradiation, which is especially important for its practical application. The active species produced from Bi/BiOBrxI1-x under visible light were hydroxyl radicals. Bi/BiOBrxI1-x could generate more hydroxyl radicals due to the Bi nanoparticles, contributing to the enhance oxidation ability. This study demonstrated the high feasibility of utilizing low-cost Bi nanoparticles as a substitute for noble metals to enhance visible-light photocatalysis.

  15. Photodetector Characteristics in Visible Light Communication

    KAUST Repository

    Ho, Kang-Ting

    2016-04-01

    Typically, in the semiconductor industry pn heterojunctions have been used as either light-emitting diodes (LED) or photodiodes by applying forward current bias or reverse voltage bias, respectively. However, since both devices use the same structure, the light emitting and detecting properties could be combine in one single device, namely LED-based photodetector. Therefore, by integrating LED-based photodetectors as either transmitter or receiver, optical wireless communication could be easily implemented for bidirectional visible light communication networks at low-cost. Therefore, this dissertation focus on the investigation of the photodetection characteristics of InGaN LED-based photodetectors for visible light communication in the blue region. In this regard, we obtain external quantum efficiency of 10 % and photoresponse rise time of 71 μs at 405-nm illumination, revealing high-performance photodetection characteristics. Furthermore, we use orthogonal frequency division multiplexing quadrature amplitude modulation codification scheme to enlarge the operational bandwidth. Consequently, the transmission rate of the communication is efficiently enhanced up to 420 Mbit/s in visible light communication.

  16. Fabrication of TiO{sub 2}/Ag{sub 2}O heterostructure with enhanced photocatalytic and antibacterial activities under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bingkun, E-mail: liubk2015@zzuli.edu.cn [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Mu, Lilong; Han, Bing [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Zhang, Jingtao [School of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Shi, Hengzhen, E-mail: shihz@zzuli.edu.cn [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China)

    2017-02-28

    Highlights: • TiO{sub 2}/Ag{sub 2}O composite photocatalyst was synthesized successfully. • The composites show better photocatalytic activity for MB under visible light. • The composites also possess good antibacterial properties. • The mechanism of enhanced photocatalytic activities was investigated. - Abstract: TiO{sub 2}/Ag{sub 2}O heterostructure prepared by a facile in situ precipitation route was used as an effective visible light-driven photocatalyst for degradation of methylene blue (MB) and inactivation of E. coli. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed that Ag{sub 2}O nanoparticles were well distributed on the surface of TiO{sub 2} microspheres. The TiO{sub 2}/Ag{sub 2}O composite with optimal mass ratio of TiO{sub 2} and Ag{sub 2}O displayed extremely good photodegradation ability and antibacterial capability under visible light irradiation, which was mainly ascribed to the synergistic effect between Ag{sub 2}O and TiO{sub 2,} including highly dispersed smaller Ag{sub 2}O particles, increased visible light absorption and efficient separation of photo-induced charge carriers. Meanwhile, the roles of the radical species in the photocatalysis process were investigated. Our results showed that the TiO{sub 2}/Ag{sub 2}O could be used as a dual functional material in water treatment of removing the organic pollutant and killing the bacterium at the same time.

  17. 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)

  18. Synthesis of MoS2/g-C3N4 nanocomposites with enhanced visible-light photocatalytic activity for the removal of nitric oxide (NO).

    Science.gov (United States)

    Wen, M Q; Xiong, T; Zang, Z G; Wei, W; Tang, X S; Dong, F

    2016-05-16

    Molybdenum disulfide and graphitic carbon nitride (MoS2-g-C3N4) nanocomposites with visible-light induced photocatalytic activity were successfully synthesized by a facile ultrasonic dispersion method. The crystalline structure and morphology of the MoS2-g-C3N4 nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microcopy (TEM), high-resolution TEM (HRTEM) and scanning electron microscopy (SEM). The optical property of the as-prepared nanocomposites was studied by ultraviolet visible diffusion reflection (UV-vis) and photoluminescence(PL) spectrum. It could be observed from the TEM image that the MoS2 nanosheets and g-C3N4 nanoparticles were well combined together. Moreover, the photocatalytic activity of MoS2-g-C3N4 composites was evaluated by the removal of nitric oxide under visible light irradiation (>400nm). The experimental results demonstrated that the nanocomposites with the MoS2 content of 1.5 wt% exhibited optimal photocatalytic activity and the corresponding removal rate of NO achieved 51.67%, higher than that of pure g-C3N4 nanoparticles. A possible photocatalytic mechanism for the MoS2-g-C3N4 nanocomposites with enhanced photocatalytic activity could be ascribed to the hetero-structure of MoS2 and g-C3N4.

  19. Visible Lasers and Emerging Color Converters for Lighting and Visible Light Communications

    KAUST Repository

    Shen, Chao

    2017-10-30

    GaN-based lasers are promising for white lighting and visible-light communication (VLC). The advances of III-nitride photonic integration, and the application of YAG crystal and perovskite-based phosphors to lighting and VLC will be discussed.

  20. Merging Visible Light Photoredox Catalysis with Metal Catalyzed C-H Activations: On the Role of Oxygen and Superoxide Ions as Oxidants.

    Science.gov (United States)

    Fabry, David C; Rueping, Magnus

    2016-09-20

    The development of efficient catalytic systems for direct aromatic C-H bond functionalization is a long-desired goal of chemists, because these protocols provide environmental friendly and waste-reducing alternatives to classical methodologies for C-C and C-heteroatom bond formation. A key challenge for these transformations is the reoxidation of the in situ generated metal hydride or low-valent metal complexes of the primary catalytic bond forming cycle. To complete the catalytic cycle and to regenerate the C-H activation catalyst, (super)stoichiometric amounts of Cu(II) or Ag(I) salts have often been applied. Recently, "greener" approaches have been developed by applying molecular oxygen in combination with Cu(II) salts, internal oxidants that are cleaved during the reaction, or solvents or additives enabling the metal hydride reoxidation. All these approaches improved the environmental friendliness but have not overcome the obstacles associated with the overall limited functional group and substrate tolerance. Hence, catalytic processes that do not feature the unfavorable aspects described above and provide products in a streamlined as well as economically and ecologically advantageous manner would be desirable. In this context, we decided to examine visible light photoredox catalysis as a new alternative to conventionally applied regeneration/oxidation procedures. This Account summarizes our recent advances in this expanding area and will highlight the new concept of merging distinct redox catalytic processes for C-H functionalizations through the application of visible light photoredox catalysis. Photoredox catalysis can be considered as catalytic electron-donating or -accepting processes, making use of visible-light absorbing homogeneous and heterogeneous metal-based catalysts, as well as organic dye sensitizers or polymers. As a consequence, photoredox catalysis is, in principle, an ideal tool for the recycling of any given metal catalyst via a coupled

  1. Merging Visible Light Photoredox Catalysis with Metal Catalyzed C–H Activations: On the Role of Oxygen and Superoxide Ions as Oxidants

    Science.gov (United States)

    2016-01-01

    Conspectus The development of efficient catalytic systems for direct aromatic C–H bond functionalization is a long-desired goal of chemists, because these protocols provide environmental friendly and waste-reducing alternatives to classical methodologies for C–C and C–heteroatom bond formation. A key challenge for these transformations is the reoxidation of the in situ generated metal hydride or low-valent metal complexes of the primary catalytic bond forming cycle. To complete the catalytic cycle and to regenerate the C–H activation catalyst, (super)stoichiometric amounts of Cu(II) or Ag(I) salts have often been applied. Recently, “greener” approaches have been developed by applying molecular oxygen in combination with Cu(II) salts, internal oxidants that are cleaved during the reaction, or solvents or additives enabling the metal hydride reoxidation. All these approaches improved the environmental friendliness but have not overcome the obstacles associated with the overall limited functional group and substrate tolerance. Hence, catalytic processes that do not feature the unfavorable aspects described above and provide products in a streamlined as well as economically and ecologically advantageous manner would be desirable. In this context, we decided to examine visible light photoredox catalysis as a new alternative to conventionally applied regeneration/oxidation procedures. This Account summarizes our recent advances in this expanding area and will highlight the new concept of merging distinct redox catalytic processes for C–H functionalizations through the application of visible light photoredox catalysis. Photoredox catalysis can be considered as catalytic electron-donating or -accepting processes, making use of visible-light absorbing homogeneous and heterogeneous metal-based catalysts, as well as organic dye sensitizers or polymers. As a consequence, photoredox catalysis is, in principle, an ideal tool for the recycling of any given metal

  2. Facile Synthesis and Characterization of N-Doped TiO2 Photocatalyst and Its Visible-Light Activity for Photo-Oxidation of Ethylene

    Directory of Open Access Journals (Sweden)

    Yu-Hao Lin

    2015-01-01

    Full Text Available A facile wet chemical method was adopted for preparing highly photoactive nitrogen doped TiO2 (N-TiO2 powders with visible responsive capability, which could be achieved by the hydrolysis of titanium isopropoxide (TTIP in the ammonium hydroxide precursor solution in various concentrations and then calcined at different temperatures. The N-TiO2 powders were characterized, and the photocatalytic activity was evaluated for the photocatalytic oxidation of ethylene gas under visible light irradiation to optimize the synthesizing conditions of N-TiO2 catalyst. The N-TiO2 photocatalytic powders were calcined in a range of temperatures from 300 to 600°C and obviously found to have greater photocatalytic activities than commercial TiO2 P25. The strong absorption in the visible light region could be ascribed to good crystallization and adapted sinter temperature of as prepared sample. XPS test demonstrated that the N was doped into TiO2 lattice and made an interstitial formation (Ti-O-N, and N doping also retarded the phase transformation from anatase to rutile as well. The N-TiO2 catalyst prepared with 150 mL ammonium hydroxide added and calcined at 500°C showed the best photocatalytic activity. The experimental results also proved the enhanced photoactivity of N-TiO2 material depends on the synthesizing conditions.

  3. Synthesis and visible-light-induced catalytic activity of Ag{sub 2}S-coupled TiO{sub 2} nanoparticles and nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Xie Yi; Heo, Sung Hwan; Kim, Yong Nam; Yoo, Seung Hwa; Cho, Sung Oh, E-mail: socho@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong, Yuseong, Daejeon 305-701 (Korea, Republic of)

    2010-01-08

    We present the synthesis and visible-light-induced catalytic activity of Ag{sub 2}S-coupled TiO{sub 2} nanoparticles (NPs) and TiO{sub 2} nanowires (NWs). Through a simple wet chemical process from a mixture of peroxo titanic acid (PTA) solution, thiourea and AgAc, a composite of Ag{sub 2}S NPs and TiO{sub 2} NPs with sizes of less than 7 nm was formed. When the NP composite was further treated with NaOH solution followed by annealing at ambient conditions, a new nanocomposite material comprising Ag{sub 2}S NPs on TiO{sub 2} NWs was created. Due to the coupling with such a low bandgap material as Ag{sub 2}S, the TiO{sub 2} nanocomposites could have a visible-light absorption capability much higher than that of pure TiO{sub 2}. As a result, the synthesized Ag{sub 2}S/TiO{sub 2} nanocomposites exhibited much higher catalytic efficiency for the decomposition of methyl orange than commercial TiO{sub 2} (Degussa P25, Germany) under visible light.

  4. Palladium nanoparticles anchored to anatase TiO2 for enhanced surface plasmon resonance-stimulated, visible-light-driven photocatalytic activity

    Directory of Open Access Journals (Sweden)

    Kah Hon Leong

    2015-02-01

    Full Text Available Freely assembled palladium nanoparticles (Pd NPs on titania (TiO2 nano photocatalysts were successfully synthesized through a photodeposition method using natural sunlight. This synthesized heterogeneous photocatalyst (Pd/TiO2 was characterized through field emission scanning electron microscopy (FESEM, high resolution transmission electron microscopy (HRTEM, X-ray diffraction (XRD, BET surface area, UV–vis diffuse reflectance spectra (UV-DRS, Raman and photoluminescence (PL analyses. The simple and smart synthesis anchored well the deposition with controlled Pd NPs size ranging between 17 and 29 nm onto the surface of TiO2. Thus, it gives the characteristic for Pd NPs to absorb light in the visible region obtained through localized surface plasmon resonance (LSPRs. Apparently, the photocatalytic activity of the prepared photocatalysts was evaluated by degrading the endocrine disrupting compound (EDC amoxicillin (AMX excited under an artificial visible light source. In the preliminary run, almost complete degradation (97.5% was achieved in 5 h with 0.5 wt % Pd loading and the degradation followed pseudo-first-order kinetics. The reusability trend proved the photostability of the prepared photocatalysts. Hence, the study provides a new insight about the modification of TiO2 with noble metals in order to enhance the absorption in the visible-light region for superior photocatalytic performance.

  5. Structure, optical properties and visible-light-induced photochemical activity of nanocrystalline ZnO films deposited by atomic layer deposition onto Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Drozd, V.E.; Titov, V.V.; Kasatkin, I.A.; Basov, L.L. [Fock Institute of Physics, Department of Physics, Saint-Petersburg State University, Ul' yanovskaya st., 1, Saint-Petersburg, 198504 (Russian Federation); Lisachenko, A.A., E-mail: a.lisachenko@spbu.ru [Fock Institute of Physics, Department of Physics, Saint-Petersburg State University, Ul' yanovskaya st., 1, Saint-Petersburg, 198504 (Russian Federation); Stroyuk, O.L., E-mail: alstroyuk@ukr.net [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 Nauky av., Kyiv 03028 (Ukraine); Kuchmiy, S.Y. [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 Nauky av., Kyiv 03028 (Ukraine)

    2014-12-31

    Nano-layers of ZnO (thickness 2–300 nm) were deposited on the surface of p-Si(100), SiO{sub x}/p-Si(100), and n-Si(111) using the atomic layer deposition technique. Morphology, microstructure, and electronic structure of the ZnO/Si(100), ZnO/SiO{sub x}/Si(100), and n- Si(111) films were characterized using scanning electron microscopy, X-ray diffraction and reflectometry, and X-ray photoelectron spectroscopy. The layers have good adhesion to the substrate, polycrystalline structure, and uniform thickness. Starting from the thickness of 4 nm, the hexagonal crystal structure of zincite (wurtzite-type) could be detected with a weak texture changing from [100] to [001] with increasing thickness of the layer. Desorption of H{sub 2}O and CO{sub 2} at ∼ 10{sup −4} Pa from the surface under irradiation with visible light (λ > 500 nm)—the interval of ZnO transparency—was measured by mass-spectrometry. This proves a sensitization of the photocatalytically active ZnO films to the visible light by silicon substrate and opens possibilities of using the composite Si/ZnO materials. - Highlights: • ZnO films (2–300-nm thick) were deposited on Si(100) by atomic layer deposition. • Si substrate sensitizes ZnO nano-layer to the visible light (λ > 500 nm). • Si/ZnO heterojunction can act as a visible-light-sensitive photocatalyst.

  6. Design for The Indoor Visible Light Communication Application System Based on LED Visible Light

    Directory of Open Access Journals (Sweden)

    Lian Wenyu

    2017-01-01

    Full Text Available This paper designs an indoor visible light communication application system based on LED. The system can modulate the original signal one or more times, move to a specific frequency band, transmit on the power line, in the LED terminal use this module to decode, restore the Ethernet signals. This design is applicable to the simplicity of the LED visible light communication applications, which provide the premise and guarantee for the construction of smart home network.

  7. Synthesis, Characterization, and Investigation of Visible Light Photocatalytic Activity of C Doped TiO2/CdS Core-Shell Nanocomposite

    Directory of Open Access Journals (Sweden)

    Atul B. Lavand

    2015-01-01

    Full Text Available Carbon (C doped TiO2/CdS core-shell nanocomposite (C/TiO2/CdS was synthesized using microemulsion method. Synthesized powder was characterized using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, energy dispersive X-ray spectroscopy (EDX, transmission electron microscopy (TEM, and UV-visible spectrophotometery. TEM images reveal that C/TiO2/CdS core-shell heterostructure is successfully prepared with CdS as a core and C doped TiO2 as a shell. UV-visible absorption spectra show that CdS nanoparticles act as a sensitizer and effectively enhance the photoabsorption capacity of C/TiO2/CdS nanocomposite in visible region. Visible light photocatalytic activity of synthesized nanocomposite was evaluated for the degradation of methylene blue. C/TiO2/CdS core-shell nanocomposite exhibits better photocatalytic activity as compared to bare TiO2, CdS, CdS/TiO2, and C doped TiO2.

  8. A novel fabrication methodology for sulfur-doped ZnO nanorods as an active photoanode for improved water oxidation in visible-light regime

    Science.gov (United States)

    Khan, A.; Ahmed, M. I.; Adam, A.; Azad, A.-M.; Qamar, M.

    2017-02-01

    Incorporation of foreign moiety in the lattice of semiconductors significantly alters their optoelectronic behavior and opens a plethora of new applications. In this paper, we report the synthesis of sulfur-doped zinc oxide (S-doped ZnO) nanorods by reacting ZnO nanorods with diammonium sulfide in vapor phase. Microscopic investigation revealed that the morphological features, such as, the length (2-4 μm) and width (100-250 nm) of the original hexagonal ZnO nanorods remained intact post-sulfidation. X-ray photoelectron spectroscopy analysis of the sulfide sample confirmed the incorporation of sulfur into ZnO lattice. The optical measurements suggested the extension of absorption threshold into visible region upon sulfidation. Photoelectrochemical (PEC) activities of pure and S-doped ZnO nanorods were compared for water oxidation in visible light (λ > 420 nm), which showed several-fold increment in the performance of S-doped ZnO sample; the observed amelioration in the PEC activity was rationalized in terms of preferred visible light absorption and low resistance of sulfide sample, as evidenced by optical and electrochemical impedance spectroscopy.

  9. Facile Synthesis of SrCO3-Sr(OH2/PPy Nanocomposite with Enhanced Photocatalytic Activity under Visible Light

    Directory of Open Access Journals (Sweden)

    Alfredo Márquez-Herrera

    2016-01-01

    Full Text Available Pyrrole monomer was chemically polymerized onto SrCO3-Sr(OH2 powders to obtain SrCO3-Sr(OH2/polypyrrole nanocomposite to be used as a candidate for photocatalytic degradation of methylene blue dye (MB. The material was characterized by Fourier transform infrared (FTIR spectroscopy, UV/Vis spectroscopy, and X-ray diffraction (XRD. It was observed from transmission electronic microscopy (TEM analysis that the reported synthesis route allows the production of SrCO3-Sr(OH2 nanoparticles with particle size below 100 nm which were embedded within a semiconducting polypyrrole matrix (PPy. The SrCO3-Sr(OH2 and SrCO3-Sr(OH2/PPy nanocomposites were tested in the photodegradation of MB dye under visible light irradiation. Also, the effects of MB dye initial concentration and the catalyst load on photodegradation efficiency were studied and discussed. Under the same conditions, the efficiency of photodegradation of MB employing the SrCO3-Sr(OH2/PPy nanocomposite increases as compared with that obtained employing the SrCO3-Sr(OH2 nanocomposite.

  10. One-step hydrothermal synthesis of In2.77S4 nanosheets with efficient photocatalytic activity under visible light

    Science.gov (United States)

    Wu, Xiang-feng; Li, Hui; Sun, Yang; Wang, Yi-jin; Zhang, Chen-xu; Gong, Xiao-dong; Wang, Yu-duan; Liu, Yu; Yang, Xin-yue

    2017-06-01

    In2.77S4 nanosheets with the band gap energy of 1.75 eV were fast prepared via a hydrothermal process. The structure, morphology and optical properties of the as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy and UV-vis diffuse reflectance spectroscopy, respectively. Rhodamine B, methyl orange and potassium dichromate solution were used to evaluate the degradation efficiency of the as-prepared samples under the visible light, respectively. Experimental results showed that the molar ratio of thioacetamide to indium nitrate hydrate significantly influenced the structure and properties of the as-prepared products. With increasing the molar ratio, the degradation efficiency of rhodamine B solution was firstly increased and then decreased. When the molar ratio was 4:1, the degradation efficiency of the as-prepared sample reached to 96% in 3 min and 100% in 9 min. Moreover, this semiconductor could degrade 88% of methyl orange solution in 30 min and 87% of potassium dichromate solution in 60 min, respectively.

  11. Effects of the preparation method on the structure and the visible-light photocatalytic activity of Ag2CrO4

    Directory of Open Access Journals (Sweden)

    Difa Xu

    2014-05-01

    Full Text Available Silver chromate (Ag2CrO4 photocatalysts are prepared by microemulsion, precipitation, and hydrothermal methods, in order to investigate the effect of preparation methods on the structure and the visible-light photocatalytic activity. It is found that the photocatalytic activity of the prepared Ag2CrO4was highly dependent on the preparation methods. The sample prepared by microemulsion method exhibits the highest photocatalytic efficiency on the degradation of methylene blue (MB under visible-light irradiation. The enhanced photocatalytic activity could be ascribed to the smaller particle size, higher surface area, relatively stronger light absorption, and blue-shift absorption edge, which result in the adsorption of more MB molecules, a shorter diffusion process of more photogenerated excitons, and a stronger oxidation ability of the photogenerated holes. Considering the universalities of microemulsion, precipitation, and hydrothermal methods, this work may also provide a prototype for the comparative study of semiconductor based photocatalysis for water purification and environmental remediation.

  12. Microbial fuel cell assisted band gap narrowed TiO2 for visible light-induced photocatalytic activities and power generation.

    Science.gov (United States)

    Khan, Mohammad Ehtisham; Khan, Mohammad Mansoob; Min, Bong-Ki; Cho, Moo Hwan

    2018-01-29

    This paper reports a simple, biogenic and green approach to obtain narrow band gap and visible light-active TiO2 nanoparticles. Commercial white TiO2 (w-TiO2) was treated in the cathode chamber of a Microbial Fuel Cell (MFC), which produced modified light gray TiO2 (g-TiO2) nanoparticles. The DRS, PL, XRD, EPR, HR-TEM, and XPS were performed to understand the band gap decline of g-TiO2. The optical study revealed a significant decrease in the band gap of the g-TiO2 (E g  = 2.80 eV) compared to the w-TiO2 (E g  = 3.10 eV). The XPS revealed variations in the surface states, composition, Ti4+ to Ti3+ ratio, and oxygen vacancies in the g-TiO2. The Ti3+ and oxygen vacancy-induced enhanced visible light photocatalytic activity of g-TiO2 was confirmed by degrading different model dyes. The enhanced photoelectrochemical response under visible light irradiation further supported the improved performance of the g-TiO2 owing to a decrease in the electron transfer resistance and an increase in charge transfer rate. During the TiO2 treatment process, electricity generation in MFC was also observed, which was ~0.3979 V corresponding to a power density of 70.39 mW/m2. This study confirms narrow band gap TiO2 can be easily obtained and used effectively as photocatalysts and photoelectrode material.

  13. Innovative, energy-efficient lighting for New York state roadways : opportunities for incorporating mesopic visibility considerations into roadway lighting practice

    Science.gov (United States)

    2008-04-01

    The present report outlines activities undertaken to assess the potential for implementing research on visibility at mesopic light levels into lighting practices for roadways in New York State. Through measurements of light levels at several roadway ...

  14. 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.

  15. Enhanced UV-Visible Light Photocatalytic Activity by Constructing Appropriate Heterostructures between Mesopore TiO2 Nanospheres and Sn3O4 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jianling Hu

    2017-10-01

    Full Text Available Novel TiO2/Sn3O4 heterostructure photocatalysts were ingeniously synthesized via a scalable two-step method. The impressive photocatalytic abilities of the TiO2/Sn3O4 sphere nanocomposites were validated by the degradation test of methyl orange and •OH trapping photoluminescence experiments under ultraviolet (UV and visible light irradiation, respectively. Especially under the visible light, the TiO2/Sn3O4 nanocomposites demonstrated a superb photocatalytic activity, with 81.2% of methyl orange (MO decomposed at 30 min after irradiation, which greatly exceeded that of the P25 (13.4%, TiO2 (0.5% and pure Sn3O4 (59.1% nanostructures. This enhanced photocatalytic performance could be attributed to the mesopore induced by the monodispersed TiO2 cores that supply sufficient surface areas and accessibility to reactant molecules. This exquisite hetero-architecture facilitates extended UV-visible absorption and efficient photoexcited charge carrier separation.

  16. A chemical bath deposition route to facet-controlled Ag{sub 3}PO{sub 4} thin films with improved visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Gunjakar, Jayavant L.; Jo, Yun Kyung; Kim, In Young; Lee, Jang Mee; Patil, Sharad B. [Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University, Seoul 03760 (Korea, Republic of); Pyun, Jae-Chul [Department of Materials Science and Engineering, College of Engineering, Yonsei University, Seoul (Korea, Republic of); Hwang, Seong-Ju, E-mail: hwangsju@ewha.ac.kr [Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University, Seoul 03760 (Korea, Republic of)

    2016-08-15

    A facile, economic, and reproducible chemical bath deposition (CBD) method is developed for the fabrication of facet-controlled Ag{sub 3}PO{sub 4} thin films with enhanced visible light photocatalytic activity. The fine-control of bath temperature, precursor, complexing agent, substrate, and solution pH is fairly crucial in preparing the facet-selective thin film of Ag{sub 3}PO{sub 4} nanocrystal. The change of precursor from silver nitrate to silver acetate makes possible the tailoring of the crystal shape of Ag{sub 3}PO{sub 4} from cube to rhombic dodecahedron and also the bandgap tuning of the deposited films. The control of [Ag{sup +}]/[phosphate] ratio enables to maximize the loading amount of Ag{sub 3}PO{sub 4} crystals per the unit area of the deposited film. All the fabricated Ag{sub 3}PO{sub 4} thin films show high photocatalytic activity for visible light-induced degradation of organic molecules, which can be optimized by tailoring the crystal shape of the deposited crystals. This CBD method is also useful in preparing the facet-controlled hybrid film of Ag{sub 3}PO{sub 4}–ZnO photocatalyst. The present study clearly demonstrates the usefulness of the present CBD method for fabricating facet-controlled thin films of metal oxosalt and its nanohybrid. - Highlights: • The crystal facet of Ag{sub 3}PO{sub 4} films can be tuned by chemical bath deposition. • The crystal shape of Ag{sub 3}PO{sub 4} is tailorable from cube to rhombic dodecahedron. • Facet-tuned Ag{sub 3}PO{sub 4} film shows enhanced visible light photocatalyst activity.

  17. Visible light communication applications in healthcare.

    Science.gov (United States)

    Muhammad, Shoaib; Qasid, Syed Hussain Ahmed; Rehman, Shafia; Rai, Aitzaz Bin Sulltan

    2016-01-01

    With the development in science, methods of communication are also improved, replacing old ones with new advanced ways in an attempt to make data transfer more secure, safer for health, and time as well as cost efficient. One of such methods is Visible Light Communication, as the name implies data is transferred through a light equipment such as incandescent or florescent bulb having speed of 10 Kb/s or LEDs approaching speed of 500 Mb/s [1]. VLC uses visible light between 384 and 789 THz [2,3]. Though range is limitation of VLC, however data transfer up-to distance of 1 to 2 km although at lower transfer rate has been reached.The VLC system comprises of light source like LED and receiver equipment, however, with advancement, now LEDs are used for both sending and receiving data. LED remains on all the time, and there is no change in brightness level during the whole process, making it safe for eyes. Currently, VLC system is facing some serious technical challenges before it could be applied in daily life.

  18. Bright visible light emission from graphene.

    Science.gov (United States)

    Kim, Young Duck; Kim, Hakseong; Cho, Yujin; Ryoo, Ji Hoon; Park, Cheol-Hwan; Kim, Pilkwang; Kim, Yong Seung; Lee, Sunwoo; Li, Yilei; Park, Seung-Nam; Yoo, Yong Shim; Yoon, Duhee; Dorgan, Vincent E; Pop, Eric; Heinz, Tony F; Hone, James; Chun, Seung-Hyun; Cheong, Hyeonsik; Lee, Sang Wook; Bae, Myung-Ho; Park, Yun Daniel

    2015-08-01

    Graphene and related two-dimensional materials are promising candidates for atomically thin, flexible and transparent optoelectronics. In particular, the strong light-matter interaction in graphene has allowed for the development of state-of-the-art photodetectors, optical modulators and plasmonic devices. In addition, electrically biased graphene on SiO2 substrates can be used as a low-efficiency emitter in the mid-infrared range. However, emission in the visible range has remained elusive. Here, we report the observation of bright visible light emission from electrically biased suspended graphene devices. In these devices, heat transport is greatly reduced. Hot electrons (∼2,800 K) therefore become spatially localized at the centre of the graphene layer, resulting in a 1,000-fold enhancement in thermal radiation efficiency. Moreover, strong optical interference between the suspended graphene and substrate can be used to tune the emission spectrum. We also demonstrate the scalability of this technique by realizing arrays of chemical-vapour-deposited graphene light emitters. These results pave the way towards the realization of commercially viable large-scale, atomically thin, flexible and transparent light emitters and displays with low operation voltage and graphene-based on-chip ultrafast optical communications.

  19. One-step hydrothermal synthesis of N-doped TiO2/C nanocomposites with high visible light photocatalytic activity

    Science.gov (United States)

    Wang, Dong-Hong; Jia, Li; Wu, Xi-Lin; Lu, Li-Qiang; Xu, An-Wu

    2012-01-01

    N-doped TiO2 nanoparticles modified with carbon (denoted N-TiO2/C) were successfully prepared by a facile one-pot hydrothermal treatment in the presence of l-lysine, which acts as a ligand to control the nanocrystal growth and as a source of nitrogen and carbon. As-prepared nanocomposites were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), electron paramagnetic resonance (EPR) spectra, and N2 adsorption-desorption analysis. The photocatalytic activities of the as-prepared photocatalysts were measured by the degradation of methyl orange (MO) under visible light irradiation at λ >= 400 nm. The results show that N-TiO2/C nanocomposites increase absorption in the visible light region and exhibit a higher photocatalytic activity than pure TiO2, commercial P25 and previously reported N-doped TiO2 photocatalysts. We have demonstrated that the nitrogen was doped into the lattice and the carbon species were modified on the surface of the photocatalysts. N-doping narrows the band gap and C-modification enhances the visible light harvesting and accelerates the separation of the photo-generated electrons and holes. As a consequence, the photocatalytic activity is significantly improved. The molar ratio of l-lysine/TiCl4 and the pH of the hydrothermal reaction solution are important factors affecting the photocatalytic activity of the N-TiO2/C the optimum molar ratio of l-lysine/TiCl4 is 8 and the optimum pH is ca. 4, at which the catalyst exhibits the highest reactivity. Our findings demonstrate that the as-obtained N-TiO2/C photocatalyst is a better and more promising candidate than well studied N-doped TiO2 alternatives as visible light photocatalysts for potential applications in

  20. High photocatalytic activity of hierarchical SiO2@C-doped TiO2 hollow spheres in UV and visible light towards degradation of rhodamine B.

    Science.gov (United States)

    Zhang, Ying; Chen, Juanrong; Hua, Li; Li, Songjun; Zhang, Xuanxuan; Sheng, Weichen; Cao, Shunsheng

    2017-10-15

    Ongoing research activities are targeted to explore high photocatalytic activity of TiO2-based photocatalysts for the degradation of environmental contaminants under UV and visible light irradiation. In this work, we devise a facile, cost-effective technique to in situ synthesize hierarchical SiO2@C-doped TiO2 (SCT) hollow spheres for the first time. This strategy mainly contains the preparation of monodisperse cationic polystyrene spheres (CPS), sequential deposition of inner SiO2, the preparation of the sandwich-like CPS@SiO2@CPS particles, and formation of outer TiO2. After the one-step removal of CPS templates by calcination at 450°C, hierarchical SiO2@C-doped TiO2 hollow spheres are in situ prepared. The morphology, hierarchical structure, and properties of SCT photocatalyst were characterized by TEM. SEM, STEM Mapping, BET, XRD, UV-vis spectroscopy, and XPS. Results strongly confirm the carbon doping in the outer TiO2 lattice of SCT hollow spheres. When the as-synthesized SCT hollow spheres were employed as a photocatalyst for the degradation of Rhodamine B under visible-light and ultraviolet irradiation, the SCT photocatalyst exhibits a higher photocatalytic activity than commercial P25, effectively overcoming the limitations of poorer UV activity for many previous reported TiO2-based photocatalysts due to doping. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. In situ preparation of (BiO)2CO3/BiOBr sheet-on-sheet heterojunctions with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Gao, Lin; Li, Xiao; Zhao, Jinyan; Zhang, Xin; Zhang, Xuhong; Yu, Haitao

    2017-09-01

    (BiO)2CO3/BiOBr sheet-on-sheet nanocomposites with different (BiO)2CO3 contents were synthesized via a in situ bubbling method and characterized by XRD, XPS, SEM, HRTEM, N2 adsorption-desorption, UV-vis DRS, PL, photocurrent and EIS. The photocatalytic activities of these samples were evaluated by degradation of methylene blue (MB) and Rhodamine B (RhB) under visible light irradiation. The results showed that the (BiO)2CO3/BiOBr composites displayed higher photocatalytic activity than the pristine (BiO)2CO3 and BiOBr. The 15 wt% (BiO)2CO3/BiOBr showed the highest photocatalytic activity under visible light irradiation. The enhanced photocatalytic activity of (BiO)2CO3/BiOBr composites could be attributed to the well-matched band structure and intimate contact interfaces between (BiO)2CO3 and BiOBr, which led to the effective transfer and separation of the photogenerated charge carriers. A possible photocatalytic mechanism for the (BiO)2CO3/BiOBr composites was also proposed based on the experimental results.

  2. Gold nanoparticles embedded in Ta 2 O 5 /Ta 3 N 5 as active visible-light plasmonic photocatalysts for solar hydrogen evolution

    KAUST Repository

    Luo, Yujing

    2014-07-10

    Here, we demonstrate a new recreating photocatalytic activity of a Nano Au/Ta2O5 composite for hydrogen evolution from water as a visible-light-responsive plasmonic photocatalyst by embedding Au nanoparticles in a Ta2O5 host lattice. The Nano Au/Ta2O 5 composite samples were prepared through a simple Pechini-type sol-gel process. Further nitridating Nano Au/Ta2O5 composite samples in ammonia flow at 1123 K yielded Nano Au/Ta3N 5 composite samples. The obtained Nano Au/Ta3N5 composite exhibited a significantly enhanced photocatalytic activity in the visible region for hydrogen evolution from water compared with blank Ta 3N5 nanoparticles. UV-visible diffuse reflectance spectra and photocatalytic activity measurements indicated that the excitation of surface plasmon resonance of Au nanoparticles is responsible for the new recreating photocatalytic activity of the Nano Au/Ta2O5 composite and significantly enhanced photocatalytic activity of the Nano Au/Ta3N5 composite for hydrogen evolution in the visible region, which might be ascribed to the charge transfer effect in Nano Au/Ta 2O5 composite and the synergetic effect of charge transfer and near-field electromagnetic effect in Nano Au/Ta3N5 composite induced by surface plasmon resonance of embedded Au nanoparticles. The current study could provide a new paradigm for designing plasmonic metal/semiconductor composite systems for photocatalytic, photovoltaic and other optoelectronic devices. © the Partner Organisations 2014.

  3. Double-shelled plasmonic Ag-TiO2 hollow spheres toward visible light-active photocatalytic conversion of CO2 into solar fuel

    Directory of Open Access Journals (Sweden)

    Shichao Feng

    2015-10-01

    Full Text Available Double-shelled hollow hybrid spheres consisting of plasmonic Ag and TiO2 nanoparticles were successfully synthesized through a simple reaction process. The analysis reveals that Ag nanoparticles were dispersed uniformly in the TiO2 nanoparticle shell. The plasmonic Ag-TiO2 hollow sphere proves to greatly enhance the photocatalytic activity toward reduction of CO2 into renewable hydrocarbon fuel (CH4 in the presence of water vapor under visible-light irradiation. The possible formation mechanism of the hollow sphere and related plasmon-enhanced photocatalytic performance were also briefly discussed.

  4. Synthesis of flower-like Ag{sub 2}O/BiOCOOH p-n heterojunction with enhanced visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shijie [Innovation & Application Institute, Zhejiang Ocean University, Zhoushan, Zhejiang Province 316022 (China); Zhejiang Provincial Key Laboratory of Health Risk Factors for Seafood, Zhoushan Municipal Center for Disease Control and Prevention, Zhoushan 316021 (China); State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Xu, Kaibing [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Research Center for Analysis and Measurement, Donghua University, Shanghai 201620 (China); Hu, Shiwei, E-mail: hushiweihai@163.com [Innovation & Application Institute, Zhejiang Ocean University, Zhoushan, Zhejiang Province 316022 (China); Jiang, Wei [Innovation & Application Institute, Zhejiang Ocean University, Zhoushan, Zhejiang Province 316022 (China); Zhejiang Provincial Key Laboratory of Health Risk Factors for Seafood, Zhoushan Municipal Center for Disease Control and Prevention, Zhoushan 316021 (China); Zhang, Junlei [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433 (China); Liu, Jianshe [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Zhang, Lisha, E-mail: lszhang@dhu.edu.cn [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China)

    2017-03-01

    Highlights: • Ag{sub 2}O/BiOCOOH p-n heterojunctions are prepared by a solvothermal deposition-precipitation method. • They consist of flower-like BiOCOOH microspheres decorated with Ag{sub 2}O nanoparticles. • Heterojunction with the Ag/Bi molar ratio of 0.2/1 showed the highest photocatalytic activity. • The photogenerated holes (h{sup +}) and superoxide radical anions (·O{sub 2}{sup −}) have been found to be the main reactive species. - Abstract: The development of efficient semiconductor heterojunction photocatalysts has drawn much attention. Herein, we have reported a kind of flower-like Ag{sub 2}O/BiOCOOH p-n heterojunction as a novel and efficient visible-light-driven photocatalyst. The Ag{sub 2}O/BiOCOOH heterojunctions have been successfully prepared via a solvothermal precipitation-deposition method. They consist of flower-like BiOCOOH microspheres (diameters: 1–2.5 μm) decorated with Ag{sub 2}O nanoparticles (size: ∼14 nm). In addition, optical characterization reveals that they have broad visible-light photo-absorption. Importantly, under visible-light irradiation (λ > 400 nm), all Ag{sub 2}O/BiOCOOH heterojunctions exhibit enhanced photocatalytic activity than pure BiOCOOH or Ag{sub 2}O for the degradation of rhodamine B (RhB) dye and para-chlorophenol (4-CP). Especially, the Ag{sub 2}O/BiOCOOH heterojunction with the Ag/Bi molar ratio of 0.2/1 shows the highest photocatalytic activity, which is even higher than the activity from the mechanical mixture (8 wt% Ag{sub 2}O + 92 wt% BiOCOOH). This enhanced photocatalytic performance could be predominantly attributed to the efficient separation of photogenerated electron-hole pairs. The photogenerated holes (h{sup +}) and superoxide radical anions (·O{sub 2}{sup −}) have been found to be the main reactive species responsible for the photodegradation of RhB dye in aqueous solution. Therefore, the Ag{sub 2}O/BiOCOOH p-n heterojunction has great potential to be used as a kind of efficient

  5. Simple fabrication of N-doped mesoporous TiO2 nanorods with the enhanced visible light photocatalytic activity.

    Science.gov (United States)

    Zhou, Xiufeng; Lu, Juan; Jiang, Jingjing; Li, Xiaobin; Lu, Mengna; Yuan, Guotao; Wang, Zuoshan; Zheng, Min; Seo, Hyo Jin

    2014-01-16

    N-doped mesoporous TiO2 nanorods were fabricated by a modified and facile sol-gel approach without any templates. Ammonium nitrate was used as a raw source of N dopants, which could produce a lot of gasses such as N2, NO2, and H2O in the process of heating samples. These gasses were proved to be vitally important to form the special mesoporous structure. The samples were characterized by the powder X-ray diffraction, X-ray photoelectron spectrometer, nitrogen adsorption isotherms, scanning electron microscopy, transmission electron microscopy, and UV-visible absorption spectra. The average length and the cross section diameter of the as-prepared samples were ca. 1.5 μm and ca. 80 nm, respectively. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The N-doped mesoporous TiO2 nanorods showed an excellent photocatalytic activity, which may be attributed to the enlarged surface area (106.4 m2 g-1) and the narrowed band gap (2.05 eV). Besides, the rod-like photocatalyst was found to be easy to recycle.

