Enhanced degradation of persistent pharmaceuticals found in wastewater treatment effluents using TiO{sub 2} nanobelt photocatalysts

Energy Technology Data Exchange (ETDEWEB)

Liang, Robert; Hu, Anming, E-mail: a2hu@uwaterloo.ca; Li, Wenjuan; Zhou, Y. Norman [University of Waterloo, Centre for Advanced Materials Joining, Department of Mechanical and Mechatronics Engineering (Canada)

2013-10-15

Pharmaceuticals in wastewater effluents are a current and emerging global problem and the development of cost-effective methods to facilitate their removal is needed to mitigate this issue. Advanced oxidation processes (AOPs), in particular UV/TiO{sub 2}, have potential for wastewater treatment. In this study, TiO{sub 2} anatase phase nanobelts (30-100 nm in width and 10 {mu}m in length) have been synthesized using a high temperature hydrothermal method as a means to photocatalyze the oxidation of pharmaceutical contaminants. We have investigated a model dye (malachite green), three pharmaceuticals and personal care products-naproxen, carbamazepine, and theophylline-that are difficult to oxidize without AOP processes. TiO{sub 2} nanobelts were exposed to 365 nm UV illumination and the measured photocatalytic degradation rates and adsorption parameters of pharmaceuticals were explored using kinetic models. Furthermore we have determined the degree of pharmaceutical degradation as a function of solution pH, illumination time, temperature, and concentration of contaminant. In addition, the roles of active oxygen species-hydroxyl radial (OH{center_dot}), positive holes (h{sup +}), and hydrogen peroxide (H{sub 2}O{sub 2})-involved were also investigated in the degradation process. These studies offer additional applications of hierarchical TiO{sub 2} nanobelt membranes, including those harnessing sunlight for water treatment.

Structural and optical properties of ZnO nanostructures electrochemically synthesized on AZO/Ag/AZO-multilayer-film-coated polyethersulfone substrates

International Nuclear Information System (INIS)

Oh, Dohyun; Yoo, Chanho; No, Youngsoo; Kim, Suyoun; Kim, Taewhan; Cho, Woonjo; Kim, Jinyoung

2012-01-01

ZnO nanostructures were formed on Al-doped ZnO (AZO)/Ag/AZO-multilayer-film-coated flexible polyethersulfone (PES) substrates at low temperature by using an electrochemical deposition method. The resistivity of the AZO/Ag/AZO multilayer films decreased with increasing thickness of the Ag film. X-ray diffraction patterns for the ZnO nanostructures showed that the crystal structure of the ZnO was hexagonal wurtzite and that the orientation was along the c-axis perpendicular to the substrate. Scanning electron microscopy images showed that the ZnO nanostructures grown at current densities of - 1.0 and - 1.5 mA/cm 2 were ZnO nanorods with diameters of 150 nm and ZnO nanoflowers with a planar dimension, respectively. Photoluminescence spectra showed that the band-edge emission peak of the ZnO nanostructures dominantly appeared in the ultraviolet region. These results showed that ZnO nanorods and nanoflowers with high quality were synthesized on AZO/Ag/AZO-multilayer-film-coated PES substrates.

Improved photocatalytic activity of ZnO coupled CuO nanocomposites synthesized by reflux condensation method

International Nuclear Information System (INIS)

Mageshwari, K.; Nataraj, D.; Pal, Tarasankar; Sathyamoorthy, R.; Park, Jinsub

2015-01-01

Highlights: • CuO–ZnO nanocomposites were synthesized by reflux condensation method. • Photodegradation of methyl orange and methylene blue dyes was investigated. • Morphological studies show 3D flower-like CuO microspheres adorned with ZnO nanorods. • Optical analysis showed characteristic absorption bands of CuO and ZnO. • CuO–ZnO nanocomposites exhibited superior photocatalytic activity than CuO. - Abstract: Nanostructured CuO–ZnO nanocomposites were successfully synthesized for different Zn 2+ concentrations by reflux condensation method without using any surfactant, and their photocatalytic activity was evaluated using methyl orange and methylene blue dyes under UV light irradiation. XRD revealed the formation of CuO–ZnO nanocomposites, composing of monoclinic CuO and hexagonal ZnO. XPS analysis revealed that CuO–ZnO nanocomposites are made up of Cu(II), Zn(II) and O. FESEM and TEM images showed that pure CuO exhibit 3D flower-like microstructure, while the CuO–ZnO nanocomposites prepared for different Zn 2+ concentrations have 3D flower-like CuO, microstructure adorned with rod-like ZnO particles. UV–Vis DRS showed absorption bands corresponding to CuO and ZnO around 960 nm and 395 nm, respectively. PL spectra of CuO–ZnO nanocomposites exhibited reduced PL emissions compared to pure CuO, indicating the low recombination rate of photogenerated electrons and holes. Photodegradation assay revealed that catalytic activity of CuO–ZnO nanocomposites increased with Zn 2+ concentration, and also effectively degrade methyl orange and methylene blue dyes when compared to pure CuO. The enhanced photocatalytic activity of CuO–ZnO nanocomposites were mainly ascribed to the reduced recombination and efficient separation of photogenerated charge carriers. The possible mechanism for the improved photocatalytic activity of CuO–ZnO nanocomposites was proposed

V2O5-C-SnO2 Hybrid Nanobelts as High Performance Anodes for Lithium-ion Batteries

Science.gov (United States)

Zhang, Linfei; Yang, Mingyang; Zhang, Shengliang; Wu, Zefei; Amini, Abbas; Zhang, Yi; Wang, Dongyong; Bao, Shuhan; Lu, Zhouguang; Wang, Ning; Cheng, Chun

2016-09-01

The superior performance of metal oxide nanocomposites has introduced them as excellent candidates for emerging energy sources, and attracted significant attention in recent years. The drawback of these materials is their inherent structural pulverization which adversely impacts their performance and makes the rational design of stable nanocomposites a great challenge. In this work, functional V2O5-C-SnO2 hybrid nanobelts (VCSNs) with a stable structure are introduced where the ultradispersed SnO2 nanocrystals are tightly linked with glucose on the V2O5 surface. The nanostructured V2O5 acts as a supporting matrix as well as an active electrode component. Compared with existing carbon-V2O5 hybrid nanobelts, these hybrid nanobelts exhibit a much higher reversible capacity and architectural stability when used as anode materials for lithium-ion batteries. The superior cyclic performance of VCSNs can be attributed to the synergistic effects of SnO2 and V2O5. However, limited data are available for V2O5-based anodes in lithium-ion battery design.

Annealed Ce{sup 3+}-doped ZnO flower-like morphology synthesized by chemical bath deposition method

Energy Technology Data Exchange (ETDEWEB)

Koao, Lehlohonolo F., E-mail: koaolf@ufs.ac.za [Department of Physics, University of the Free State (Qwa Qwa campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, Francis B.; Tsega, Moges [Department of Physics, University of the Free State (Qwa Qwa campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Swart, Hendrik C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

2016-01-01

We have successfully synthesized ZnO:xmol% Ce{sup 3+} (0≤x≤10 mol%) doped nanopowders via the chemical bath deposition method (CBD) technique at low temperature (80 °C) and annealed in air at 700 °C. The X-ray diffraction patterns showed that all the undoped and Ce-doped ZnO nanopowders have a hexagonal wurtzite polycrystalline structure with an average crystallite size of about 46 nm. Weak diffraction peaks related mainly to cerium oxide were also detected at higher concentrations of Ce{sup 3+} (x=5–10 mol%). The scanning electron microscopy study revealed that the nanopowder samples were assembled in flower-shaped undoped ZnO and pyramid-shaped Ce{sup 3+}-doped ZnO nanostructures. The UV–vis spectra showed that the absorption edges shifted slightly to the longer wavelengths with the increase in the Ce{sup 3+} ions concentration. Moreover, the photoluminescence (PL) results showed a relative weak visible emission for the Ce{sup 3+}-doped ZnO nanoparticles compared to the undoped ZnO. The effects of Ce{sup 3+}-doping on the structure and PL of ZnO nanopowders are discussed in detail.

A novel synthesis of α-MoO3 nanobelts and the characterization

International Nuclear Information System (INIS)

Chiang, Tzu Hsuan; Yeh, Hung Che

2014-01-01

Highlights: • This work provided a novel method for the fabrication of α-MoO 3 nanobelts. • A growth mechanism associated with the formation of α-MoO 3 nanobelts. • The thickness of the α-MoO 3 belts decreased as the sintering time increased. • The crystallite size of sintered α-MoO 3 belts increased with increases of sintering time. -- Abstract: This study investigated the reaction of ethylene glycol with ammonium molybdate tetrahydrate that the reaction product had the structural characteristics of α-MoO 3 (molybdenum trioxide) nanobelts. This work provided a novel and effective method for the fabrication of high-quality α-MoO 3 nanobelts. The initial reaction was very simple, only requiring reaction at reaction time of 40 min at 120 °C to form MoO 3 ·H 2 O, which was then converted to α-MoO 3 by sintering at 300 °C for 1 h. The α-MoO 3 nanobelts were formed at a sintering temperature of 700 °C for 3 h. The structure and morphology of the α-MoO 3 nanobelts were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The α-MoO 3 nanobelts that were obtained after sintering at 700 °C for 3 h were 99 nm thick, 500 μm length and had an average width of 10 μm. The (0 2 0), (0 4 0), (0 6 0), and (0 1 0 0) planes were observed in XRD, implying that the α-MoO 3 nanobelts grew with a strongly-preferred orientation

MnV2O6.V2O5 cross-like nanobelt arrays: synthesis, characterization and photocatalytic properties

International Nuclear Information System (INIS)

Abbood, Hayder A.; Ahmed, Khalid Abdelazez Mohamed; Ren, Yong; Huang, Kaixun

2013-01-01

Single-crystalline MnV 2 O 6 .V 2 O 5 cross-like nanobelt arrays were successfully synthesized by hydrothermal reaction. The products were characterized by X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. The effects of the reaction conditions such as pH, V 5+ /Mn 2+ ratio, carboxymethyl cellulose concentration and reaction time on the morphology of the products were studied. The band gap of the as-prepared products was calculated via diffuse reflectance spectral analysis and their activity of photocatalytic oxidation was evaluated by photodegradation of methylene blue under visible-light irradiation. The results showed that the degradation efficiency of methylene blue catalyzed by the calcinated products is remarkably enhanced due to Mn doping, suggesting that MnV 2 O 6 .V 2 O 5 cross-like nanobelt arrays are a good candidate for visible-light-driven photocatalysts. (orig.)