  6. Biomimetic synthesis of Ag3PO4-NPs/Cu-NWs with visible-light-enhanced photocatalytic activity for degradation of the antibiotic ciprofloxacin.

    Science.gov (United States)

    Liu, Yuling; Wu, Qingsheng; Zhao, Yaping

    2017-05-16

    1D Ag3PO4-NPs/Cu-NWs have been constructed to enhance visible-light-driven photocatalytic activity via biomimetic synthesis. Cu nanowires (NWs) were synthesized by a facile hydrothermal method. During the process of biomimetic synthesis, the porous PTFE film, which can mimic the transport process of cell membranes, plays an important role in controlling the transport speed of silver ions (Ag(+)) to decrease the reaction speed. Thus inhibition of the replacement reaction of Ag(+)/Cu and the uniform growth of Ag3PO4 nanoparticles (NPs) with a diameter of about 10 nm on Cu-NWs can be realized simultaneously. The diameter of Ag3PO4-NPs/Cu-NW is about 70 nm. Owing to the high electron transport of single crystal Cu-NWs, the free electrons in Ag3PO4 are transferred out to promote photogenerated electron-hole pair separation. The stability of Ag3PO4 NPs of the Ag3PO4-NPs/Cu-NWs was improved and the photodecomposition no longer occurred. Meanwhile, the band-gap of Ag3PO4 decreased to 2.07 eV after being coated on Cu-NWs and expanded the absorption scope of visible-light. In addition, the active species-trapping experiments indicated that the holes and ˙O2(-) play important roles in the photocatalytic reactions. The novel Ag3PO4-NPs/Cu-NWs were used for the degradation of ciprofloxacin (CPFX) for the first time and showed high photocatalytic degradation performance. After visible-light irradiation for 15 min, the degradation rates of CPFX with pure Ag3PO4 NPs and AC0.3 as catalysts were about 27% and 53%. In the end, the degradation efficiency of Ag3PO4-NPs/Cu-NWs was 6.07 times that of the pure Ag3PO4 NPs.

  7. Lethal effects of short-wavelength visible light on insects

    OpenAIRE

    Hori, Masatoshi; Shibuya, Kazuki; Sato, Mitsunari; Saito, Yoshino

    2014-01-01

    We investigated the lethal effects of visible light on insects by using light-emitting diodes (LEDs). The toxic effects of ultraviolet (UV) light, particularly shortwave (i.e., UVB and UVC) light, on organisms are well known. However, the effects of irradiation with visible light remain unclear, although shorter wavelengths are known to be more lethal. Irradiation with visible light is not thought to cause mortality in complex animals including insects. Here, however, we found that irradiatio...

  8. Visible-light activity of N-LiInO{sub 2}: Band structure modifications through interstitial nitrogen doping

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kaiqiang [College of Material Science and Engineering, Hunan University, Changsha, 410082 (China); Xu, Difa, E-mail: xudifa@sina.com [Hunan Key Laboratory of Applied Environmental Photocatalysis, Changsha University, Changsha, 410022 (China); Zhang, Xiangchao; Luo, Zhuo; Wang, Yutang [Hunan Key Laboratory of Applied Environmental Photocatalysis, Changsha University, Changsha, 410022 (China); Zhang, Shiying, E-mail: cdzhangshiying@163.com [College of Material Science and Engineering, Hunan University, Changsha, 410082 (China); Hunan Key Laboratory of Applied Environmental Photocatalysis, Changsha University, Changsha, 410022 (China)

    2017-01-01

    Highlights: • The interstitial nitrogen doping into LiInO{sub 2} is achieved at low temperature. • The band gap narrowing to an extent of 2.8 eV from 3.5 eV is observed. • The doping favours charge carrier separation and photocatalytic activity. • Superoxide radical is the dominant active specie in the pollutant degradation. - Abstract: Element doping is a promising strategy to improve the photo-response and photocatalytic activity of semiconductor photocatalyst with a wide band gap. To reduce the band gap of LiInO{sub 2} that is considered as a novel photocatalyst, nitrogen-doped LiInO{sub 2} (N-LiInO{sub 2}) is successfully fabricated by treating LiInO{sub 2} and urea at 200 °C. It is found that interstitial instead of substitutional configurations are formed in the crystal structure of N-LiInO{sub 2} due to the low-treating temperature and rich-oxygen conditions. The interstitial N-doping forms a doping state with 0.6 eV above the valence band maximum and a defect state with 0.1 eV below the conduction band minimum, reducing the band gap of LiInO{sub 2} from 3.5 to 2.8 eV. N-LiInO{sub 2} exhibits higher photocatalytic activity towards methylene blue (MB) degradation under 380 nm light irradiation, which is 1.4 times that of pure LiInO{sub 2}. The enhanced photocatalytic activity of N-LiInO{sub 2} is attributed to the extended light absorption and the improved charge carrier separation, which result in more reactive species participating in the photcatalytic process. This work provides a further understanding on tuning the band structure of semiconductor photocatalyst by N-doping strategies.

  9. Visible-light active thin-film WO3 photocatalyst with controlled high-rate deposition by low-damage reactive-gas-flow sputtering

    Science.gov (United States)

    Oka, Nobuto; Murata, Akiyo; Nakamura, Shin-ichi; Jia, Junjun; Iwabuchi, Yoshinori; Kotsubo, Hidefumi; Shigesato, Yuzo

    2015-10-01

    A process based on reactive gas flow sputtering (GFS) for depositing visible-light active photocatalytic WO3 films at high deposition rates and with high film quality was successfully demonstrated. The deposition rate for this process was over 10 times higher than that achieved by the conventional sputtering process and the process was highly stable. Furthermore, Pt nanoparticle-loaded WO3 films deposited by the GFS process exhibited much higher photocatalytic activity than those deposited by conventional sputtering, where the photocatalytic activity was evaluated by the extent of decomposition of CH3CHO under visible light irradiation. The decomposition time for 60 ppm of CH3CHO was 7.5 times more rapid on the films deposited by the GFS process than on the films deposited by the conventional process. During GFS deposition, there are no high-energy particles bombarding the growing film surface, whereas the bombardment of the surface with high-energy particles is a key feature of conventional sputtering. Hence, the WO3 films deposited by GFS should be of higher quality, with fewer structural defects, which would lead to a decrease in the number of centers for electron-hole recombination and to the efficient use of photogenerated holes for the decomposition of CH3CHO.

  10. Visible-light active thin-film WO3 photocatalyst with controlled high-rate deposition by low-damage reactive-gas-flow sputtering

    Directory of Open Access Journals (Sweden)

    Nobuto Oka

    2015-10-01

    Full Text Available A process based on reactive gas flow sputtering (GFS for depositing visible-light active photocatalytic WO3 films at high deposition rates and with high film quality was successfully demonstrated. The deposition rate for this process was over 10 times higher than that achieved by the conventional sputtering process and the process was highly stable. Furthermore, Pt nanoparticle-loaded WO3 films deposited by the GFS process exhibited much higher photocatalytic activity than those deposited by conventional sputtering, where the photocatalytic activity was evaluated by the extent of decomposition of CH3CHO under visible light irradiation. The decomposition time for 60 ppm of CH3CHO was 7.5 times more rapid on the films deposited by the GFS process than on the films deposited by the conventional process. During GFS deposition, there are no high-energy particles bombarding the growing film surface, whereas the bombardment of the surface with high-energy particles is a key feature of conventional sputtering. Hence, the WO3 films deposited by GFS should be of higher quality, with fewer structural defects, which would lead to a decrease in the number of centers for electron-hole recombination and to the efficient use of photogenerated holes for the decomposition of CH3CHO.

  11. Highly antibacterial activity of N-doped TiO{sub 2} thin films coated on stainless steel brackets under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Shuai; Liu, Bo; Fan, Lingying; Yue, Ziqi [Department of Orthodontics, School of Stomatology, Lanzhou University, Lanzhou 730000 (China); Liu, Bin [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Cao, Baocheng, E-mail: caobch@lzu.edu.cn [Department of Orthodontics, School of Stomatology, Lanzhou University, Lanzhou 730000 (China)

    2014-08-01

    In this study, the radio frequency (RF) magnetron sputtering method was used to prepare a TiO{sub 2} thin film on the surface of stainless steel brackets. Eighteen groups of samples were made according to the experimental parameters. The crystal structure and surface morphology were characterized by X-ray diffraction, and scanning electron microscopy, respectively. The photocatalytic properties under visible light irradiation were evaluated by measuring the degradation ratio of methylene blue. The sputtering temperature was set at 300 °C, and the time was set as 180 min, the ratio of Ar to N was 30:1, and annealing temperature was set at 450 °C. The thin films made under these parameters had the highest visible light photocatalytic activity of all the combinations of parameters tested. Antibacterial activities of the selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. The results demonstrated the thin film prepared under the parameters above showed the highest antibacterial activity.

  12. Easy dispersion and excellent visible-light photocatalytic activity of the ultrathin urea-derived g-C3N4 nanosheets

    Science.gov (United States)

    Yang, Yuxin; Geng, Lei; Guo, Yingna; Meng, Jiaqi; Guo, Yihang

    2017-12-01

    Ultrathin two-dimensional (2D) g-C3N4 nanosheets (UCNS) are facilely prepared by liquid-exfoliation of the urea-derived g-C3N4via an HCl-assisted hydrothermal treatment method. The UCNS are served as the novel visible-light-driven photocatalyst to degrade a typical organic pollutant, p-nitrophenol (PNP), in an aqueous solution. By the combination of the advantages of plentiful exposed active sites, fast photogenerated charge carrier separation rate, aligned energy levels and easy dispersion in an aqueous solution, the UCNS exhibit considerably enhanced visible-light photocatalytic activity toward the degradation of the target compound in comparison of their bulk g-C3N4 counterpart, melamine-derived g-C3N4 nanoparticles or Degussa P25 TiO2. The indirect chemical probe experimental results indicate that both the superoxide radicals and the photogenerated holes are responsible for the complete decomposition of PNP. Additionally, the UCNS can be reused at least four times without obvious activity loss and morphology change, exhibiting the excellent reusability in photodegradation aqueous organic pollutants.

  13. Highly antibacterial activity of N-doped TiO2 thin films coated on stainless steel brackets under visible light irradiation

    Science.gov (United States)

    Cao, Shuai; Liu, Bo; Fan, Lingying; Yue, Ziqi; Liu, Bin; Cao, Baocheng

    2014-08-01

    In this study, the radio frequency (RF) magnetron sputtering method was used to prepare a TiO2 thin film on the surface of stainless steel brackets. Eighteen groups of samples were made according to the experimental parameters. The crystal structure and surface morphology were characterized by X-ray diffraction, and scanning electron microscopy, respectively. The photocatalytic properties under visible light irradiation were evaluated by measuring the degradation ratio of methylene blue. The sputtering temperature was set at 300 °C, and the time was set as 180 min, the ratio of Ar to N was 30:1, and annealing temperature was set at 450 °C. The thin films made under these parameters had the highest visible light photocatalytic activity of all the combinations of parameters tested. Antibacterial activities of the selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. The results demonstrated the thin film prepared under the parameters above showed the highest antibacterial activity.

  14. Advances and prospects in visible light communications

    Science.gov (United States)

    Hongda, Chen; Chunhui, Wu; Honglei, Li; Xiongbin, Chen; Zongyu, Gao; Shigang, Cui; Qin, Wang

    2016-01-01

    Visible light communication (VLC) is an emerging technology in optical wireless communication (OWC) that has attracted worldwide research in recent years. VLC can combine communication and illumination together, which could be applied in many application scenarios such as visible light communication local area networks (VLANs), indoor localization, and intelligent lighting. In recent years, pioneering and significant work have been made in the field of VLC. In this paper, an overview of the recent progress in VLC is presented. We also demonstrate our recent experiment results including bidirectional 100 Mbit/s VLAN or Li-Fi system based on OOK modulation without blue filter. The VLC systems that we proposed are good solutions for high-speed VLC application systems with low-cost and low-complexity. VLC technology shows a bright future due to its inherent advantages, shortage of RF spectra and ever increasing popularity of white LEDs. Project supported by the National High Technology Research and Development Program of China (Nos. 2015AA033303, 2013AA013602, 2013AA013603, 2013AA03A104), the National Natural Science Foundation of China (Nos. 61178051, 61321063, 61335010, 61178048, 61275169), and the National Basic Research Program of China (Nos. 2013CB329205, 2011CBA00608).

  15. Synthesize and characterize of Ag{sub 3}VO{sub 4}/TiO{sub 2} nanorods photocatalysts and its photocatalytic activity under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Xuejun [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian 116600 (China); Dong, Yuying, E-mail: dongy@dlnu.edu.cn [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian 116600 (China); Zhang, Xiaodong, E-mail: fatzhxd@126.com [Environment and Low-Carbon Research Center, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Cui, Yubo [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian 116600 (China)

    2016-03-15

    Graphical abstract: - Highlights: • Ag{sub 3}VO{sub 4}/TiO{sub 2} nanorods were prepared by sol–gel with hydrothermal method. • Toluene removal efficiency was 70% in 4 h using the Ag{sub 3}VO{sub 4}/TiO{sub 2}. • Benzyl alcohol and benzaldehyde were intermediates, and partially mineralized. - Abstract: In this paper, in order to expand the light response range of TiO{sub 2}, Ag{sub 3}VO{sub 4}/TiO{sub 2} nanorods photocatalysts were fabricated by a simple sol–gel method with microwave and hydrothermal method. The as-prepared samples were characterized by XRD, SEM, DRS, XPS and N{sub 2} adsorption–desorption. Meanwhile, their photocatalytic properties were investigated by the degradation of toluene under visible light irradiation. The degradation conversation of toluene had gotten to about 70% in 1% Ag{sub 3}VO{sub 4}/TiO{sub 2} nanorods after reaction 4 h. The predominant photocatalytic activity can be attributed to its strong absorption in visible light region and excellent charge separation characteristics. By using in situ FTIR, benzyl alcohol and benzaldehyde species could be observed during the reaction and the formed intermediates would be partially oxidized into CO{sub 2} and H{sub 2}O. Electron spin resonance confirmed that OH· and O{sub 2}·{sup −} were involved in the photocatalytic degradation of toluene.

  16. Surface plasmon resonance enhanced visible-light-driven photocatalytic activity in Cu nanoparticles covered Cu{sub 2}O microspheres for degrading organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yahui, E-mail: chengyahui@nankai.edu.cn [Department of Electronics and Key Laboratory of Photo-Electronic Thin Film Devices and Technology of Tianjin, Nankai University, Tianjin 300071 (China); Lin, Yuanjing [Department of Electronics and Key Laboratory of Photo-Electronic Thin Film Devices and Technology of Tianjin, Nankai University, Tianjin 300071 (China); Xu, Jianping [Institute of Material Physics, Key Laboratory of Display Materials and Photoelectric Devices, Ministry of Education, Tianjin University of Technology, Tianjin 300384 (China); He, Jie; Wang, Tianzhao; Yu, Guojun; Shao, Dawei; Wang, Wei-Hua; Lu, Feng [Department of Electronics and Key Laboratory of Photo-Electronic Thin Film Devices and Technology of Tianjin, Nankai University, Tianjin 300071 (China); Li, Lan [Institute of Material Physics, Key Laboratory of Display Materials and Photoelectric Devices, Ministry of Education, Tianjin University of Technology, Tianjin 300384 (China); Du, Xiwen [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); Wang, Weichao [Department of Electronics and Key Laboratory of Photo-Electronic Thin Film Devices and Technology of Tianjin, Nankai University, Tianjin 300071 (China); Liu, Hui, E-mail: liuhui@nankai.edu.cn [Department of Electronics and Key Laboratory of Photo-Electronic Thin Film Devices and Technology of Tianjin, Nankai University, Tianjin 300071 (China); Zheng, Rongkun [School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia)

    2016-03-15

    Graphical abstract: - Highlights: • Cu NPs introduce the SPR and result in an increase of visible light absorption. • The photocatalytic activity of Cu{sub 2}O/Cu improves greatly due to the SPR effect. • A dark catalytic activity is observed stemming from the Fenton-like reaction. • The • O{sub 2}{sup −} and • OH radicals contribute to the photocatalytic process. • The • OH radicals contribute to the dark catalytic process. - Abstract: Micron-sized Cu{sub 2}O with different coverage of Cu nanoparticles (NPs) on the sphere has been synthesized by a redox procedure. The absorption spectra show that Cu NPs induce the surface plasmon resonance (SPR) at the wavelength of ∼565 nm. Methylene blue (MB) photodegrading experiments under visible-light display that the Cu{sub 2}O–Cu–H{sub 2}O{sub 2} system exhibits a superior photocatalytic activity to Cu{sub 2}O–H{sub 2}O{sub 2} or pure H{sub 2}O{sub 2} with an evident dependency on Cu coverage. The maximum photodegradation rate is 88% after visible-light irradiating for 60 min. The role of the Cu NPs is clarified through photodegradation experiments under 420 nm light irradiation, which is different from the SPR wavelength of Cu NPs (∼565 nm). By excluding the SPR effect, it proves that Cu SPR plays a key role in the photodegradation. Besides, a dark catalytic activity is observed stemming from the Fenton-like reaction with the aid of H{sub 2}O{sub 2}. The radical quenching experiments indicate that both • O{sub 2}{sup −} and • OH radicals contribute to the photocatalysis, while the dark catalysis is only governed by the • OH radicals, leading to a lower activity comparing with the photocatalysis. Therefore, with introducing Cu NPs and H{sub 2}O{sub 2}, the Cu{sub 2}O-based photocatalytic activity could be significantly improved due to the SPR effect and dark catalysis.

  17. Indoor visible light communication with smart lighting technology

    Science.gov (United States)

    Das Barman, Abhirup; Halder, Alak

    2017-02-01

    An indoor visible-light communication performance is investigated utilizing energy efficient white light by 2D LED arrays. Enabled by recent advances in LED technology, IEEE 802.15.7 standardizes high-data-rate visible light communication and advocates for colour shift keying (CSK) modulation to overcome flicker and to support dimming. Voronoi segmentation is employed for decoding N-CSK constellation which has superior performance compared to other existing decoding methods. The two chief performance degrading effects of inter-symbol interference and LED nonlinearity is jointly mitigated using LMS post equalization at the receiver which improves the symbol error rate performance and increases field of view of the receiver. It is found that LMS post equalization symbol at 250MHz offers 7dB SNR improvement at SER10-6

  18. Macroscopic invisibility cloaking of visible light

    DEFF Research Database (Denmark)

    Chen, Xianzhong; Luo, Y.; Zhang, Jingjing

    2011-01-01

    invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region...... to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale...

  19. Synthesis, characterization and visible light photocatalytic activity of Cr 3+ , Ce 3+ and N co-doped TiO 2 for the degradation of humic acid

    KAUST Repository

    Rashid, S. G.

    2015-01-01

    The synthesis, characterization and photocatalytic activity of Cr3+ and Ce3+ co-doped TiON (N-doped TiO2) for the degradation of humic acid with exposure to visible light is reported. The synthesized bimetal (Cr3+ + Ce3+) modified TiON (Cr-Ce/TiON), with an evaluated bandgap of 2.1 eV, exhibited an enhanced spectral response in the visible region as compared to pure and Ce3+ doped TiON (Ce/TiON). The XRD analysis revealed the insertion of Cr3+ and Ce3+ in the crystal lattice along with Ti4+ and N that resulted in the formation of a strained TiON anatase structure with an average crystallite size of ∼10 nm. Raman analysis also supported the formation of stressed rigid structures after bimetal doping. HRTEM confirmed the homogeneous distribution of both the doped metallic components in the crystal lattice of TiON without the formation of surface oxides of either Cr3+ or Ce3+. Electron energy loss spectroscopy (EELS) analysis revealed no change in the oxidation of either Cr or Ce during the synthesis. The synthesized Cr-Ce/TiON catalyst exhibited appreciable photocatalytic activity for the degradation of humic acid on exposure to visible light. Additionally, a noticeable mineralization of carbon rich humic acid was also witnessed. The photocatalytic activity of the synthesized catalyst was compared with pristine and Ce3+ doped TiON. © The Royal Society of Chemistry 2015.

  20. Facile Synthesis of g-C3N4 Nanosheets/ZnO Nanocomposites with Enhanced Photocatalytic Activity in Reduction of Aqueous Chromium(VI) under Visible Light

    Science.gov (United States)

    Yuan, Xiaoya; Zhou, Chao; Jing, Qiuye; Tang, Qi; Mu, Yuanhua; Du, An-ke

    2016-01-01

    Graphitic-C3N4 nanosheets (CN)/ZnO photocatalysts (CN/ZnO) with different CN loadings were successfully prepared via a simple precipitation-calcination in the presence of exfoliated C3N4 nanosheets. Their morphology and structure were thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL). The results showed that hexagonal wurzite-phase ZnO nanoparticles were randomly distributed onto the CN nanosheets with a well-bonded interface between the two components in the CN/ZnO composites. The performance of the photocatalytic Cr(VI) reduction indicated that CN/ZnO exhibited better photocatalytic activity than pure ZnO under visible-light irradiation and the photocatalyst composite with a lower loading of CN sheets eventually displayed higher activity. The enhanced performance of CN/ZnO photocatalysts could be ascribed to the increased absorption of the visible light and the effective transfer and separation of the photogenerated charge carriers. PMID:28335301

  1. Facile Synthesis of g-C₃N₄ Nanosheets/ZnO Nanocomposites with Enhanced Photocatalytic Activity in Reduction of Aqueous Chromium(VI) under Visible Light.

    Science.gov (United States)

    Yuan, Xiaoya; Zhou, Chao; Jing, Qiuye; Tang, Qi; Mu, Yuanhua; Du, An-Ke

    2016-09-14

    Graphitic-C₃N₄ nanosheets (CN)/ZnO photocatalysts (CN/ZnO) with different CN loadings were successfully prepared via a simple precipitation-calcination in the presence of exfoliated C₃N₄ nanosheets. Their morphology and structure were thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL). The results showed that hexagonal wurzite-phase ZnO nanoparticles were randomly distributed onto the CN nanosheets with a well-bonded interface between the two components in the CN/ZnO composites. The performance of the photocatalytic Cr(VI) reduction indicated that CN/ZnO exhibited better photocatalytic activity than pure ZnO under visible-light irradiation and the photocatalyst composite with a lower loading of CN sheets eventually displayed higher activity. The enhanced performance of CN/ZnO photocatalysts could be ascribed to the increased absorption of the visible light and the effective transfer and separation of the photogenerated charge carriers.

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

    Science.gov (United States)

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

    2014-04-30

    A series of Ag@AgBr grafted graphitic carbon nitride (Ag@AgBr/g-C3N4) plasmonic photocatalysts are fabricated through photoreducing AgBr/g-C3N4 hybrids prepared by deposition-precipitation method. The phase and chemical structures, electronic and optical properties as well as morphologies of Ag@AgBr/g-C3N4 heterostructures are well-characterized. Subsequently, the photocatalytic activity of Ag@AgBr/g-C3N4 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-C3N4 compared with g-C3N4 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Facile Synthesis of g-C3N4 Nanosheets/ZnO Nanocomposites with Enhanced Photocatalytic Activity in Reduction of Aqueous Chromium(VI under Visible Light

    Directory of Open Access Journals (Sweden)

    Xiaoya Yuan

    2016-09-01

    Full Text Available Graphitic-C3N4 nanosheets (CN/ZnO photocatalysts (CN/ZnO with different CN loadings were successfully prepared via a simple precipitation-calcination in the presence of exfoliated C3N4 nanosheets. Their morphology and structure were thoroughly characterized by powder X-ray diffraction (XRD, scanning electron microscopy (SEM, high-resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, UV-Vis diffuse reflectance spectroscopy (DRS and photoluminescence spectra (PL. The results showed that hexagonal wurzite-phase ZnO nanoparticles were randomly distributed onto the CN nanosheets with a well-bonded interface between the two components in the CN/ZnO composites. The performance of the photocatalytic Cr(VI reduction indicated that CN/ZnO exhibited better photocatalytic activity than pure ZnO under visible-light irradiation and the photocatalyst composite with a lower loading of CN sheets eventually displayed higher activity. The enhanced performance of CN/ZnO photocatalysts could be ascribed to the increased absorption of the visible light and the effective transfer and separation of the photogenerated charge carriers.

  4. Heterojunctions of p-BiOI Nanosheets/n-TiO2 Nanofibers: Preparation and Enhanced Visible-Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Kexin Wang

    2016-01-01

    Full Text Available p-BiOI nanosheets/n-TiO2 nanofibers (p-BiOI/n-TiO2 NFs have been facilely prepared via the electrospinning technique combining successive ionic layer adsorption and reaction (SILAR. Dense BiOI nanosheets with good crystalline and width about 500 nm were uniformly assembled on TiO2 nanofibers at room temperature. The amount of the heterojunctions and the specific surface area were well controlled by adjusting the SILAR cycles. Due to the synergistic effect of p-n heterojunctions and high specific surface area, the obtained p-BiOI/n-TiO2 NFs exhibited enhanced visible-light photocatalytic activity. Moreover, the p-BiOI/n-TiO2 NFs heterojunctions could be easily recycled without decreasing the photocatalytic activity owing to their one-dimensional nanofibrous structure. Based on the above, the heterojunctions of p-BiOI/n-TiO2 NFs may be promising visible-light-driven photocatalysts for converting solar energy to chemical energy in environment remediation.

  5. A Simple Method for the Preparation of TiO2 /Ag-AgCl@Polypyrrole Composite and Its Enhanced Visible-Light Photocatalytic Activity.

    Science.gov (United States)

    Yao, Tongjie; Shi, Lei; Wang, Hao; Wang, Fangxiao; Wu, Jie; Zhang, Xiao; Sun, Jianmin; Cui, Tieyu

    2016-01-01

    A novel and facile method was developed to prepare a visible-light driven TiO2 /Ag-AgCl@polypyrrole (PPy) photocatalyst with Ag-AgCl nanoparticles supported on TiO2 nanofibers and covered by a thin PPy shell. During the synthesis, the PPy shell and Ag-AgCl nanoparticles were prepared simultaneously onto TiO2 nanofibers, which simplified the preparation procedure. In addition, because Ag-AgCl aggregates were fabricated via partly etching the Ag nanoparticles, their size was well controlled at the nanoscale, which was beneficial for improvement of the contact surface area. Compared with reference photocatalysts, the TiO2 /Ag-AgCl@PPy composite exhibited an enhanced photodegradation activity towards rhodamine B under visible-light irradiation. The superior photocatalytic property originated from synergistic effects between TiO2 nanofibers, Ag-AgCl nanoparticles and the PPy shell. Furthermore, the TiO2 /Ag-AgCl@PPy composite could be easily separated and recycled without obvious reduction in activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Transformation from Ag@Ag3PO4 to Ag@Ag2SO4 hybrid at room temperature: preparation and its visible light photocatalytic activity

    Science.gov (United States)

    Wei, Ting; Gao, Shanmin; Wang, Qingyao; Xu, Hui; Wang, Zeyan; Huang, Baibiao; Dai, Ying

    2017-02-01

    In the present study, Ag/Ag2SO4 hybrid photocatalysts were obtained via a facile redox-precipitation reaction approach by using Ag@Ag3PO4 nanocomposite as the precursor and KMnO4 as the oxidant. Multiple techniques, such as X-ray diffraction pattern (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and Brunauer-Emmett-Teller (BET), photocurrent and electrochemical impedance spectroscopy (EIS), were applied to investigate the structures, morphologies, optical, and electronic properties of as-prepared samples. The photocatalytic activities were evaluated by photodegradation of organic rhodamine B (RhB) and methyl orange (MO) under visible light irradiation. It was found that pure Ag2SO4 can partially transform into metallic Ag during the photocatalytic degradation of organic pollutants, but the Ag/Ag2SO4 hybrids can maintain its structure stability and show enhanced visible light photocatalytic activity because of the surface plasma resonance effect of the metallic Ag.

  7. Hydrothermal synthesis, characterization and enhanced visible-light photocatalytic activity of Co-doped Zn2SnO4 nanoparticles

    Science.gov (United States)

    Hu, Xiaofei; Hao, Hongshun; Guo, Weihua; Jin, Shanshan; Li, Hong; Hou, Hongman; Zhang, Gongliang; Yan, Shuang; Gao, Wenyuan; Liu, Guishan

    2017-06-01

    Various molar concentrations of Co-doped Zn2SnO4 nanoparticles were synthesized by hydrothermal method. The as-prepared samples were characterized by XRD, XPS, FESEM, TEM, UV-Vis and PL. The result of XPS revealed that the Co dopant displayed a chemical state of Co2+ in Zn2SnO4 lattice. UV-Vis results revealed that the absorption edge of samples shifted towards visible light region gradually with the increase of Co doping content. The PL intensity weakened significantly for the Co-doped Zn2SnO4, which indicates that the recombination of photo-generated electrons and holes was suppressed strongly. The photocatalytic activity of Zn2SnO4 was observed by photodegradation of RhB under visible light irradiation. The influences of Co doping content on photocatalytic activity of Zn2SnO4 were investigated. The experiment results indicated that the maximum degradation rate of RhB was 93% in 120 min when Co2+ molar concentration was 2 mol%. Furthermore, a possible mechanism of photocatalytic degradation of RhB was discussed.

  8. Photocatalytic degradation of gaseous toluene on Fe-TiO{sub 2} under visible light irradiation: A study on the structure, activity and deactivation mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Sun Song; Ding Jianjun [National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029 (China); Bao Jun, E-mail: baoj@ustc.edu.cn [National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029 (China); Gao Chen [National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029 (China); Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Qi Zeming; Yang Xiaoyan; He Bo; Li Chengxiang [National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029 (China)

    2012-04-01

    The Fe-TiO{sub 2} photocatalysts synthesized by a sol-gel method have the mesoporous structure with a narrow pore size distribution, large pore volume and high surface area. The incorporated Fe{sup 3+} substitutes the octahedrally coordinated Ti{sup 4+} in the TiO{sub 2} lattice to extend the absorption of TiO{sub 2} to visible light region and promote the formation of electron-hole pair. Additionally, the separation and transportation efficiency increase with the doping of Fe{sup 3+} increasing from 0.1% to 0.7%, while decreases remarkably with the doping concentration increasing from 0.7% to 1.5%. The Fe-TiO{sub 2} shows excellent photocatalytic performance for toluene degradation under visible light irradiation. The optimal Fe/Ti ratio is 0.7%. Partial deactivation of the photocatalytic activity was observed after 20 consecutive reaction runs. From the in situ DRIFTS experiment, the deactivation reason can be attributed to the formation of stable intermediates, such as benzaldehyde and benzoic acid, which occupied the active sites on the surface of the photocatalyst. The adsorbed benzaldehyde and benzoic acid can be removed with heat treatment at 653 K for 3 h and the deactivated photocatalyst can be regenerated completely.

  9. A chemical bath deposition route to facet-controlled Ag3PO4 thin films with improved visible light photocatalytic activity

    Science.gov (United States)

    Gunjakar, Jayavant L.; Jo, Yun Kyung; Kim, In Young; Lee, Jang Mee; Patil, Sharad B.; Pyun, Jae.-Chul.; Hwang, Seong-Ju

    2016-08-01

    A facile, economic, and reproducible chemical bath deposition (CBD) method is developed for the fabrication of facet-controlled Ag3PO4 thin films with enhanced visible light photocatalytic activity. The fine-control of bath temperature, precursor, complexing agent, substrate, and solution pH is fairly crucial in preparing the facet-selective thin film of Ag3PO4 nanocrystal. The change of precursor from silver nitrate to silver acetate makes possible the tailoring of the crystal shape of Ag3PO4 from cube to rhombic dodecahedron and also the bandgap tuning of the deposited films. The control of [Ag+]/[phosphate] ratio enables to maximize the loading amount of Ag3PO4 crystals per the unit area of the deposited film. All the fabricated Ag3PO4 thin films show high photocatalytic activity for visible light-induced degradation of organic molecules, which can be optimized by tailoring the crystal shape of the deposited crystals. This CBD method is also useful in preparing the facet-controlled hybrid film of Ag3PO4-ZnO photocatalyst. The present study clearly demonstrates the usefulness of the present CBD method for fabricating facet-controlled thin films of metal oxosalt and its nanohybrid.

  10. Photocatalytic Reduction Activity of 001  TiO2 Codoped with F and Fe under Visible Light for Bromate Removal

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2016-01-01

    Full Text Available The presence of bromate in water is a well-known problem because of its toxic effects on human health, particularly its carcinogenic potential. Photocatalytic reduction is an attractive process for bromate removal. F- and Fe-codoped TiO2 (F-Fe-TiO2 with a {001} facet was successfully prepared, and its bromate-removal activity under visible light was examined. The microstructure, morphology, and chemical state of the doping elements and the optical property of the photocatalysts were examined using transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, electron paramagnetic resonance (EPR, photoluminescence spectroscopy (PLS, and UV-Vis diffuse reflectance spectra (DRS. The results indicate that the optical properties of F-Fe-TiO2 with the {001} facet and cuboid morphology were obviously improved and its photocatalytic activity was significantly enhanced. The bromate solution of 100 μg/L was thoroughly removed with 0.5 g/L dosage of 1.0% F- and 0.08% Fe-codoped TiO2 composite within 1 hour under visible light.

  11. Solvothermal fabrication of activated semi-coke supported TiO2-rGO nanocomposite photocatalysts and application for NO removal under visible light

    Science.gov (United States)

    Yang, Weiwei; Li, Chunhu; Wang, Liang; Sun, ShengNan; Yan, Xin

    2015-10-01

    The photocatalysts of activated semi-coke supported TiO2-rGO nanocomposite (TiO2-rGO/ASC) with different contents of reduced graphene oxide were fabricated by one-step solvothermal method for NO removal under visible light irradiation. It was confirmed that 8% content of reduced graphene oxide presented the best NO photooxidation performance under visible light irradiation at 70 °C with 350-400 mg/m3 NO,5% O2 and 5% relative humidity. The reasons for improved activity were discussed, alloyed with the mechanism of producing CO. Detailed structural information of TiO2-rGO/ASC photocatalysts was characterized by scanning electron microscope (SEM), energy dispersive X-ray Spectroscopy (EDX), X-ray diffraction analysis (XRD), UV-Vis diffuse reflectance spectra (UV-Vis DRS) and photoluminescence (PL), which indicated that the introduction of rGO was responsible for well dispersion, smaller crystalline size, red shift of absorption band and suppressing quick photo-induced charges recombination of TiO2-rGO/ASC photocatalysts. Optimization of operational parameters with 70 °C, 8% O2 and 8% relative humidity were also obtained. Deactivation of TiO2-rGO/ASC photocatalysts for NO removal was investigated by Fourier-transform infrared (FTIR) analysis. Regeneration experiments showed that thermal vapor regeneration would be optimal method owing to excellent regenerative capacity and inexpensive procedure.

  12. Controllable synthesis of Bi2WO6 nanoplate self-assembled hierarchical erythrocyte microspheres via a one-pot hydrothermal reaction with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Yang, Zhenya; Huang, Lin; Xie, Yanyu; Lin, Zheguan; Fan, Yunyan; Liu, Dan; Chen, Lu; Zhang, Zizhong; Wang, Xuxu

    2017-05-01

    This work provides a simple approach of the F--assisted one-pot hydrothermal reaction to successfully synthesize Bi2WO6 hierarchical erythrocyte microspheres. The importance role of F- was systematically investigated by comparing different type of halogen ions, hydrothermal temperature and time. The possible growth mechanism of Bi2WO6 hierarchical structures was proposed. The hierarchical erythrocytes were formed through the well-ordered and oriented self-assembly of thin Bi2WO6 nanoplate primary subunits. F- ions were absorbed on Bi2WO6 nanoplate surface to suppress the nanoplate stack but to induce a self-assembly through the edge interaction of Bi2WO6 nanoplates into erythrocyte-like hierarchical microspheres superstructures. This erythrocyte structure narrowed the band gap energy and enhanced the visible-light photocatalytic activity of Bi2WO6. Moreover, superoxide radical anions and h+ were revealed as the main active species responding for the RhB degradation on Bi2WO6 under visible light irradiation.

  13. Synergetic effects of I- ions and BiOI on visible-light-activity enhancement of wide-band-gap (BiO)2CO3

    Science.gov (United States)

    Liang, Lei; Cao, Jing; Lin, Haili; Guo, Xiaomin; Zhang, Meiyu; Chen, Shifu

    2017-08-01

    The wide-band-gap semiconductor (BiO)2CO3 was modified by interior doping with I- ions and surface loading with BiOI to prepare a highly efficient visible-light active photocatalyst for the degradation of methyl orange and phenol. The interior I- ions elevate the valence band position of (BiO)2CO3 and induce visible-light photocatalytic activity, while the in-situ-formed BiOI/I-(BiO)2CO3 heterojunction significantly improves the separation of photoinduced charge carriers. By the action of the reactive species h+ and rad O2-, methyl orange and phenol were degraded over the novel BiOI/I-(BiO)2CO3 composite at rates that were 18- and 4-times, respectively, those of unmodified (BiO)2CO3. Thus, the findings presented here may be widely applied in the development of wide-band-gap semiconductor photocatalytic systems for the highly efficient removal of contaminants from wastewater.