Structural and photoluminescence properties of aligned Sb-doped ZnO nanocolumns synthesized by the hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Fang Xuan [School of Science, Changchun University of Science and Technology, 7089-WeiXing Road, Changchun, 130022 (China); Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone Changchun, 130033 (China); Li Jinhua [School of Science, Changchun University of Science and Technology, 7089-WeiXing Road, Changchun, 130022 (China); Zhao Dongxu, E-mail: dxzhao2000@yahoo.com.c [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone Changchun, 130033 (China); Li Binghui; Zhang Zhenzhong; Shen Dezhen [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone Changchun, 130033 (China); Wang Xiaohua; Wei Zhipeng [School of Science, Changchun University of Science and Technology, 7089-WeiXing Road, Changchun, 130022 (China)

2010-08-02

Aligned Sb-doped ZnO nanocolumns were synthesized by a simple hydrothermal method. Based on the analyses of the X-ray diffraction and photoluminescence result, it could be confirmed that the Sb has successfully doped in the ZnO crystal lattices to form an accepter energy level. At 85 K, the recombination of the acceptor-bound exciton was predominant in PL spectrum, which was attributed to the transition of the (Sb{sub Zn}-2V{sub Zn}) complex bound exciton. The acceptor binding energy had been calculated to be 123 meV.

Structural and photoluminescence properties of aligned Sb-doped ZnO nanocolumns synthesized by the hydrothermal method

International Nuclear Information System (INIS)

Fang Xuan; Li Jinhua; Zhao Dongxu; Li Binghui; Zhang Zhenzhong; Shen Dezhen; Wang Xiaohua; Wei Zhipeng

2010-01-01

Aligned Sb-doped ZnO nanocolumns were synthesized by a simple hydrothermal method. Based on the analyses of the X-ray diffraction and photoluminescence result, it could be confirmed that the Sb has successfully doped in the ZnO crystal lattices to form an accepter energy level. At 85 K, the recombination of the acceptor-bound exciton was predominant in PL spectrum, which was attributed to the transition of the (Sb Zn -2V Zn ) complex bound exciton. The acceptor binding energy had been calculated to be 123 meV.

Antitubercular activity of ZnO nanoparticles prepared by solution combustion synthesis using lemon juice as bio-fuel.

Science.gov (United States)

Gopala Krishna, Prashanth; Paduvarahalli Ananthaswamy, Prashanth; Trivedi, Priyanka; Chaturvedi, Vinita; Bhangi Mutta, Nagabhushana; Sannaiah, Ananda; Erra, Amani; Yadavalli, Tejabhiram

2017-06-01

In this study, we report the synthesis, structural and morphological characteristics of zinc oxide (ZnO) nanoparticles using solution combustion synthesis method where lemon juice was used as the fuel. In vitro anti-tubercular activity of the synthesized ZnO nanoparticles and their biocompatibility studies, both in vitro and in vivo were carried out. The synthesized nanoparticles showed inhibition of Mycobacterium tuberculosis H37Ra strain at concentrations as low as 12.5μg/mL. In vitro cytotoxicity study performed with normal mammalian cells (L929, 3T3-L1) showed that ZnO nanoparticles are non-toxic with a Selectivity Index (SI) >10. Cytotoxicity performed on two human cancer cell lines DU-145 and Calu-6 indicated the anti-cancer activity of ZnO nanoparticles at varied concentrations. Results of blood hemolysis indicated the biocompatibility of ZnO nanoparticles. Furthermore, in vivo toxicity studies of ZnO nanoparticles conducted on Swiss albino mice (for 14days as per the OECD 423 guidelines) showed no evident toxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

The Effect of Sodium Dodecyl Sulfate (SDS and Cetyltrimethylammonium Bromide (CTAB on the Properties of ZnO Synthesized by Hydrothermal Method

Directory of Open Access Journals (Sweden)

Yun Hin Taufiq-Yap

2012-10-01

Full Text Available ZnO nanostructures were synthesized by hydrothermal method using different molar ratios of cetyltrimethylammonium bromide (CTAB and Sodium dodecyl sulfate (SDS as structure directing agents. The effect of surfactants on the morphology of the ZnO crystals was investigated by field emission scanning electron microscopy (FESEM and transmission electron microscopy (TEM techniques. The results indicate that the mixture of cationic-anionic surfactants can significantly modify the shape and size of ZnO particles. Various structures such as flakes, sheets, rods, spheres, flowers and triangular-like particles sized from micro to nano were obtained. In order to examine the possible changes in other properties of ZnO, characterizations like powder X-ray diffraction (PXRD, thermogravimetric and differential thermogravimetric analysis (TGA-DTG, FTIR, surface area and porosity and UV-visible spectroscopy analysis were also studied and discussed.