  14. Determination of photo-catalytic activity of un-doped and Mn-doped TiO{sub 2} anatase powders on acetaldehyde under UV and visible light

    Energy Technology Data Exchange (ETDEWEB)

    Papadimitriou, Vassileios C., E-mail: bpapadim@chemistry.uoc.gr [Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete (Greece); Stefanopoulos, Vassileios G.; Romanias, Manolis N. [Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete (Greece); Papagiannakopoulos, Panos, E-mail: panosp@chemistry.uoc.gr [Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete (Greece); Sambani, Kyriaki; Tudose, Valentin; Kiriakidis, George [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, PO Box 1527,Vasilika Vouton, 71110 Heraklion, Crete (Greece)

    2011-12-01

    Titanium dioxide (TiO{sub 2}) photocatalytic powder materials doped with various levels of manganese (Mn) were synthesized to be used as additives to wall painting in combating indoor and outdoor air pollution. The heterogeneous photocatalytic degradation of gaseous acetaldehyde (CH{sub 3}CHO) on Mn-TiO{sub 2} surfaces under ultraviolet and visible (UV/Vis) irradiation was investigated, by employing the Photochemical Static Reactor coupled with Fourier-Transformed Infrared spectroscopy (PSR/FTIR) technique. Experiments were performed by exposing acetaldehyde ({approx} 400 Pa) and synthetic air mixtures ({approx} 1.01 Multiplication-Sign 10{sup 5} Pa total pressure) on un-doped TiO{sub 2} and doped with various levels of Mn (0.1-33% mole percentage) under UV and visible irradiation at room temperature. Photoactivation was initiated using either UV or visible light sources with known emission spectra. Initially, the photo-activity of CH{sub 3}CHO under the above light sources, and the physical adsorption of CH{sub 3}CHO on Mn-TiO{sub 2} samples in the absence of light were determined prior to the photocatalytic experiments. The photocatalytic loss of CH{sub 3}CHO on un-doped TiO{sub 2} and Mn-TiO{sub 2} samples in the absence and presence of UV or visible irradiation was measured over a long time period ( Almost-Equal-To 60 min), to evaluate their relative photocatalytic activity. The gaseous photocatalytic end products were also determined using absorption FTIR spectroscopy. Carbon dioxide (CO{sub 2}) was identified as the main photocatalysis product. It was found that 0.1% Mn-TiO{sub 2} samples resulted in the highest photocatalytic loss of CH{sub 3}CHO under visible irradiation. This efficiency was drastically diminished at higher levels of Mn doping (1-33%). The CO{sub 2} yields were the highest for 0.1% Mn-TiO{sub 2} samples under UV irradiation, in agreement with the observed highest CH{sub 3}CHO decomposition rates. It was demonstrated that low-level (0

  15. Facile fabrication of BiOI decorated NaNbO3 cubes: A p-n junction photocatalyst with improved visible-light activity

    Science.gov (United States)

    Sun, Meng; Yan, Qing; Shao, Yu; Wang, Changqian; Yan, Tao; Ji, Pengge; Du, Bin

    2017-09-01

    To enhance the separation efficiency of photo-generated carriers, a p-n junction photocatalyst BiOI/NaNbO3 has been fabricated by a facile method. The obtained samples were characterized by XRD, SEM, TEM, HRTEM, PL, N2 sorption-desorption and DRS. DRS results showed that the light absorption edges of BiOI/NaNbO3 hybrids were red-shifted with the increase of BiOI content. The SEM and TEM images revealed that the BiOI was widely decorated over the surfaces of NaNbO3 cubes. The formation of p-n heterojunction at their interfaces was proved by the HRTEM image. The visible light-driven photocatalytic activity was evaluated by the degradation of methylene blue (MB) in aqueous solution. Compared with single NaNbO3 and BiOI, the BiOI/NaNbO3 hybrid photocatalysts have exhibited significantly enhanced activities. Meanwhile, the mass ratio of BiOI/NaNbO3 displayed important influence on the MB degradation. The hybrid photocatalyst with BiOI content of 40% performed the optimal activity. This activity enhancement should be attributed to the strong visible light absorption, the high migration and separation efficiency of photo-induced carriers. The photocurrent and PL measurements confirmed that the interfacial charge separation efficiency was greatly improved by coupling BiOI with NaNbO3. Controlled experiments proved that the degradation of pollutants was mainly attributed to the oxidizing ability of the generated holes (h+), ·O2-, and ·OH radicals.

  16. Facile synthesis of amino-functionalized titanium metal-organic frameworks and their superior visible-light photocatalytic activity for Cr(VI) reduction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hou [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Yuan, Xingzhong, E-mail: yxz@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Wu, Yan [College of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); Zeng, Guangming [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Chen, Xiaohong [School of Business, Central South University, Changsha 410083 (China); Leng, Lijian; Wu, Zhibin; Jiang, Longbo [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environment Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Li, Hui [Institute of Bio-energy, Hunan Academy of Forestry, Changsha 410004 (China)

    2015-04-09

    Highlights: • NH{sub 2} functionalized MIL-125(Ti) was fabricated by a facile solvothermal method. • The photocatalyst could reduce Cr(VI)–Cr(III) under visible light irradiation. • The Ti{sup 3+}–Ti{sup 4+} intervalence electron transfer is important for Cr(VI) reduction. • Used NH{sub 2}-MIL-125(Ti) can be recycled for the photocatalytic reduction. - Abstract: Porous metal-organic frameworks (MOFs) have been arousing a great interest in exploring the application of MOFs as photocatalyst in environment remediation. In this work, two different MOFs, Ti-benzenedicarboxylate (MIL-125(Ti)) and amino-functionalized Ti-benzenedicarboxylate (NH{sub 2}-MIL-125(Ti)) were successfully synthesized via a facile solvothermal method. The MIL-125(Ti) and NH{sub 2}-MIL-125(Ti) were well characterized by XRD, SEM, XPS, N{sub 2} adsorption–desorption measurements, thermogravimetric analysis and UV–vis diffuse reflectance spectra (DRS). It is revealed that the NH{sub 2}-MIL-125(Ti) has well crystalline lattice, large surface area and mesoporous structure, chemical and thermal stability, and enhanced visible-light absorption up to 520 nm, which was associated with the chromophore (amino group) in the organic linker. Compared with MIL-125(Ti), NH{sub 2}-MIL-125(Ti) exhibited more efficient photocatalytic activity for Cr(VI) reduction from aqueous solution under visible-light irradiation. The addition of hole scavenger, the hole scavenger concentration and the pH value of the reaction solution played important roles in the photo-catalytic reduction of Cr(VI). The presence of Ti{sup 3+}–Ti{sup 4+} intervalence electron transfer was the main reason for photo-excited electrons transportation from titanium-oxo clusters to Cr(VI), facilitating the Cr(VI) reduction under the acid condition. It was demonstrated that amino-functionalized Ti(IV)-based MOFs could be promising visible-light photocatalysts for the treatment of Cr(VI)-contained wastewater.

  17. Lethal effects of short-wavelength visible light on insects

    Science.gov (United States)

    Hori, Masatoshi; Shibuya, Kazuki; Sato, Mitsunari; Saito, Yoshino

    2014-12-01

    We investigated the lethal effects of visible light on insects by using light-emitting diodes (LEDs). The toxic effects of ultraviolet (UV) light, particularly shortwave (i.e., UVB and UVC) light, on organisms are well known. However, the effects of irradiation with visible light remain unclear, although shorter wavelengths are known to be more lethal. Irradiation with visible light is not thought to cause mortality in complex animals including insects. Here, however, we found that irradiation with short-wavelength visible (blue) light killed eggs, larvae, pupae, and adults of Drosophila melanogaster. Blue light was also lethal to mosquitoes and flour beetles, but the effective wavelength at which mortality occurred differed among the insect species. Our findings suggest that highly toxic wavelengths of visible light are species-specific in insects, and that shorter wavelengths are not always more toxic. For some animals, such as insects, blue light is more harmful than UV light.

  18. In{sub 2}S{sub 3}/carbon nanofibers/Au ternary synergetic system: Hierarchical assembly and enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xin; Shao, Changlu, E-mail: clshao@nenu.edu.cn; Li, Xinghua, E-mail: lixh781@nenu.edu.cn; Lu, Na; Wang, Kexin; Miao, Fujun; Liu, Yichun

    2015-02-11

    Graphical abstract: We describe a route to synthesize In{sub 2}S{sub 3}/CNFs/Au ternary synergetic system with high efficiency visible-light photocatalytic activity. - Highlights: • Synthesis of In{sub 2}S{sub 3}/CNFs/Au ternary synergetic system. • Enhanced visible-light photocatalytic activity. • Easy photocatalyst separation and reuse. - Abstract: In this paper, carbon nanofibers (CNFs) were successfully synthesized by electrospinning technique. Next, Au nanoparticles (NPs) were assembled on the electrospun CNFs through in situ reduction method. By using the obtained Au NPs modified CNFs (CNFs/Au) as hard template, the In{sub 2}S{sub 3}/CNFs/Au composites were synthesized through hydrothermal technique. The results showed that the super long one-dimensional (1D) CNFs (about 306 nm in average diameter) were well connected to form a nanofibrous network; and, the Au NPs with 18 nm in average diameter and In{sub 2}S{sub 3} nanosheets with 5–10 nm in thickness were uniformly grown onto the surface of CNFs. Photocatalytic studies revealed that the In{sub 2}S{sub 3}/CNFs/Au composites exhibited highest visible-light photocatalytic activities for the degradation of Rhodamine B (RB) compared with pure In{sub 2}S{sub 3} and In{sub 2}S{sub 3}/CNFs. The enhanced photocatalytic activity might arise from the high separation efficiency of photogenerated electron–hole pairs based on the positive synergetic effect between In{sub 2}S{sub 3}, CNFs and Au components in this ternary photocatalytic system. Meanwhile, the In{sub 2}S{sub 3}/CNFs/Au composites with hierarchical structure possess a strong adsorption ability towards organic dyes, which also contributed to the enhancement of photocatalytic activity. Moreover, the In{sub 2}S{sub 3}/CNFs/Au composites could be recycled easily by sedimentation due to their nanofibrous network structure.

  19. Enhanced visible-light photocatalytic H2-generation activity of carbon/g-C3N4 nanocomposites prepared by two-step thermal treatment.

    Science.gov (United States)

    Xu, Quanlong; Jiang, Chuanjia; Cheng, Bei; Yu, Jiaguo

    2017-08-15

    Photocatalytic hydrogen (H2) production from water by using solar energy and a photocatalyst is a green and sustainable route to tackle the energy issues. Herein, carbon/g-C3N4 nanocomposites were successfully synthesized via a two-step thermal treatment of urea and glucose with different ratios. As confirmed by X-ray photoelectron spectroscopy, a C-O-C bond was formed between carbon and g-C3N4, which leads to a strong interaction between carbon and g-C3N4. The prepared samples were evaluated for photocatalytic H2 generation under visible light irradiation. The experimental results indicate that the carbon/g-C3N4 nanocomposites show great photocatalytic H2 evolution activity, as high as 410.1 μmol g(-1) h(-1), which is 13.6-fold of pure g-C3N4. The enhanced photocatalytic performance not only originates from the enlarged surface area and extended visible light response range, but also from the effectively separated photo-generated charge carriers. This spatial charge separation greatly suppresses the recombination of photo-generated hole-electron pairs and facilitates efficient H2 production. This work provides a facile way to design highly efficient carbon nitride-based photocatalysts for potential application in photocatalytic reaction by using solar energy.

  20. Synthesis of Nitrogen-Doped ZnS with Camellia Brushfield Yellow Nanostructures for Enhanced Photocatalytic Activity under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Gang-Juan Lee

    2013-01-01

    Full Text Available Nitrogen modified zinc sulfide photocatalysts were successfully prepared and characterized by X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, high-resolution transmission electron microscopy (HR-TEM, X-ray photoelectron spectroscopy (XPS, and surface area analysis. Thermal decomposition of the semisolid was carried out under nitrogen conditions at 500°C for 2 hours, and a series of nitrogen-doped ZnS photocatalysts were produced by controlling inflow flow rate of nitrogen at 15–140 mL/min. Optical characterizations of the synthesized N-doping ZnS substantially show the shifted photoabsorption properties from ultraviolet (UV region to visible light. The band gaps of nitrogen-doped ZnS composite catalysts were calculated to be in the range of 2.58~2.74 eV from the absorptions edge position. The 15N/ZnS catalyst shows the highest photocatalytic activity, which results in 75.7% degradation of Orange II dye in 5 hrs by visible light irradiation, compared with pristine ZnS and higher percentage N-doping ZnS photocatalysts.

  1. 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.

  2. 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.

  3. Characterization and photocatalytic activity of poly(3-hexylthiophene)-modified TiO2 for degradation of methyl orange under visible light.

    Science.gov (United States)

    Wang, Desong; Zhang, Jie; Luo, Qingzhi; Li, Xueyan; Duan, Yandong; An, Jing

    2009-09-30

    Poly(3-hexylthiophene) (P3HT) was synthesized via chemical oxidative polymerization with anhydrous FeCl(3) as oxidant, 3-hexylthiophene as monomer, chloroform as solvent. TiO(2) nanoparticles modified by a small amount of P3HT (TiO(2)/P3HT) were prepared by blending TiO(2) nanoparticles and P3HT in chloroform solution. The resulting photocatalysts were characterized by the methods of TEM, XRD, FT-IR, XPS and UV-vis diffuse reflectance spectroscope. The photocatalytic activity of TiO(2)/P3HT was investigated by degrading methyl orange under visible light. The degradation rate of methyl orange was 88.5 and 13.5% when it was degradated by TiO(2)/P3HT and neat TiO(2)(P-25) for 10h, respectively. In addition, TiO(2)/P3HT nanocomposites showed excellent photocatalytic stability after 10 cycles under visible light irradiation. A possible mechanism for the photocatalytic oxidative degradation was also discussed.

  4. 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.

  5. In-situ anion exchange fabrication of porous ZnO/ZnSe heterostructural microspheres with enhanced visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hairui, E-mail: liuhairui1@126.com [College of Physics & Electrics Engineering, Henan Normal University, Henan Key Laboratory of Photovoltaic Materials, Xinxiang 453007 (China); Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, Shanxi, 030024 (China); College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Hu, Yanchun [College of Physics & Electrics Engineering, Henan Normal University, Henan Key Laboratory of Photovoltaic Materials, Xinxiang 453007 (China); He, Xia [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, Shanxi, 030024 (China); Jia, Husheng, E-mail: jia_husheng@126.com [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, Shanxi, 030024 (China); College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Liu, Xuguang; Xu, Bingshe [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, Shanxi, 030024 (China)

    2015-11-25

    Porous ZnO microspheres were fabricated by an ultrasonic irradiation technique. Subsequently, through a facile in-situ anion exchange reaction between the ZnO microsphere and sodium selenite, spherical ZnO/ZnSe heterostructures with different ratios of the two components were fabricated. The as-obtained products were characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV–vis spectrometry. The results reveal that the secondary ZnSe nanoparticles are grown on the surface of pre-grown ZnO microspheres. Compared with pure ZnO microspheres, the ZnO/ZnSe hetero-microspheres show enhance visible-light photocatalytic activity for degradation of methylene blue (MB) and 4-nitrophenol (4-NP). The enhanced photocatalytic performance is attributed to fast separation and transport of photogenerated electrons and holes derived from the coupling effect of ZnSe and ZnO heterostructure. Photoluminescent spectra further indicate that the ZnO/ZnSe heterostructures greatly suppress the charge recombination of photogenerated electron–hole pairs, which would be beneficial to improve their photocatalytic activity. Finally, the photocatalytic mechanism of the ZnO/ZnSe heterostructures is proposed. - Graphical abstract: Porous ZnO/ZnSe heterostructures with different ratios of the two components were fabricated and present enhance visible-light photocatalytic activity for degradation of methylene blue (MB) and 4-nitrophenol (4-NP). The enhanced photocatalytic performance is attributed to fast separation and transport of photogenerated electrons and holes derived from the coupling effect of ZnSe and ZnO heterostructure. - Highlights: • Spherical ZnO/ZnSe porous composites were fabricated by in-situ anion exchange. • ZnO/ZnSe composites exhibited enhanced visible-light photocatalytic activity. • The matching band gap improves the separation of

  6. Facile Synthesis of High {001} Facets Dominated BiOCl Nanosheets and Their Selective Dye-Sensitized Photocatalytic Activity Induced by Visible Light

    Directory of Open Access Journals (Sweden)

    Da Zhang

    2016-01-01

    Full Text Available Single-crystal BiOCl nanosheets, with high {001} facets exposed, were synthesized through a facile hydrolysis reaction under general atmospheric pressure, without adding any organic surfactant or agent. The thickness of the BiOCl nanosheets is about 20 nm, and the diameter is arranged from 200 to 400 nm. The structure of the BiOCl nanosheets was characterized by X-ray diffraction, energy disperse X-ray spectrum, transmission electron microscopy, and selective area electron diffraction. Moreover, three different dyes were used as model molecules to test the photocatalytic activity of BiOCl nanosheets under visible light. It was found that the BiOCl nanosheets possess selective photocatalytic behavior as their activity over RhB is much higher than that over MO or MB. Based on the analysis of the experimental results, the potential mechanism was discussed.

  7. Facile synthesis of ultrathin SnNb2O6 nanosheets towards improved visible-light photocatalytic H2-production activity.

    Science.gov (United States)

    Zhou, Chao; Zhao, Yufei; Shang, Lu; Shi, Run; Wu, Li-Zhu; Tung, Chen-Ho; Zhang, Tierui

    2016-07-07

    Ultrathin SnNb2O6 nanosheets with a thickness of ∼3 nm were synthesized via a facile hydrothermal route using ultrathin K4Nb6O17 nanosheets as the precursor. This ultrathin nanosheets with a large specific surface area of 71.1 m(2) g(-1) showed improved visible-light photocatalytic H2-production activity in lactic acid aqueous solution, which is about 4 and 14 times higher than that of 50 nm-thick SnNb2O6 nanosheets and bulk SnNb2O6 powders, respectively. The higher activity of ultrathin nanosheets was mainly attributed to their larger specific surface area and much better charge transfer efficiency.

  8. N-doped P25 TiO2-amorphous Al2O3 composites: one-step solution combustion preparation and enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Li, Fa-tang; Zhao, Ye; Hao, Ying-juan; Wang, Xiao-jing; Liu, Rui-hong; Zhao, Di-shun; Chen, Dai-mei

    2012-11-15

    Nitrogen-doped Degussa P25 TiO2-amorphous Al2O3 composites were prepared via facile solution combustion. The composites were characterised using X-ray diffraction, high-resolution transmission microscopy, scanning electron microscopy, nitrogen adsorption-desorption measurements, X-ray photoelectron spectroscopy, UV-vis light-diffusion reflectance spectrometry (DRS), zeta-potential measurements, and photoluminescence spectroscopy. The DRS results showed that TiO2 and amorphous Al2O3 exhibited absorption in the UV region. However, the Al2O3/TiO2 composite exhibited visible-light absorption, which was attributed to N-doping during high-temperature combustion and to alterations in the electronic structure of Ti species induced by the addition of Al. The optimal molar ratio of TiO2 to Al2O3 was 1.5:1, and this composite exhibited a large specific surface area of 152 m2/g, surface positive charges, and enhanced photocatalytic activity. These characteristics enhanced the degradation rate of anionic methylene orange, which was 43.6 times greater than that of pure P25 TiO2. The high visible-light photocatalytic activity was attributed to synthetic effects between amorphous Al2O3 and TiO2, low recombination efficiency of photo-excited electrons and holes, N-doping, and a large specific surface area. Experiments that involved radical scavengers indicated that OH and O2- were the main reactive species. A potential photocatalytic mechanism was also proposed. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Synthesis and characterization of novel Sm2O3/S-doped g-C3N4 nanocomposites with enhanced photocatalytic activities under visible light irradiation

    Science.gov (United States)

    Jourshabani, Milad; Shariatinia, Zahra; Badiei, Alireza

    2018-01-01

    Novel Sm2O3/S-doped g-C3N4 (CNS) composites were synthesized with in situ method by simultaneous combining S doping in carbon nitride structure to produce CNS as well as hybridization of CNS with the Sm2O3 semiconductor. The obtained composite photocatalysts with different Sm2O3 contents were characterized by XRD, FT-IR, XPS, TEM, BET, DRS and PL techniques and their photocatalytic activities were investigated for the degradation of methylene blue (MB) as a model pollutant in aqueous solution under visible-light irradiation. The XRD structure phase and TEM morphology results showed that stacking degree of π-conjugated system in the CNS structure was disrupted in the precense of Sm2O3 particles. The optimal Sm2O3 loading value was determined to be 8.9 wt% and its corresponding MB photodegradation rate was about 93% after 150 min light irradiation, which was indeed greater compared with those of the individual CNS and Sm2O3 samples. This enhanced photocatalytic performance was originated from characteristics of the hybrid formed between the Sm2O3 and CNS so that it improved the effective charge transfer through interfacial interactions between both components. In addition, the CNS synthesized by S doping exhibited a significant enhancement in the photocatalytic activity relative to that of the pure g-C3N4; this was mostly caused by the increase in its visible light harvesting ability and charge mobility. The possible mechanism for the photocatalytic degradation of MB was suggested and discussed in detail based on the findings acquired from radical/hole trapping experiments.

  10. Surfactant-free synthesis of Cu2O hollow spheres and their wavelength-dependent visible photocatalytic activities using LED lamps as cold light sources.

    Science.gov (United States)

    Wang, Yuxi; Huang, Da; Zhu, Xingzhong; Ma, Yujie; Geng, Huijuan; Wang, Ying; Yin, Guilin; He, Dannong; Yang, Zhi; Hu, Nantao

    2014-01-01

    A facile synthesis route of cuprous oxide (Cu2O) hollow spheres under different temperatures without the aid of a surfactant was introduced. Morphology and structure varied as functions of reaction temperature and duration. A bubble template-mediated formation mechanism was proposed, which explained the reason of morphology changing with reaction temperature. The obtained Cu2O hollow spheres were active photocatalyst for the degradation of methyl orange under visible light. A self-designed equipment of light emitting diode (LED) cold light sources with the wavelength of 450, 550, and 700 nm, respectively, was used for the first time in the photocatalysis experiment with no extra heat introduced. The most suitable wavelength for Cu2O to photocatalytic degradation is 550 nm, because the light energy (2.25 eV) is closest to the band gap of Cu2O (2.17 eV). These surfactant-free synthesized Cu2O hollow spheres would be highly attractive for practical applications in water pollutant removal and environmental remediation.

  11. Enhanced visible light photocatalytic activity in SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Hao; Zhao, Xiaoru, E-mail: xrzhao@nwpu.edu.cn; Duan, Libing; Liu, Ruidi; Li, Hui

    2017-04-15

    Highlights: • Novel SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures were successfully synthesized. • The core-shell structures exhibited enhanced visible light photocatalytic activity. • The enhanced photocatalytic activity was due to synergic action of SnO{sub 2} and g-C{sub 3}N{sub 4}. - Abstract: SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures were successfully synthesized by simple calcination of SnO{sub 2} microspheres and urea in a muffle furnace. The investigation of morphologies and microstructures showed that g-C{sub 3}N{sub 4} was wrapped tightly on the surface of SnO{sub 2} microspheres with large intimate interface contact areas between the g-C{sub 3}N{sub 4} shells and SnO{sub 2} cores. The X-ray photoelectron spectroscopy results and photoluminescence spectra demonstrated that the intimate interface contacts could facilitate the transfer and separation of the photogenerated charge carriers at their interface, thus the recombination of the photogenerated electron-hole pairs was impeded. The photocatalytic activity of the synthesized composites was evaluated by the photodegradation of methyl orange under visible light irradiation. It was found that SnO{sub 2}@g-C{sub 3}N{sub 4} exhibited higher photodegradation rate (k = 0.013 min{sup −1}) than that of g-C{sub 3}N{sub 4} (k = 0.008 min{sup −1}) and pure SnO{sub 2}. The enhanced photocatalytic activity could be attributed to the synergic action of SnO{sub 2} and g-C{sub 3}N{sub 4}.

  12. Enhanced Visible Light Photocatalytic Activity of V2O5 Cluster Modified N-Doped TiO2 for Degradation of Toluene in Air

    Directory of Open Access Journals (Sweden)

    Fan Dong

    2012-01-01

    Full Text Available V2O5 cluster-modified N-doped TiO2 (N-TiO2/V2O5 nanocomposites photocatalyst was prepared by a facile impregnation-calcination method. The effects of V2O5 cluster loading content on visible light photocatalytic activity of the as-prepared samples were investigated for degradation of toluene in air. The results showed that the visible light activity of N-doped TiO2 was significantly enhanced by loading V2O5 clusters. The optimal V2O5 loading content was found to be 0.5 wt.%, reaching a removal ratio of 52.4% and a rate constant of 0.027 min−1, far exceeding that of unmodified N-doped TiO2. The enhanced activity is due to the deposition of V2O5 clusters on the surface of N-doped TiO2. The conduction band (CB potential of V2O5 (0.48 eV is lower than the CB level of N-doped TiO2 (−0.19 V, which favors the photogenerated electron transfer from CB of N-doped TiO2 to V2O5 clusters. This function of V2O5 clusters helps promote the transfer and separation of photogenerated electrons and holes. The present work not only displays a feasible route for the utilization of low cost V2O5 clusters as a substitute for noble metals in enhancing the photocatalysis but also demonstrates a facile method for preparation of highly active composite photocatalyst for large-scale applications.

  13. Study of the visible light activity of Pt and Au-TiO2 photocatalysts in organic pollutants degradation

    Directory of Open Access Journals (Sweden)

    Jairo Antonio Cubillos-Lobo

    2017-01-01

    Full Text Available Los fotocatalizadores Pt-TiO2 y Au-TiO2 se prepararon por fotodeposición del metal noble sobre el TiO2 sulfatado. Se encontró que las propiedades ópticas, el estado de oxidación y el tamaño de partícula de las especies metálicas (Pt o Au juegan un papel fundamental en la actividad fotocatalítica del TiO2 bajo luz visible. La actividad fotocatalítica del TiO2 en la degradación de fenol y naranja de metilo aumentó significativamente a través de los tratamientos de sulfatación y metalización de este óxido. La más alta velocidad de degradación bajo luz UV-Visible y visible, se alcanzó usando el fotocatalizador Pt-S-TiO2; esto se debe principalmente a la modificación de las propiedades ópticas del TiO2 inducidas por la platinización, también a la buena distribución y al pequeño tamaño de las partículas de Pt. Se encontró, además, que este catalizador presenta una buena estabilidad después de dos ciclos de reacción en la degradación de fenol bajo luz UV-Visible. El fotocatalizador Pt-S-TiO2 fue activo también bajo luz solar directa y bajo las condiciones medioambientales de la ciudad de Tunja (Boyacá, Colombia.

  14. Preparation of α-SnWO{sub 4}/SnO{sub 2} heterostructure with enhanced visible-light-driven photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Shiyue; Zhang, Min; Di, Junwei; Wang, Zuoshan [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Long, Yumei, E-mail: Yumeilong@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou (China); Li, Weifeng, E-mail: liweifeng@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China)

    2015-12-01

    Graphical abstract: SnO{sub 2}-hybridized α-SnWO{sub 4} nanocomposites were prepared and they exhibited favorable photocatalytic activity for the degradation of MO under visible light irradiation. A detailed photocatalytic mechanism based on heterostructure was given. - Highlights: • α-SnWO{sub 4}/SnO{sub 2} heterostructure was prepared by a two-step hydrothermal route. • The attachment of SnO{sub 2} nanocrystals on α-SnWO{sub 4} nanoplates increases BET surface area. • The α-SnWO{sub 4}/SnO{sub 2} heterojunction efficiently hinders the recombination of photogenerated electrons and holes. • α-SnWO{sub 4}/SnO{sub 2} nanocomposite exhibits excellent photocatalytic activity under visible light irradiation. - Abstract: In this work, a novel α-SnWO{sub 4}/SnO{sub 2} heterostructure was synthesized via a facile two-step hydrothermal method. The as-prepared products were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scan electron microscopy (SEM) and transmission electron microscopy (TEM), which confirmed the typical orthorhombic α-SnWO{sub 4} phase, plate-like morphology and α-SnWO{sub 4}/SnO{sub 2} heterostructure. The photocatalytic studies revealed that the attachment of SnO{sub 2} nanoparticles on the surface of α-SnWO{sub 4} plates can remarkably improve their photocatalytic activities and the α-SnWO{sub 4}/SnO{sub 2} heterostructure exhibited the best photocatalytic properties in the degradation of methyl orange (MO) under visible light irradiation. The degradation rate of MO on α-SnWO{sub 4}/SnO{sub 2} plate was 97% within 40 min and the photocatalytic degradation reaction followed the pseudo-first-order kinetics. The enhanced photocatalytic property was ascribed to the large surface area and the heterojuction between α-SnWO{sub 4} and SnO{sub 2}, which can facilitate efficient charge separation of photogenerated electron–hole pairs. Furthermore, α-SnWO{sub 4}/SnO{sub 2} nanocomposite demonstrated good

  15. Facile synthesis of AgI/BiOI-Bi{sub 2}O{sub 3} multi-heterojunctions with high visible light activity for Cr(VI) reduction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qi [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); The Brook Byer Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332 (United States); Shi, Xiaodong; Liu, Enqin [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); Crittenden, John C. [The Brook Byer Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332 (United States); Ma, Xiangjuan; Zhang, Yi [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); Cong, Yanqing, E-mail: yqcong@hotmail.com [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China)

    2016-11-05

    Graphical abstract: Highly visible-light-active AgI/BiOI-Bi{sub 2}O{sub 3} with multi-heterojunctions was developed. - Highlights: • Visible-light-active AgI/BiOI-Bi{sub 2}O{sub 3} with multi-heterojunctions was prepared. • Highly enhanced photocatalytic reduction of Cr(VI) was observed. • k{sub Cr(VI)} on AgI/BiOI-Bi{sub 2}O{sub 3} increased by ca.16 times relative to Bi{sub 2}O{sub 3}. • Decreased E{sub g}, shifted E{sub fb} and reduced charge transfer resistance were observed. • Simultaneous reduction of Cr(VI) and degradation of organics were achieved. - Abstract: AgI sensitized BiOI-Bi{sub 2}O{sub 3} composite (AgI/BiOI-Bi{sub 2}O{sub 3}) with multi-heterojunctions was prepared using simple etching-deposition process. Different characterization techniques were performed to investigate the structural, optical and electrical properties of the as-prepared photocatalysts. It was found that the ternary AgI/BiOI-Bi{sub 2}O{sub 3} composite exhibited: (1) improved photocurrent response, (2) smaller band gap, (3) greatly reduced charge transfer resistance and (4) negative shift of flat band potential, which finally led to easier generation and more efficient separation of photo-generated electron-hole pairs at the hetero-interfaces. Thus, for the reduction of Cr(VI), AgI/BiOI-Bi{sub 2}O{sub 3} exhibited excellent photocatalytic activity under visible light irradiation at near neutral pH. AgI/BiOI-Bi{sub 2}O{sub 3} was optimized when the initial molar ratio of KI to Bi{sub 2}O{sub 3} and AgNO{sub 3} to Bi{sub 2}O{sub 3} was 1:1 and 10%, respectively. The estimated k{sub Cr(VI)} on optimized AgI/BiOI-Bi{sub 2}O{sub 3} was about 16 times that on pure Bi{sub 2}O{sub 3}. Good stability was also observed in cyclic runs, indicating that the current multi-heterostructured photocatalyst is highly desirable for the remediation of Cr(VI)-containing wastewater.

  16. Defect induced visible-light-activated near-infrared emissions in Gd3-x-y-zYbxBiyErzGa5O12

    Science.gov (United States)

    Tong, Liping; Saito, Katsuhiko; Guo, Qixin; Zhou, Han; Fan, Tongxiang; Zhang, Di

    2017-11-01

    Visible-light-activated near-infrared luminescent materials are promising photoluminescent materials due to their convenience and low cost. Crystal defects can seriously affect the performance of luminescent materials, and better understanding of the complexity of the structural disorder and electronic structures of such materials opens up new possibilities in luminescent material development. In this work, we successfully design a novel, effective, visible-light-activated near-infrared luminescent Gd3Ga5O12: 4.2%Yb3+, 8.4%Er3+, and 4.2%Bi3+ system based on first principles. This exhibits strong emission intensity and high luminous efficiency (0.993) and also has a lifetime (7.002 ms) that is at least twice as long as the longest lifetime reported in published papers. We utilize density functional theory with an effective LSDA + U method to study the structural properties of Gd3-x-y-zGa5O12: xYb3+, yBi3+, zEr3+ (GGG: Yb3+, Bi3+, Er3+). The d and f electron orbits of rare-earth ions are considered for an effective Hund exchange. Detailed analysis reveals that GGG: 4.2%Yb3+, 8.4%Er3+, 4.2%Bi3+ has the smallest cell volume because of the strong covalent bonds of Bi-O, Er-O, and Yb-O. Bi 3d is a hybridized state that acts as sensitizing ions during the process of luminescence in GGG: Yb3+, Bi3+, Er3+. Together with experimental and theoretical results, we analyze the influence of defects on emission intensity. The locations of Yb3+, Er3+, and Bi3+ are determined by X-ray absorption fine structure measurements, which are in agreement with the model constructed using first principles. This work may provide innovative guidance for the design of high-performance visible-light-activated near-infrared luminophores based on calculations and a new methodology for application of coherent laser radar and optical communication.

  17. Enhanced photodegradation activity of methyl orange over Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Jin, E-mail: lj328520504@126.com; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao; Wu, Jingxia; Liang, Huiping

    2016-05-15

    Highlights: • Novel visible-light-driven Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites are synthesized. • Ag{sub 2}CrO{sub 4}/SnS{sub 2} exhibits higher photocatalytic activity than pure Ag{sub 2}CrO{sub 4} and SnS{sub 2}. • Ag{sub 2}CrO{sub 4}/SnS{sub 2} exhibits excellent stability for the photodegradation of MO. • The possible photocatalytic mechanism was discussed in detail. - Abstract: Novel Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites were prepared by a simple chemical precipitation method and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. The visible light photocatalytic tests showed that the Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites enhanced photocatalytic activities for the photodegradation of methyl orange (MO) under visible light irradiation (λ > 420 nm), and the optimum rate constant of Ag{sub 2}CrO{sub 4}/SnS{sub 2} at a weight content of 1.0% Ag{sub 2}CrO{sub 4} for the degradation of MO was 2.2 and 1.5 times larger than that of pure Ag{sub 2}CrO{sub 4} and SnS{sub 2}, respectively. The improved activity could be attributed to high separation efficiency of photogenerated electrons-hole pairs on the interface of Ag{sub 2}CrO{sub 4} and SnS{sub 2}, which arised from the synergistic effect between Ag{sub 2}CrO{sub 4} and SnS{sub 2}. Moreover, the possible photocatalytic mechanism with superoxide radical anions and holes species as the main reactive species in photocatalysis process was proposed on the basis of experimental results.

  18. PAPR analysis for OFDM visible light communication.

    Science.gov (United States)

    Wang, Jiaheng; Xu, Yang; Ling, Xintong; Zhang, Rong; Ding, Zhi; Zhao, Chunming

    2016-11-28

    Orthogonal frequency-division multiplexing (OFDM) is a practical technology in visible light communication (VLC) for high-speed transmissions. However, one of its operational limitations is the peak-to-average power ratio (PAPR) of the transmitted signal. In this paper, we analyze the PAPR distributions of four VLC OFDM schemes, namely DC-biased optical OFDM (DCO-OFDM), asymmetrically clipped optical OFDM (ACO-OFDM), pulse amplitude modulated discrete multitone (PAM-DMT), and Flip-OFDM. Both lower and upper clippings are considered. We analytically derive the complementary cumulative distribution functions (CCDFs) of the PAPRs of the clipped VLC OFDM signals, and investigate the impact of lower and upper clippings on PAPR distributions. Our analytical results, as verified by numerical simulations, provide useful insights and guidelines for VLC OFDM system designs.

  19. Coded source imaging simulation with visible light

    Energy Technology Data Exchange (ETDEWEB)

    Wang Sheng [State Key Laboratory of Nuclear Physics and Technology and School of Physics, IHIP, Peking University, Yiheyuan Lu 5, Beijing 100871 (China); Zou Yubin, E-mail: zouyubin@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology and School of Physics, IHIP, Peking University, Yiheyuan Lu 5, Beijing 100871 (China); Zhang Xueshuang; Lu Yuanrong; Guo Zhiyu [State Key Laboratory of Nuclear Physics and Technology and School of Physics, IHIP, Peking University, Yiheyuan Lu 5, Beijing 100871 (China)

    2011-09-21

    A coded source could increase the neutron flux with high L/D ratio. It may benefit a neutron imaging system with low yield neutron source. Visible light CSI experiments were carried out to test the physical design and reconstruction algorithm. We used a non-mosaic Modified Uniformly Redundant Array (MURA) mask to project the shadow of black/white samples on a screen. A cooled-CCD camera was used to record the image on the screen. Different mask sizes and amplification factors were tested. The correlation, Wiener filter deconvolution and Richardson-Lucy maximum likelihood iteration algorithm were employed to reconstruct the object imaging from the original projection. The results show that CSI can benefit the low flux neutron imaging with high background noise.