Polypyrrole-coated samarium oxide nanobelts: fabrication, characterization, and application in supercapacitors

Science.gov (United States)

Liu, Peng; Wang, Yunjiao; Wang, Xue; Yang, Chao; Yi, Yanfeng

2012-11-01

Polypyrrole-coated samarium oxide nanobelts were synthesized by the in situ chemical oxidative surface polymerization technique based on the self-assembly of pyrrole on the surface of the amine-functionalized Sm2O3 nanobelts. The morphologies of the polypyrrole/samarium oxide (PPy/Sm2O3) nanocomposites were characterized using transmission electron microscope. The UV-vis absorbance of these samples was also investigated, and the remarkable enhancement was clearly observed. The electrochemical behaviors of the PPy/Sm2O3 composites were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The results indicated that the PPy/Sm2O3 composite electrode was fully reversible and achieved a very fast Faradaic reaction. After being corrected into the weight percentage of the PPy/Sm2O3 composite at a current density of 20 mA cm-2 in a 1.0 M NaNO3 electrolyte solution, a maximum discharge capacity of 771 F g-1 was achieved in a half-cell setup configuration for the PPy/Sm2O3 composites electrode with the potential application to electrode materials for electrochemical capacitors.

Probing defects in chemically synthesized ZnO nanostrucures by positron annihilation and photoluminescence spectroscopy

International Nuclear Information System (INIS)

Chaudhuri, S. K.; Das, D.; Ghosh, Manoranjan; Raychaudhuri, A. K.

2010-01-01

The present article describes the size induced changes in the structural arrangement of intrinsic defects present in chemically synthesized ZnO nanoparticles of various sizes. Routine x-ray diffraction and transmission electron microscopy have been performed to determine the shapes and sizes of the nanocrystalline ZnO samples. Detailed studies using positron annihilation spectroscopy reveals the presence of zinc vacancy. Whereas analysis of photoluminescence results predict the signature of charged oxygen vacancies. The size induced changes in positron parameters as well as the photoluminescence properties, has shown contrasting or nonmonotonous trends as size varies from 4 to 85 nm. Small spherical particles below a critical size (∼23 nm) receive more positive surface charge due to the higher occupancy of the doubly charge oxygen vacancy as compared to the bigger nanostructures where singly charged oxygen vacancy predominates. This electronic alteration has been seen to trigger yet another interesting phenomenon, described as positron confinement inside nanoparticles. Finally, based on all the results, a model of the structural arrangement of the intrinsic defects in the present samples has been reconciled.

Probing defects in chemically synthesized ZnO nanostrucures by positron annihilation and photoluminescence spectroscopy

Science.gov (United States)

Chaudhuri, S. K.; Ghosh, Manoranjan; Das, D.; Raychaudhuri, A. K.

2010-09-01

The present article describes the size induced changes in the structural arrangement of intrinsic defects present in chemically synthesized ZnO nanoparticles of various sizes. Routine x-ray diffraction and transmission electron microscopy have been performed to determine the shapes and sizes of the nanocrystalline ZnO samples. Detailed studies using positron annihilation spectroscopy reveals the presence of zinc vacancy. Whereas analysis of photoluminescence results predict the signature of charged oxygen vacancies. The size induced changes in positron parameters as well as the photoluminescence properties, has shown contrasting or nonmonotonous trends as size varies from 4 to 85 nm. Small spherical particles below a critical size (˜23 nm) receive more positive surface charge due to the higher occupancy of the doubly charge oxygen vacancy as compared to the bigger nanostructures where singly charged oxygen vacancy predominates. This electronic alteration has been seen to trigger yet another interesting phenomenon, described as positron confinement inside nanoparticles. Finally, based on all the results, a model of the structural arrangement of the intrinsic defects in the present samples has been reconciled.

Large-scale syntheses of uniform ZnO nanorods and ethanol gas sensors application

International Nuclear Information System (INIS)

Chen Jin; Li Jin; Li Jiahui; Xiao Guoqing; Yang Xiaofeng

2011-01-01

Research highlights: → The uniform ZnO nanorods could be synthesized by a low temperature, solution-based method. → The results showed that the sample had uniform rod-like morphology with a narrow size distribution and highly crystallinity. → Room-temperature photoluminescence spectra of these nanorods show an exciton emission around 382 nm and a weak deep level emission, indicating the nanorods have high quality. → The sensor exhibited high sensitivity and fast response to ethanol gas at a work temperature of 400 deg. C. - Abstract: Uniform ZnO nanorods with a gram scale were prepared by a low temperature and solution-based method. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL). The results showed that the sample had uniform rod-like morphology with a narrow size distribution and highly crystallinity. Room-temperature PL spectra of these nanorods show an exciton emission around 382 nm and a negligible deep level emission, indicating the nanorods have high quality. The gas-sensing properties of the materials have been investigated. The results indicate that the as-prepared nanorods show much better sensitivity and stability. The n-type semiconductor gas sensor exhibited high sensitivity and fast response to ethanol gas at a work temperature of 400 deg. C. ZnO nanorods are excellent potential candidates for highly sensitive gas sensors and ultraviolet laser.

Optically stimulated luminescence of ZnO obtained by thermal treatment of ZnS chemically synthesized; Luminiscencia opticamente estimulada de ZnO obtenido por tratamiento termico de ZnS sintetizado quimicamente

Energy Technology Data Exchange (ETDEWEB)

Cruz V, C.; Burruel I, S.E.; Orante B, V.R.; Grijalva M, H.; Perez S, R.; Bernal, R. [Universidad de Sonora, A.P. 130, Hermosillo (Mexico)

2005-07-01

In this work, we report the optically stimulated luminescence (OSL) dosimetry of new nano phosphors of ZnO obtained by thermal annealing of chemically synthesized ZnS powder. The synthesized ZnS nano powder was compressed in order to form pellet shaped pellets, which were afterwards subjected to a thermal annealing at 700 C during 24 h under air atmosphere. X-ray diffraction (XRD) patterns and energy-disperse X-ray Spectrometry (EDS) analyses confirmed the transformation of ZnS to ZnO. Samples were exposed to several doses of beta radiation up to 600 Gy, and the optically stimulated luminescence with 470 nm wavelength light was recorded as a function of dose. The intensity of the OSL signal increases by increasing dose, for what it is concluded that these new phosphor materials are suitable to be used in optically stimulated luminescence dosimetry. (Author)

Microwave assisted synthesis of ZnO nanoparticles for lighting and dye removal application

Energy Technology Data Exchange (ETDEWEB)

Kumar, Vijay, E-mail: vijays_phy@rediffmail.com [Department of Physics, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Gohain, M. [Department of Chemistry, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Som, S.; Kumar, Vinod [Department of Physics, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Bezuindenhoudt, B.C.B. [Department of Chemistry, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Swart, Hendrik C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa)

2016-01-01

In this study, we report on the synthesis of ZnO nanoparticles (NPs) via the microwave-assisted technique. The as-synthesized ZnO nanoparticles were annealed at 500 °C for three hours. The ZnO NPs were characterized by X-ray diffraction (XRD) and scanning electron microscopic techniques. XRD results confirmed the formation of as-synthesized ZnO powder oriented along the (101) direction. The Kubelka–Munk function has been employed to determine the band gap of the ZnO powder. ZnO powder has been studied by photoluminescence (PL) before and after annealing to identify the emission of defects in the visible range. The intensity of the PL emission has decreased after annealing. The synthesized ZnO samples were also studied for methyl orange dye removal from waste water. It has been found that the as-synthesized ZnO shows better adsorption behaviour as compared to the annealed sample.

Nanowires and nanobelts, v.2 nanowires and nanobelts of functional materials

CERN Document Server

Wang, Zhong Lin

2010-01-01

Nanowires, nanobelts, nanoribbons, nanorods ..., are a new class of quasi-one-dimensional materials that have been attracting a great research interest in the last few years. These non-carbon based materials have been demonstrated to exhibit superior electrical, optical, mechanical and thermal properties, and can be used as fundamental building blocks for nano-scale science and technology, ranging from chemical and biological sensors, field effect transistors to logic circuits. Nanocircuits built using semiconductor nanowires demonstrated were declared a ""breakthrough in science"" by Science

Analysis of tensile strain enhancement in Ge nano-belts on an insulator surrounded by dielectrics

International Nuclear Information System (INIS)

Lu Wei-Fang; Li Cheng; Huang Shi-Hao; Lin Guang-Yang; Wang Chen; Yan Guang-Ming; Huang Wei; Lai Hong-Kai; Chen Song-Yan

2013-01-01

Ge nano-belts with large tensile strain are considered as one of the promising materials for high carrier mobility metal—oxide—semiconductor transistors and efficient photonic devices. In this paper, we design the Ge nano-belts on an insulator surrounded by Si 3 N 4 or SiO 2 for improving their tensile strain and simulate the strain profiles by using the finite difference time domain (FDTD) method. The width and thickness parameters of Ge nano-belts on an insulator, which have great effects on the strain profile, are optimized. A large uniaxial tensile strain of 1.16% in 50-nm width and 12-nm thickness Ge nano-belts with the sidewalls protected by Si 3 N 4 is achieved after thermal treatments, which would significantly tailor the band gap structures of Ge-nanobelts to realize the high performance devices. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Defect-mediated photoluminescence up-conversion in cadmium sulfide nanobelts (Conference Presentation)

Science.gov (United States)

Morozov, Yurii; Kuno, Masaru K.

2017-02-01

The concept of optical cooling of solids has existed for nearly 90 years ever since Pringsheim proposed a way to cool solids through the annihilation of phonons via phonon-assisted photoluminescence (PL) up-conversion. In this process, energy is removed from the solid by the emission of photons with energies larger than those of incident photons. However, actually realizing optical cooling requires exacting parameters from the condensed phase medium such as near unity external quantum efficiencies as well as existence of a low background absorption. Until recently, laser cooling has only been successfully realized in rare earth doped solids. In semiconductors, optical cooling has very recently been demonstrated in cadmium sulfide (CdS) nanobelts as well as in hybrid lead halide perovskites. For the former, large internal quantum efficiencies, sub-wavelength thicknesses, which decrease light trapping, and low background absorption, all make near unity external quantum yields possible. Net cooling by as much as 40 K has therefore been possible with CdS nanobelts. In this study, we describe a detailed investigation of the nature of efficient anti-Stokes photoluminescence (ASPL) in CdS nanobelts. Temperature-dependent PL up-conversion and optical absorption studies on individual NBs together with frequency-dependent up-converted PL intensity spectroscopies suggest that ASPL in CdS nanobelts is defect-mediated through involvement of defect levels below the band gap.