  20. Enhanced photocatalytic activity of nitrogen and indium co-doped mesoporous TiO{sub 2} nanocomposites for the degradation of 2,4-dinitrophenol under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Myilsamy, M. [Department of Chemistry, SSN College of Engineering, Kalavakkam-603110, Tamil Nadu (India); Mahalakshmi, M., E-mail: mahalakshmim@ssn.edu.in [Department of Chemistry, SSN College of Engineering, Kalavakkam-603110, Tamil Nadu (India); Murugesan, V. [Department of Chemistry, Anna University, Chennai-600025, Tamil Nadu (India); Subha, N. [Department of Chemistry, SSN College of Engineering, Kalavakkam-603110, Tamil Nadu (India)

    2015-07-01

    Graphical abstract: - Highlights: • Mesoporous N/In{sub 2}O{sub 3}–TiO{sub 2} nanocomposite materials were prepared by sol-gel route. • N/In{sub 2}O{sub 3}–TiO{sub 2} shifted the light absorption band-edge position to visible region. • 0.3 wt% N/In{sub 2}O{sub 3}–TiO{sub 2} showed high surface area, pore volume and pore size. • N{sup −} and In{sup 3+} substitution enhanced adsorption of 2,4-DNP and OH{sup −} ions. • Indium doping efficiently extended the life time of electron–hole pair. - Abstract: Mesoporous N/In{sub 2}O{sub 3}–TiO{sub 2} nanocomposite photocatalysts were synthesized by sol-gel route using Pluronic P123 as the structure directing template. The synthesized composite materials were successfully characterized by X-ray powder diffraction, high resolution transmission electron microscopy, N{sub 2} adsorption–desorption studies, X-ray photoelectron spectroscopy, diffuse reflectance UV–vis spectroscopy, Fourier transform infrared spectroscopy and photoluminescence spectroscopy. The photocatalytic activities of all the synthesized catalysts were evaluated for the degradation of 2,4-dinitrophenol under visible light irradiation. The results demonstrated that the mesoporous N/In{sub 2}O{sub 3}–TiO{sub 2} showed higher efficiency than meso TiO{sub 2}, N-TiO{sub 2} and In{sub 2}O{sub 3}–TiO{sub 2} under visible light irradiation and the optimum molar ratio of N and In to Ti is 0.3 wt%. DRUV–vis revealed that the substitution of N{sup −} and In{sup 3+} dopants on TiO{sub 2} lattice shifted the light absorption to the longer wavelength and reduced the band gap energy. The enhanced {sup •} OH radicals formation during the photocatalytic reaction was revealed by photoluminescence spectra. The photoluminescence spectra of synthesized catalysts revealed that the efficient charge separation of photo induced charge carriers for 0.3 wt% N/In{sub 2}O{sub 3}–TiO{sub 2} nanocomposite. The enhanced surface area, large pore volume

  1. Synthesis and characterization of cube-like Ag@AgCl-doped TiO2/fly ash cenospheres with enhanced visible-light photocatalytic activity

    Science.gov (United States)

    Liu, Shaomin; Zhu, Jinglin; Yang, Qing; Xu, Pengpeng; Ge, Jianhua; Guo, Xuetao

    2016-03-01

    A cube-like Ag@AgCl-doped TiO2/fly ash cenosphere composite (denoted Ag@AgCl-TiO2/fly ash cenospheres) was successfully synthesized via a two-step approach. The as-prepared catalysts were characterized by scanning electron microscopy, X-ray diffraction, diffuse reflectance ultraviolet-visible spectroscopy, Brunauer-Emmett-Teller, and X-ray photoelectron spectroscopy. The photocatalytic experiment showed that the rhodamine B degradation rate with Ag@AgCl-TiO2/fly ash cenospheres was 1.56 and 1.33 times higher than that with AgCl-TiO2/fly ash cenospheres and Ag@AgCl, respectively. The degradation ratio of rhodamine B with Ag@AgCl-TiO2/fly ash cenospheres was nearly 100% within 120 min under visible light. Analysis of active species indicated that radO2- and h+ dominated the reaction, and radOH participated in the photocatalytic reactions as an active species. A mechanism for the photocatalytic degradation by the Ag@AgCl-TiO2/fly-ash cenospheres was also proposed based on the experimental results.

  2. Preparation of efficient visible-light-driven BiOBr/Bi{sub 2}O{sub 3} heterojunction composite with enhanced photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qizhao, E-mail: qizhaosjtu@gmail.com [College of Chemistry and Chemical Engineering, Northwest Normal University, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of Gansu Polymer Materials, Lanzhou, 730070 (China); Jiao, Danhua; Lian, Juhong; Ma, Qiong; Yu, Jie [College of Chemistry and Chemical Engineering, Northwest Normal University, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of Gansu Polymer Materials, Lanzhou, 730070 (China); Huang, Haohao, E-mail: scuthhh@hotmail.com [College of Materials Science and Engineering, South China University of Technology, Guangzhou, 510640 (China); Zhong, Junbo; Li, Jianzhang [Key Laboratory of Green Chemistry of Sichuan Institutes of Higher Education Institutes of Sichuan, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science and Engineering, Zigong, 643000 (China)

    2015-11-15

    Highly efficient novel photocatalysts BiOBr/Bi{sub 2}O{sub 3} with various proportion of BiOBr were synthesized via accommodating the pH value of solution and were applied to decontaminate methyl orange (MO) and methylene blue (MB). The samples were characterized by Fourier transform infrared spectrophotometry (FT-IR), X-ray diffractometry (XRD), Scanning electron microscopy (SEM), UV–vis diffuse reflectance spectra, and N{sub 2} physisorption. Though both the individual BiOBr and Bi{sub 2}O{sub 3} showed very low photocatalytic efficiency under visible light irradiation, the BiOBr/Bi{sub 2}O{sub 3} composites exhibited superior activity for MO and MB under visible light, and 75% BiOBr/Bi{sub 2}O{sub 3} (pH = 6) composite showed the highest degradation rate, which was 1.4 times than that of pure BiOBr. The photocatalytic activity investigating on MB also showed a same result. In addition, the catalyst can be separated easily for reuse and no obvious loss of photocatalytic activity were observed after three consecutive runs. - Highlights: • Highly efficient novel photocatalysts BiOBr/Bi{sub 2}O{sub 3} with various proportions of BiOBr were synthesized via a facile hydrolysis. • Investigating the influence of photocatalysts on the degradation of MO by accommodating pH values. • The mechanism was proposed based on the synergistic effect between BiOBr and Bi{sub 2}O{sub 3}.

  3. Facile in situ hydrothermal synthesis of g-C{sub 3}N{sub 4}/SnS{sub 2} composites with excellent visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Fang; Zhao, Lina; Pei, Xule [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang 330063 (China); College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Xubiao, E-mail: luoxubiao@126.com [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang 330063 (China); College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Shenglian, E-mail: sllou@hnu.edu.cn [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang 330063 (China); College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2017-03-01

    The g-C{sub 3}N{sub 4}/SnS{sub 2} composites were prepared by in situ hydrothermal method, and the effect of g-C{sub 3}N{sub 4} content on the physical and chemical properties, and photocatalytic performance of g-C{sub 3}N{sub 4}/SnS{sub 2} composites was investigated. The introduction of g-C{sub 3}N{sub 4} enhanced the visible-light absorption of SnS{sub 2}, and reduced the recombination rate of electron-hole pairs. The photocatalytic performance of g-C{sub 3}N{sub 4}/SnS{sub 2} composites was also obviously influenced by g-C{sub 3}N{sub 4} content, and it was found that 15% g-C{sub 3}N{sub 4}/SnS{sub 2} composite exhibited the highest photocatalytic activity and excellent regeneration, which was attributed to the most efficient charge separation, the largest specific surface area and the formation of dominant active species (h{sup +} and ·O{sub 2}{sup −} radicals) during the photocatalytic process. - Graphical abstract: Photocatalytic mechanism of g-C{sub 3}N{sub 4}/SnS{sub 2} composites. - Highlights: • g-C{sub 3}N{sub 4}/SnS{sub 2} composites were fabricated by a in situ hydrothermal process. • g-C{sub 3}N{sub 4} content was optimized, and the optimal g-C{sub 3}N{sub 4} content is 15%. • 15% g-C{sub 3}N{sub 4}/SnS{sub 2} shows the highest visible-light photocatalytic activity. • g-C{sub 3}N{sub 4}/SnS{sub 2} composites exhibit excellent reusability.

  4. Fabrication of ternary reduced graphene oxide/SnS2/ZnFe2O4composite for high visible-light photocatalytic activity and stability.

    Science.gov (United States)

    Deng, Fang; Lu, Xiaoying; Pei, Xule; Luo, Xubiao; Luo, Shenglian; Dionysiou, Dionysios D

    2017-06-15

    Metal sulfides are promising photocatalysts for efficient removal of organic pollutants in wastewater. However, the practical application of these catalysts is limited due to the fast recombination of charge carriers and poor catalyst stability. In this study, ternary reduced graphene oxide/SnS 2 /ZnFe 2 O 4 (rGO/SnS 2 /ZnFe 2 O 4 ) composites were synthesized by a hydrothermal process, and rGO content was optimized. The surface morphology, crystal structure, optical and electrochemical properties of rGO/SnS 2 /ZnFe 2 O 4 composites were characterized. The adsorption capacity and visible-light photocatalytic activity of rGO/SnS 2 /ZnFe 2 O 4 were influenced by rGO content with results revealing an optimal rGO content of 7wt.%. The 7% rGO/SnS 2 /ZnFe 2 O 4 composite demonstrated the highest visible-light photocatalytic activity with almost 100% 2-nitrophenol removal, which could be attributed to the efficient charge separation, and the formation of O 2 - , h + and a few OH radicals. The possible photocatalytic mechanism of rGO/SnS 2 /ZnFe 2 O 4 composites was also provided based on the role of rGO and the energy bands of SnS 2 and ZnFe 2 O 4 . Moreover, rGO/SnS 2 /ZnFe 2 O 4 composites exhibit excellent reusability without an obvious decline in the photocatalytic activity after four degradation-regeneration cycles. The results indicate that ternary rGO/SnS 2 /ZnFe 2 O 4 composites have good prospect in practical removal of organic pollutants in wastewater due to high efficiency and excellent stability. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. MoS2 quantum dots decorated g-C3N4/Ag heterostructures for enhanced visible light photocatalytic activity

    Science.gov (United States)

    Fu, Yanhui; Liang, Wei; Guo, Jinqiu; Tang, Hua; Liu, Shuaishuai

    2018-02-01

    A novel MoS2 quantum dots (QDs) decorated g-C3N4/Ag heterostructured photocatalyst has been synthesized via a two-step method including in situ microemulsion-assisted reduction and wetness impregnation method. The obtained heterostructure photocatalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectrosxopy (PL). The photocatalytic activity was evaluated by the degradation of methyl orange (MO) under visible-light irradiation. The MoS2 QDs decorated hybrid photocatalysts exhibited significantly enhanced photocatalytic performance. The concentration of Ag and MoS2 QDs showing the optimal photocatalytic performance was determined to be 10% and 0.3% respectively, which exceeded the photocatalytic performance of pure g-C3N4 by more than 4.7 times. Recycling experiments confirmed that the hybrid catalysts had superior cycle performance and stability. The enhanced photocatalytic activity of MoS2 QDs decorated g-C3N4/Ag hybrid photocatalysts can be mainly ascribed to enhanced visible-light absorption, the efficient separation of photogenerated charge carriers and the stronger oxidation and reduction ability through a Z-scheme system composed of g-C3N4, Ag and MoS2 QDs, in which Ag nanoparticles act as the charge separation center. The evidence of the Z-scheme photocatalytic mechanism of the composite photocatalysts was obtained from the active species trapping experiments.

  6. Monoclinic BiVO{sub 4} micro-/nanostructures: Microwave and ultrasonic wave combined synthesis and their visible-light photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yafang; Li, Guangfang; Yang, Xiaohui; Yang, Hao; Lu, Zhong [Key Laboratory for Green Chemical Process of Ministry of Education and Hubei Novel Reactor and Green Chemical Technology Key Laboratory, Wuhan Institute of Technology, Xiongchu Avenue, Wuhan 430073 (China); Chen, Rong, E-mail: rchenhku@hotmail.com [Key Laboratory for Green Chemical Process of Ministry of Education and Hubei Novel Reactor and Green Chemical Technology Key Laboratory, Wuhan Institute of Technology, Xiongchu Avenue, Wuhan 430073 (China); Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Lumo Road, Wuhan 430074 (China)

    2013-02-25

    Graphical abstract: Monoclinic BiVO{sub 4} with different sizes and morphologies were synthesized by a facile microwave and ultrasonic wave combined technique for the first time and exhibited different optical properties and visible-light-driven photocatalytic efficiency. Highlights: Black-Right-Pointing-Pointer BiVO{sub 4} nanostructures were prepared by microwave and ultrasonic wave combined method. Black-Right-Pointing-Pointer BiVO{sub 4} nanostructures could be modulated by varying the solvent and pH value. Black-Right-Pointing-Pointer Different BiVO{sub 4} nanostructures exhibited different photocatalytic activities. Black-Right-Pointing-Pointer The photocatalytic performance was influenced by the band gap, phase and size. - Abstract: Monoclinic bismuth vanadate (m-BiVO{sub 4}) micro-/nanostructures with different sizes and morphologies were successfully prepared via a facile and rapid microwave and ultrasonic wave combined technique. The obtained BiVO{sub 4} products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and UV-vis diffuse reflection spectroscopy (DRS). It was found that the solvent and pH value had a significant influence on morphology, size and crystalline structure of the product. Nut-like, potato-like and broccoli-like monoclinic BiVO{sub 4} were fabricated in different solvents. The crystal phase could be modulated by varying the pH value of reaction system. The photocatalytic activities of the products were also evaluated by the degradation of Rhodamine B (RhB) under visible light irradiation. The result revealed that the photocatalytic activities of BiVO{sub 4} nanostructures were closely related to the crystalline phase, band gap and particle size. Monoclinic BiVO{sub 4} nanoparticles with small crystal size and large band gap exhibited remarkable photocatalytic performance.

  7. Enhanced photoresponse towards visible light in Ru doped titania nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Khan, M. Alam [School of Semiconductor and Chemical Engineering and Solar Energy Research Center, Chonbuk National University, 664-14 Dukjin dong, 1Ga, Jeonju 719-756 (Korea, Republic of); School of Display and Chemical Engineering, Yeungnam University, 214-1 Dae-Dong, Gyeongsan 712-749 (Korea, Republic of); Han, Do Hung [School of Display and Chemical Engineering, Yeungnam University, 214-1 Dae-Dong, Gyeongsan 712-749 (Korea, Republic of); Yang, O.-Bong [School of Semiconductor and Chemical Engineering and Solar Energy Research Center, Chonbuk National University, 664-14 Dukjin dong, 1Ga, Jeonju 719-756 (Korea, Republic of)], E-mail: obyang@chonbuk.ac.kr

    2009-01-01

    Doping of ruthenium by the ion exchange method to the hydrothermally synthesized titania nanotube (TiNT) was found to be an effective photocatalyst active under visible light for methylene blue dye decoloration. The well dispersed and well embedded ionized ruthenium particles of about {approx}2-4 nm significantly reduced the band gap energy of synthesized TiNTs from 3.1 eV to 2.56 eV in (Ru(IE)/TiNT). The loading method, size of ruthenium particles and metal dispersion pattern at the nanotube textures have great influence on its photocatalytic performances exhibiting higher photocatalytic activity (>80%) of methylene blue dye. However, large aggregated ruthenium particles (sizes {approx}12-60 nm) on Ru(IM)/TiNT prepared by impregnation method failed to respond in visible light. The prepared catalysts were analysed by TEM, FESEM, FE-SEMEDX, XRD, UV-vis DRS spectra, XPS and BET surface area techniques.

  8. Gd, I-doped TiO2 thin films coated on solid waste material: synthesis, characterization, and photocatalytic activity under UV or visible light irradiation

    Science.gov (United States)

    Deng, Siwei; Yu, Jiang; Yang, Chun; Chang, Jiahua; Wang, Yizheng; Wang, Ping; Xie, Shiqian

    2017-10-01

    In this work, titanium dioxide thin films doped with different concentrations of gadolinium (Gd) and iodine (I) were synthesized using the sol-gel method and successfully coated on solid waste material (made in our lab) by dipping, resulting in the titanium dioxide thin-film-coated material (TiO2M). Then, the doped titanium dioxide thin films were characterized by X-ray diffraction (XRD), SEM, and UV-Vis spectroscopy; the optimum coating cycle was evaluated by removal rates of COD and ammonia nitrogen in raw wastewater and secondary effluent. Moreover, the photocatalytic activity was determined by degradation efficiency of methyl orange. The results showed that TiO2M had desirable reusability and the photocatalytic activity was attractive under ultraviolet light irradiation. Furthermore, it is found that the amount of dopant in TiO2 was a key parameter in increasing the photoactivity. 1% Gd-doped TiO2M exhibited the best photocatalytic activity for the degradation of methyl orange with the removal rate reaching 85.55%. The result was in good agreement with the observed smaller crystallite size and profitable crystal structure (anatase phase). Besides, the TiO2M (0.8% Gd-doped TiO2M, 1% Gd-doped TiO2M, 10% I-doped TiO2M, and 5% I-1% Gd-doped TiO2M) with desirable photocatalytic activity at ultraviolet light irradiation was selected for the visible light photocatalytic experiments with taking methyl orange as the target pollutants. The results showed that all of them exhibited the similar photocatalytic activity after 7 h of sunlight irradiation (around 90% removal effect). In general, this research developed a very effective and environmentally friendly photocatalyst for pollutant degradation.

  9. One-pot synthesis of ternary Ag₂CO₃/Ag/AgCl photocatalyst in natural geothermal water with enhanced photocatalytic activity under visible light irradiation.

    Science.gov (United States)

    Yao, Xiaxi; Liu, Xiaoheng

    2014-09-15

    Geothermal water is a clean, cheap and renewable resource and it is widely distributed all over the world. In this work, ternary Ag2CO3/Ag/AgCl photocatalyst has been successfully synthesized via a one-pot precipitation method in natural geothermal water at room temperature, wherein the geothermal water serves as the source of chlorine and carbonate. The results suggest that the Ag/AgCl nanoparticles are anchored on the surface of Ag2CO3 and Ag2CO3/Ag/AgCl composite shows strong absorption ability in the visible light region. The evaluation of the photocatalytic activity indicates that the as-synthesized Ag2CO3/Ag/AgCl photocatalyst exhibits higher photocatalytic performance for the degradation of methylene blue (MB) aqueous solution under visible light irradiation than one-component (Ag2CO3), two-component (Ag/AgCl, Ag2CO3/AgCl) and the mechanical mixture of Ag2CO3 and Ag/AgCl. The trapping experiments confirmed that holes (h(+)) and (•)O2(-) were the two main active species in the photocatalytic process. Finally, a possible Z-scheme photocatalytic mechanism of the charge transfer was proposed for the enhanced photocatalytic performance. This work may open up new insights into the application of cheap geothermal water resources in the word and provide new opportunities for facile fabrication of Ag/AgCl-based photocatalysts. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Enhancing visible light photocatalytic activity of direct Z-scheme SnS{sub 2}/Ag{sub 3}PO{sub 4} heterojunction photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Jin, E-mail: lj328520504@126.com; Zhou, Xiaosong; Ma, Lin; Xu, Limei; Xu, Xuyao; Du, Zhihua; Zhang, Jinquan

    2016-09-15

    Highlights: • Novel direct Z-scheme SnS{sub 2}/Ag{sub 3}PO{sub 4} heterojunction photocatalysts are synthesized. • SnS{sub 2}/Ag{sub 3}PO{sub 4} exhibits much higher photocatalytic activity than pure SnS{sub 2} and Ag{sub 3}PO{sub 4}. • A possible photocatalytic mechanism was discussed in detail. - Abstract: Novel direct Z-scheme SnS{sub 2}/Ag{sub 3}PO{sub 4} heterojunction photocatalysts were successfully fabricated with SnS{sub 2} nanoplates hybridized by Ag{sub 3}PO{sub 4} nanoparticals via a facile hydrothermal and precipitation method and applied for the photocatalytic degradation of methyl orange in aqueous solution under visible light irradiation (λ > 420 nm). It was found that the photocatalytic performance of the SnS{sub 2} (2.0 wt%)/Ag{sub 3}PO{sub 4} heterojunction photocatalyst with 2.0 wt% SnS{sub 2} content was much higher than that of individual SnS{sub 2} and Ag{sub 3}PO{sub 4}. The enhanced photocatalytic activity could be ascribed to the efficient separation of photogenerated electrons and holes through the formation of direct Z-scheme system composed of SnS{sub 2} and Ag{sub 3}PO{sub 4}. Furthermore, the recycling experiments revealed that the photocorrosion behavior of Ag{sub 3}PO{sub 4} was strongly inhibited by SnS{sub 2}, it may be due to the photogenerated electrons of Ag{sub 3}PO{sub 4} would be quickly combined with the photogenerated holes of SnS{sub 2}. This work will be useful for the design of other direct Z-scheme visible-light-driven photocatalytic systems for application in energy conversion and environmental remediation.

  11. Synthesis of porous carbon-doped g-C{sub 3}N{sub 4} nanosheets with enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Nan, E-mail: baonan@sdu.edu.cn [School of Environmental Science and Engineering, Shandong Key Laboratory of Water Pollution Control and Resource Reuse, Shandong University, Shanda South Road 27, Jinan 250100 (China); Hu, Xinde [School of Environmental Science and Engineering, Shandong Key Laboratory of Water Pollution Control and Resource Reuse, Shandong University, Shanda South Road 27, Jinan 250100 (China); Zhang, Qingzhe [Institut National de la Recherche Scientifique (INRS), Centre Énergie Materiaux et Télécommunications, Université du Québec, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X 1S2, Canada (Canada); Miao, Xinhan; Jie, Xiuyan; Zhou, Shuai [School of Environmental Science and Engineering, Shandong Key Laboratory of Water Pollution Control and Resource Reuse, Shandong University, Shanda South Road 27, Jinan 250100 (China)

    2017-05-01

    Highlights: • NSs-APAM photocatalysts were synthesized by a green and handy route. • APAM was used as the intercalator and carbon source in the preparation. • The combination of photo-induced charge carriers was greatly restrained. • Significantly enhanced visible-light photocatalytic activity was witnessed. • The NSs-APAM also showed a good recycling stability. - Abstract: The porous carbon-doped g-C{sub 3}N{sub 4} nanosheets photocatalysts (NSs-APAM) were synthesized using anionic polyacrylamide (APAM) as the intercalator and carbon source via the thermal treatment method. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption, X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance absorption spectra (UV-DRS) and photoluminescence spectroscopy (PL). The results indicate that the APAM can effectively induce the formation of high-quality nanosheets (NSs) with narrowed bandgap. The specific surface area of NSs-APAM is 118.6 m{sup 2}/g, which is 5-fold larger than bulk g-C{sub 3}N{sub 4}. The carbon doping could narrow the bandgap, from 2.75 eV of g-C{sub 3}N{sub 4} NSs without carbon doping (NSs-Water) to 2.41 eV of NSs-APAM. The two-dimensional NSs structure facilitates the charge separation by shortening the diffusion distance to the surface of photocatalysts. The synergic effects of the carbon doping and unique structural properties contributed to the superior photocatalytic activity of NSs-APAM with 95% degradation rate towards X–3 B after 30 min visible-light irradiation.

  12. Controllable synthesis of Bi2MoO6 nanosheets and their facet-dependent visible-light-driven photocatalytic activity

    Science.gov (United States)

    Yang, Zixin; Shen, Min; Dai, Ke; Zhang, Xuehao; Chen, Hao

    2018-02-01

    Bi2MoO6 nanosheets with exposed {010} facets were selectively synthesized through hydrothermal method by adjusting the pH value in the presence of cetyltrimethyl ammonium bromide (CTAB) as the templates. The effects of CTAB content and hydrothermal conditions on the morphologies and crystal phases of the products were determined by using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy (DRS), Fourier-transform infrared spectroscopy (FTIR), Raman spectrometry, and Brunauer-Emmett-Teller surface area analyses. It is found that Bi2MoO6 nanosheets with relatively large particle sizes (plate length 0.5-3 μm) and special anisotropic growth along the {010} plane can be obtained from an alkaline hydrothermal environment. The band gap of Bi2MoO6 can be fine-tuned from 2.30 to 2.57 eV by adjusting the pH value of hydrothermal solution. The pH value has a significant effect on the composition of hydrothermal precursors, which results in Bi2MoO6 nanosheets with different ratio of {010} faces, especially the formation of Bi2O3 in the primary stage of the hydrothermal treatment is a key factor for the exposure of {010} facets. The visible-light-driven photocatalytic activities of the Bi2MoO6 products with different ratio of {010} facets exposed are investigated through the degradation of Rhodamine B, oxytetracycline, and tetracycline. Bi2MoO6 nanosheets synthesized at pH 10.0 with highest {010} facet exposed ratio exhibited highly efficient visible light photocatalytic activity for pollutant decomposition, which can be mainly attributed to the flake structures, the crystallinity and most importantly, the exposed {010} facet which generate high concentration of rad O2-.

  13. Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Anamika [Department of Life Sciences, University of Mumbai, Santacruz (E), Mumbai 400 098 (India); Dutta, Dimple P., E-mail: dimpled@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ballal, A. [Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Fulekar, M.H. [School of Environment and Sustainable Development, Central University of Gujarat, Gandhinagar 382 030, Gujarat (India)

    2014-03-01

    Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.

  14. Preparation, characterization and visible-light-driven photocatalytic activity of a novel Fe(III) porphyrin-sensitized TiO{sub 2} nanotube photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Meng [National Engineering Lab of Textile Fiber Materials & Processing Technology, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Wan, Junmin, E-mail: wwjm2001@126.com [National Engineering Lab of Textile Fiber Materials & Processing Technology, Zhejiang Sci-Tech University, Hangzhou 310018 (China); State Key Laboratory of advanced Textiles Materials and Manufacture Technology, MOE, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Hu, Zhiwen; Peng, Zhiqin; Wang, Bing [National Engineering Lab of Textile Fiber Materials & Processing Technology, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Wang, Huigang [State Key Laboratory of advanced Textiles Materials and Manufacture Technology, MOE, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2017-01-01

    Highlights: • FeTCPP-TNT photocatalysts are synthesized. • FeTCPP and tube-like structure are helpful to induce interfacial charge transfer at surface junction. • FeTCPP and tube-like structure are favorable for enhancing photocatalytic activity. • The photocatalytic mechanism of FeTCPP-TNT is proposed. • The photocatalyst are proven to be effective and chemically-stable catalysts. - Abstract: Iron(III) meso-tetra(4-carboxyphenyl) porphyrin (FeTCPP) loaded on the surface of TiO{sub 2} nanotubes (TNTs) has been successfully prepared through improved hydrothermal and heating reflux process. The new photocatalyst has been characterized and analyzed by TEM/EDS, BET, XRD, FT-IR, DRS, PL, XPS and EPR. The photocatalytic activity of FeTCPP/TNT nanocomposite was evaluated by the photodegradation of MB under visible light irradiation. The degradation results showed a purification of more than 90% MB in simulating wastewater, and confirmed that the prepared FeTCPP/TNT nanocomposite has acquired superior photocatalytic activitiy. The 6 times cycled results suggested the great stability of the photocatalyst. These results confirmed the FeTCPP played an important role in capturing photons and expanding the absorption wavelength to the visible light region, and the FeTCPP/TNT photocatalyst is also beneficial for the electron transfer and long-distance transmission, and could efficiently increase the separation of the electron-hole pairs, and accelerate the decomposition of organic pollutants. In addition, nano-sized structures can increase adsorption capability.

  15. Facile One-Step Route for the Development of in Situ Cocatalyst-Modified Ti(3+) Self-Doped TiO2 for Improved Visible-Light Photocatalytic Activity.

    Science.gov (United States)

    Kumar, Raju; Govindarajan, Sivakumar; Siri Kiran Janardhana, Reddy Kunda; Rao, Tata Narasinga; Joshi, Shrikant Vishwanath; Anandan, Srinivasan

    2016-10-05

    Development of visible-light-driven photocatalysts by employing a relatively simple, efficient, and cost-effective one-step process is essential for commercial applications. Herein, we report for the first time the synthesis of in situ Cu-ion modified Ti(3+) self-doped rutile TiO2 by such a facile one-step solution precursor plasma spray (SPPS) process using a water-soluble titanium precursor. In the SPPS process, Ti(3+) self-doping on Ti(4+) of rutile TiO2 is found to take place because of electron transfer from the created oxygen vacancies to Ti(4+)-ions. In situ Cu modification of the above Ti(3+) self-doped rutile TiO2 by additionally introducing a Cu solution into plasma plume is also demonstrated. While the Ti(3+) self-doping induces broad absorption in the visible-light region, the addition of Cu ion leads to even broader absorption in the visible region owing to resulting synergistic properties. The above materials were evaluated for various self-cleaning photocatalytic applications under visible-light illumination. Cu-ion modified Ti(3+) self-doped rutile TiO2 is noted to exhibit a remarkably enhanced visible-light activity in comparison with Ti(3+) self-doped rutile TiO2, with the latter itself outperforming commercial TiO2 photocatalysts, thereby suggesting the suitability of the material for indoor applications. The broad visible-light absorption by Ti(3+) self-doping, the holes with strong oxidation power generated in the valence band, and electrons in Ti(3+) isolated states that are effectively separated into the high reductive sites of Cu ions upon visible-light irradiation, accounts for improved photocatalytic activity. Moreover, the synthesis process (SPPS) provides a valuable alternative to orthodox multistep processes for the preparation of such visible-light-driven photocatalysts.

  16. 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.

  17. RhB-sensitized effect on the enhancement of photocatalytic activity of BiOCl toward bisphenol-A under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Xiaoming; Fan, Caimei, E-mail: fancm@163.com; Wang, Yawen; Wang, Yunfang; Zhang, Xiaochao

    2014-10-30

    Graphical abstract: - Highlights: • BiOCl with narrow band gap energy was synthesized successfully. • The addition of RhB could enhance the reaction rate of BPA prominently. • RhB exhibited photosensitized effect in BPA degradation with as-prepared BiOCl. • The main active species involved in BPA degradation was h{sup +} and O{sub 2}·{sup −}. • The double-electron-source reaction mechanism was proposed. - Abstract: A bismuth oxychloride (BiOCl) photocatalyst with visible light activity was successfully synthesized using NaBiO{sub 3} and HCl as raw materials. The crystal structure, morphology, and UV–vis diffuse reflectance spectra of the as-synthesized BiOCl were characterized. Rhodamine B (RhB), as a photosensitizer, can remarkably enhance light utilization and improve the photocatalytic activity of BiOCl toward bisphenol-A (BPA). The effects of BiOCl dosage, RhB dosage, BPA initial concentration and initial solution pH on the photocatalytic performance of BiOCl were studied. The photocatalytic oxidation of BPA followed pseudo first-order kinetics, and the highest photodegradation efficiency of BPA was observed using a BiOCl dosage of 1.5 g L{sup −1} and RhB dosage of 5 mg L{sup −1} in BPA solution (c{sub 0} = 20 mg L{sup −1}, pH = 6) under visible light irradiation for 30 min. Under these conditions, the reaction rate constant of the system was 11.3 times greater than that of BiOCl without RhB. The superior photocatalytic activity observed was attributed to the sensitization effect of RhB. Experimental scavenging results revealed that h{sup +} and O{sub 2}·{sup −} are the main active species involved in BPA degradation. The as-synthesized BiOCl exhibited good photocatalytic stability during photodegradation, which suggests promising prospects in the practical application of organic pollutant photodegradation.

  18. Preparation and Characterization of Mn/N Co-Doped TiO2 Loaded on Wood-Based Activated Carbon Fiber and Its Visible Light Photodegradation

    Directory of Open Access Journals (Sweden)

    Xiaojun Ma

    2015-09-01

    Full Text Available Using MnSO4·H2O as manganese source and urea as nitrogen source, Mn/N co-doped TiO2 loaded on wood-based activated carbon fiber (Mn/Ti-N-WACF was prepared by sol–gel method. Mn/Ti-N-WACF with different Mn doping contents was characterized by scanning electron microscopy, X-ray diffraction (XRD and X-ray photoelectron spectroscopies (XPS, and ultraviolet-visible spectrophotometer. Results showed that the loading rate of TiO2 in Mn/Ti-N-WACF was improved by Mn/N co-doping. After calcination at 450 °C, the degree of crystallinity of TiO2 was reduced due to Mn/N co-doption in the resulting Mn/Ti-N-WACF samples, but the TiO2 crystal phase was not changed. XPS spectra revealed that some Ti4+ ions from the TiO2 lattice of Mn/Ti-N-WACF system were substituted by doped Mn. Moreover, new bonds formed within N–Ti–N and Ti–N–O because of the doped N that substituted some oxygen atoms in the TiO2 lattice. Notably, the degradation rate of methylene blue for Mn/Ti-N-WACF was improved because of the co-doped Mn/N under visible-light irradiation.

  19. One novel material with high visible-light activity: hexagonal Cu flakelets embedded in the petals of BiOBr flower-nanospheres

    Science.gov (United States)

    Liu, Yuling; Wu, Qingsheng

    2017-02-01

    The novel BiOBr flower-nanospheres embedded by hexagonal Cu have been synthesized successfully through an ingenious design, by one-step solvothermal process with two kinds of bifunctional reagents, namely, 1-hexadecyl-3-methylimidazolium bromide [C16min]Br and ethylene glycol (EG). Pure BiOBr flower-sphere has been synthesized by solvothermal process. In the result of Cu-embedded BiOBr flower-nanospheres, the diameter of the flower-sphere is about 1.5 μm (±0.1) with hexagon copper about 10-nm side length in the petals of BiOBr flower-nanospheres. The Cu-embedded BiOBr composites exhibit high photocatalytic activity than pure BiOBr, which was investigated by the degradation of rhodamine B solution (RhB) and methyl orange solution (MO) under simulative visible-light irradiation. Nearly 100 and 80% of conversion can be achieved from the degradation of RhB and MO after 1.5 h, respectively. The high ability of photocatalysis may be attributed to the narrow-band-gap semiconductor BiOBr, high electron transportation of copper, and the coupling of Cu and BiOBr. It can lead to the strong absorption in the visible region and improve the separation of photogenerated electron-hole pairs.

  20. Copper(II) coordination polymers: tunable structures and a different activation effect of hydrogen peroxide for the degradation of methyl orange under visible light irradiation.

    Science.gov (United States)

    Liu, Lu; Wu, Dongqing; Zhao, Bei; Han, Xiao; Wu, Jie; Hou, Hongwei; Fan, Yaoting

    2015-01-21

    By tuning the synthesis conditions, based on a conformation-sensitive ligand, 1,4-bis(1,2,4-triazole-1-methylene)-2,3,5,6-tetramethyl benzene (btmx) and Cu(NO3)2·3H2O/CuCl2·2H2O, we have obtained three Cu(ii) coordination polymers with diverse structures, namely, {[Cu(btmx)2(H2O)]·2NO3}n (), {[Cu(btmx)2(Cl)2]·5H2O}n () and [Cu(btmx)(Cl)2]n (). Complex exhibits a novel 2D → 3D interpenetrating structure with a point symbol of 6(3). Complex features an irregular 2D grid with (4(4)·6(2)) topology. The structure of complex is a 1D double chain structure. The ultraviolet-visible absorption spectra and TG curves of these complexes are also presented and discussed. Moreover, under visible light, the coordination polymers , , and display a different activation effect of hydrogen peroxide (H2O2) for the photocatalytic decomposition of methyl orange (MO), which indicates that the coordination polymers may have bright prospects in the field of photocatalytic degradation of dyes.

  1. One novel material with high visible-light activity: hexagonal Cu flakelets embedded in the petals of BiOBr flower-nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuling; Wu, Qingsheng, E-mail: qswu@tongji.edu.cn [Tongji University, School of Chemical Science and Engineering (China)

    2017-02-15

    The novel BiOBr flower-nanospheres embedded by hexagonal Cu have been synthesized successfully through an ingenious design, by one-step solvothermal process with two kinds of bifunctional reagents, namely, 1-hexadecyl-3-methylimidazolium bromide [C{sub 16}min]Br and ethylene glycol (EG). Pure BiOBr flower-sphere has been synthesized by solvothermal process. In the result of Cu-embedded BiOBr flower-nanospheres, the diameter of the flower-sphere is about 1.5 μm (±0.1) with hexagon copper about 10-nm side length in the petals of BiOBr flower-nanospheres. The Cu-embedded BiOBr composites exhibit high photocatalytic activity than pure BiOBr, which was investigated by the degradation of rhodamine B solution (RhB) and methyl orange solution (MO) under simulative visible-light irradiation. Nearly 100 and 80% of conversion can be achieved from the degradation of RhB and MO after 1.5 h, respectively. The high ability of photocatalysis may be attributed to the narrow-band-gap semiconductor BiOBr, high electron transportation of copper, and the coupling of Cu and BiOBr. It can lead to the strong absorption in the visible region and improve the separation of photogenerated electron–hole pairs.

  2. Rational construction of Z-scheme Ag2CrO4/g-C3N4 composites with enhanced visible-light photocatalytic activity

    Science.gov (United States)

    Luo, Jin; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao

    2016-12-01

    Novel visible-light driven Z-scheme Ag2CrO4/g-C3N4 composites with different contents of Ag2CrO4 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-C3N4 and Ag2CrO4, the Ag2CrO4/g-C3N4 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 Ag2CrO4/g-C3N4 composite at a theoretical weight content of 8.0% Ag2CrO4 for the photodegradation of MO was 0.0068 min-1, which was 5.7 and 4.3 times higher than that of pure g-C3N4 and Ag2CrO4, respectively. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electrons and holes at the Ag2CrO4/g-C3N4 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 Ag2CrO4/g-C3N4 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 conversion and environmental remediation.

  3. Strong Visible Light Photocatalytic Activity of Magnetically Recyclable Sol-Gel-Synthesized ZnFe2O4 for Rhodamine B Degradation

    Science.gov (United States)

    Xu, Xiaoli; Xiao, Lingbo; Jia, Yanmin; Hong, Yuantign; Ma, Jiangping; Wu, Zheng

    2018-01-01

    Visible light-responsive ZnFe2O4 photocatalyst with a spinel structure was synthesized via a sol-gel method. The visible light photocatalysis of ZnFe2O4 was investigated by decomposing Rhodamine B (RhB) solution. Under ˜30 min of visible light irradiation, the decomposition ratio of RhB is up to ˜97.4%. The excellent photocatalytic performance of ZnFe2O4 photocatalyst is attributed to the high effective oxidation-reduction reaction caused by light irradiation excitation. With the increase of decomposition time, the wavelength of the maximum absorption peak of RhB solutions shifts from 557 nm to 498 nm ("blue shift"), which is because of the N-deethylation and cleavage of the conjugated chromophore structure of RhB. ZnFe2O4 photocatalyst also exhibits a weak ferromagnetism performance. The decomposition ratio of RhB for the magnetically recycled ZnFe2O4 is ˜94.6%. Strong visible light photocatalysis and convenience of magnetic recycling make ZnFe2O4 promising for photocatalytic applications in dye wastewater treatment.

  4. Bi25VO40 microcube with step surface for visible light photocatalytic reduction of Cr(VI): Enhanced activity and ultrasound assisted regeneration.