Hierarchical structures of ZnO spherical particles synthesized solvothermally

Science.gov (United States)

Saito, Noriko; Haneda, Hajime

2011-12-01

We review the solvothermal synthesis, using a mixture of ethylene glycol (EG) and water as the solvent, of zinc oxide (ZnO) particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i) EG restricts the growth of ZnO microcrystals, (ii) EG promotes the self-assembly of small crystallites into spheroidal particles and (iii) the high water content of EG results in hollow spheres.

Ab initio study on mechanical-bending-induced ferroelectric phase transition in ultrathin perovskite nanobelts

International Nuclear Information System (INIS)

Li, H.F.; Zhang, G.H.; Zheng, Yue; Wang, Biao; Chen, W.J.

2014-01-01

Based on first-principles calculations, we systematically investigated the structural, ferroelectric (FE), energetic and electronic properties of bended ultrathin PbTiO 3 and BaTiO 3 nanobelts in between flat sheet and nanotube configurations. It is found that both PbTiO 3 and BaTiO 3 ultrathin nanobelts can possess axial antiferrodistortive structural distortion (AFD distortion), and the magnitude of the AFD rotation angle is obviously determined by the bending curvature of the nanobelts. Meanwhile, spontaneous polarization can be retained in these single-unit-cell-thick nanobelts with contributions from the axial improper ferroelectricity and the radial flexoelectricity, which indicates that ultrathin perovskite nanobelts do not have a critical thickness. On the other hand, we found that the AFD distortion is stable and significant in PbTiO 3 nanobelts while it is metastable in BaTiO 3 nanobelts in comparison with the stable non-AFD structure without AFD distortion. This is due to the competition between AFD distortion and circumferential lattice extension in releasing the elastic energy in BaTiO 3 material. Moreover, we found that the electronic structure and bandgap of the nanobelts can be tuned by the bending curvature, indicating potential control of transport properties by mechanical bending. Our results gave more insight into the inherence of improper ferroelectricity in low-dimensional perovskite ferroelectrics

Vanadium dioxide nanobelts: Hydrothermal synthesis and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Zakharova, G.S., E-mail: volkov@ihim.uran.ru [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620041 (Russian Federation); Hellmann, I. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Volkov, V.L. [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620041 (Russian Federation); Taeschner, Ch.; Bachmatiuk, A.; Leonhardt, A.; Klingeler, R.; Buechner, B. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

2010-09-15

VO{sub 2} (B) nanobelts were prepared by a hydrothermal method at 180 {sup o}C using V{sub 2}O{sub 5}.nH{sub 2}O sol and H{sub 2}C{sub 2}O{sub 4}.2H{sub 2}O as starting agents. The obtained nanobelts have diameters ranging from 50 to 100 nm in width, 20-30 nm in thickness with lengths up to 1.5 {mu}m. Measurements of the static magnetic susceptibility provide evidence for two phase transitions at T{sub 1} = 225 K and T{sub 2} = 290 K, respectively. Below T{sub 1}, the data suggest the presence quasi-free as well as of strongly antiferromagnetic correlated spins associated to V{sup 4+}-ions.

Spatially Correlated, Single Nanomaterial-Level Structural and Optical Profiling of Cu-Doped ZnO Nanorods Synthesized via Multifunctional Silicides

Directory of Open Access Journals (Sweden)

Johnson Truong

2018-04-01

Full Text Available We demonstrate a straightforward and effective method to synthesize vertically oriented, Cu-doped ZnO nanorods (NRs using a novel multipurpose platform of copper silicide nanoblocks (Cu3Si NBs preformed laterally in well-defined directions on Si. The use of the surface-organized Cu3Si NBs for ZnO NR growth successfully results in densely assembled Cu-doped ZnO NRs on each NB platform, whose overall structures resemble thick bristles on a brush head. We show that Cu3Si NBs can uniquely serve as a catalyst for ZnO NRs, a local dopant source of Cu, and a prepatterned guide to aid the local assembly of the NRs on the growth substrate. We also ascertain the crystalline structures, optical properties, and spectroscopic signatures of the Cu-doped ZnO NRs produced on the NBs, both at each module of NRs/NB and at their ensemble level. Subsequently, we determine their augmented properties relative to the pristine form of undoped ZnO NRs and the source material of Cu3Si NBs. We provide spatially correlated structural and optical data for individual modules of Cu-doped ZnO NRs assembled on a Cu3Si NB by resolving them along the different positions on the NB. Ensemble-averaged versus individual behaviors of Cu-doped ZnO NRs on Cu3Si NBs are then compared. We further discuss the potential impact of such ZnO-derived NRs on their relatively unexplored biological and biomedical applications. Our efforts will be particularly useful when exploiting each integrated module of self-aligned, Cu-doped ZnO NRs on a NB as a discretely addressable, active element in solid-state sensors and miniaturized luminescent bioprobes.