    Science.gov (United States)

    Wang, Pei; Ji, Wenda; Li, Mingmeng; Zhang, Gaoke; Wang, Jinlong

    2017-09-01

    In this study, a kind of bismuth vanadium (Bi25VO40) microcube with step surface was successfully synthesized by a fast and mild hydrothermal method. The reaction time and hydrothermal temperature are the key factors which are accounted for the formation of this unique structure. The as-prepared Bi25VO40 microcube exhibited considerably higher visible light photocatalytic activity compared with the smooth one, revealing that fabrication of Bi25VO40 with step surface was an effective method to improve the photocatalytic activity. The enhanced photocatalytic activity over this Bi25VO40 could be attributed to its enhanced separation efficiency of photo-generated holes and electrons. In addition, the XPS analysis of the Bi25VO40 after photo-reduction showed that most of highly toxic Cr(VI) were reduced into less dangerous Cr(III). The XRD results indicated the reduced Cr(III) existed in the form of Cr2O3 and Cr3O8 on the catalyst surface and occupied the active site, counting for the decreased activity after multiple use. A facile ultrasound treatment facilitated the regeneration of deactivated photocatalyst by removing the adsorbed Cr2O3 and Cr3O8, improving the removal ratio of Cr(VI) over the photocatalyst from 74.0% to 85.6% after four recycling use, which make it applicable for the photocatalytic removal of a typical Cr(VI) pollutant continuously. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Visible light photocatalytic activities of ZnFe{sub 2}O{sub 4}/ZnO nanoparticles for the degradation of organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Rameshbabu, R. [SRM Research Institute, SRM University, Kattankulathur, Kanchipuram 603203, Tamil Nadu (India); Kumar, Niraj [SRM Research Institute, SRM University, Kattankulathur, Kanchipuram 603203, Tamil Nadu (India); Centre for Materials Science and Nano Devices, Department of Physics and Nanotechnology, SRM University Kattankulathur, Kanchipuram 603203, Tamil Nadu (India); Karthigeyan, A., E-mail: karthigeyan.a@ktr.srmuniv.ac.in [Centre for Materials Science and Nano Devices, Department of Physics and Nanotechnology, SRM University Kattankulathur, Kanchipuram 603203, Tamil Nadu (India); Neppolian, B., E-mail: neppolian.b@res.srmuniv.ac.in [SRM Research Institute, SRM University, Kattankulathur, Kanchipuram 603203, Tamil Nadu (India)

    2016-09-15

    ZnFe{sub 2}O{sub 4}/ZnO nanoparticles have been synthesized by co-precipitation method using polyvinyl alcohol (PVA) as surfactant. The phase formation of synthesized products was systematically investigated from powder X-ray diffraction. Cubic ZnFe{sub 2}O{sub 4} and hexagonal ZnO were identified in accordance with different molar concentrations of Fe{sup 3+} ions. The morphology and functionality were analyzed using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. The optical properties and change in the band gap from UV to visible region upon increasing molar concentration of Fe{sup 3+} ions were analyzed from diffuse reflectance spectra (DRS). Superparamagnetic property was observed for synthesized ZnFe{sub 2}O{sub 4}/ZnO nanoparticles using vibrating sample magnetometer (VSM). The methylene blue and methyl orange were taken as model dyes to illustrate the photocatalytic activity of synthesized products under visible light irradiation. Maximum degradation of 99% for methyl orange (MO) was achieved by the use of 13 nm sized ZnFe{sub 2}O{sub 4}/ZnO nanoparticles as catalyst and a minutely less activity was observed for the methylene blue (MB) degradation (98%), when the photocatalytic processes were carried out for 5 h and 6 h, respectively. - Highlights: • Co-precipitation method is proposed to synthesize magnetic nanoparticles. • Modifications in the molar concentration lead to the shift in absorption edge. • Superparamagnetic property is demonstrated for the nanoparticles. • Two dye pollutants are utilized to demonstrate the photocatalytic activity.

  6. Formation of bioactive N-doped TiO2 on Ti with visible light-induced antibacterial activity using NaOH, hot water, and subsequent ammonia atmospheric heat treatment.

    Science.gov (United States)

    Kawashita, Masakazu; Endo, Naoko; Watanabe, Tomoaki; Miyazaki, Toshiki; Furuya, Maiko; Yokota, Kotoe; Abiko, Yuki; Kanetaka, Hiroyasu; Takahashi, Nobuhiro

    2016-09-01

    Titanium (Ti) treated with NaOH and hot water, and heated in an ammmonia (NH3) gas atmosphere for 1 or 3h exhibited in vitro apatite formation within 7days when soaked in simulated body fluid (SBF). Moreover, the treated Ti decomposed methylene blue and showed excellent bactericidal activity against Escherichia coli under visible light irradiation. The surface treatment resulted in the formation of a fine network of N-doped anatase-type titania (TiO2-xNx) on the Ti surface, which was responsible for both the apatite formation in SBF and the visible light-induced antibacterial activity. These preliminary results highlight the efficacy of our simple method for producing novel bioactive Ti with visible light-induced antibacterial activity, which could be applied to orthopaedic and dental implants without the risk of infection. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Preparation of High Activity Ga and Cu Doped ZnS by Hydrothermal Method for Hydrogen Production under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Melody Kimi

    2015-01-01

    Full Text Available Ga(0.1,Cu(x-ZnS (x=0.01, 0.03, 0.05 photocatalysts were successfully synthesized by hydrothermal method. The synthesized Ga and Cu codoped ZnS photocatalysts showed photocatalytic property effective for hydrogen production from aqueous solution containing Na2SO3 and Na2S as sacrificial reagent under visible light irradiation. The rate of hydrogen production was found to be strongly dependent on Cu doping content. The highest photocatalytic activity is observed for Ga(0.1,Cu(0.01-ZnS with hydrogen production rate of 114 µmol/h. The addition of Ga as codoped increased the photocatalytic activity to 58 times as compared to single doped Cu-ZnS. The Ga and Cu codoped ZnS photocatalysts are also stable under long irradiation. The enhancement in the photocatalytic activity of Ga and Cu codoped photocatalyst can be attributed to the synergistic effect between Ga and Cu. The photocatalytic activity was greatly enhanced with the addition of 0.5 wt% Ru as cocatalyst with a hydrogen production rate of 744 µmol/h.

  8. Visible light activity of Ag-loaded and guanidine nitrate-doped nano-TiO2: Degradation of dichlorophenol and antibacterial properties

    Science.gov (United States)

    To utilize visible light, co-doped nano-TiO2 was prepared via “one pot” synthesis using mild reaction conditions and benign precursors. Synthesis was optimized using an appropriate experimental design taking into account silver content and calcination temperature. The optimized ...

  9. One-pot synthesis of belt-like Bi2S3/BiOCl hierarchical composites with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Mi, Yuwei; Li, Haiping; Zhang, Yongfang; Zhang, Renjie; Hou, Wanguo

    2017-11-01

    One-dimensional (1D) belt-like Bi2S3/BiOCl composites were synthesized by a facile one-pot solvothermal method, using bismuth subsalicylate as the Bi source and, in particular, as the morphological template. The synthesized composites were characterized by many techniques, such as XRD, SEM, XPS, TEM and UV-vis diffuse reflectance and photoluminescence spectra. Photocatalytic activity of the composites was evaluated via catalytic degradation of salicylic acid (SA) and Rhodamine B (RhB) under visible light irradiation. The belt-like composites show a heterojunction structure in which the Bi2S3 nanoparticles are uniformly dispersed in the BiOCl matrix with dominant exposed (010) facets. They exhibit enhanced photodegradation efficiency in comparison with pure belt-like Bi2S3 and BiOCl. With increasing Bi2S3 content, the photodegradation efficiency of the composites increases then decreases. The Bi2S3/BiOCl composite with a Bi2S3 content of ∼2% exhibits the highest photocatalytic activity. The apparent first-order photodegradation rate constants of the composite for SA (∼0.048 h-1) and RhB (∼0.299 min-1) are significantly higher than those of the pure BiOCl and Bi2S3 for SA (∼0 and ∼0.0007 h-1) and RhB (∼0.102 and ∼0.002 min-1), respectively. The enhancement in photocatalytic activity is attributed to the efficient separation of photoinduced electrons and holes along with the increased specific surface area and visible-light absorption. The holes and superoxide radicals are the major active species. In addition, the belt-like Bi2S3/BiOCl photocatalysts exhibit excellent stability and reusability. This work provides a facile strategy for synthesis of 1D hierarchical Bi-based composite photocatalysts, and demonstrates the potential of belt-like Bi2S3/BiOCl composites for application in environmental remediation.

  10. Synthesis and characterization of CdS nanocrystallites and OMWCNT-supported cadmium sulfide composite and their photocatalytic activity under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Pawar, Amol S. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098 (India); Garje, Shivram S., E-mail: ssgarje@chem.mu.ac.in [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400 098 (India); Revaprasadu, Neerish [Department of Chemistry, University of Zululand, Private Bag X1001, Kwadlangezwa, 3886 (South Africa)

    2016-11-01

    CdS nanocrystallites and CdS- oxidized multiwalled carbon nanotubes (OMWCNT) composite were prepared by the solvothermal decomposition of a single-source molecular precursor, [Cd(pip.dtc){sub 2}] (pip.dtc = piperidine dithiocarbamate) in the presence of ethylene glycol. The as prepared CdS nanocrystallites and CdS-OMWCNT composite were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), UV-vis and Raman spectroscopy. Peak broadening in the XRD shows the formation of nanocrystalline CdS. TEM images of CdS nanocrystallites revealed the nearly spherical shape morphology of the particles, whereas, TEM images of composite showed the deposition of CdS nanocrystallites on the OMWCNT. EDX measurements matches with a 1:1 stoichiometry of Cd and S in CdS nanocrystallites, whereas, that of the composite showed the presence of Cd and S along with C. The vibrational properties of CdS nanocrystallites and their composite with OMWCNT were studied by Raman spectroscopy. Furthermore, the photocatalytic activity studies for the degradation of methylene blue under visible light irradiation using these materials were carried out. The surface area calculated using BET surface analyzer for CdS-OMWCNT composite (148.31 m{sup 2}/g) was found to be more compared to bare CdS nanocrystallites (56.78 m{sup 2}/g). The CdS-OMWCNT composite exhibited very good photocatalytic activity for the degradation of methylene blue under visible light irradiation which has been attributed to the increased surface area and synergistic effect in the composite compared to bare CdS nanocrystallites. - Highlights: • The carbon based nanocomposite of CdS (CdS-OMWCNT) have been prepared. • Simple solvothermal decomposition method has been used. • Single-source molecular precursor in presence of carbon nanotubes has been employed. • The photocatalytic activity of CdS NPs and CdS-OMWCNT composite

  11. Effect of SiO{sub 2} addition on photocatalytic activity, water contact angle and mechanical stability of visible light activated TiO{sub 2} thin films applied on stainless steel by a sol gel method

    Energy Technology Data Exchange (ETDEWEB)

    Momeni, Mansour [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Saghafian, Hasan, E-mail: Saghafian@iust.ac.ir [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Center of Excellence for High Strength Alloys Technology (CEHSAT), Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Golestani-Fard, Farhad [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Center of Excellence for Advanced Materials, Iran University of Science and Technology, P.O. Box 16845-195, Tehran (Iran, Islamic Republic of); Barati, Nastaran; Khanahmadi, Amirhossein [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2017-01-15

    Highlights: • Adding SiO{sub 2} to N doped TiO{sub 2} films increased the band gap energy of the films. • SiO{sub 2} addition encouraged crack formation in N doped TiO{sub 2} thin films. • Addition of SiO{sub 2} weakened visible light activity and hydrophilicity of TiO{sub 2} films. • All films passed nanoscratch testing without detachment from the substrates. • Results propose using non-silica films on steel for application in visible light. - Abstract: Nanostructured N doped TiO{sub 2}/20%SiO{sub 2} thin films were developed on steel surface via sol gel method using a painting airbrush. Thin films then were calcined at various temperatures in a range of 400–600 °C. The effect of SiO{sub 2} addition on phase composition and microstructural evolution of N doped TiO{sub 2} films were studied using XRD and FESEM. Optical properties, visible light photocatalytic activity, hydrophilic behavior, and mechanical behavior of the films were also investigated by DRS, methylene blue degradation, water contact angle measurements, and nanoscratch testing. Results indicated that the band gap energy of N doped TiO{sub 2}/SiO{sub 2} was increased from 2.93 to 3.09 eV. Crack formation during calcination was also significantly promoted in the composite films. All composite films demonstrated weaker visible light photocatalytic activities and lower mechanical stability in comparison with N doped TiO{sub 2} films. Moreover, the N doped TiO{sub 2}/SiO{sub 2} film calcined at 600 °C showed undesirable hydrophilic behavior with a water contact angle of 57° after 31 h of visible light irradiation. Outcomes of the present study reveal some different results to previous reports on TiO{sub 2}/SiO{sub 2} films. In general, we believe the differences in substrate material as well as application in visible light are the main reasons for the above mentioned contradiction.

  12. Preparation of Ag/AgCl/BiMg{sub 2}VO{sub 6} composite and its visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Rui [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (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); Liu, Jiu [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China)

    2013-05-15

    Graphical abstract: - Abstract: A novel composite photocatalyst Ag/AgCl/BiMg{sub 2}VO{sub 6} was synthesized by depositing Ag/AgCl nanoparticles on BiMg{sub 2}VO{sub 6} substrate via a precipitation–photoreduction method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDXA), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectrophotometer (UV–vis DRS). The photocatalyst showed high and stable photocatalytic activity for photocatalytic degradation of acid red G under visible-light irradiation (λ > 420 nm). In addition, the active ·O{sub 2}{sup −} and h{sup +}, as main reactive species, played the major roles during the reaction process. The high photocatalytic activity of the composite may be related to the efficient electron–hole pairs separation at the photocatalyst interfaces, as well as the surface plasmon resonance of Ag nanoparticles formed on AgCl particles in the degradation reaction.

  13. Visible light photocatalytic activity enhancement and mechanism of AgBr/Ag3PO4 hybrids for degradation of methyl orange.

    Science.gov (United States)

    Cao, Jing; Luo, Bangde; Lin, Haili; Xu, Benyan; Chen, Shifu

    2012-05-30

    Novel AgBr/Ag(3)PO(4) hybrids were synthesized via an in situ anion-exchange method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS) and UV-vis diffuse reflectance spectroscopy (DRS). Under visible light (λ>420 nm), AgBr/Ag(3)PO(4) degraded methyl orange (MO) efficiently and displayed much higher photocatalytic activity than that of pure AgBr or Ag(3)PO(4). X-ray photoelectron spectroscopy (XPS) suggests that AgBr/Ag(3)PO(4) transformed to be Ag@AgBr/Ag(3)PO(4)@Ag system while remained good photocatalytic activity after 5 times of cycle experiments. In addition, the quenching effects of different scavengers proved that reactive OH and h(+) played the major role for the MO degradation. The photocatalytic activity enhancement of AgBr/Ag(3)PO(4) is closely related to the efficient separation of electron-hole pairs derived from the matching band potentials between AgBr and Ag(3)PO(4), as well as the good electron trapping role of Ag nanoparticles in situ formed on the surfaces of AgBr and Ag(3)PO(4) particles during the photocatalytic reaction. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Hydrothermal synthesis of graphitic carbon nitride-BiVO4 composites with enhanced visible light photocatalytic activities and the mechanism study

    Science.gov (United States)

    Guo, Feng; Shi, Weilong; Lin, Xue; Che, Guangbo

    2014-11-01

    Novel graphitic carbon nitride (C3N4) and bismuth vanadate (BiVO4) composite photocatalysts were successfully synthesized by a facile hydrothermal method. The scanning electron microscopy (SEM) revealed that an intimate interface between C3N4 and BiVO4 formed in the composites. Compared with the pure C3N4 and BiVO4, the C3N4-BiVO4 photocatalysts showed remarkably the higher photocatalytic activities in degrading rhodamine B (Rh B). The best active heterojunction proportion was 0.5C3N4-0.5BiVO4. Over this catalyst, the 100% degradation of Rh B (0.002 mmol L-1) was obtained under visible light irradiation (λ>420 nm) for 40 min. The active species in Rh B degradation were examined by adding a series of scavengers. The study on photocatalytic mechanism revealed that the electrons injected directly from the conduction band of C3N4 to that of BiVO4, resulting in the production of superoxide radical (O2•-) and hydroxyl radical (OH•) in the conduction band of BiVO4. Simultaneously, the rich holes in the valence band of g-C3N4 oxidized Rh B directly to promote the photocatalytic degradation reaction.

  15. Preparation of Pd-loaded La-doped TiO{sub 2} nanotubes and investigation of their photocatalytic activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zong, Lanlan; Li, Qiuye, E-mail: qiuyeli@henu.edu.cn; Zhang, Jiwei; Wang, Xiaodong; Yang, Jianjun [Henan University, Key Laboratory for Special Functional Materials (China)

    2013-11-15

    Orthorhombic titanic acid nanotubes (TAN) have large BET surface area and small-diameter one-dimensional nanotubular morphology, so they can work as a good supporter and a precursor of TiO{sub 2}. However, in our former research, we found that calcination of TAN to anatase TiO{sub 2} would destroy the nanotubular structure and decrease the BET surface area sharply. In this work, we utilized the pillar effect of the foreign nanoparticles (La{sub 2}O{sub 3}) to keep the nanotubular morphology of TiO{sub 2}, and obtained the anatase TiO{sub 2} nanotubes with large BET surface area. For improving the photocatalytic activity, Pd nanoparticles were loaded as the electron traps on the surface of La-doped TiO{sub 2} by photo-deposition method. The photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, diffuse reflectance spectra, and N{sub 2} adsorption–desorption isotherms measurement. Their photocatalytic activities were evaluated by the removal of propylene under visible light irradiation (λ ≥ 420 nm). The results showed that the photocatalytic activity of Pd-loaded La-doped TiO{sub 2} nanotubes improved effectively compared with that of La-doped TiO{sub 2} and pure TiO{sub 2}.

  16. Magnetically separable CuFe{sub 2}O{sub 4}/AgBr composite photocatalysts: Preparation, characterization, photocatalytic activity and photocatalytic mechanism under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yalei; Lin, Cuiping; Bi, Huijie; Liu, Yonggang; Yan, Qishe, E-mail: Qisheyanzzu@163.com

    2017-01-15

    Highlights: • CuFe{sub 2}O{sub 4}/AgBr composites were prepared by a facile sol-gel and hydrothermal method. • Visible-light response and high photocatalytic performance. • Excellent magnetic properties. • Different reactive species had different effects on degradation different pollutants. - Abstract: The CuFe{sub 2}O{sub 4} and CuFe{sub 2}O{sub 4}/AgBr composites with different CuFe{sub 2}O{sub 4} contents were prepared by a facile sol-gel and hydrothermal method, respectively. The as-synthesized photocatalysts were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectrum (UV–vis DRS). Their magnetic properties, photocatalytic degradation activities on methyl orange (MO) and tetracycline hydrochloride (TC) solution and photocatalytic mechanism were investigated in detail. The results revealed that the CuFe{sub 2}O{sub 4}/AgBr composites exhibited significantly higher photocatalytic activities than the pure CuFe{sub 2}O{sub 4}. The enhanced photocatalytic activity could be attributed to the matched band structure of two components and more effective charge transportation and separations. In addition, the quenching investigation of different scavengers demonstrated that h{sup +}, ·OH, ·O{sub 2}{sup −} reactive species played different roles in the decolorization of MO and degradation of TC.

  17. Hexaarylbiimidazoles as Visible Light Thiol–Ene Photoinitiators

    Science.gov (United States)

    Clarkson, Brian H.; Scott, Timothy F.

    2015-01-01

    Objectives The aim of this study is to determine if hexaarylbiimidazoles (HABIs) are efficient, visible light-active photoinitiators for thiol–ene systems. We hypothesize that, owing to the reactivity of lophyl radicals with thiols and the necessarily high concentration of thiol in thiol–ene formulations, HABIs will effectively initiate thiol–ene polymerization upon visible light irradiation. Methods UV-vis absorption spectra of photoinitiator solutions were obtained using UV-vis spectroscopy, while EPR spectroscopy was used to confirm radical species generation upon HABI photolysis. Functional group conversions during photopolymerization were monitored using FTIR spectroscopy, and thermomechanical properties were determined using dynamic mechanical analysis. Results The HABI derivatives investigated exhibit less absorptivity than camphorquinone at 469 nm; however, they afford increased sensitivity at this wavelength when compared with bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide. Photolysis of the investigated HABIs affords lophyl radicals. Affixing hydroxyhexyl functional groups to the HABI core significantly improved solubility. Thiol–ene resins formulated with HABI photoinitiators polymerized rapidly upon irradiation with 469 nm. The glass transition temperatures of the thiol–ene resin formulated with a bis(hydroxyhexyl)-functionalized HABI and photopolymerized at room and body temperature were 49.5±0.5°C and 52.2±0.1°C, respectively. Significance Although thiol–enes show promise as continuous phases for composite dental restorative materials, they show poor reactivity with the conventional camphorquinone/tertiary amine photoinitiation system. Conversely, despite their relatively low visible light absorptivity, HABI photoinitiators afford rapid thiol–ene photopolymerization rates. Moreover, minor structural modifications suggest pathways for improved HABI solubility and visible light absorption. PMID:26119702

  18. Fabrication of TiO{sub 2}/MoS{sub 2}@zeolite photocatalyst and its photocatalytic activity for degradation of methyl orange under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weiping; Xiao, Xinyan, E-mail: cexyxiao@scut.edu.cn; Zheng, Lili; Wan, Caixia

    2015-12-15

    Graphical abstract: A novel approach was developed for fabrication of TiO{sub 2}/MoS{sub 2}@zeolite photocatalyst using bulk MoS{sub 2} as a photosensitizer and zeolite as carrier. The as-prepared TiO{sub 2}/MoS{sub 2}@zeolite composite exhibited excellent photocatalytic performance for degradation of methyl orange under visible-light irradiation. - Highlights: • Ultrasound-exfoliation and hydrothermal reforming technique were employed for generating nano-MoS{sub 2} from micro-MoS{sub 2}. • The embedded sensitizer composite mode of (TiO{sub 2}/MoS{sub 2}/TiO{sub 2}) was used in the fabrication of TiO{sub 2}/MoS{sub 2}@zeolite composite photocatalyst. • The photocatalytic mechanism of TiO{sub 2}/MoS{sub 2}@zeolite photocatalyst was presented. - Abstract: TiO{sub 2}/MoS{sub 2}@zeolite composite photocatalysts with visible-light activity were fabricated via a simple ultrasonic-hydrothermal synthesis method, using TiCl{sub 4} as Ti source, MoS{sub 2} as a direct sensitizer, glycerol water solution with certain dispersion agent as hydrolytic agent, and zeolite as carrier. The structure, morphology, composition, optical properties, and specific surface area of the as-prepared photocatalysts were characterized by using XRD, FTIR, SEM–EDS, TEM, XPS, UV–vis, PL and BET analyzer, respectively. And the photocatalytic degradation of methyl orange (MO) in aqueous suspension has been employed to evaluate the photocatalytic activity and degradation kinetics of as-prepared photocatalysts with xenon lamp as irradiation source. The results indicate that: (1) TiO{sub 2}/MoS{sub 2}@zeolite composite photocatalysts exhibit enhanced photocatalytic activities for methyl orange (MO) degradation compared to Degussa P25; (2) photocatalytic degradation of MO obeys Langmuir–Hinshelwood kinetic model (pseudo-first order reaction), and its degradation rate constant (k{sub app}) (2.304 h{sup −1}) is higher than that of Degussa P25 (0.768 h{sup −1}); (3) the heterostructure

  19. Visible Light Communication Physical Layer Design for Jist Simulation

    Directory of Open Access Journals (Sweden)

    Tomaš Boris

    2014-12-01

    Full Text Available Current advances in computer networking consider using visible light spectrum to encode and decode digital data. This approach is relatively non expensive. However, designing appropriate MAC or any other upper layer protocol for Visible Light Communication (VLC requires appropriate hardware. This paper proposes and implements such hardware simulation (physical layer that is compatible with existing network stack.

  20. Non-noble metal Bi deposition by utilizing Bi{sub 2}WO{sub 6} as the self-sacrificing template for enhancing visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shixin [Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Zhang, Yihe, E-mail: zyh@cugb.edu.cn [Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Li, Min [Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Du, Xin [Research Center for Bioengineering and Sensing Technology, Department of Chemistry& Biological Engineering, University of Science & Technology Beijing, Beijing 100083 (China); Huang, Hongwei, E-mail: hhw@cugb.edu.cn [Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China)

    2017-01-01

    Highlights: • Bi metal deposited Bi{sub 2}WO{sub 6} photocatalyst is synthesized via an in-situ reduction. • The light absorption of Bi{sub 2}WO{sub 6} is enhanced by Bi metal. • Charge separation efficiency of Bi{sub 2}WO{sub 6} is increased by Bi metal. • Bi-Bi{sub 2}WO{sub 6} shows highly promoted photocatalytic activity for phenol degradation. - Abstract: Bi metal deposited on Bi{sub 2}WO{sub 6} composite photocatalysts have been successfully synthesized via a simple in-situ reduction method at room temperature with using Bi{sub 2}WO{sub 6} as self-sacrificing template and NaBH{sub 4} as reducing agent. The reduction extent can be easily modulated by controlling the concentration of NaBH{sub 4} solution. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectra, N{sub 2} adsorption-desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), diffuse reflection spectroscopy (DRS) and photoelectrochemical measurements were carried out to analyze the phase, morphology, optical property and photoelectrochemical property of the as-prepared samples. The photocatalytic activity is surveyed by degradation of phenol under visible light (λ > 420 nm), which showed that the BWO-0.2 photocatalyst exhibited the highest efficiency, which was over 3 times as high as pure Bi{sub 2}WO{sub 6}. The enhanced photocatalytic activity should be attributed to strengthened photoabsorption and charge separation efficiency derived from the surface plasmon resonance (SPR) of Bi metal.

  1. Enhancing optical absorption of metal–organic frameworks for improved visible light photocatalysis

    NARCIS (Netherlands)

    Nasalevich, M.A.; Goesten, M.G.; Savenije, T.J.; Kapteijn, F.; Gascon, J.

    2013-01-01

    NH2-MIL-125(Ti) has been post-synthetically functionalized with dye-like molecular fragments. The new material (methyl red-MIL- 125(Ti)) exhibits improved light absorption over a wide range of the visible spectrum, and shows enhanced photocatalytic oxidation activity under visible light

  2. One step synthesis of P-doped g-C3N4 with the enhanced visible light photocatalytic activity

    Science.gov (United States)

    Liu, Sen; Zhu, Honglei; Yao, Wenqing; Chen, Kai; Chen, Daimei

    2018-02-01

    In our work, P doped Graphitic nitride (g-C3N4) was prepared by the simple copolymerization of melamine and melamine phosphate. The melamine phosphate ester polymer is a complex of an s-triazine and phosphoric acid polymer, thus it will be favourable for P atom to incorporate into the Csbnd N network of g-C3N4. The doped P atoms may produce the delocalized lone electron and form the Lewis acid sites. The obtained P-doped g-C3N4 showed the higher photocatalytic activity in photodegradation of MB and 2,4-Dichlorophenol than g-C3N4. The optimum photocatatlytic activity of P-C3N4 with the weight ration of melamine phosphate and melamine at 0.06 is 2 times as higher as the pure g-C3N4 in MB photodegradation, and 1.5 times higher in 2,4-Dichlorophenol photodegradation. The enhancement of photodegradation efficiency is due to the delocalization effect of lone electron, promoting the separation of photogenerated charges, and the larger band gap of P doped g-C3N4.

  3. Novel Ag{sub 3}PO{sub 4}/MoO{sub 3}p-n heterojunction with enhanced photocatalytic activity and stability under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Wei, E-mail: tengw@just.edu.cn [Department of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003 (China); Tan, Xiangjun [Department of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003 (China); Li, Xinyong [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Sciences and Technology, Dalian University of Technology, Dalian, 116024 (China); Tang, Yubin [Department of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003 (China)

    2017-07-01

    Graphical abstract: Excellent photocatalytic activity and stability are achieved over Ag{sub 3}PO{sub 4}/MoO{sub 3}p-n heterostructure nanocatalyst, which was increased the charge separation efficiencies. - Highlights: • The Ag{sub 3}PO{sub 4}/MoO{sub 3}p-n heterostructure nanocatalyst was synthesized successfully. • The composite nanocatalyst possesses excellent photocatalytic activity and stability. • The effective separation of electron-hole pairs were mainly depend on the inner electric field of p-n heterojunction. - Abstract: Ag{sub 3}PO{sub 4}/MoO{sub 3}p-n heterojunction have been successfully fabricated by using a simple in situ solvent method. SEM, TEM, XRD, XPS and electrochemical techniques were used to study the structural and electrochemical characteristics of the resulting materials. The photocatalytic activity of the obtained composite was tested by the degradation of organic dye (methylene blue) under visible-light irradiation. The photocatalytic activity of Ag{sub 3}PO{sub 4}/MoO{sub 3} remained 92.5% after four recycling runs, which was much higher than that of the pure Ag{sub 3}PO{sub 4} (54%). The obtained results confirm that the novel Ag{sub 3}PO{sub 4}/MoO{sub 3} heterostructure exhibited significantly higher photocatalytic activities and improved stability compared with bare Ag{sub 3}PO{sub 4}. The excellent photocatalytic activity came from the effective separation of the electron-hole pairs under the effect of built-in electric field in the interfacial the of the p-n heterojunction, and then made the holes more available for dyes oxidation.

  4. Effect of annealing temperature and time on structure, morphology and visible-light photocatalytic activities Ag{sub 3}PO{sub 4} microparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuang; Gu, Xiuquan, E-mail: xqgu@cumt.edu.cn; Zhao, Yulong; Qiang, Yinghuai, E-mail: yhqiang@cumt.edu.cn

    2015-11-15

    Graphical abstract: Photocatalytic activities (a) and fitting curves (b) and recyclability (c) of Ag{sub 3}PO{sub 4} MPs annealed at various temperature (RT-500 °C) under a visible-light irradiation. - Highlights: • Ag{sub 3}PO{sub 4} microparticles were sintered in air at various temperatures from 100 to 500 °C. • Sintering leaded to the aggregation of Ag{sub 3}PO{sub 4} microparticles, while it didn’t descend the photocatalytic activity significantly. • The best photocatalytic activity appeared in the samples which underwent 400 °C sintering for 30 min. • The enhanced photocatalytic activity of the 400 °C sintered samples was attributed to the enhanced carrier transport and the improved crystallized quality. - Abstract: Ag{sub 3}PO{sub 4} microparticles (MPs) were annealed in air at various temperatures (100–500 °C) and time (30–120 min). It is surprising that both the phase structure and photocatalytic (PC) activities didn’t descend even if the powders samples were annealed at 400 °C for 30 min, which made it possible to obtain Ag{sub 3}PO{sub 4} films similar to the common semiconductor photocatalysts, such as TiO{sub 2}. However, the particle sizes of MPs were observed to get increased significantly, resulting in a lowering of the specific surface area and a change of color. By excluding a few common causes, the excellent PC activities of the sintered samples are speculated to the improved crystallized quality, which also makes it possible to construct the photoelectrodes based on Ag{sub 3}PO{sub 4} films for water splitting or photoelectric conversion.

  5. Role of oxygen active species in the photocatalytic degradation of phenol using polymer sensitized TiO{sub 2} under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Dongdong [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Qiu Rongliang [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)], E-mail: eesqrl@mail.sysu.edu.cn; Song Lin [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Department of Environmental Engineering, Jinan University, Guangzhou 510630 (China); Eric, Brewer [Viridian Environmental LLC, VA 22207 (United States); Mo Yueqi [College of Material Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Huang Xiongfei [School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2009-04-30

    The role of dissolved oxygen, and of active species generated by photo-induced reactions with oxygen, in the photocatalytic degradation of phenol was investigated using polymer [poly-(fluorene-co-thiophene) with thiophene content of 30%, so-called PFT30] sensitized TiO{sub 2} (PFT30/TiO{sub 2}) under visible light irradiation. The photoluminescent (PL) quantum yield of PFT30/TiO{sub 2} was about 30% of that of PFT30/Al{sub 2}O{sub 3}, proving that electron transfer took place between the polymer and TiO{sub 2}. The result that photocatalytic degradation of phenol was almost stopped when the solution was saturated with N{sub 2} proved the importance of O{sub 2}. Addition of NaN{sub 3}, an effective quencher of singlet oxygen ({sup 1}O{sub 2}), caused about a 40% decrease in the phenol degradation ratio. Addition of alcohols caused about a 60% decrease in the phenol photodegradation ratio, indicating that the hydroxyl radicals (OH{center_dot}), whose presence was confirmed by electron spin resonance (ESR) spectroscopy, was the predominant active species in aqueous solution. In anhydrous solution, singlet oxygen ({sup 1}O{sub 2}) was the predominant species. These results indicate that oxygen plays a very important role in the photocatalytic degradation of phenol.

  6. Controlled structural and compositional characteristic of visible light active ZnO/CuO photocatalyst for the degradation of organic pollutant

    Science.gov (United States)

    Harish, S.; Archana, J.; Sabarinathan, M.; Navaneethan, M.; Nisha, K. D.; Ponnusamy, S.; Muthamizhchelvan, C.; Ikeda, H.; Aswal, D. K.; Hayakawa, Y.

    2017-10-01

    Degradation of organic pollutant using ZnO/CuO composites has become an attractive method for detoxification of water. The effect of copper acetate concentration and the functional properties of nanocomposites were investigated. The morphological analysis revealed that CuO nanoparticles dispersed uniformly on the surface of ZnO nanorods. X-ray photoelectron spectra analysis showed peak shift in the electronic states of Zn and Cu states. Elemental clearly confirms the presence of CuO were uniformly distributed on the surface of ZnO. The photocatalytic activity of ZnO/CuO composites was enhanced compared to pure ZnO under visible light irradiation. The optimal CuO content for the photocatalytic activity of the ZnO/CuO composites is 1%, which is almost ten times higher than that of pure ZnO. Owing to these synergic advantages, the degradation efficiency of ZnO/CuO composites reached 92.52% after 5 min of irradiation. The synergistic photocatalytic mechanism was proposed based on the photodegradation results.

  7. In situ synthesis of hierarchical flower-like Bi{sub 2}S{sub 3}/BiOCl composite with enhanced visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Saihua [State Key Laboratory of Fire Science, University of Science and Technology of China, Jinzhai Road 96, Hefei, Anhui 230026 (China); Department of Civil and Architectural Engineering, City University of Hong Kong and USTC-CityU Joint Advanced Research Centre, Suzhou (China); Zhou, Keqing [State Key Laboratory of Fire Science, University of Science and Technology of China, Jinzhai Road 96, Hefei, Anhui 230026 (China); Shi, Yongqian [State Key Laboratory of Fire Science, University of Science and Technology of China, Jinzhai Road 96, Hefei, Anhui 230026 (China); Department of Civil and Architectural Engineering, City University of Hong Kong and USTC-CityU Joint Advanced Research Centre, Suzhou (China); Lo, Siuming [Department of Civil and Architectural Engineering, City University of Hong Kong and USTC-CityU Joint Advanced Research Centre, Suzhou (China); Xu, Haiyan [Nano Science and Technology Institute, University of Science and Technology of China, Jinzhai Road 96, Hefei, Anhui 230027 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Jinzhai Road 96, Hefei, Anhui 230026 (China); Gui, Zhou, E-mail: zgui@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Jinzhai Road 96, Hefei, Anhui 230026 (China)

    2014-01-30

    Novel BiOCl micro-flower was synthesized by a facile method and used as a precursor to produce Bi{sub 2}S{sub 3}/BiOCl composites. The Bi{sub 2}S{sub 3}/BiOCl composites, synthesized by in situ etching of BiOCl precursor with thiacetamide (TAA) solution, maintain the hierarchical flower-like structure and exhibit a large surface area. X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), and UV–vis diffuse reflectance spectroscopy (DRS) were employed to study the structures, morphologies and optical properties of the as-prepared samples. Under visible light (λ > 400 nm), the flower-like Bi{sub 2}S{sub 3}/BiOCl composite displayed much higher photocatalytic activity than single Bi{sub 2}S{sub 3}, BiOCl and 2D plate-like Bi{sub 2}S{sub 3}/BiOCl composite for the degradation of rhodamine B (RhB). The increased photocatalytic activity of Bi{sub 2}S{sub 3}/BiOCl could be attributed to the formation of the heterostructure between Bi{sub 2}S{sub 3} and BiOCl and large surface area of the hierarchical structure, which effectively separate the photoinduced electron–hole pairs and suppress their recombination.

  8. Surface modification of m-BiVO{sub 4} with wide band-gap semiconductor BiOCl to largely improve the visible light induced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Jing, E-mail: caojing@mail.ipc.ac.cn [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, Anhui 235000 (China); State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Zhou, Chunchun; Lin, Haili; Xu, Benyan [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, Anhui 235000 (China); Chen, Shifu, E-mail: chshifu@chnu.edu.cn [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, Anhui 235000 (China)

    2013-11-01

    Monoclinic BiVO{sub 4} (m-BiVO{sub 4}) was modified with wide band-gap semiconductor BiOCl to construct novel BiOCl/m-BiVO{sub 4} heterojunctions. The as-synthesized samples were systematically characterized by X-ray diffraction (XRD), Fourier-transform infrared spectra (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrum (EDS) and UV–vis diffuse reflectance spectra (DRS). The photocatalytic activities of BiOCl/m-BiVO{sub 4} were evaluated by measuring the degradation of methyl orange, rhodamine B and acid orange II under visible light (λ > 420 nm). The results showed that BiOCl/m-BiVO{sub 4} had excellent photocatalytic performance compared with pure m-BiVO{sub 4}, BiOCl, P25 and N-TiO{sub 2}, especially 30% BiOCl/m-BiVO{sub 4} exhibited the highest photocatalytic activity. The heterojunctions between BiOCl and m-BiVO{sub 4} highly separated the photocarriers and yielded enhanced photocatalytic performance of BiOCl/m-BiVO{sub 4}.

  9. Ultrathin g-C3 N4 Nanosheets Coupled with AgIO3 as Highly Efficient Heterostructured Photocatalysts for Enhanced Visible-Light Photocatalytic Activity.

    Science.gov (United States)

    Li, Yunfeng; Li, Kai; Yang, Yang; Li, Leijiao; Xing, Yan; Song, Shuyan; Jin, Rongchao; Li, Mei

    2015-12-01

    The photocatalytic activity of graphite-like carbon nitride (g-C3 N4 ) could be enhanced by heterojunction strategies through increasing the charge-separation efficiency. As a surface-based process, the heterogeneous photocatalytic process would become more efficient if a larger contact region existed in the heterojunction interface. In this work, ultrathin g-C3 N4 nanosheets (g-C3 N4 -NS) with much larger specific surface areas are employed instead of bulk g-C3 N4 (g-C3 N4 -B) to prepare AgIO3 /g-C3 N4 -NS nanocomposite photocatalysts. By taking advantage of this feature, the as-prepared composites exhibit remarkable performances for photocatalytic wastewater treatment under visible-light irradiation. Notably, the optimum photocatalytic activity of AgIO3 /g-C3 N4 -NS composites is almost 80.59 and 55.09 times higher than that of pure g-C3 N4 -B towards the degradation of rhodamine B and methyl orange pollutants, respectively. Finally, the stability and possible photocatalytic mechanism of the AgIO3 /g-C3 N4 -NS system are also investigated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Cross-linked g-C3 N4 /rGO nanocomposites with tunable band structure and enhanced visible light photocatalytic activity.

    Science.gov (United States)

    Li, Yibing; Zhang, Haimin; Liu, Porun; Wang, Dan; Li, Ying; Zhao, Huijun

    2013-10-11

    Cross-linked rather than non-covalently bonded graphitic carbon nitride (g-C3 N4 )/reduced graphene oxide (rGO) nanocomposites with tunable band structures have been successfully fabricated by thermal treatment of a mixture of cyanamide and graphene oxide with different weight ratios. The experimental results indicate that compared to pure g-C3 N4 , the fabricated CN/rGO nanocomposites show narrowed bandgaps with an increased in the rGO ratio. Furthermore, the band structure of the CN/rGO nanocomposites can be readily tuned by simply controlling the weight ratio of the rGO. It is found that an appropriate rGO ratio in nanocomposite leads to a noticeable positively shifted valence band edge potential, meaning an increased oxidation power. The tunable band structure of the CN/rGO nanocomposites can be ascribed to the formation of C-O-C covalent bonding between the rGO and g-C3 N4 layers, which is experimentally confirmed by Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) data. The resulting nanocomposites are evaluated as photocatalysts by photocatalytic degradation of rhodamine B (RhB) and 4-nitrophenol under visible light irradiation (λ > 400 nm). The results demonstrate that the photocatalytic activities of the CN/rGO nanocomposites are strongly influenced by rGO ratio. With a rGO ratio of 2.5%, the CN/rGO-2.5% nanocomposite exhibits the highest photocatalytic efficiency, which is almost 3.0 and 2.7 times that of pure g-C3 N4 toward photocatalytic degradation of RhB and 4-nitrophenol, respectively. This improved photocatalytic activity could be attributed to the improved visible light utilization, oxidation power, and electron transport property, due to the significantly narrowed bandgap, positively shifted valence band-edge potential, and enhanced electronic conductivity. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A facile fabrication of nitrogen-doped electrospun In{sub 2}O{sub 3} nanofibers with improved visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Na; Shao, Changlu, E-mail: clshao@nenu.edu.cn; Li, Xinghua, E-mail: lixh781@nenu.edu.cn; Miao, Fujun; Wang, Kexin; Liu, Yichun

    2017-01-01

    Highlights: • N-doped In{sub 2}O{sub 3} nanofibers are facilely fabricated by gaseous ammonia treatment. • Adjusting the annealing temperature leads to different N-doped In{sub 2}O{sub 3} nanofibers. • Nitrogen doping was found to be interstitial mode. • N-In{sub 2}O{sub 3} exhibited effective charge carrier separation and photocatalytic activity. • The photocatalysts can be easily separated from the reaction system. - Abstract: Semiconductor photocatalysis demonstrates to be an effective approach for eliminating most types of environment contaminants and for producing hydrogen. Herein, a facile synthesis route combining electrospinning technique and thermal treatment method under NH{sub 3} atmosphere has been presented as a straightforward protocol for the fabrication of nitrogen-doped In{sub 2}O{sub 3} (N-In{sub 2}O{sub 3}) nanofibers, the nitrogen content of which can be well controlled by adjusting the annealing temperature. Photocatalytic tests show that the N-In{sub 2}O{sub 3} nanofibers demonstrate an improved degradation rate of Rhodamine B (RB) compared with pure In{sub 2}O{sub 3} nanofibers under visible-light irradiation. This can be attributed to the nitrogen atom introducing at interstitial sites as well as the generation of oxygen vacancy on the surface of In{sub 2}O{sub 3} nanofibers, resulting in the enhanced utilization of visible light for the N-In{sub 2}O{sub 3} nanofibers. Furthermore, the obtained N-In{sub 2}O{sub 3} nanofibers with the advantage of ultra-long one-dimensional nanostructures can be recycled several times by facile sedimentation and hence present almost no decrease in photocatalytic activity indicative of a well regeneration capability. Therefore, the as-fabricated nitrogen-doped In{sub 2}O{sub 3} nanofibers as a promising photocatalyst present good photocatalytic degradation of organic pollutant in waste water for practical application.

  12. Preparation, characterization, and photocatalytic activity of sulfate-modified titania for degradation of methyl orange under visible light.

    Science.gov (United States)

    Parida, K M; Sahu, N; Biswal, N R; Naik, B; Pradhan, A C

    2008-02-15

    Hydrated titania was prepared by a sol-gel method, taking tetraisopropyl orthotitanate as starting material, and then promoted with different weight percentages of sulfate by an incipient wetness impregnation method. The materials were characterized by various advanced techniques such as PXRD, BET surface area, N(2) adsorption-desorption measurements, FTIR, and SEM. Analytical results demonstrated that TiO(2) is mesoporous in nature, and sulfate modification could inhibit the phase transformation and enhance the thermal stability of TiO(2). It was also found that sulfate modification could reduce the crystallite size and increase the specific surface area of the catalysts. The degradation of methyl orange under solar radiation was investigated to evaluate the photocatalytic activity of these materials. Effects of different parameters such as pH of the solution, amount of catalyst, additives, and kinetics were investigated. At 2.5 wt% sulfate loading, the average percentage of degradation of methyl orange was nearly two times than that of neat TiO(2). The photocatalytic degradation followed first-order kinetics.

  13. Cu2ZnSnS4-Au heterostructures: Toward green photocatalytic materials active under visible light

    Science.gov (United States)

    Dilsaver, Patrick Steven

    Solar energy is a potentially limitless source of clean power, but needs an effective means of conversion and storage to be feasible. Semiconductor-metal heterostructures have been studied as potential photocatalysts for use in solar-to-chemical energy conversion as a way of converting solar energy. This thesis examines pathways towards the synthesis of Cu2ZnSnS 4-Au, a novel semiconductor-metal heterostructure. Cu2ZnSnS 4 (CZTS) is attractive for use in this area because it has a narrow bandgap (1.5 eV) and is made of relatively earth-abundant and non-toxic elements. There are four methods studied in this thesis for the fabrication of CZTS-Au, two use AuCl3 as a precursor and two utilize pre-formed Au nanoparticles. Both precursors were studied under thermal and photochemical deposition conditions. The resulting products were characterized to determine the most effective pathway to fabricate these heterostructures. AuCl 3 under thermal deposition conditions proved to be the best pathway due to the well-defined monodisperse product. We also studied whether Au metal islands could be effectively removed while leaving the CZTS nanocrystals intact. The results of this experiment were mixed. It does seem that smaller Au nanoparticles are removed, but larger amalgams remain attached to the CZTS nanorods and remain inseparable despite numerous efforts. Finally, CZTS-Au was tested for photocatalytic activity using the model system of methylene blue reduction. CZTS-Au was found to convert methylene blue to leucomethylene blue at a much higher rate than bare CZTS. These results open up a new area of CZTS-metal heterostructures for the purpose of finding greener photocatalysts for solar-to-chemical energy conversion.

  14. The Development of Visible-Light Photoredox Catalysis in Flow.

    Science.gov (United States)

    Garlets, Zachary J; Nguyen, John D; Stephenson, Corey R J

    2014-04-01

    Visible-light photoredox catalysis has recently emerged as a viable alternative for radical reactions otherwise carried out with tin and boron reagents. It has been recognized that by merging photoredox catalysis with flow chemistry, slow reaction times, lower yields, and safety concerns may be obviated. While flow reactors have been successfully applied to reactions carried out with UV light, only recent developments have demonstrated the same potential of flow reactors for the improvement of visible-light-mediated reactions. This review examines the initial and continuing development of visible-light-mediated photoredox flow chemistry by exemplifying the benefits of flow chemistry compared with conventional batch techniques.

  15. Enhanced visible light photocatalysis through fast crystallization of zinc oxide nanorods

    Directory of Open Access Journals (Sweden)

    Sunandan Baruah

    2010-11-01

    Full Text Available Hydrothermally grown ZnO nanorods have inherent crystalline defects primarily due to oxygen vacancies that enhance optical absorption in the visible spectrum, opening up possibilities for visible light photocatalysis. Comparison of photocatalytic activity of ZnO nanorods and nanoparticle films on a test contaminant methylene blue with visible light irradiation at 72 kilolux (klx showed that ZnO nanorods are 12–24% more active than ZnO nanoparticulate films. This can be directly attributed to the increased effective surface area for adsorption of target contaminant molecules. Defects, in the form of interstitials and vacancies, were intentionally created by faster growth of the nanorods by microwave activation. Visible light photocatalytic activity was observed to improve by ≈8% attributed to the availability of more electron deficient sites on the nanorod surfaces. Engineered defect creation in nanostructured photocatalysts could be an attractive solution for visible light photocatalysis.

  16. Synthesis, characterization and photocatalytic activity of cubic-like CuCr2O4 for dye degradation under visible light irradiation

    Science.gov (United States)

    Yuan, Wenhui; Liu, Xiaoxia; Li, Li

    2014-11-01

    CuCr2O4 nanoparticles with cubic-like morphology were prepared via hydrothermal synthesis method without template. The CuCr2O4 samples were characterized by thermogravimetry and differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS) and Zeta potentials, respectively. The results indicated that cubic-like CuCr2O4 could be successfully synthesized by calcining the precursor at 600 °C, and the calcination temperature greatly influenced the morphology and optical performance of CuCr2O4. The pH at the point of zero charge (pHpzc) of the CuCr2O4 calcined at 600 °C was about 4.52. The photocatalytic activity of CuCr2O4 was evaluated for degradation of rhodamine B (RhB), methylene blue (MB), and methyl orange (MO) in the presence of H2O2 under visible light irradiation and the effects of the calcination temperature, dosage of photocatalyst, etc., on photocatalytic activity were studied in detail. The photocatalytic results revealed that the CuCr2O4 photocatalyst was of high activity for degradation of RhB (96.8%) and MB (99.5%), but very low activity for degradation of MO (14%). The CuCr2O4 sample calcined at 600 °C possesses the best photocatalytic activity, and the optimal dosage of the CuCr2O4 photocatalyst is 0.4 g/L.

  17. Solvothermal fabrication and enhanced visible light photocatalytic activity of Cu{sub 2}O-reduced graphene oxide composite microspheres for photodegradation of Rhodamine B

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Lingling [Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Normal University, Huangshi 435002 (China); Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Hubei Normal University, Huangshi 435002 (China); Wang, Guohong, E-mail: wanggh2003@163.com [Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Normal University, Huangshi 435002 (China); Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Hubei Normal University, Huangshi 435002 (China); Hao, Ruirui [Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Normal University, Huangshi 435002 (China); Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Hubei Normal University, Huangshi 435002 (China); Han, Deyan, E-mail: handeyan@sohu.com [Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Normal University, Huangshi 435002 (China); Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Hubei Normal University, Huangshi 435002 (China); Cao, Sheng [Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Normal University, Huangshi 435002 (China); Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, Hubei Normal University, Huangshi 435002 (China)

    2015-12-15

    Graphical abstract: - Highlights: • Cu{sub 2}O-reduced graphene oxide composite spheres were successfully prepared. • The graphene oxide loading played an important role in photocatalytic activity. • A possible enhanced photocatalytic mechanism was proposed. - Abstract: The addition of graphene oxide (GO) in the semiconductors has been regarded as one of the effective methods to enhance their photocatalytic activity. In this study, Cu{sub 2}O-reduced graphene oxide (Cu{sub 2}O-rGO) composites with low loading (0–0.5 wt.%) of graphene oxide (GO) were produced by a one-step green solvothermal method in ethanol system by using Cu(NO{sub 3}){sub 2}·3H{sub 2}O and glutamic acid as copper precursor and reducing agent, respectively. During the solvothermal treatment, GO was reduced to rGO. The as-prepared Cu{sub 2}O-reduced graphene oxide composite microspheres exhibited enhanced photocatalytic activity toward the degradation of RhB aqueous solution under visible light irradiation. At the optimal loading of graphene oxide (0.05 wt.%), Cu{sub 2}O-rGO composites showed the highest photocatalytic activity, exceeding that of pure Cu{sub 2}O and commercial Degussa P25 by a factor of 2.9 and 7.9, respectively. The enhanced photocatalytic activity may be ascribed to the strong coupling interaction between Cu{sub 2}O particles and rGO nanosheets, which reduces the recombination of charge carriers.

  18. Facile in situ synthesis of wurtzite ZnS/ZnO core/shell heterostructure with highly efficient visible-light photocatalytic activity and photostability

    Science.gov (United States)

    Xiao, Jian-Hua; Huang, Wei-Qing; Hu, Yong-sheng; Zeng, Fan; Huang, Qin-Yi; Zhou, Bing-Xin; Pan, Anlian; Li, Kai; Huang, Gui-Fang

    2018-02-01

    High photocatalytic activity and photostability are the pursuit of the goal for designing promising photocatalysts. Herein, using ZnO to encapsulate ZnS nanoparticles is proposed as an effective strategy to enhance photocatalytic activity and anti-photocorrosion. The ZnS/ZnO core/shell heterostructures are obtained via an annealing treatment of ZnS nanoparticles produced by a facile wet chemical approach. Due to its small size, the nascent cubic sphalerite ZnS (s-ZnS) converts into a hexagonal wurtzite ZnS (w-ZnS)/ZnO core/shell structure after annealing treatment. In situ oxidation leads to increasing ZnO, simultaneously decreasing the w-ZnS content in the resultant w-ZnS/ZnO with thermal annealing time. The w-ZnS/ZnO core/shell heterostructures show high photocatalytic activity, demonstrated by the photodegradation rate of methylene blue being up to ten-fold and seven-fold higher than that of s-ZnS under UV and visible light irradiation, respectively, and the high capability of degrading rhodamine B. The enhanced photocatalytic activity may be attributed to the large specific surface and improved charge carrier separation at the core/shell interface. Moreover, it displays high photostability owing to the protection of the ZnO shell, greatly inhibiting the photocorrosion of ZnS. This facile in situ oxidation is effective and easily scalable, providing opportunities for developing novel core/shell structure photocatalysts with high activity and photostability.

  19. Photocatalytic activity of Al{sub 2}O{sub 3}-doped TiO{sub 2} thin films activated with visible light on the bacteria Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Barajas-Ledesma, E., E-mail: edgar_acuario112@hotmail.com [Instituto de Investigaciones Metalurgicas, edificio ' U' , Ciudad Universitaria, UMSNH, Morelia, Michoacan, Mexico, C.P. 58000 (Mexico); Garcia-Benjume, M.L. [Instituto de Investigaciones Metalurgicas, edificio ' U' , Ciudad Universitaria, UMSNH, Morelia, Michoacan, Mexico, C.P. 58000 (Mexico); Espitia-Cabrera, I. [Facultad de Ingenieria Quimica, edificio ' M' , Ciudad Universitaria, UMSNH, Morelia, Michoacan, Mexico, C.P. 58000 (Mexico); Bravo-Patino, A. [Centro Multidisciplinario de Estudios en Biotecnologia, Km 9.5 Carretera Morelia-Zinapecuaro, Posta Veterinaria, Morelia, Michoacan, Mexico, C.P. 58262 (Mexico); Espinoza-Beltran, F.J. [CINVESTAV-Queretaro Libramiento Norponiente 2000, Fracc. Real de Juriquilla, Santiago de Queretaro, Queretaro, Mexico, C.P. 76230 (Mexico); Mostaghimi, J. [Faculty of Applied Science and Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario, M5S 3G8 (Canada); Contreras-Garcia, M.E. [Instituto de Investigaciones Metalurgicas, edificio ' U' , Ciudad Universitaria, UMSNH, Morelia, Michoacan, Mexico, C.P. 58000 (Mexico)

    2010-10-25

    Al{sub 2}O{sub 3}-doped TiO{sub 2} thin films were prepared by combining electrophoretic deposition (EPD) with sputtering. A Corning* glass was used as a substrate, in which a titanium film was deposited by sputtering. Then, a precursor sol was prepared with Ti(n-OBu){sub 4} and Al(s-OBu){sub 3} and used as the medium for EPD. Next, the thin films were sintered and, finally, characterised by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). Several cultures of Escherichia coli, strain XL1-Blue, were prepared. Nine experiments were carried out. In three of them, an inoculum (a low amount of a product that contains bacteria) was prepared without a film; in the other six Al{sub 2}O{sub 3}-doped TiO{sub 2} film-coated glass substrates were irradiated with visible light before they were introduced in the inoculum. The SEM and EDS results showed that TiO{sub 2}-Al{sub 2}O{sub 3} films were obtained, covering all the glass substrate and with uniform size of particles forming them, and that the aluminium was distributed uniformly on the film. XRD results showed that rutile phase was obtained. By TEM, the structure of TiO{sub 2} was demonstrated. Al{sub 2}O{sub 3}-doped TiO{sub 2} thin films were successful at eliminating E. coli.

  20. Ionic liquid-assisted photochemical synthesis of ZnO/Ag{sub 2}O heterostructures with enhanced visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Shuo; Zhang, Yiwei, E-mail: zhangchem@seu.edu.cn; Zhou, Yuming, E-mail: ymzhou@seu.edu.cn; Zhang, Chao; Fang, Jiasheng; Sheng, Xiaoli

    2017-07-15

    Highlights: • ZnO/Ag{sub 2}O 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{sub 2}O heterostructures had the enhanced photocatalytic ability. • Photocatalytic activity is a result of the combination of various factors. - Abstract: ZnO/Ag{sub 2}O 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{sub 2}O materials exhibited self-assembled flower-like architecture whose size was about 3 μm. Moreover, as-prepared ZnO/Ag{sub 2}O 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{sup +} 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{sub 2}O materials, which can be beneficial for environmental protection.

  1. Preparation of Single-Crystalline AgIn5S8 Octahedrons with Exposed {111} Facets and Its Visible-Light-Responsive Photocatalytic H2 Production Activity.

    Science.gov (United States)

    Song, Shuaishuai; Liang, Zechen; Fu, Wenli; Peng, Tianyou

    2017-05-24

    Although AgIn5S8 as one kind of ternary chalcogenides has been extensively investigated due to its band-edge positions meeting the thermodynamic requirement for water photosplitting, very little attention has been focused on the crystallinity and facet effects of AgIn5S8 on its photocatalytic activity. Herein, a facile hydrothermal route was developed to fabricate regular single-crystalline AgIn5S8 octahedrons with only {111} facets exposed. Also, the effects of the hydrothermal reaction conditions on the composition, crystal phase, crystallinity, and morphology of the obtained AgxInyS(x+3y/2) products (hereafter denoted as AIS-x, where x represents the pH value of the reaction solution) were investigated, and it was found that the accurately released S2- ions from the thermal decomposition of thioacetamide (TAA) is the central factor for the nucleation and growth of the AgIn5S8 octahedrons. The experimental results indicate that the resultant regular AgIn5S8 octahedrons (AIS-10.6) exhibit the best photocatalytic activity for H2 production among those AgxInyS(x+3y/2) products, and the higher crystallinity and fewer defects of the AgIn5S8 octahedrons compared to the other AgxInyS(x+3y/2) products can retard the photogenerated charge recombination, while those indium atoms with higher density in the exposed {111} facets might be beneficial for the photocatalytic H2 production reaction by acting as active sites to promote the charge separation and transfer processes. The results presented here provide new insights into the significance of crystallinity and exposed facets in the visible-light-responsive activity of AgIn5S8, thus paving new ways into the design and synthesis of high-performance, cost-effective AgIn5S8 photocatalysts for H2 production.

  2. Enhanced visible light activity on direct contact Z-scheme g-C3N4-TiO2 photocatalyst

    Science.gov (United States)

    Li, Juan; Zhang, Min; Li, Qiuye; Yang, Jianjun

    2017-01-01

    Direct contact Z-scheme g-C3N4-TiO2 nanocomposites without an electron mediator are prepared via simple annealing the mixture of bulk g-C3N4 and nanotube titanic acid (NTA) in air at 600 °C for 2 h. In the process of annealing, the bulk g-C3N4 transformed to ultra-thin g-C3N4 nanosheets, and NTA converted to a novel anatase TiO2, then the two components formed a close interaction. The XPS result reveals that some amount of nitrogen is doped into this novel-TiO2, and g-C3N4 nanosheets exist in the composites. The results of XRD, TEM and TG indicate that the thickness of g-C3N4 nanosheets is very thin. The ESR spectrum shows the existence of Ti3+ and single-electron-trapped oxygen vacancy in the 30%g-C3N4-TiO2 composites. In photocatalytic activity test, the 30%g-C3N4-TiO2 nanocomposites showed an excellent photo-oxidation activity of propylene under visible light irradiation (λ≥ 420 nm), and the removal efficiency of propylene reached as high as 56.6%, and the activity kept nearly 82% after four consecutive recycles. Photoluminescence (PL) result using terephthalic acid (TA) as a probe molecule indicated that the g-C3N4-TiO2 nanocomposites displayed a Z-sheme photocatalytic reaction system and this should be the main reason for the high photocatalytic activity. A possible photocatalytic mechanism was proposed on the basis of PL result and transient photocurrent-time curves.

  3. Novel g-C3N4/CoO Nanocomposites with Significantly Enhanced Visible-Light Photocatalytic Activity for H2 Evolution.

    Science.gov (United States)

    Mao, Zhiyong; Chen, Jingjing; Yang, Yanfang; Wang, Dajian; Bie, Lijian; Fahlman, Bradley D

    2017-04-12

    Novel g-C3N4/CoO nanocomposite application for photocatalytic H2 evolution were designed and fabricated for the first time in this work. The structure and morphology of g-C3N4/CoO were investigated by a wide range of characterization methods. The obtained g-C3N4/CoO composites exhibited more-efficient utilization of solar energy than pure g-C3N4 did, resulting in higher photocatalytic activity for H2 evolution. The optimum photoactivity in H2 evolution under visible-light irradiation for g-C3N4/CoO composites with a CoO mass content of 0.5 wt % (651.3 μmol h(-1) g(-1)) was up to 3 times as high as that of pure g-C3N4 (220.16 μmol h(-1) g(-1)). The remarkably increased photocatalytic performance of g-C3N4/CoO composites was mainly attributed to the synergistic effect of the junction or interface formed between g-C3N4 and CoO.

  4. 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.

  5. Preparation of well-dispersed Mg-doped LaCoO3 nanocrystals with controllable particle size and high visible-light photocatalytic activity.

    Science.gov (United States)

    Sun, Shangmei; Pang, Guangsheng; Huang, Yuliang; Li, Chunguang; Feng, Shouhua

    2010-08-01

    Mg-doped LaCoO3 nanocrystals are prepared by a modified sol-gel method. Excess MgO is used to inhibit the crystal growth and agglomeration during the calcination process. A series of Mg-doped LaCoO3 nanocrystals with average crystallite size varying from 13.4 to 31.6 nm can be obtained by changing the molar ratio of Mg:La from 4:1 to 1:10 in the reaction mixture. The largest BET surface area observed is 64.5 m2/g if the molar ratio of Mg:La is 4:1. The product can be well dispersed in water and a very stable colloid formed without any stabilizer. The photocatalytic performance of Mg-doped LaCoO3 nanocrystals is evaluated by the degradation of Reactive Brilliant Red X-3B solution. The well-dispersed Mg-doped LaCoO3 nanocrystals exhibit high visible-light photocatalytic activity.

  6. Synthesis of hierarchical ZnV2O6 nanosheets with enhanced activity and stability for visible light driven CO2 reduction to solar fuels

    Science.gov (United States)

    Bafaqeer, Abdullah; Tahir, Muhammad; Amin, Nor Aishah Saidina

    2018-03-01

    Hierarchical nanostructures have lately garnered enormous attention because of their remarkable performances in energy storage and catalysis applications. In this study, novel hierarchical ZnV2O6 nanosheets, formulated by one-step solvothermal method, for enhanced photocatalytic CO2 reduction with H2O to solar fuels has been investigated. The structure and properties of the catalysts were characterized by XRD, FESEM, TEM, BET, UV-vis, Raman and PL spectroscopy. The hierarchical ZnV2O6 nanosheets show excellent performance towards photoreduction of CO2 with H2O to CH3OH, CH3COOH and HCOOH under visible light. The main product yield, CH3OH of 3253.84 μmol g-cat-1 was obtained over ZnV2O6, 3.4 times the amount of CH3OH produced over the ZnO/V2O5 composite (945.28 μmol g-cat-1). In addition, CH3OH selectivity of 39.96% achieved over ZnO/V2O5, increased to 48.78% in ZnV2O6 nanosheets. This significant improvement in photo-activity over ZnV2O6 structure was due to hierarchical structure with enhanced charge separation by V2O5. The obtained ZnV2O6 hierarchical nanosheets exhibited excellent photocatalytic stability for selective CH3OH production.

  7. Facile fabrication of Bi{sub 2}S{sub 3}/SnS{sub 2} heterojunction photocatalysts with efficient photocatalytic activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiaomin; Huang, Guanbo [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Gao, Haihuan [Tianjin Fourth Middle School, Tianjin 300021 (China); Pan, Cheng; Wang, Huan [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Yan, Jing, E-mail: yanjingls2012@163.com [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); Liu, Yu [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Qiu, Haixia [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); Ma, Ning [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Gao, Jianping [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China)

    2016-07-25

    In this work, Bi{sub 2}S{sub 3}/SnS{sub 2} heterojunction photocatalysts were prepared by combining a hydrothermal technique and a facile in situ growth method. The nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma spectroscopy, X-ray photoelectron spectroscopy, UV–Vis diffusion reflectance spectroscopy and room-temperature photoluminescence spectra. Their photocatalytic performances were evaluated by degrading methyl orange (MO) in aqueous solution (50 mg/L) under visible light (λ > 420 nm) irradiation. It was found that when the mass percentage of Bi{sub 2}S{sub 3} in Bi{sub 2}S{sub 3}/SnS{sub 2} was 7.95 wt%, the as-prepared Bi{sub 2}S{sub 3}/SnS{sub 2} nanocomposite showed the best photocatalytic activity for the degradation of MO. The highly improved performance of the Bi{sub 2}S{sub 3}/SnS{sub 2} nanocomposite was mainly ascribed to the efficient charge separation. - Highlights: • Facile fabrication of novel Bi{sub 2}S{sub 3}/SnS{sub 2} heterojunction photocatalysts. • High-performance photocatalyst for the degradation of organic pollutants. • Good recyclability of catalyst without photo-corrosion. • The photocatalytic mechanism was proposed.

  8. Enhancement of the visible light photocatalytic activity of heterojunction In{sub 2}O{sub 3}/BiVO{sub 4} composites

    Energy Technology Data Exchange (ETDEWEB)

    Yin, J.Z.; Jian, Z.C.; Pan, M.L.; Zhang, Y.Q.; Fei, Z.B. [South China University of Technology, School of Environment and Energy, Guangzhou (China); Huang, S.B. [South China University of Technology, School of Environment and Energy, Guangzhou (China); South China University of Technology, State Key Laboratory of Pulp and Paper Engineering, Guangzhou (China); Xu, X.R. [South China University of Technology, Analytical and Testing Center, Guangzhou (China)

    2015-09-15

    Novel In{sub 2}O{sub 3}/BiVO{sub 4} heterojunction composite photocatalysts with tunable In{sub 2}O{sub 3} content were prepared using a mild hydrothermal method. The structure, composition, and optical properties of the In{sub 2}O{sub 3}/BiVO{sub 4} composites were determined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-Vis diffuse reflectance spectroscopy, Brunauer-Emmett-Teller surface analysis, and X-ray photoelectron spectroscopy. Furthermore, photocatalytic activities of the as-prepared composites were investigated by studying the degradation of methylene blue (MB) solutions under simulated visible light irradiation (λ > 420 nm). It was found that the 50 % proportion of In{sub 2}O{sub 3} in the In{sub 2}O{sub 3}/BiVO{sub 4} composite exhibited the highest photocatalytic performance, leading to 91 % decomposition of MB within 240 min of irradiation. (orig.)

  9. Facile synthesis of AgI/BiOI-Bi2O3 multi-heterojunctions with high visible light activity for Cr(VI) reduction.

    Science.gov (United States)

    Wang, Qi; Shi, Xiaodong; Liu, Enqin; Crittenden, John C; Ma, Xiangjuan; Zhang, Yi; Cong, Yanqing

    2016-11-05

    AgI sensitized BiOI-Bi2O3 composite (AgI/BiOI-Bi2O3) with multi-heterojunctions was prepared using simple etching-deposition process. Different characterization techniques were performed to investigate the structural, optical and electrical properties of the as-prepared photocatalysts. It was found that the ternary AgI/BiOI-Bi2O3 composite exhibited: (1) improved photocurrent response, (2) smaller band gap, (3) greatly reduced charge transfer resistance and (4) negative shift of flat band potential, which finally led to easier generation and more efficient separation of photo-generated electron-hole pairs at the hetero-interfaces. Thus, for the reduction of Cr(VI), AgI/BiOI-Bi2O3 exhibited excellent photocatalytic activity under visible light irradiation at near neutral pH. AgI/BiOI-Bi2O3 was optimized when the initial molar ratio of KI to Bi2O3 and AgNO3 to Bi2O3 was 1:1 and 10%, respectively. The estimated kCr(VI) on optimized AgI/BiOI-Bi2O3 was about 16 times that on pure Bi2O3. Good stability was also observed in cyclic runs, indicating that the current multi-heterostructured photocatalyst is highly desirable for the remediation of Cr(VI)-containing wastewater. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Self-assembled 3D flowerlike hierarchical Fe3O4@Bi2O3 core-shell architectures and their enhanced photocatalytic activity under visible light.

    Science.gov (United States)

    Wang, Yang; Li, Shikuo; Xing, Xianran; Huang, Fangzhi; Shen, Yuhua; Xie, Anjian; Wang, Xiufang; Zhang, Jian

    2011-04-18

    Three-dimensional (3D) flowerlike hierarchical Fe(3)O(4)@Bi(2)O(3) core-shell architectures were synthesized by a simple and direct solvothermal route without any linker shell. The results indicated that the size of the 3D flowerlike hierarchical microspheres was about 420 nm and the shell was composed of several nanosheets with a thickness of 4-10 nm and a width of 100-140 nm. The saturation magnetization of the superparamagnetic composite microspheres was about 41 emu g(-1) at room temperature. Moreover, the Fe(3)O(4)@Bi(2)O(3) composite microspheres showed much higher (7-10 times) photocatalytic activity than commercial Bi(2)O(3) particles under visible-light irradiation. The possible formation mechanism was proposed for Ostwald ripening and the self-assembled process. This novel composite material may have potential applications in water treatment, degradation of dye pollutants, and environmental cleaning, for example. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Facile Synthesis, Characterization, and Visible-light Photocatalytic Activities of 3D Hierarchical Bi2S3 Architectures Assembled by Nanoplatelets

    Directory of Open Access Journals (Sweden)

    Tiekun Jia

    2016-10-01

    Full Text Available 3D hierarchical Bi2S3 architectures have been successfully synthesized via a simple and effective hydrothermal process. The as-prepared Bi2S3 samples were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, nitrogen adsorption- desorption isotherms, and UV-vis diffuse reflectance spectrum (DRS. The observation of field emission scanning electron microscope (FESEM images showed that numerous nanoplatelets are randomly arranged and interconnected with each other, which are assembled into 3D hierarchical Bi2S3 architectures. The photocatalytic activity of the as-prepared Bi2S3 samples was evaluated by the degradation of Rhodamine B (RhB under visible light irradiation. The effect of hydrothermal temperature, reaction time, pH value and shape on the photocatalytic efficiency of the as-prepared Bi2S3 samples was investigated. The results showed that 3D hierarchical Bi2S3 architectures prepared at 165 °C for 12 h at a pH of 2.4 exhibits high photocatalytic efficiency, which could be ascribed to the synergetic effect of the shape, surface area, crystallinity, band gap and crystalline size.

  12. Metal organic framework g-C3N4/MIL-53(Fe) heterojunctions with enhanced photocatalytic activity for Cr(VI) reduction under visible light

    Science.gov (United States)

    Huang, Wenyuan; Liu, Ning; Zhang, Xiaodong; Wu, Minghong; Tang, Liang

    2017-12-01

    In this study, hybrid nanocomposites based on Fe-based MOF and graphitic carbon nitride (g-C3N4) were developed by a facile solvothermal method. The as-prepared materials were characterized by XRD, FESEM, TEM, XPS and PL analysis. It was showed that the introduction of a certain amount of g-C3N4 on the surface of MIL-53(Fe) would improve the separation and migration rate of photo-induced charges, consequently resulting in the boost of photocatalytic efficiency. Compared with g-C3N4 and MIL-53(Fe), the CMFe composites displayed more excellent visible light-resposive photocatalytic activity for the reduction of Cr(VI). The optimal doping content of g-C3N4 in g-C3N4/MIL-53(Fe) composite was determined to be 3.0 wt%, and it showed about 2.1 and 2.0 times as high photocatalytic efficiency for the reduction of Cr(VI) as that of pure g-C3N4 and MIL-53(Fe), respectively. Meanwhile, the composite exhibited good reusability and stability in the process of cyclic experiments. A possible photocatalytic reaction mechanism was also investigated in detail by the related electrochemical analysis.

  13. The preparation of CuS/TiO2 nanotube arrays with high-active under visible light by ultrasonic-assisted hydrothermal method

    Science.gov (United States)

    Li, Lixia; Ya, Jing; Xiang, Liyun; Liu, Zhifeng; Lei, E.

    2017-10-01

    Ultrasound provided a good dispersion of CuS on TiO2NTs. In order to prepare CuS/TiO2NTs with a good heterostructure, the CuS particles must establish contact with TiO2NTs uniformly. The hydrothermal process was divided into two phases, and different times of ultrasound were introduced before each stage. The effects of ultrasonic-assisted hydrothermal method on the structure and photoelectric properties of CuS/TiO2NTs were investigated by SEM, XRD, photocurrent, and degradation of MB. The results show that the introduction of ultrasound before the hydrothermal treatment can cause damage to the TiO2NTs. However, the ultrasound between the two hydrothermal stages makes CuS distributed in the TiO2NTs uniformly, and the amount of CuS can be increased. The photocurrent reaches 32 mA/cm2 at 1.5 V, and meanwhile the photocatalytic activity under visible light is also improved.

  14. Cartilage tissue engineering application of injectable gelatin hydrogel with in situ visible-light-activated gelation capability in both air and aqueous solution.

    Science.gov (United States)

    Lin, Hang; Cheng, Anthony Wai-Ming; Alexander, Peter G; Beck, Angela M; Tuan, Rocky S

    2014-09-01

    Chondroprogenitor cells encapsulated in a chondrogenically supportive, three-dimensional hydrogel scaffold represents a promising, regenerative approach to articular cartilage repair. In this study, we have developed an injectable, biodegradable methacrylated gelatin (mGL)-based hydrogel capable of rapid gelation via visible light (VL)-activated crosslinking in air or aqueous solution. The mild photocrosslinking conditions permitted the incorporation of cells during the gelation process. Encapsulated human-bone-marrow-derived mesenchymal stem cells (hBMSCs) showed high, long-term viability (up to 90 days) throughout the scaffold. To assess the applicability of the mGL hydrogel for cartilage tissue engineering, we have evaluated the efficacy of chondrogenesis of the encapsulated hBMSCs, using hBMSCs seeded in agarose as control. The ability of hBMSC-laden mGL constructs to integrate with host tissues after implantation was further investigated utilizing an in vitro cartilage repair model. The results showed that the mGL hydrogel, which could be photopolymerized in air and aqueous solution, supports hBMSC growth and TGF-β3-induced chondrogenesis. Compared with agarose, mGL constructs laden with hBMSCs are mechanically stronger with time, and integrate well with native cartilage tissue upon implantation based on push-out mechanical testing. VL-photocrosslinked mGL scaffold thus represents a promising scaffold for cell-based repair and resurfacing of articular cartilage defects.

  15. Cu2ZnSnS4@TiO2 p-n heterostructured nanosheet arrays: Controllable hydrothermal synthesis and enhanced visible light-driven photocatalytic activity

    Science.gov (United States)

    Gan, Tian; Li, Yan; Wang, Xiang-Zhuo; Wang, Xiao-Tian; Wang, Cheng-Wei

    2017-06-01

    We have designed and fabricated a novel particle/sheet p-n heterostructural nanosheet arrays of Cu2ZnSnS4@TiO2 via a facile two-step hydrothermal method. The results from characterizations of SEM, TEM, XRD, Raman spectra, XPS, and UV-vis spectrophotometer indicate that p-type Cu2ZnSnS4 (CZTS) nanoparticles were successfully assembled on the vertically oriented TiO2 nanosheet arrays, forming three-dimensional distributed p-n heterostructural film photocatalyst, which could efficiently expand spectral response, promote photoinduced charges separation, and increase the specific surface areas for photocatalytic reaction, and then strengthen samples' visible light-driven photocatalytic activity. Furthermore, we found that the absorption edges of the samples exhibited the red shift from 390 nm to 700 nm with the CZTS deposition time. The results of photocatalytic degradation methyl orange (MO) showed that the new type CZTS@TiO2 p-n heterostructural nanosheet arrays with 24 h hydrothermal reaction revealed the optimal degradation rate of K = 1.2 h-1, about 6.6 times higher than that of the pure TiO2 nanosheet arrays under the same conditions; and also demonstrated an excellent stability and reusability during the cyclic experiments, which would be primarily attributed to optimal loading capacities of CZTS nanoparticles and an adequate built-in electric field at their interfaces of p-n heterostructures.

  16. Synthesis of MoS{sub 2}/g-C{sub 3}N{sub 4} nanosheets as 2D heterojunction photocatalysts with enhanced visible light activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Juan [School of Chemical Engineering, Northwest University, Xi’an 710069 (China); Department of Environmental Engineering and Chemistry, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Liu, Enzhou; Ma, Yongning [School of Chemical Engineering, Northwest University, Xi’an 710069 (China); Hu, Xiaoyun [School of Physics, Northwest University, Xi’an 710069 (China); Wan, Jun; Sun, Lin [School of Chemical Engineering, Northwest University, Xi’an 710069 (China); Fan, Jun, E-mail: fanjun@nwu.edu.cn [School of Chemical Engineering, Northwest University, Xi’an 710069 (China)

    2016-02-28

    Graphical abstract: TEM image and schematic diagram of photocatalytic mechanism of 2D MoS{sub 2}/g-C{sub 3}N{sub 4} composites. - Highlights: • g-C{sub 3}N{sub 4} nanosheets coupled with MoS{sub 2} nanosheets as 2D heterojunction photocatalysts were synthesized successfully. • The 2D MoS{sub 2}/g-C{sub 3}N{sub 4} heterojunctions show higher photocatalytic activity than pure g-C{sub 3}N{sub 4}. • The photocatalytic mechanism of the 2D MoS{sub 2}/g-C{sub 3}N{sub 4} heterojunction was described. - Abstract: g-C{sub 3}N{sub 4} nanosheets coupled with MoS{sub 2} nanosheets as 2D heteroconjuction were prepared via a facile impregnation and calcination method. The structure characterization clearly indicated that MoS{sub 2} nanosheets were successfully horizontal loaded on g-C{sub 3}N{sub 4} nanosheets. The investigation indicated that the formation of 2D heterojunction between the g-C{sub 3}N{sub 4} nanosheets and MoS{sub 2} nanosheets promoted the charge transfer and enhanced separation efficiency of photoinduced electron–hole pairs. Furthermore, the measurement of photocatalytic activity for the degradation of rhodamine B and methyl orange revealed that the as-prepared 2D MoS{sub 2}/g-C{sub 3}N{sub 4} heterojunction exhibited the significantly enhanced photocatalytic activity and considerable stability under visible light irradiation. The 2D MoS{sub 2}/g-C{sub 3}N{sub 4} heterojunction prepared with 3 wt% of MoS{sub 2} exhibited the optimal photodegradable efficiency. The present work shows that the formation of 2D heterojunction should be a good strategy to design efficient photocatalysts.