Investigating the Implementation of ZnO Nanoparticles as a Tunable UV Detector for Different Skin Types

Science.gov (United States)

Mosayebi, Pegah; Dorranian, Davoud; Behzad, Kasra

A facile chemical reduction method was used to synthesize ZnO nanoparticles (NPs) in ethylene glycol solvent at two different calcination temperatures. As a result of variation in the calcination temperature, ZnO NPs with two different sizes were achieved. The NPs were investigated for their structural and optical characteristics using X-ray diffraction and ultraviolet (UV)-Vis spectroscopy. The synthesized ZnO NPs exhibited a hexagonal structure with sizes of 46 and 65nm. The synthesized NPs were then used to investigate dye photocatalytic behavior of products as a tunable UV detector for different skin types. The dye degradation and decolorization of methylene blue in the presence of ZnO NP, following UV radiation as a function of time, were studied at different pH levels. The optical absorption spectra were then taken every 15min for all samples. The UV-Vis spectroscopy spectra revealed that optical absorption of solution was decreased upon UV exposure as a function of time. Photocatalytic reaction indicated that the dye degradation and decolorization rate were accelerated with the increase of pH level. Therefore, a tunable UV detector for different skin types could be engineered by varying the pH level of solution to avoid human skin burning.

Parametric analysis of the growth of colloidal ZnO nanoparticles synthesized in alcoholic medium

International Nuclear Information System (INIS)

Fonseca, A. S.; Figueira, P. A.; Pereira, A. S.; Santos, R. J.; Trindade, T.; Nunes, M. I.

2017-01-01

The growth kinetics of nanosized ZnO was studied considering the influence of different parameters (mixing degree, temperature, alcohol chain length, reactant concentration and Zn/OH ratios) on the synthesis reaction and modelling the outputs using typical kinetic growth models, which were then evaluated by means of a sensitivity analysis. The Zn/OH ratio, the temperature and the alcohol chain length were found to be essential parameters to control the growth of ZnO nanoparticles, whereas zinc acetate concentration (for Zn/OH = 0.625) and the stirring during the ageing stage were shown to not have significant influence on the particle size growth. This last operational parameter was for the first time investigated for nanoparticles synthesized in 1-pentanol, and it is of outmost importance for the implementation of continuous industrial processes for mass production of nanosized ZnO and energy savings in the process. Concerning the nanoparticle growth modelling, the results show a different pattern from the more commonly accepted diffusion-limited Ostwald ripening process, i.e. the Lifshitz–Slyozov–Wagner (LSW) model. Indeed, this study shows that oriented attachment occurs during the early stages whereas for the later stages the particle growth is well represented by the LSW model. This conclusion contributes to clarify some controversy found in the literature regarding the kinetic model which better represents the ZnO NPs’ growth in alcoholic medium.

Parametric analysis of the growth of colloidal ZnO nanoparticles synthesized in alcoholic medium

Energy Technology Data Exchange (ETDEWEB)

Fonseca, A. S. [National Research Centre for the Working Environment (Denmark); Figueira, P. A.; Pereira, A. S. [Universidade de Aveiro, Departamento de Química—CICECO (Portugal); Santos, R. J. [Universidade do Porto, Laboratory of Separation and Reaction Engineering-Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia (Portugal); Trindade, T. [Universidade de Aveiro, Departamento de Química—CICECO (Portugal); Nunes, M. I., E-mail: isanunes@ua.pt [Universidade de Aveiro, Centre for Environmental and Marine Studies (CESAM), Dep. de Ambiente e Ordenamento (Portugal)

2017-02-15

The growth kinetics of nanosized ZnO was studied considering the influence of different parameters (mixing degree, temperature, alcohol chain length, reactant concentration and Zn/OH ratios) on the synthesis reaction and modelling the outputs using typical kinetic growth models, which were then evaluated by means of a sensitivity analysis. The Zn/OH ratio, the temperature and the alcohol chain length were found to be essential parameters to control the growth of ZnO nanoparticles, whereas zinc acetate concentration (for Zn/OH = 0.625) and the stirring during the ageing stage were shown to not have significant influence on the particle size growth. This last operational parameter was for the first time investigated for nanoparticles synthesized in 1-pentanol, and it is of outmost importance for the implementation of continuous industrial processes for mass production of nanosized ZnO and energy savings in the process. Concerning the nanoparticle growth modelling, the results show a different pattern from the more commonly accepted diffusion-limited Ostwald ripening process, i.e. the Lifshitz–Slyozov–Wagner (LSW) model. Indeed, this study shows that oriented attachment occurs during the early stages whereas for the later stages the particle growth is well represented by the LSW model. This conclusion contributes to clarify some controversy found in the literature regarding the kinetic model which better represents the ZnO NPs’ growth in alcoholic medium.

Optical properties and photocatalytic activities of spherical ZnO and flower-like ZnO structures synthesized by facile hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

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

2013-10-25

Highlights: •Spherical ZnO and flower-like ZnO were prepared via a facile hydrothermal method. •The as-prepared ZnO showed high photocatalytic activity over MO degradation. •The as-prepared ZnO were well crystallized and exhibited good optical properties. -- Abstract: Spherical ZnO and flower-like ZnO were prepared by facile hydrothermal method at 180 °C and 160 °C, respectively. The as-prepared samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and UV–vis diffuse reflectance spectroscopy (DRS) spectra. The optical properties of as-prepared sample, such as photoluminescence (PL) spectra and Raman spectra were studied. The photocatalytic activities of the as-prepared ZnO particles were investigated by degrading the methyl orange (MO) under UV light irradiation. The photocatalytic studies showed that the organic pollutants have been almost completely degraded and mineralized after irradiation of the UV light. These results indicated that the as-prepared ZnO particles exhibited good optical properties and high photocatalytic activities.