  17. Visible light emission from porous silicon carbide

    DEFF Research Database (Denmark)

    Ou, Haiyan; Lu, Weifang

    2017-01-01

    Light-emitting silicon carbide is emerging as an environment-friendly wavelength converter in the application of light-emitting diode based white light source for two main reasons. Firstly, SiC has very good thermal conductivity and therefore a good substrate for GaN growth in addition to the small...

  18. A Carpet Cloak for Visible Light

    Science.gov (United States)

    2011-01-01

    of transformation optical devices at visible frequencies. KEYWORDS:Optical metamaterials , invisibility cloak , transformation optics, nanofabrication...Berkeley, California 94720, United States Invisibility cloaks , a family of optical illusion devices that routeelectromagnetic (EM) waves around an object...EM properties, known as metamaterials ,1,2 have been used to control the propagation of EM waves. Metamaterials have been applied to cloaking using the

  19. Visible light responsive sulfated rare earth doped TiO(2)@fumed SiO(2) composites with mesoporosity: enhanced photocatalytic activity for methyl orange degradation.

    Science.gov (United States)

    Zhan, Changchao; Chen, Feng; Yang, Jintao; Dai, Daoxing; Cao, Xiaohua; Zhong, Mingqiang

    2014-02-28

    Visible light (VL) responsive mesoporous sulfated rare earth ions (Nd(3+), La(3+), Y(3+)) incorporated TiO2@fumed SiO2 photocatalysts were prepared by sol-gel method with P123 (EO20PO70EO20) as a template. The resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption measurements (BET), UV-vis diffuse reflectance spectroscopy, photoluminescence (PL) spectra, Fourier transform infrared spectroscopy (FTIR) and thermal analyses (TG-DTA). In comparison with nondoped sample, RE-doped samples showed not only an increase in the surface areas and pore volumes, but also an inhibition of titania phase transition from anatase to rutile. Photo-degradation results revealed that RE-doped samples could greatly improve the photocatalytic activity, and the experimental degradation rates of methyl orange (MO) were higher than that catalyzed by undoped samples and Degussa P-25, obeyed the order of Nd(3+)>La(3+)>Y(3+). Nd-doped sample expressed the highest photoactivity and the optimal dosage was 0.25mol%, which resulted in MO degradation rates of 99.8% and 90.05% irradiation under UV for 60min and VL (λ>400nm) for 40h, respectively. The enhanced photocatalytic activity could be attributed to the higher specific area, good crystallinity, strong VL absorption and effective separation of photogenerated electron-hole pairs in the catalyst. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. 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.

  1. Pt-Decorated g-C3N4/TiO2 Nanotube Arrays with Enhanced Visible-Light Photocatalytic Activity for H2 Evolution.

    Science.gov (United States)

    Gao, Zhi-Da; Qu, Yong-Fang; Zhou, Xuemei; Wang, Lei; Song, Yan-Yan; Schmuki, Patrik

    2016-06-01

    Aligned TiO2 nanotube layers (TiNTs) grown by self-organizing anodization of a Ti-substrate in a fluoride-based electrolyte were decorated with graphitic-phase C3N4 (g-C3N4) via a facile chemical vapor deposition approach. In comparison with classical TiO2 nanotubes (anatase), the g-C3N4/TiNTs show an onset of the photocurrent at 2.4 eV (vs. 3.2 eV for anatase) with a considerably high photocurrent magnitude in the visible range. After further decoration with Pt nanoparticles, we obtained a visible-light responsive platform that showed, compared with g-C3N4-free TiNTs, a strong enhancement for photoelectrochemical and bias-free H2 evolution (15.62 μLh(-1) cm(-2)), which was almost a 98-fold increase in the H2 production rate of TiNTs (0.16 μLh(-1) cm(-2)). In a wider context, the g-C3N4-combined 3 D nanoporous/nanotubular structure thus provides a platform with significant visible-light response in photocatalytic applications.

  2. Heterojunctions of mixed phase TiO2 nanotubes with Cu, CuPt, and Pt nanoparticles: interfacial band alignment and visible light photoelectrochemical activity

    Science.gov (United States)

    Kar, Piyush; Zhang, Yun; Mahdi, Najia; Thakur, Ujwal K.; Wiltshire, Benjamin D.; Kisslinger, Ryan; Shankar, Karthik

    2018-01-01

    Anodically formed, vertically oriented, self-organized cylindrical TiO2 nanotube arrays composed of the anatase phase undergo an interesting morphological and phase transition upon flame annealing to square-shaped nanotubes composed of both anatase and rutile phases. This is the first report on heterojunctions consisting of metal nanoparticles (NPs) deposited on square-shaped TiO2 nanotube arrays (STNAs) with mixed rutile and anatase phase content. A simple photochemical deposition process was used to form Cu, CuPt, and Pt NPs on the STNAs, and an enhancement in the visible light photoelectrochemical water splitting performance for the NP-decorated STNAs was observed over the bare STNAs. Under narrow band illumination by visible photons at 410 nm and 505 nm, Cu NP-decorated STNAs performed the best, producing photocurrents 80% higher and 50 times higher than bare STNAs, respectively. Probing the energy level structure at the NP–STNA interface using ultraviolet photoelectron spectroscopy revealed Schottky barrier formation in the NP-decorated STNAs, which assists in separating the photogenerated charge carriers, as also confirmed by longer charge carrier lifetimes in NP-decorated STNAs. While all the NP-decorated STNAs showed enhanced visible light absorption compared to the bare STNAs, only the Cu NPs exhibited a clear plasmonic behavior with an extinction cross section that peaked at 550 nm.

  3. Exceptional Visible-Light Activities of TiO2-Coupled N-Doped Porous Perovskite LaFeO3 for 2,4-Dichlorophenol Decomposition and CO2 Conversion.

    Science.gov (United States)

    Humayun, Muhammad; Qu, Yang; Raziq, Fazal; Yan, Rui; Li, Zhijun; Zhang, Xuliang; Jing, Liqiang

    2016-12-20

    In this work, TiO2-coupled N-doped porous perovskite-type LaFeO3 nanocomposites as highly efficient, cheap, stable, and visible-light photocatalysts have successfully been prepared via wet chemical processes. It is shown that the amount-optimized nanocomposite exhibits exceptional visible-light photocatalytic activities for 2,4-dichlorophenol (2,4-DCP) degradation by ∼3-time enhancement and for CO2 conversion to fuels by ∼4-time enhancement, compared to the resulting porous LaFeO3 with rather high photoactivity due to its large surface area. It is clearly demonstrated, by means of various experimental data, especially for the ·OH amount evaluation, that the obviously enhanced photoactivities are attributed to the increased specific surface area by introducing pores, to the extended visible-light absorption by doping N to create surface states, and to the promoted charge transfer and separation by coupling TiO2. Moreover, it is confirmed from radical trapping experiments that the photogenerated holes are the predominant oxidants in the photocatalytic degradation of 2,4-DCP. Furthermore, a possible photocatalytic degradation mechanism for 2,4-DCP is proposed mainly based on the resultant crucial intermediate, 2-chlorosuccinic acid with m/z = 153, that readily transform into CO2 and H2O. This work opens up a new feasible route to synthesize visible-light-responsive high-activity perovskite-type nanophotocatalysts for efficient environmental remediation and energy production.

  4. CO2 SEQUESTRATION AND RECYCLE BY PHOTOCATALYSIS WITH VISIBLE LIGHT

    Energy Technology Data Exchange (ETDEWEB)

    Steven S.C. Chuang

    2001-10-01

    Visible light-photocatalysis could provide a cost-effective route to recycle CO{sub 2} to useful chemicals or fuels. Development of an effective catalyst for the photocatalytic synthesis requires (i) the knowledge of the surface band gap and its relation to the surface structure, (ii) the reactivity of adsorbates and their reaction pathways, and (iii) the ability to manipulate the actives site for adsorption, surface reaction, and electron transfer. The objective of this research is to study the photo-catalytic activity of TiO{sub 2}-base catalyst. A series of TiO{sub 2}-supported metal catalysts were prepared for determining the activity and selectivity for the synthesis of methane and methanol. 0.5 wt% Cu/SrTiO{sub 3} was found to be the most active and selective catalyst for methanol synthesis. The activity of the catalyst decreased in the order: Ti silsesquioxane > Cu/SrTiO{sub 3} > Pt/TiO{sub 2} > Cu/TiO{sub 2} > TiO{sub 2} > Rh/TiO{sub 2}. To further increase the number of site for the reaction, we propose to prepare monolayer and multiplayer TiOx on high surface area mesoporous oxides. These catalysts will be used for in situ IR study in the Phase II research project to determine the reactivity of adsorbates. Identification of active adsorbates and sites will allow incorporation of acid/basic sites to alter the nature of CO{sub 2} and H{sub 2}O adsorbates and with Pt/Cu sites to direct reaction pathways of surface intermediates, enhancing the overall activity and selectivity for methanol and hydrocarbon synthesis. The overall goal of this research is to provide a greater predictive capability for the design of visible light-photosynthesis catalysts by a deeper understanding of the reaction kinetics and mechanism as well as by better control of the coordination/chemical environment of active sites.

  5. Visible light activity of pulsed layer deposited BiVO{sub 4}/MnO{sub 2} films decorated with gold nanoparticles: The evidence for hydroxyl radicals formation

    Energy Technology Data Exchange (ETDEWEB)

    Trzciński, Konrad, E-mail: trzcinskikonrad@gmail.com [Faculty of Chemistry, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Szkoda, Mariusz [Faculty of Chemistry, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Sawczak, Mirosław [Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid Flow Machinery, Fiszera 14, 80-231 Gdansk (Poland); Karczewski, Jakub [Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland); Lisowska-Oleksiak, Anna [Faculty of Chemistry, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk (Poland)

    2016-11-01

    Highlights: • The BiVO{sub 4} + MnO{sub 2} photoactive layers were prepared by pulsed laser deposition method. • Prepared layers can act as photoanodes for water splitting. • The thin BiVO{sub 4} + MnO{sub 2} film can be used as photocatalyst for methylene blue degradation. • The formation of hydroxyl radicals during photocatalys illumination has been proved. • The dropcasted GNP improved significantly photocatalytic properties of tested layers. - Abstract: Thin films containing BiVO{sub 4} and MnO{sub 2} deposited on FTO and modified by Au nanoparticles were studied towards their photoelectrochemical and photocatalytical activities in an aqueous electrolyte. Electrodes were prepared by the pulsed laser deposition (PLD) method. The surfactant-free ablation process was used for preparation of the gold nanoparticles (GNP) water suspension. Obtained layers of varied thicknesses (27–115 nm) were characterized using Raman spectroscopy, UV–vis spectroscopy and scanning electron microscopy. Electrochemical methods such as electrochemical impedance spectroscopy, linear voltammetry and chronoamperometry under visible light illumination and in the dark were applied to characterize layers as photoanodes. Simple modification of the BiVO{sub 4} + MnO{sub 2} layer by drop-casting of small amount of colloidal gold (1.5 × 10{sup −14} mol of GNP on 1 cm{sup 2}) leads to enhancement of the generated photocurrent recorded at E = 0.5 V vs. Ag/AgCl (0.1 M KCl) from 63 μA/cm{sup 2} to 280 μA/cm{sup 2}. Photocatalytical studies were also exploited towards decomposition of methylene blue (MB). A possible mechanism of MB photodegradation was proposed. The formation of hydroxyl radicals was detected by photoluminescence spectra using terephthalic acid as the probe molecule.

  6. Photovoltaic cells based on ternary P3HT:PCBM:polymethine dye active layer transparent in the visible range of light

    Energy Technology Data Exchange (ETDEWEB)

    Bliznyuk, Valery N., E-mail: vblizny@clemson.edu [Department of Materials Science and Engineering, Clemson University, Clemson, SC, 29634 (United States); Gasiorowski, Jacek [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Ishchenko, Alexander A.; Bulavko, Gennadiy V. [Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 Murmanskaya str., Kiev 02660 (Ukraine); Rahaman, Mahfujur [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Hingerl, Kurt [Center for Interface and Nanoanalytics, Johannes Kepler University, Linz 4040 (Austria); Zahn, Dietrich R.T. [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Sariciftci, Niyazi S. [Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Johannes Kepler University, Linz 4040 (Austria)

    2016-12-15

    Highlights: • Addition of a polymethine dye to P3HT:PCBM bulk-heterojunction (BHJ) films leads to a compositionally induced transparency in the system. • Variation of the complex refractive index in binary and ternary BHJ films has been studied with spectroscopic ellipsometry. • Power conversion efficiency of ternary BHJ solar cells is determined by the dye composition and photodoping. - Abstract: Optical and photovoltaic properties were studied for ternary photovoltaic cells containing a traditional donor-acceptor bulk-heterojunction (BHJ) active layer modified with polymethine dye molecules in a broad range of compositions and wavelengths. An effect of composition induced optical transparency, due to the strong modification of the density of states, was observed for symmetrical compositions with approximately equal amount of components. Based on our spectroscopic ellipsometry and atomic force microscopy (AFM) studies we can suggest that the variation of the refractive index, which is significantly reduced in the visible range for ternary systems, is involved in the physical mechanism of the phenomenon. Despite of an addition of the IR absorbing component (which allows broadening of the absorption band to up to 800 nm) no improvement in the power conversion efficiency (PCE) is observed in comparison to the binary BHJ system (P3HT:PCBM). Nevertheless, we believe that further advance of the efficiency will be possible if the energy levels will be chemically designed to avoid formation of charge traps at the BHJ interface during light excitation. Such fine adjustment of the system should become possible with a proper choice of polymer:dye composition due to a high versatility of the polymethine dyes demonstrated in previous studies.

  7. Fabrication of RuO2-Ag3PO4 heterostructure nanocomposites: Investigations of band alignment on the enhanced visible light photocatalytic activity.

    Science.gov (United States)

    Dhanabal, Rengasamy; Velmathi, Sivan; Bose, Arumugam Chandra

    2018-02-15

    The RuO2-Ag3PO4 heterostructured nanocomposite was successfully synthesized by facile in situ deposition of porous ruthenium oxide (RuO2) nanoparticles on the surface of the silver phosphate (Ag3PO4). Under visible light irradiation, the 0.5wt.% RuO2-Ag3PO4 heterostructure photocatalyst exhibits enhanced photocatalytic efficiency compared to other composites of RuO2-Ag3PO4 and Ag3PO4. The optimized 0.5wt.% RuO2-Ag3PO4 nanocomposites exhibited 1.5 times enhanced photocatalytic activity towards the degradation of methylene blue (MB) than Ag3PO4. Moreover, the degradation rate of 0.5wt.% RuO2-Ag3PO4 nanocomposite towards the cationic dyes MB and rhodamine B (RhB) was nearly 6.6 times and 4.7 times higher than that towards the anionic dye methyl orange (MO). The formed heterojunction electric field of 310mV at the interface between RuO2 and Ag3PO4 heterostructure induces downward band bending of Ag3PO4. Also, this electric field increases the separation efficiency of electrons-holes resulting higher degradation efficiency. The quenching effect of scavengers test confirms that holes are reactive species and the RuO2-Ag3PO4 nanocomposite is highly stable, exhibited 88% of MB degradation after 4 recycles. The RuO2-Ag3PO4 nanocomposites inhibit self oxidation of Ag3PO4 resulting improved efficiency and stability. Copyright © 2017. Published by Elsevier B.V.

  8. Nanostructure sensitization of transition metal oxides for visible-light photocatalysis

    Science.gov (United States)

    Chen, Hongjun

    2014-01-01

    Summary To better utilize the sunlight for efficient solar energy conversion, the research on visible-light active photocatalysts has recently attracted a lot of interest. The photosensitization of transition metal oxides is a promising approach for achieving effective visible-light photocatalysis. This review article primarily discusses the recent progress in the realm of a variety of nanostructured photosensitizers such as quantum dots, plasmonic metal nanostructures, and carbon nanostructures for coupling with wide-bandgap transition metal oxides to design better visible-light active photocatalysts. The underlying mechanisms of the composite photocatalysts, e.g., the light-induced charge separation and the subsequent visible-light photocatalytic reaction processes in environmental remediation and solar fuel generation fields, are also introduced. A brief outlook on the nanostructure photosensitization is also given. PMID:24991507

  9. Nanostructure sensitization of transition metal oxides for visible-light photocatalysis

    Directory of Open Access Journals (Sweden)

    Hongjun Chen

    2014-05-01

    Full Text Available To better utilize the sunlight for efficient solar energy conversion, the research on visible-light active photocatalysts has recently attracted a lot of interest. The photosensitization of transition metal oxides is a promising approach for achieving effective visible-light photocatalysis. This review article primarily discusses the recent progress in the realm of a variety of nanostructured photosensitizers such as quantum dots, plasmonic metal nanostructures, and carbon nanostructures for coupling with wide-bandgap transition metal oxides to design better visible-light active photocatalysts. The underlying mechanisms of the composite photocatalysts, e.g., the light-induced charge separation and the subsequent visible-light photocatalytic reaction processes in environmental remediation and solar fuel generation fields, are also introduced. A brief outlook on the nanostructure photosensitization is also given.

  10. Enhanced visible light activity on direct contact Z-scheme g-C{sub 3}N{sub 4}-TiO{sub 2} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Li, Juan [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China); College of Chemistry and Chemical Engineering, Henan University, Kaifeng, 475004 (China); Zhang, Min [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China); Li, Qiuye, E-mail: qiuyeli@henu.edu.cn [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China); Yang, Jianjun, E-mail: yangjianjun@henu.edu.cn [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China)

    2017-01-01

    Highlights: • The g-C{sub 3}N{sub 4}-TiO{sub 2} composites were obtained by simple solid state sintering. • The composites were direct contact Z-scheme without an electron mediator. • TiO{sub 2} with large amount of SETOV was obtained by dehydration of NTA. - Abstract: Direct contact Z-scheme g-C{sub 3}N{sub 4}-TiO{sub 2} nanocomposites without an electron mediator are prepared via simple annealing the mixture of bulk g-C{sub 3}N{sub 4} and nanotube titanic acid (NTA) in air at 600 °C for 2 h. In the process of annealing, the bulk g-C{sub 3}N{sub 4} transformed to ultra-thin g-C{sub 3}N{sub 4} nanosheets, and NTA converted to a novel anatase TiO{sub 2}, then the two components formed a close interaction. The XPS result reveals that some amount of nitrogen is doped into this novel-TiO{sub 2}, and g-C{sub 3}N{sub 4} nanosheets exist in the composites. The results of XRD, TEM and TG indicate that the thickness of g-C{sub 3}N{sub 4} nanosheets is very thin. The ESR spectrum shows the existence of Ti{sup 3+} and single-electron-trapped oxygen vacancy in the 30%g-C{sub 3}N{sub 4}-TiO{sub 2} composites. In photocatalytic activity test, the 30%g-C{sub 3}N{sub 4}-TiO{sub 2} nanocomposites showed an excellent photo-oxidation activity of propylene under visible light irradiation (λ≥ 420 nm), and the removal efficiency of propylene reached as high as 56.6%, and the activity kept nearly 82% after four consecutive recycles. Photoluminescence (PL) result using terephthalic acid (TA) as a probe molecule indicated that the g-C{sub 3}N{sub 4}-TiO{sub 2} nanocomposites displayed a Z-sheme photocatalytic reaction system and this should be the main reason for the high photocatalytic activity. A possible photocatalytic mechanism was proposed on the basis of PL result and transient photocurrent-time curves.

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

    OpenAIRE

    Jamal Al-Sabahi; Tanujjal Bora; Mohammed Al-Abri; Joydeep Dutta

    2016-01-01

    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 we...

  12. Implementasi Visible Light Communication (VLC Pada Sistem Komunikasi

    Directory of Open Access Journals (Sweden)

    ARSYAD RAMADHAN DARLIS

    2017-06-01

    Full Text Available Abstrak Perkembangan teknologi telah menunjukkan peningkatan yang cukup signifikan, terutama untuk bidang komunikasi. Hal ini terbukti dengan banyaknya media komunikasi baik itu nirkabel dan kabel. Pada penelitian ini dimanfaatkan cahaya tampak sebagai media dalam sistem komunikasi, dimana selama ini cahaya hanya digunakan sebagai penerangan saja. Visible Light Communication (VLC adalah sebuah teknologi komunikasi yang memanfaatkan pancaran cahaya tampak dari lampu pada sistem komunikasi. Sistem komunikasi visible light ini terdiri dari pemancar dan penerima. Pemancar terdiri dari Light Emitting Dioda, audio transformator dan baterai, dan pada penerima terdiri dari solar cell dan photodioda, amplifier dan catu daya. Hal-hal yang dapat mempengaruhi hasil output sistem komunikasi adalah jarak, terang cahaya lampu pemancar dan cahaya luar. Pada penelitian ini, komunikasi menggunakan VLC dapat dilakukan pada jarak pengiriman data sebesar 2,5 m dan dengan range frekuensi 600 Hz sampai dengan 45 kHz dimana data dapat disalurkan dengan baik. Kata kunci: Visible light, Sistem komunikasi, Light Emitting Dioda, solar cell, photodioda. Abstract Technological developments have shown a significant increase, especially in the field of communication. This is proved by the many communications media using both wireless and wired. This study utilized the visible light as a medium of communication system, which has been used as an illumination light only. Visible Light Communication (VLC is a communication technology which utilize visible light emitted from the lamp in the communication system. The visible light communication system consists of a transmitter and receiver. The transmitter consists of a Light Emitting Diode, audio transformer and battery, and the receiver consists of a solar cell and a photodiode, amplifier and power supply. Things that can affect the output of the communication system is the distance, bright light and outdoor light. In the research

  13. Security in Visible Light Communication: Novel Challenges and Opportunities

    Directory of Open Access Journals (Sweden)

    Christian ROHNER

    2015-09-01

    Full Text Available As LED lighting becomes increasingly ubiquitous, Visible Light Communication is attracting the interest of academia and industry as a complement to RF as the physical layer for the Internet of Things. Aside from its much greater spectral availability compared to RF, visible light has several attractive properties that may promote its uptake: its lack of health risks, its opportunities for spatial reuse, its relative immunity to multipath fading, its lack of electromagnetic interference, and its inherently secure nature: differently from RF, light does not penetrate through walls. In this paper, we outline the security implications of Visible Light Communication, review the existing contributions to this under-explored space, and survey the research opportunities that we envision for the near future.

  14. Invisibility Cloaking Based on Geometrical Optics for Visible Light

    Science.gov (United States)

    Ichikawa, H.; Oura, M.; Taoda, T.

    2013-06-01

    Optical cloaking has been one of unattainable dreams and just a subject in fiction until recently. Several different approaches to cloaking have been proposed and demonstrated: stealth technology, active camouflage and transformation optics. The last one would be the most formal approach modifying electromagnetic field around an object to be cloaked with metamaterials. While cloaking based on transformation optics, though valid only at single frequency, is experimentally demonstrated in microwave region, its operation in visible spectrum is still distant from realisation mainly owing to difficulty in fabricating metamaterial structure whose elements are much smaller than wavelength of light. Here we show that achromatic optical cloaking in visible spectrum is possible with the mere principle based on geometrical optics. In combining a pair of polarising beam splitters and right-angled prisms, rays of light to be obstructed by an object can make a detour to an observer, while unobstructed rays go straight through two polarising beam splitters. What is observed eventually through the device is simply background image as if nothing exists in between.

  15. 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.

  16. Ternary ZnO/AgI/Ag{sub 2}CO{sub 3} nanocomposites: Novel visible-light-driven photocatalysts with excellent activity in degradation of different water pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Golzad-Nonakaran, Behrouz; Habibi-Yangjeh, Aziz, E-mail: ahabibi@uma.ac.ir

    2016-12-01

    ZnO/AgI/Ag{sub 2}CO{sub 3} nanocomposites with different Ag{sub 2}CO{sub 3} contents were fabricated by a facile ultrasonic-irradiation method. The resultant samples were fairly characterized using XRD, EDX, SEM, TEM, UV–vis DRS, FT-IR, and PL techniques to reveal their microstructure, purity, morphology, and spectroscopic properties. Photocatalytic activity of the prepared samples was investigated by photodegradation of four dye pollutants (rhodamine B, methyl orange, methylene blue, and fuchsine) under visible-light irradiation. The photocatalytic experiments in degradation of rhodamine B showed that the ternary ZnO/AgI/Ag{sub 2}CO{sub 3} (30%) nanocomposite has an enhanced activity nearly 19 and 14 times higher than those of the binary ZnO/Ag{sub 2}CO{sub 3} and ZnO/AgI photocatalysts, respectively. Based on the obtained results, the highly enhanced activity was attributed to generation of more electron-hole pairs under visible-light irradiation and separation of the photogenerated charge carriers due to formation of tandem n-n heterojunctions between counterparts of the nanocomposite. The active species trapping experiments were also examined and it was showed that superoxide ion radicals play a vital role in the photocatalytic degradation reaction. More importantly, the ternary photocatalyst demonstrated good photostability. - Highlights: • ZnO/AgI/Ag{sub 2}CO{sub 3} nanocomposites were fabricated by an ultrasonic-irradiation method. • The activity was investigated by photodegradation of four dyes under visible light. • ZnO/AgI/Ag{sub 2}CO{sub 3} (30%) nanocomposite has the best activity under visible light. • Activity is 19 and 14-folds higher than ZnO/Ag{sub 2}CO{sub 3} and ZnO/AgI in degradation of RhB.

  17. 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.

  18. A Highly Active System for the Metal-Free Aerobic Photocyanation of Tertiary Amines with Visible Light: Application to the Synthesis of Tetraponerines and Crispine A.

    Science.gov (United States)

    Orejarena Pacheco, Julio Cesar; Lipp, Alexander; Nauth, Alexander M; Acke, Fabian; Dietz, Jule-Philipp; Opatz, Till

    2016-04-04

    A highly efficient metal-free catalytic system for the aerobic photocyanation of tertiary amines with visible light is reported. The use of air as terminal oxidant offers an improved safety profile compared with pure oxygen, the used compact fluorescent lamp (CFL) light sources are highly economical, and no halogenated solvents are required. This system not only proves to be effective for a wide variety of trialkylamines, pharmaceuticals, and alkaloids but remarkably also allows the lowest catalyst loading (0.00001 mol% or 0.1 ppm) ever reported for an organic dye. Bruylants reactions and C-alkylation/decyanations were performed on the obtained α-aminonitriles to demonstrate the postfunctionalization of complex molecules. The catalytic system is furthermore applied in the short and effective syntheses of the alkaloids (±)-crispine A and the tetraponerines T7 and T8. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Hydrothermal synthesis of hierarchical rose-like Bi{sub 2}WO{sub 6} microspheres with high photocatalytic activities under visible-light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    He Jinyun, E-mail: hejinyun@glite.edu.cn [Sate Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Key Laboratory of New Processing Technology for Nonferrous Metals and Materials, Ministry of Education, Guilin University of Technology, Guilin 541004 (China); Wang Weimin, E-mail: wangwm@hotmail.com [Sate Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Long Fei; Zou Zhengguang [Key Laboratory of New Processing Technology for Nonferrous Metals and Materials, Ministry of Education, Guilin University of Technology, Guilin 541004 (China); Fu Zhengyi [Sate Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Xu Zhe [Hubei Province Supervision and Testing Institute For Building Materials Product Quality, Wuhan 430071 (China)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer Rose-like Bi{sub 2}WO{sub 6} microspheres were synthesized through a hydrothermal route. Black-Right-Pointing-Pointer Thiourea and acetic acid were used as complexing agents. Black-Right-Pointing-Pointer The microspheres were constructed by many nanoflakes with nanocrystals on them. Black-Right-Pointing-Pointer The structure was formed through a hierarchical assembly process. Black-Right-Pointing-Pointer The photocatalyst showed excellent visible-light-driven photocatalytic performance. - Abstract: Hierarchical rose-like Bi{sub 2}WO{sub 6} photocatalyst was successfully synthesized through a simple hydrothermal route using thiourea and acetic acid as complexing agents. The as-synthesized product was determined as pure orthorhombic Bi{sub 2}WO{sub 6} based on the results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. The photocatalyst had an average diameter of 2-3 {mu}m and it was constructed by many nanoflakes. The surfaces of these nanoflakes were coarse and had many nanocrystals on them. The hierarchical rose-like structure was formed through a typical hierarchical assembly process with the synergistic action of acetic acid and thiourea. The photocatalyst showed excellent visible-light-driven photocatalytic performance, it could decompose rhodamine B(RhB) within 50 min. This excellent performance resulted from its special microstructure and the relatively large surface area.

  20. VISIBLE LIGHT INDUCED PHOTOCATALYTIC DEGRADATION OF ...

    African Journals Online (AJOL)

    a

    Photocatalytic degradation of eosin and erythrosin-B (xanthene dyes) has been carried out using anthracene semiconductor ... KEY WORDS: Photocatalytic, Degradation, Xanthene dyes, Immobilized anthracene ... light intensity was measured with the help of a solarimeter (Surya Mapi Model CEL 201, India). The progress ...

  1. VISIBLE LIGHT INDUCED PHOTOCATALYTIC DEGRADATION OF ...

    African Journals Online (AJOL)

    a

    ABSTRACT. Photocatalytic degradation of eosin and erythrosin-B (xanthene dyes) has been carried out using anthracene semiconductor immobilized on polyethylene films. Effect of various parameters like pH, concentration of dyes, amount of semiconductor and light intensity have been studied on the rate of reaction.

  2. Microtruss structures with enhanced elasticity fabricated through visible light photocuring

    Directory of Open Access Journals (Sweden)

    Hari Nanthakumar

    Full Text Available We report on the fabrication of an open cellular solid structure using visible light photocuring in combination with light-induced self-writing. A visible light sensitive photopolymer is irradiated with multiple arrays of microscale optical beams, which are generated from LEDs. These beams undergo self-trapping and elicit the inscription of microscale, solid struts into the medium. This process creates a structure consisting of multiple, intersecting struts that form a microtruss structure. Such structures retain their elasticity at higher temperatures as compared to a bulk film of the same thickness. This is the first demonstration of visible light photocuring of photopolymers into a microtruss structure, as well as investigation into their elastic properties under tension. Keywords: Polymers, Self-trapping, Microstructures, Cellular solids

  3. A comparative study of optical concentrators for visible light communications

    Science.gov (United States)

    Mulyawan, Rahmat; Gomez, Ariel; Chun, Hyunchae; Rajbhandari, Sujan; Manousiadis, Pavlos P.; Vithanage, Dimali A.; Faulkner, Grahame; Turnbull, Graham A.; Samuel, Ifor D. W.; Collins, Stephen; O'Brien, Dominic

    2017-01-01

    Given the imminent radio frequency spectrum crunch, Visible Light Communication (VLC) is being proposed as an alternative wireless technology allowing for scalable connectivity to potentially millions of mobile and Internet-of- Things (IoT) devices. A VLC system uses a photo-detector (PD) receiver that converts the optically modulated light from a light source into a modulated electrical signal. The corresponding receiver electrical bandwidth is typically inversely proportional to the PD active area. Consequently, to construct a high-speed VLC link, the PD active area is often substantially reduced and an optical concentrator is used to enhance the receiver collection area. However, to achieve high concentrating factor, the link field-of-view (FOV) needs to be narrow due to the étendue conservation in linear passive optical systems. This paper studies a Fluorescent Concentrator (FC) that breaks this étendue conservation. The FC is not only based on reflective and refractive principles but also makes use of fluorescence process. A comparison between the FC and conventional optical concentrators, namely Compound Parabolic Concentrator (CPC) is also investigated. The trade-off between received signal strength and incoming link angle is demonstrated over 60° coverage. Experimental results show that performance degradation as the link angle increases using FC-based receivers is significantly lower than for conventional CPC.

  4. Ultraviolet and visible light penetration of epidermis

    Energy Technology Data Exchange (ETDEWEB)

    Eggset, G.; Kavli, G.; Volden, G. (Tromsoe Univ. (Norway). Dept. of Dermatology); Krokan, H. (Tromsoe Univ. (Norway). Inst. of Medical Biology)

    1984-10-01

    Light penetration in untanned skin and skin tanned with UVB (middlewave ultraviolet light) or PUVA (Psoralen photochemotherapy) was compared. Transmission at different wavelengths was measured through sheets of intact epidermis isolated by a suction blister technique. Thick epidermis was collected from a newly formed palmar friction bulla. For these studies a monochromator was used and the range of wavelengths examined was 280-700 nm. The transmission was considerably lower in tanned skin and the difference was most pronounced in the UV range. In the UVB range (290-320 nm), transmission was 13-43% for untanned epidermis, 8-12% for UVB tanned and slightly lower for PUVA tanned epidermis. At wavelengths below 325 nm only a few per cent of light penetrate through thick palmar epidermis. Both UVB and PUVA induce increased melanin content and thickening of the epidermis. Our results indicate that melanin is the most efficient protection against UVA while thickening of epidermis may be as important as the increased melanin content for the protection of living basal cells against the harmful UVB rays.

  5. High activity of Ag-doped Cd0.1Zn0.9S photocatalyst prepared by the hydrothermal method for hydrogen production under visible-light irradiation

    Directory of Open Access Journals (Sweden)

    Leny Yuliati

    2014-05-01

    Full Text Available Background: The hydrothermal method was used as a new approach to prepare a series of Ag-doped Cd0.1Zn0.9S photocatalysts. The effect of Ag doping on the properties and photocatalytic activity of Cd0.1Zn0.9S was studied for the hydrogen production from water reduction under visible light irradiation.Results: Compared to the series prepared by the co-precipitation method, samples prepared by the hydrothermal method performed with a better photocatalytic activity. The sample with the optimum amount of Ag doping showed the highest hydrogen production rate of 3.91 mmol/h, which was 1.7 times higher than that of undoped Cd0.1Zn0.9S. With the Ag doping, a red shift in the optical response was observed, leading to a larger portion of the visible light absorption than that of without doping. In addition to the larger absorption in the visible-light region, the increase in photocatalytic activity of samples with Ag doping may also come from the Ag species facilitating electron–hole separation.Conclusion: This study demonstrated that Ag doping is a promising way to enhance the activity of Cd0.1Zn0.9S photocatalyst.

  6. Improved spring model-based collaborative indoor visible light positioning

    Science.gov (United States)

    Luo, Zhijie; Zhang, WeiNan; Zhou, GuoFu

    2016-06-01

    Gaining accuracy with indoor positioning of individuals is important as many location-based services rely on the user's current position to provide them with useful services. Many researchers have studied indoor positioning techniques based on WiFi and Bluetooth. However, they have disadvantages such as low accuracy or high cost. In this paper, we propose an indoor positioning system in which visible light radiated from light-emitting diodes is used to locate the position of receivers. Compared with existing methods using light-emitting diode light, we present a high-precision and simple implementation collaborative indoor visible light positioning system based on an improved spring model. We first estimate coordinate position information using the visible light positioning system, and then use the spring model to correct positioning errors. The system can be employed easily because it does not require additional sensors and the occlusion problem of visible light would be alleviated. We also describe simulation experiments, which confirm the feasibility of our proposed method.

  7. High-quality elliptical iron glycolate nanosheets: selective synthesis and chemical conversion into FexOy nanorings, porous nanosheets, and nanochains with enhanced visible-light photocatalytic activity

    Science.gov (United States)

    Tong, Guoxiu; Liu, Yun; Wu, Tong; Ye, Yucheng; Tong, Chaoli

    2015-10-01

    This paper describes an original and facile polyol-mediated solvothermal synthesis of elliptical iron glycolate nanosheets (IGNSs) combined with precursor thermal conversion into γ-Fe2O3 and α-Fe2O3/γ-Fe2O3 porous nanosheets (PNSs), α-Fe2O3 nanochains (NCs), and elliptical Fe3O4 nanorings (NRs). The IGNSs were produced via the oxidation-reduction and co-precipitation reactions in the presence of iron(iii) salts, ethylene glycol, polyethylene glycol, and ethylenediamine. Control over Fe3+ concentration, temperature, and time can considerably modulate the size and phase of the products. The IGNSs can be transformed to γ-Fe2O3 and α-Fe2O3/γ-Fe2O3 PNSs, α-Fe2O3 NCs, and elliptical Fe3O4 NRs by heat treatment under various annealing temperatures and ambiences. The PNSs and NCs exhibited high soft magnetic properties and coercivity, respectively. Visible-light photocatalytic activity toward RhB in the presence of H2O2 by PNSs and NCs was phase-, SBET, size-, porosity-, and local structure-dependent, following the order: α-Fe2O3 NCs > α-Fe2O3/γ-Fe2O3 PNSs > γ-Fe2O3 PNSs > IGNSs. In particular, α-Fe2O3/γ-Fe2O3 PNSs possessed significantly enhanced photocatalytic activity with good recyclability and could be conveniently separated by an applied magnetic field because of high magnetization. We believe that the as-prepared α-Fe2O3/γ-Fe2O3 PNSs have potential practical use in waste water treatment and microwave absorption.This paper describes an original and facile polyol-mediated solvothermal synthesis of elliptical iron glycolate nanosheets (IGNSs) combined with precursor thermal conversion into γ-Fe2O3 and α-Fe2O3/γ-Fe2O3 porous nanosheets (PNSs), α-Fe2O3 nanochains (NCs), and elliptical Fe3O4 nanorings (NRs). The IGNSs were produced via the oxidation-reduction and co-precipitation reactions in the presence of iron(iii) salts, ethylene glycol, polyethylene glycol, and ethylenediamine. Control over Fe3+ concentration, temperature, and time can

  8. Effect of calcination temperature on structure and photocatalytic activity under UV and visible light of nanosheets from low-cost magnetic leucoxene mineral

    Science.gov (United States)

    Charerntanom, Wissanu; Pecharapa, Wisanu; Pavasupree, Suttipan; Pavasupree, Sorapong

    2017-07-01

    This research has experimentally synthesized the nanosheets from the naturally-mineral magnetic leucoxene under the hydrothermal synthesis condition of 105 °C for 24 h. Magnetic leucoxene was utilized as the starting material due to its high TiO2 content (70-80%) and inexpensiveness. The characterization of the synthesized nanosheets was subsequently carried out: the crystalline structure, the chemical composition, the shape, the size and the specific surface area, by the X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) specific surface area analysis. The analysis results indicated that the starting magnetic leucoxene is of rutile phase while the synthesized nanosheets are of titanate structure (H2TixO2x + 1). After calcination at the temperature range of 300 and 400 °C, the calcined samples demonstrated TiO2 (B). At 500 and 600 °C, the calcined nanosheets revealed a bi-crystalline mixture consisting of TiO2 (B) and anatase TiO2. At 700-1000 °C, the crystalline structure shows anatase and rutile phase. At 1100 °C, the prepared samples consisted of a mixture of anatase, rutile phase of TiO2, and Fe2O3 phase. The synthesized product also exhibited the flower-like morphology with 2-5 μm in diameter, and the nanosheets structure was slightly curved, with 100 nm to 2 μm in width and 1-3 nm in thickness. At 100-200 °C showed sheets-like structure. At 300-1100 °C, the calcined nanosheets became unstable and began to decompose and transform into nanoparticles. The increasing size of nanoparticle decreased the specific surface area of the nanosheets, caused by increasing calcination temperature. Furthermore, the BET specific surface area of the nanosheets was approximately 279.8 m2/g. More importantly, the synthesized nanosheets achieved the higher photocatalytic activity under UV and visible light than did the commercial TiO2 nanoparticles (JRC-01, JRC-03

  9. Visible and ultraviolet light sources based nonlinear interaction of lasers

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer; Tidemand-Lichtenberg, Peter; Jain, Mayank

    Different light sources can be used for optically stimulated luminescence measurements and usually a halogen lamp in combination with filters or light emitting diodes (LED’s) are used to provide the desired stimulation wavelength. However lasers can provide a much more well-defined beam, very...... for synthesizing any wavelength in the visible and ultraviolet light based sum frequency generation between two lasers is presented....

  10. 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.

  11. Aviation signal lighting : impacts of lighting characteristics on visibility.

    Science.gov (United States)

    2011-01-01

    This paper summarizes research on visual responses to colored light signals in the aviation and : roadway environment and on government requirements for lighting along airfields. The objective : is to identify gaps in the knowledge about how individu...

  12. Enhancement of Light via Surface Plasmon Coupling in the Visible

    Science.gov (United States)

    Ray, Emily A.

    The incidence of light with momentum components outside the light cone on the surface of a negative permittivity material results in the excitation of a surface plasmon polariton and the enhancement of the incident signal when there is momentum and energy conservation. This process has an impact across many fields including imaging, optical computing, signaling, and photovoltaic devices, among others. I examine the role and tunability of light-surface plasmon interactions in several applications. I demonstrate a tuned metamaterial grating system that allows the signal from evanescent waves to be detected in the far field in the visible regime. I fabricate a metamaterial that is tuned to support surface plasmons that couple to visible light across a wide range of wavelengths. I characterize the plasmonic response through a simple technique wherein a the reflection from a subwavelength grating on a metamaterial indicates surface plasmon coupling when its intensity dips. With this I demonstrate that the reflection trends match well with simulation, indicating that coupling of light to surface plasmons occurs at the expected crossing points. The strength of coupling (denoted by the drop in reflection) however, is less than expected. Transmission measurements reveal a depolarizing effect that accounts for the decrease in evanescent light enhancement by the surface plasmons and is due to the surface roughness at the interfaces between the metal and dielectric. I also use a tuned metamaterial perforated with a subwavelength array of circular apertures to exhibit extraordinary transmission in the visible. I compare the transmission of the metamaterial to that of a thin film of Ag with equivalent thickness that has fewer plasmon modes and a resonance position in the UV to find that for 400 nm, both thin films exhibit a transmission minimum at 650 nm. Both film spectra have plasmon-aided extraordinary transmission peaks where there is momentum and energy conservation between

  13. Visible-light-driven Ag/AgBr/ZnFe2O4composites with excellent photocatalytic activity for E. coli disinfection and organic pollutant degradation.

    Science.gov (United States)

    Xu, Yuanguo; Liu, Qingqing; Liu, Chenchen; Zhai, Yunpeng; Xie, Meng; Huang, Liying; Xu, Hui; Li, Huaming; Jing, Junjie

    2018-02-15

    Visible-light-driven (VLD) Ag/AgBr/ZnFe 2 O 4 composites with different weight ratios of ZnFe 2 O 4 were synthesized via a facile hydrothermal method. The ZnFe 2 O 4 was evenly dispersed on the surface of Ag/AgBr particles with the diameter about 20 nm. The obtained Ag/AgBr/ZnFe 2 O 4 composites exhibited the high bacterial disinfection efficiency and inactivated bacteria after 120 min visible illumination, which was better than those of with pure ZnFe 2 O 4 and Ag/AgBr. Due to the introduction of ZnFe 2 O 4 , the Ag/AgBr/ZnFe 2 O 4 inactivated bacterial cells through the generation of H 2 O 2 , which generated from the electron reduction on the conduction band of ZnFe 2 O 4 in the system. The photocatalytic experiments indicated that as-prepared samples showed the good photocatalytic performance toward degradation of methyl orange (MO) dye. In a word, the Ag/AgBr/ZnFe 2 O 4 composites, as the antibacterial photocatalyst, is a promising candidate material in wastewater decontamination. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Visible light photocatalytic activities of template free porous graphitic carbon nitride-BiOBr composite catalysts towards the mineralization of reactive dyes

    Science.gov (United States)

    Kanagaraj, Thamaraiselvi; Thiripuranthagan, Sivakumar; Paskalis, Sahaya Murphin Kumar; Abe, Hideki

    2017-12-01

    Template free porous g-C3N4 (pGCN) and flower like bismuth oxybromide catalysts were synthesized by poly condensation and precipitation methods respectively. Various weight percentages of porous GCN-BiOBr composite catalysts (x% pGCN-BiOBr where x = 5, 10, 30, 50 & 70 wt% of pGCN) were synthesized by impregnation method. All the synthesized catalysts were characterized by X-Ray diffractometer, Fourier transform infrared spectrophotometer, BET surface area analyzer, UV Visible diffuse reflectance spectrophotometer, X-Ray photoelectron spectrophotometer, SEM with Energy dispersive X-ray analyzer (SEM/EDAX) and elemental mapping, Transmission electron microscope, Photoluminescence spectrophotometer and Electrochemical impedance. Photocatalytic degradation of all the synthesized catalysts were tested towards the harmful reactive dyes such as reactive blue 198 (RB 198), reactive black 5 (RB 5) and reactive yellow 145 (RY 145) in presence of visible irradiation. Among the catalysts 30% pGCN-BiOBr resulted in the highest photocatalytic activity towards the degradation of all the three dyes in presence of UV, visible and solar irradiations. Kinetics studies on the photocatalytic mineralization of dyes indicated that it followed pseudo first order. HPLC, TOC and COD studies confirm that the dyes are mineralized into CO2, water and mineral salts.

  15. Tubular g-C3 N4 Isotype Heterojunction: Enhanced Visible-Light Photocatalytic Activity through Cooperative Manipulation of Oriented Electron and Hole Transfer.

    Science.gov (United States)

    Tong, Zhenwei; Yang, Dong; Sun, Yuanyuan; Nan, Yanhu; Jiang, Zhongyi

    2016-08-01

    A tubular g-C3 N4 isotype heterojunction (TCNH) photocatalyst was designed for cooperative manipulation of the oriented transfer of photogenerated electrons and holes to pursue high catalytic performance. The adduct of cyanuric acid and melamine (CA·M) is first hydrothermally treated to assemble into hexagonal prism crystals; then the hybrid precursors of urea and CA·M crystals are calcined to form tubular g-C3 N4 isotype heterojunctions. Upon visible-light irradiation, the photogenerated electrons transfer from g-C3 N4 (CA·M) to g-C3 N4 (urea) driven by the conduction band offset of 0.05 eV, while the photogenerated holes transfer from g-C3 N4 (urea) to g-C3 N4 (CA·M) driven by the valence band offset of 0.18 eV, which renders oriented transfer of the charge carriers across the heterojunction interface. Meanwhile, the tubular structure of TCNH is favorable for oriented electron transfer along the longitudinal dimension, which greatly decreases the chance of charge carrier recombination. Consequently, TCNH exhibits a high hydrogen evolution rate of 63 μmol h(-1) (0.04 g, λ > 420 nm), which is nearly five times of the pristine g-C3 N4 and higher than most of the existing g-C3 N4 photocatalysts. This study demonstrates that isotype heterojunction structure and tubular structure can jointly manipulate the oriented transfer of electrons and holes, thus facilitating the visible-light photocatalysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. High visibility two-photon interference with classical light.

    Science.gov (United States)

    Hong, Peilong; Xu, Lei; Zhai, Zhaohui; Zhang, Guoquan

    2013-06-17

    Two-photon interference with independent classical sources, in which superposition of two indistinguishable two-photon paths plays a key role, is of limited visibility with a maximum value of 50%. By using a random-phase grating to modulate the wavefront of a coherent light, we introduce superposition of multiple indistinguishable two-photon paths, which enhances the two-photon interference effect with a signature of visibility exceeding 50%. The result shows the importance of phase control in the control of high-order coherence of classical light.

  17. Graphene quantum dot sensitized leaf-like InVO4/BiVO4 nanostructure: a novel ternary heterostructured QD-RGO/InVO4/BiVO4 composite with enhanced visible-light photocatalytic activity.

    Science.gov (United States)

    Lin, Xue; Wang, Yushuang; Zheng, Jia; Liu, Chang; Yang, Yang; Che, Guangbo

    2015-11-28

    Leaf-like InVO4/BiVO4 nanostructures with sizes of 2-5 μm were synthesized by a simple hydrothermal method. Graphene quantum dots (QD-RGO) were then deposited onto the surfaces of the leaf-like InVO4/BiVO4 crystals through a facile deposition-precipitation technique. Under visible light irradiation (λ > 420 nm), the QD-RGO/InVO4/BiVO4 photocatalyst degraded rhodamine B (Rh B) efficiently and displayed a much higher photocatalytic activity than pure BiVO4, InVO4, RGO/InVO4, RGO/BiVO4 or an InVO4/BiVO4 hybrid. The InVO4/BiVO4 photocatalyst with 3 wt% of QD-RGO exhibited the highest photocatalytic efficiency. The quenching effects of different scavengers demonstrated that O2˙(-) played a major role in Rh B degradation. It was elucidated that the excellent photocatalytic activity of QD-RGO/InVO4/BiVO4 for the degradation of Rh B under visible light (λ > 420 nm) can be ascribed to the extended absorption in the visible light region resulting from the QD-RGO loading, the high specific surface area, and the efficient separation of photogenerated electrons and holes through the QD-RGO/InVO4/BiVO4 heterostructure.

  18. Visible light guided manipulation of liquid wettability on photoresponsive surfaces

    Science.gov (United States)

    Kwon, Gibum; Panchanathan, Divya; Mahmoudi, Seyed Reza; Gondal, Mohammed A.; McKinley, Gareth H.; Varanasi, Kripa K.

    2017-04-01

    Photoresponsive titania surfaces are of great interest due to their unique wettability change upon ultraviolet light illumination. However, their applications are often limited either by the inability to respond to visible light or the need for special treatment to recover the original wettability. Sensitizing TiO2 surfaces with visible light-absorbing materials has been utilized in photovoltaic applications. Here we demonstrate that a dye-sensitized TiO2 surface can selectively change the wettability towards contacting liquids upon visible light illumination due to a photo-induced voltage across the liquid and the underlying surface. The photo-induced wettability change of our surfaces enables external manipulation of liquid droplet motion upon illumination. We show demulsification of surfactant-stabilized brine-in-oil emulsions via coalescence of brine droplets on our dye-sensitized TiO2 surface upon visible light illumination. We anticipate that our surfaces will have a wide range of applications including microfluidic devices with customizable wettability, solar-driven oil-water clean-up and demulsification technologies.

  19. A Visible-Light-Sensitive Caged Serotonin

    OpenAIRE

    Cabrera, R.; Filevich, O; Garcia-Acosta, B; Athilingam, J; Bender, KJ; Poskanzer, KE; R. Etchenique

    2017-01-01

    Serotonin, or 5-hydroxytryptamine (5HT), is an important neurotransmitter in the nervous system of both vertebrates and invertebrates. Deficits in 5HT signaling are responsible for many disabling psychiatric conditions, and its molecular machinery is the target of many pharmaceuticals. We present a new 5HT phototrigger, the compound [Ru(bpy)2(PMe3)(5HT)]2+, where PMe3 is trimethylphosphine. As with other ruthenium-bipyridyl based caged compounds, [Ru(bpy)2(PMe3)(5HT)]2+ presents activity in t...

  20. Effect of calcination temperature on the structure and visible-light photocatalytic activities of (N, S and C) co-doped TiO{sub 2} nano-materials

    Energy Technology Data Exchange (ETDEWEB)

    Lei, X.F., E-mail: leixuefei69@163.com [School of Resources and Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004 (China); Institute of Metallurgical Resource and Environmental Engineering, Northeastern University, Shenyang 110819 (China); Liaoning Key Laboratory of Metallurgical Resource Recycling Science, Shenyang 110819 (China); Liaoning Engineering and Technology Research Center of Boron Resource, Comprehensive Utilization, Shenyang 110819 (China); Liaoning Provincial Universities Key Laboratory of Boron Resource Ecological, Utilization Technology and Boron Materials, Shenyang 110819 (China); Xue, X.X.; Yang, H. [Institute of Metallurgical Resource and Environmental Engineering, Northeastern University, Shenyang 110819 (China); Liaoning Key Laboratory of Metallurgical Resource Recycling Science, Shenyang 110819 (China); Liaoning Engineering and Technology Research Center of Boron Resource, Comprehensive Utilization, Shenyang 110819 (China); Liaoning Provincial Universities Key Laboratory of Boron Resource Ecological, Utilization Technology and Boron Materials, Shenyang 110819 (China); Chen, C.; Li, X.; Niu, M.C.; Gao, X.Y.; Yang, Y.T. [School of Resources and Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004 (China)

    2015-03-30

    Graphical abstract: (N, S and C) co-doped TiO{sub 2} samples show good photocatalytic activity for Cr(VI) reduction under visible light irradiation. - Highlights: • (N, S and C) co-doping in TiO{sub 2} can preserve the anatase form to higher temperature. • (N, S and C) co-doped TiO{sub 2} samples can absorb both UV and visible light. • The band gap energy of the sample significantly reduced after (N, S and C) co-doping. • (N, S and C) co-doped TiO{sub 2} samples effective for visible light induced reduction of Cr(VI). - Abstract: The (N, S and C) co-doped TiO{sub 2} samples (NSC-TiO{sub 2}) were synthesized by the sol–gel method combining with the high energy ball milling method calcined at the different temperature (400–700 °C), employing butyl titanate as the titanium source and thiourea as the doping agent. The structures of NSC-TiO{sub 2} samples were characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (DRS), X-ray photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetry and differential thermal analysis (TG–DTA), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), scanning electron microscopy (SEM) and nitrogen adsorption–desorption isotherms. The photocatalytic activities were checked through the photocatalytic reduction of Cr(VI) as a model compound under visible light irradiation. The results showed that the (N, S and C) co-doping and the calcination temperature played important role on the microstructure and photocatalytic activity of the samples. According to XPS spectra, sulfur was mainly attributed to the Ti−O−S bond; nitrogen was ascribed to the Ti−O−N and Ti−N bonds; carbon was assigned to the Ti−O−C bond in the NSC-TiO{sub 2} samples. (N, S and C) co-doped TiO{sub 2} samples calcinated at 500 °C exhibits higher photocatalytic activity than that of the other samples under visible light irradiation, which can be

  1. Novel ternary component Ag-SrTa{sub 2}O{sub 6}/g-C{sub 3}N{sub 4} photocatalyst: Synthesis, optical properties and visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yiguo; Zhao, Yanxia; Zhao, Yingjie; Lang, Junyu; Xin, Xin; Wang, Xiaojing, E-mail: wang_xiao_jing@hotmail.com

    2015-12-15

    Graphical abstract: A novel ternary component Ag-SrTa{sub 2}O{sub 6}/g-C{sub 3}N{sub 4} photocatalytic system was successfully developed, which showed efficient visible light photocatalytic activity toward Cr(VI) photoreduction and methyl orange degradation. - Highlights: • Ag-SrTa{sub 2}O{sub 6}/g-C{sub 3}N{sub 4} was found to be efficient photocatalyst for visible light Cr(VI) photoreduction and methyl orange degradation. • The matching of the band structure between SrTa{sub 2}O{sub 6} and g-C{sub 3}N{sub 4} induced an efficient photogenerated electron transfer process. • Ag nanoparticles played critical roles in enhancing the photocatalytic activity of Ag-SrTa{sub 2}O{sub 6}/g-C{sub 3}N{sub 4} heterojunctions. - Abstract: In this work, we report on the synthesis of a novel ternary component Ag-SrTa{sub 2}O{sub 6}/g-C{sub 3}N{sub 4} photocatalytic system with efficient visible light photocatalytic activity toward Cr(VI) photoreduction and methyl orange degradation. The samples were carefully characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy, Fourier transformed infrared spectroscopy and photocatalytic test. It is found that SrTa{sub 2}O{sub 6} was deposited on the surface of g-C{sub 3}N{sub 4} and that obtained SrTa{sub 2}O{sub 6}/g-C{sub 3}N{sub 4} heterojunction photocatalyst showed strong absorption in the visible light region. Photocatalytic test indicated that the as-prepared SrTa{sub 2}O{sub 6}/g-C{sub 3}N{sub 4} heterojunction showed increased photocatalytic activity toward Cr(VI) photoreduction and methyl orange degradation in comparison with the bare SrTa{sub 2}O{sub 6} and g-C{sub 3}N{sub 4} under visible light irradiation. The matching of the band structure between SrTa{sub 2}O{sub 6} and g-C{sub 3}N{sub 4} induced an efficient photogenerated electron transfer from the conduction band of g-C{sub 3}N{sub 4} to the conduction band of SrTa{sub 2}O{sub 6

  2. Development of Visible Light-Responsive Sensitized Photocatalysts

    Directory of Open Access Journals (Sweden)

    Donghua Pei

    2012-01-01

    Full Text Available The paper presents a review of studies about the visible-light-promoted photodegradation of the contaminants and energy conversion with sensitized photocatalysts. Herein we studied mechanism, physical properties, and synergism effect of the sensitized photocatalysts as well as the method for enhancing the photosensitized effect. According to the reported studies in the literature, inorganic sensitizers, organic dyes, and coordination metal complexes were very effective sensitizers that were studied mostly, of which organic dyes photosensitization is the most widely studied modified method. Photosensitization is an important way to extend the excitation wavelength to the visible range, and therefore sensitized photocatalysts play an important role in the development of visible light-responsive photocatalysts for future industrialized applications. This paper mainly describes the types, modification, photocatalytic performance, application, and the developments of photosensitization for environmental application.

  3. Synthesis and characterization of noble metal nanocomposites: Ag/Fe3O4/ZnO and Ag/Fe3O4/CuO/ZnO for better photocatalytic activity under visible light irradiation

    Science.gov (United States)

    Tju, H.; Prakoso, S. P.; Taufik, A.; Saleh, R.

    2017-04-01

    Nobel metal such as silver (Ag) nanoparticles have been proven could enhance photocatalytic activity under visible light irradiation and prevent recombination of electron and hole. Fe3O4/ZnO and Fe3O4/CuO/ZnO has been investigated in our previous study. So in this work, a magnetic Ag/Fe3O4/ZnO and Ag/Fe3O4/CuO/ZnO nanocomposites were successfully synthesized using sol-gel method. The as-synthesized products were characterized by X-ray diffraction and ultraviolet-visible (UV-Vis) spectroscopy. The results showed that the nanocomposites were the combination of the desired nanoparticles. From the UV-Vis absorption spectra, we found the surface plasmon resonance (SPR) to be around ~440 nm. Under visible light irradiation, the Ag/Fe3O4/ZnO and Ag/Fe3O4/CuO/ZnO nanocomposites exhibited much higher photocatalytic activity than the Fe3O4/ZnO and Fe3O4/CuO/ZnO. The effect of catalyst dosage and initial concentration of methylene blue (MB) were also tested. To understand the mechanism in photocatalytic activity, several scavengers were tested. The reusability study suggested that the prepared nanocomposites can still maintain the degradation efficiency after four cycles, showing great potential for water purification.

  4. Using Polarization features of visible light for automatic landmine detection

    NARCIS (Netherlands)

    Jong, W. de; Schavemaker, J.G.M.

    2007-01-01

    This chapter describes the usage of polarization features of visible light for automatic landmine detection. The first section gives an introduction to land-mine detection and the usage of camera systems. In section 2 detection concepts and methods that use polarization features are described.

  5. Integrating TEMPO and Its Analogues with Visible-Light Photocatalysis.

    Science.gov (United States)

    Lang, Xianjun; Zhao, Jincai

    2018-01-16

    Visible light has risen to become a very important facilitator for selective radical reactions enabled by well-cognized photocatalysts. The renaissance of visible-light photocatalysis on this matter partly relies on integrating it with other fields of catalysis. In parallel, 2,2,6,6-tetramethylpiperidin N-oxide (TEMPO), a quintessential persistent radical, has a wide range of uses owing to its exceptional redox behavior, which gives rise to its latest prominence in catalysis. Therefore, integrating the catalysis of TEMPO with photocatalysis to perform visible-light-induced selective reactions becomes a very convenient marriage of merits. In this context, the integration of different types of photocatalysts, including metal complexes, metal-free organic dyes, and semiconductors, with TEMPO for outstanding organic transformations will be summarized. To expand further the catalytic repertoire, the integration of TEMPOH analogues such as NHPI (N-hydroxyphthalimide) and NHS (N-hydroxysuccinimide) with photocatalysis will also be discussed. Hopefully, these advances will pave the way for more breakthroughs by integrating TEMPO and its analogues with photocatalysis to lead to a valuable blueprint for visible-light-induced selective organic transformations. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Seeing elements by visible-light digital camera.

    Science.gov (United States)

    Zhao, Wenyang; Sakurai, Kenji

    2017-03-31

    A visible-light digital camera is used for taking ordinary photos, but with new operational procedures it can measure the photon energy in the X-ray wavelength region and therefore see chemical elements. This report describes how one can observe X-rays by means of such an ordinary camera - The front cover of the camera is replaced by an opaque X-ray window to block visible light and to allow X-rays to pass; the camera takes many snap shots (called single-photon-counting mode) to record every photon event individually; an integrated-filtering method is newly proposed to correctly retrieve the energy of photons from raw camera images. Finally, the retrieved X-ray energy-dispersive spectra show fine energy resolution and great accuracy in energy calibration, and therefore the visible-light digital camera can be applied to routine X-ray fluorescence measurement to analyze the element composition in unknown samples. In addition, the visible-light digital camera is promising in that it could serve as a position sensitive X-ray energy detector. It may become able to measure the element map or chemical diffusion in a multi-element system if it is fabricated with external X-ray optic devices. Owing to the camera's low expense and fine pixel size, the present method will be widely applied to the analysis of chemical elements as well as imaging.

  7. Seeing elements by visible-light digital camera

    Science.gov (United States)

    Zhao, Wenyang; Sakurai, Kenji

    2017-01-01

    A visible-light digital camera is used for taking ordinary photos, but with new operational procedures it can measure the photon energy in the X-ray wavelength region and therefore see chemical elements. This report describes how one can observe X-rays by means of such an ordinary camera - The front cover of the camera is replaced by an opaque X-ray window to block visible light and to allow X-rays to pass; the camera takes many snap shots (called single-photon-counting mode) to record every photon event individually; an integrated-filtering method is newly proposed to correctly retrieve the energy of photons from raw camera images. Finally, the retrieved X-ray energy-dispersive spectra show fine energy resolution and great accuracy in energy calibration, and therefore the visible-light digital camera can be applied to routine X-ray fluorescence measurement to analyze the element composition in unknown samples. In addition, the visible-light digital camera is promising in that it could serve as a position sensitive X-ray energy detector. It may become able to measure the element map or chemical diffusion in a multi-element system if it is fabricated with external X-ray optic devices. Owing to the camera’s low expense and fine pixel size, the present method will be widely applied to the analysis of chemical elements as well as imaging. PMID:28361916

  8. Visible light photocatalytic properties of novel molybdenum treated ...

    Indian Academy of Sciences (India)

    Visible light photocatalytic properties of novel molybdenum treated carbon nanotube/titania composites. FENG-JUN ZHANG† and WON-CHUN OH. ∗. School of Materials and Chemical Engineering, Anhui University of Architecture, Anhui Hefei 230022,. P. R. China. †Department of Advanced Materials & Engineering, ...

  9. Rational construction of Z-scheme Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites with enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Jin, E-mail: lj328520504@126.com; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao

    2016-12-30

    Highlights: • Novel visible-light driven Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites were synthesized. • Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} exhibited enhanced visible-light photocatalytic activity. • The reasons for the enhanced photocatalytic activity were revealed. - Abstract: Novel visible-light driven Z-scheme Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites with different contents of Ag{sub 2}CrO{sub 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{sub 3}N{sub 4} and Ag{sub 2}CrO{sub 4}, the Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 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{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composite at a theoretical weight content of 8.0% Ag{sub 2}CrO{sub 4} for the photodegradation of MO was 0.0068 min{sup −1}, which was 5.7 and 4.3 times higher than that of pure g-C{sub 3}N{sub 4} and Ag{sub 2}CrO{sub 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{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 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{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composite for MO degradation under visible light irradiation. Ultimately, a tentative Z-scheme photodegradation mechanism

  10. UV Blocking Glass: Low Cost Filters for Visible Light Photocatalytic Assessment

    Directory of Open Access Journals (Sweden)

    Charles W. Dunnill

    2014-01-01

    Full Text Available A number of commercially available art protection products have been compared and assessed for their suitability as UV blocking filters in the application of “visible light” photocatalytic research. Many groups claiming visible light photocatalytic success employ filters to block out stray UV radiation in order to justify that their photocatalysts are indeed visible light photocatalysts and not UV light photocatalysts. These filters come in varying degrees of ability and price and many authors fail to correctly characterise their filters in individual papers. The use of effective filters to prevent both false positive and false negative results is important to maintain scientific rigor and create accurate understanding of the subject. The optimum UV filter would have the highest UV blocking properties (<390 nm and simultaneously the highest visible light transmission (390–750 nm. Single and double layers of each of the glass products were assessed as well as laminate products. The conclusions show an inexpensive and highly effective setup for the conduction of visible light photochemistry that should be incorporated as a standard part in any researcher’s work where the claim of visible light activity is made.

  11. Recent progress on doped ZnO nanostructures for visible-light photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Samadi, Morasae; Zirak, Mohammad [Department of Physics, Sharif University of Technology, P.O. Box 11555-9161, Tehran (Iran, Islamic Republic of); Naseri, Amene [Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11365-8639, Tehran (Iran, Islamic Republic of); Khorashadizade, Elham [Department of Physics, Sharif University of Technology, P.O. Box 11555-9161, Tehran (Iran, Islamic Republic of); Moshfegh, Alireza Z., E-mail: moshfegh@sharif.edu [Department of Physics, Sharif University of Technology, P.O. Box 11555-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11365-8639, Tehran (Iran, Islamic Republic of)

    2016-04-30

    Global environmental pollution and energy supply demand have been regarded as important concerns in recent years. Metal oxide semiconductor photocatalysts is a promising approach to apply environmental remediation as well as fuel generation from water splitting and carbon dioxide reduction. ZnO nanostructures have been shown promising photocatalytic activities due to their non-toxic, inexpensive, and highly efficient nature. However, its wide band gap hinders photo-excitation for practical photocatalytic applications under solar light as an abundant, clean and safe energy source. To overcome this barrier, many strategies have been developed in the last decade to apply ZnO nanostructured photocatalysts under visible light. In this review, we have classified different approaches to activate ZnO as a photocatalyst in visible-light spectrum. Utilization of various nonmetals, transition metals and rare-earth metals for doping in ZnO crystal lattice to create visible-light-responsive doped ZnO photocatalysts is discussed. Generation of localized energy levels within the gap in doped ZnO nanostructures has played an important role in effective photocatalytic reaction under visible-light irradiation. The effect of dopant type, ionic size and its concentration on the crystal structure, electronic property and morphology of doped ZnO with a narrower band gap is reviewed systematically. Finally, a comparative study is performed to evaluate two classes of metals and nonmetals as useful dopants for ZnO nanostructured photocatalysts under visible light. - Highlights: • Metals and nonmetals used as a dopant to shift ZnO band gap toward visible-light. • Modification of electronic structure played a crucial role in doped ZnO activity. • Correlation between dopant's characteristics and ZnO visible activity was reviewed. • Photo-degradation of doped ZnO was studied and compared for different dopants.

  12. Synergetic Enhancement of the Photocatalytic Activity of TiO2 with Visible Light by Sensitization Using a Novel Push-Pull Zinc Phthalocyanine

    Directory of Open Access Journals (Sweden)

    A. Luna-Flores

    2017-01-01

    Full Text Available A new one-pot synthesis of a novel A3B-type asymmetric zinc phthalocyanine (AZnPc was developed. The phthalocyanine complex was characterized unambiguously and used to prepare a TiO2 hybrid photocatalyst to enhance its photocatalytic activity in the visible range. Different compositions of the phthalocyanine dye were tested in order to find the optimum amount of sensitizer to get the highest activity during the photocatalytic tests. The hybrid photocatalyst was characterized by UV-Vis diffuse reflectance (DRS and Fourier transform infrared spectroscopy (FT-IR and its photocatalytic activity was compared with that of the individual components considering the effects of sensitization on their efficiency to degrade Rhodamine B as a model reaction. A synergic improvement of the photocatalytic activity for the hybrid system was explained in terms of an improved electron injection from the photo-activated phthalocyanine to the TiO2. Considering the structural features of the phthalocyanine sensitizer and their effect on aggregation, some mechanistic aspects of its binding to TiO2 are suggested to account for the photocatalytic activity enhancement. Finally, the inhibitory effect on the sprouting of chia seeds (Salvia hispanica was evaluated in order to test the toxicity of the water effluent obtained after the photodegradation process. According to our growth inhibition assays, it was found that the Rh-B degradation by-products do not lead to an acute toxicity.

  13. Visible-Light-Responsive Catalyst Development for Volatile Organic Carbon Remediation Project

    Science.gov (United States)

    Zeitlin, Nancy; Hintze, Paul E.; Coutts, Janelle

    2015-01-01

    Photocatalysis is a process in which light energy is used to 'activate' oxidation/reduction reactions. Unmodified titanium dioxide (TiO2), a common photocatalyst, requires high-energy UV light for activation due to its large band gap (3.2 eV). Modification of TiO2 can reduce this band gap, leading to visible-light-responsive (VLR) photocatalysts. These catalysts can utilize solar and/or visible wavelength LED lamps as an activation source, replacing mercury-containing UV lamps, to create a "greener," more energy-efficient means for air and water revitalization. Recently, KSC developed several VLR catalysts that, on preliminary evaluation, possessed high catalytic activity within the visible spectrum; these samples out-performed existing commercial VLR catalysts.

  14. A possible mechanism for visible light-induced wound healing.

    Science.gov (United States)

    Lipovsky, Anat; Nitzan, Yeshayahu; Lubart, Rachel

    2008-09-01

    Chronic wounds resistant to conventional therapy have been treated successfully with low energy lasers and light emitting diodes (LEDs) in the visible and near IR region. It has been proposed that production of low level reactive oxygen species (ROS) following illumination is the first step of photobiomodulation. It was also shown that white light (400-800 nm) has similar stimulatory effects as lasers and LEDs. ROS at higher levels are toxic to cells and bacteria. In the present study, we examined the phototoxicity of broadband (400-800 nm, 120 J/cm(2)) visible light on the survival of several pathogenic bacteria: Staphylococcus aureus 195, Pseudomonas aeruginosa 1316, Escherichia coli 1313, and Serratia marcescens. These bacteria were chosen due to their high prevalence in infected wounds. The survival of bacterial cells following illumination was monitored by counting the number of colony forming units before and after exposure to light. Illumination with white light, 120 J/cm(2), caused a reduction of 62%, 83%, and 56% in the colony count of E. coli 1313, S. aureus 195 and S. marcescens, respectively, though no reduction in the viability of P. aeruginosa 1316 was demonstrated. The phototoxic effect was found to involve induction of ROS production by the bacteria. It was also found that illumination of S. aureus 195 and E. coli 1313 in the presence of pyocyanin, known to be secreted by P. aeruginosa, had a stronger bactericidal effect compared to illumination alone. Visible light at high intensity can kill bacteria in infected wounds. Thus, illumination of infected wounds with intense visible light, prior to low intensity illumination for stimulating wound closure, may reduce infection and promote healing.

  15. Efficient visible-light photocatalytic oxidation of gaseous NO with graphitic carbon nitride (g–C{sub 3}N{sub 4}) activated by the alkaline hydrothermal treatment and mechanism analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Haoyu; Ou, Man [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Nanjing AIREP Environmental Protection Technology Co., Ltd., Nanjing, Jiangsu 210091 (China); Zhong, Qin, E-mail: zq304@mail.njust.edu.cn [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Nanjing AIREP Environmental Protection Technology Co., Ltd., Nanjing, Jiangsu 210091 (China); Zhang, Shule; Yu, Lemeng [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094 (China); Nanjing AIREP Environmental Protection Technology Co., Ltd., Nanjing, Jiangsu 210091 (China)

    2015-12-30

    Highlights: • Various porous g–C{sub 3}N{sub 4} samples were obtained by the alkaline hydrothermal treatment. • 0.12CN possesses the largest BET specific surface area and pore volume. • The NO conversion in the presence of 0.12CN reaches 40.4%. • Reasons for the enhanced PCO performance with treated g–C{sub 3}N{sub 4} was analyzed. • Further mechanism of the PCO of NO relevant with active species was investigated. - Abstract: In this paper, an enhanced visible-light photocatalytic oxidation (PCO) of NO (∼400 ppm) in the presence of the graphitic carbon nitride (g–C{sub 3}N{sub 4}) treated by the alkaline hydrothermal treatment is evaluated. Various g–C{sub 3}N{sub 4} samples were treated in different concentrations of NaOH solutions and the sample treated in 0.12 mol L{sup −1} of NaOH solution possesses the largest BET specific surface area as well as the optimal ability of the PCO of NO. UV–vis diffuse reflection spectra (DRS) and photoluminescence (PL) spectra were also conducted, and the highly improved photocatalytic performance is ascribed to the large specific surface area and high pore volume, which provides more adsorption and active sites, the wide visible-light adsorption edge and the narrow band gap, which is favorable for visible-light activation, as well as the decreased recombination rate of photo-generated electrons and holes, which could contribute to the production of active species. Fluorescence spectra and a trapping experiment were conducted to further the mechanism analysis of the PCO of NO, illustrating that superoxide radicals (·O{sub 2}{sup −}) play the dominant role among active species in the PCO of NO.

  16. Visible-light photocatalytic performances of TiO2 nanoparticles modified by trace derivatives of PVA

    Directory of Open Access Journals (Sweden)

    Le SHI

    2016-10-01

    Full Text Available In order to study the visible-light photocatalytic activity and catalysis stability of nanocomposites, a TiO2-based visible-light photocatalyst is prepared by surface-modification of TiO2 nanoparticles using trace conjugated derivatives from polyvinyl alcohol (DPVA via a facile method. The obtained DPVA/TiO2 nanocomposites are characterized by X-ray diffraction (XRD, Fourier transform infrared Spectra (FT-IR, scanning electron microscopy (SEM, UV-vis diffuse reflection spectroscopy (DRS, and X-ray photoelectron spectroscopy (XPS. With Rhodamine B (RhB as a model pollutant, the visible-light photocatalytic activity and stability of DPVA/TiO2 nanocomposites are investigated by evaluating the RhB decomposition under visible light irradiation. The results reveal that the trace conjugated polymers on the TiO2 surface doesn’t change the crystalline and crystal size of TiO2 nanoparticles, but significantly enhances their visible-light absorbance and visible-light photocatalytic activity. The nanocomposite with the PVA and TiO2 mass ratio of 1∶200 exhibits the highest visible-light photocatalytic activity. The investigated nanocomposites exhibit well visible-light photoctatalytic stability. The photogenerated holes are thought as the main active species for the RhB photodegradation in the presence of the DPVA/TiO2 nanocomposites.

  17. Visible light communication: Applications, architecture, standardization and research challenges

    Directory of Open Access Journals (Sweden)

    Latif Ullah Khan

    2017-05-01

    Full Text Available The Radio Frequency (RF communication suffers from interference and high latency issues. Along with this, RF communication requires a separate setup for transmission and reception of RF waves. Overcoming the above limitations, Visible Light Communication (VLC is a preferred communication technique because of its high bandwidth and immunity to interference from electromagnetic sources. The revolution in the field of solid state lighting leads to the replacement of florescent lamps by Light Emitting Diodes (LEDs which further motivates the usage of VLC. This paper presents a survey of the potential applications, architecture, modulation techniques, standardization and research challenges in VLC.

  18. Preparation of Porous F-WO3/TiO2 Films with Visible-Light Photocatalytic Activity by Microarc Oxidation

    Directory of Open Access Journals (Sweden)

    Chung-Wei Yeh

    2012-01-01

    Full Text Available Porous F-WO3/TiO2 (mTiO2 films are prepared on titanium sheet substrates using microarc oxidation (MAO technique. The X-ray diffraction patterns show that visible-light (Vis enabling mTiO2 films with a very high content of anatase TiO2 and high loading of WO3 are successfully synthesized at a low applied voltage of 300 V using electrolyte contenting NaF and Na2WO4 without subsequent heat treatment. The cross-sectional transmission electron microscopy micrograph reveals that the mTiO2 films feature porous networks connected by many micron pores. The diffused reflection spectrum displays broad absorbance across the UV-Vis regions and a significant red shift in the band gap energy (∼2.23 eV for the mTiO2 film. Owing to the high specific surface area from the porous microstructure, the mTiO2 film shows a 61% and 50% rate increase in the photocatalytic dye degradation, as compared with the N,C-codoped TiO2 films under UV and Vis irradiation, respectively.

  19. Acid-free co-operative self-assembly of graphene-ZnO nanocomposites and its defect mediated visible light photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Parameshwari, R. [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India); Jothivenkatachalam, K. [Department of Chemistry, Anna University, Tiruchirappalli 620024, Tamil Nadu (India); Banks, Craig E. [Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD (United Kingdom); Jeganathan, K., E-mail: kjeganathan@yahoo.com [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India)

    2017-02-01

    We propose an acid-free and environmental friendly surfactant based approach to anchor zinc oxide (ZnO) nanoparticles on graphene. Herein, liquid-phase exfoliated graphene in water by ultrasonic waves has been used to prepare graphene-ZnO (G-ZnO) nanocomposites that circumvent the use of various toxic acids and chemicals which are generally used in the preparation of graphene-based nanocomposites. Oxygen vacancy related defect peaks observed by Raman and photoluminescence confirm the formation of C–O–Zn bond due to the synergistic interaction of carbon and zinc via oxygen atoms in G-ZnO nanocomposites. The enhanced photocatalytic behavior of G-ZnO under visible light as evaluated using the dye Rhodamine B holds its genesis from the intrinsic oxygen defects in G-ZnO. Furthermore, graphene acts as electron sink for accumulation of charges from defect levels of ZnO, which controls recombination of charge carriers. It is envisaged that the acid-free and facile strategy can be a potential route for the preparation of graphene-based hybrid materials using liquid-phase exfoliation methodology.

  20. Acid-free co-operative self-assembly of graphene-ZnO nanocomposites and its defect mediated visible light photocatalytic activities