Effects of surface passivation on α-Si_3N_4 nanobelts: A first-principles study

International Nuclear Information System (INIS)

Xiong, Li; Dai, Jianhong; Song, Yan; Wen, Guangwu; Qin, Chunlin

2016-01-01

Highlights: • The stability and electronic properties of α-Si_3N_4 nanobelts are theoretically studied. • The surface of α-Si_3N_4 nanobelts are passivated with H, OH, F and Cl atoms. • The structural stability of nanobelts decreases in the order of OH, F, Cl, and H passivations. • The surface passivation greatly changes the electronic structures of α-Si_3N_4 nanobelts. - Abstract: The energetic stability and electronic structures of H, OH, F, or Cl passivated α-Si_3N_4 nanobelts orientating along various directions are systematically investigated via first-principles calculations. The results show that the stability of nanobelts is more sensitive to the surface passivation than growth direction. It decreases in the order of (100% OH), (50% H, 50% OH), (50% H, 50% F), (100% F), (50% H, 50% Cl), (100% Cl), (100% H), and unpassivation. H atoms prefer to bond with surface N atoms of nanobelts, while OH, F and Cl prefer to bond with Si atoms of nanobelts. In addition, the surface passivation greatly changes the electronic structures of nanobelts. The OH and F passivations result in the larger band gaps than the Cl passivation. While the coverage of OH, F or Cl increases to 100%, their band gaps decrease significantly, indicating an improvement of electrical properties, which is good agreement with the experimental findings. The 100% Cl-passivated nanobelt orientating along the [011] direction possesses the smallest band gap of 1.038 eV. The band gaps are found to be affected by a competition between quantum confinement effect and the role of the surface passivated groups or atoms at the band-gap edges.

Optical and Morphological Properties of ZnO- and TiO2-Derived Nanostructures Synthesized via a Microwave-Assisted Hydrothermal Method

Directory of Open Access Journals (Sweden)

Nosipho Moloto

2012-01-01

Full Text Available A microwave-assisted hydrothermal method was used to synthesize ZnO and TiO2 nanostructures. The experimental results show that the method resulted in crystalline monodispersed ZnO nanorods that have pointed tips with hexagonal crystal phase. TiO2 nanotubes were also formed with minimum bundles. The mechanism for the formation of the tubes was validated by HRTEM results. The optical properties of both ZnO and TiO2 nanostructures showed characteristics of strong quantum confinement regime. The photoluminescence spectrum of TiO2 nanotubes shows good improvement from previously reported data.

Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Iandolo, Donata; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Linköping University, SE-601 74 Norrköping (Sweden); Pozina, Galia; Khranovskyy, Volodymyr; Liu, Xianjie [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

2016-04-28

Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5 M exhibit stronger yellow emission (∼575 nm) compared to those based on 1:1 and 1:3 M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination.

Polypyrrole-coated samarium oxide nanobelts: fabrication, characterization, and application in supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Liu Peng, E-mail: pliu@lzu.edu.cn; Wang Yunjiao; Wang Xue; Yang Chao; Yi Yanfeng [College of Chemistry and Chemical Engineering, Lanzhou University, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry (China)

2012-11-15

Polypyrrole-coated samarium oxide nanobelts were synthesized by the in situ chemical oxidative surface polymerization technique based on the self-assembly of pyrrole on the surface of the amine-functionalized Sm{sub 2}O{sub 3} nanobelts. The morphologies of the polypyrrole/samarium oxide (PPy/Sm{sub 2}O{sub 3}) nanocomposites were characterized using transmission electron microscope. The UV-vis absorbance of these samples was also investigated, and the remarkable enhancement was clearly observed. The electrochemical behaviors of the PPy/Sm{sub 2}O{sub 3} composites were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The results indicated that the PPy/Sm{sub 2}O{sub 3} composite electrode was fully reversible and achieved a very fast Faradaic reaction. After being corrected into the weight percentage of the PPy/Sm{sub 2}O{sub 3} composite at a current density of 20 mA cm{sup -2} in a 1.0 M NaNO{sub 3} electrolyte solution, a maximum discharge capacity of 771 F g{sup -1} was achieved in a half-cell setup configuration for the PPy/Sm{sub 2}O{sub 3} composites electrode with the potential application to electrode materials for electrochemical capacitors.

Electrochemical Sensing, Photocatalytic and Biological Activities of ZnO Nanoparticles: Synthesis via Green Chemistry Route

Science.gov (United States)

Yadav, L. S. Reddy; Archana, B.; Lingaraju, K.; Kavitha, C.; Suresh, D.; Nagabhushana, H.; Nagaraju, G.

2016-05-01

In this paper, we have successfully synthesized ZnO nanoparticles (Nps) via solution combustion method using sugarcane juice as the novel fuel. The structure and morphology of the synthesized ZnO Nps have been analyzed using various analytical tools. The synthesized ZnO Nps exhibit excellent photocatalytic activity for the degradation of methylene blue dye, indicating that the ZnO Nps are potential photocatalytic semiconductor materials. The synthesized ZnO Nps also show good electrochemical sensing of dopamine. ZnO Nps exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Eschesichia coli and Staphylococcus aureus using agar well diffusion method. Furthermore, the ZnO Nps show good antioxidant activity by potentially scavenging 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The above studies clearly demonstrate versatile applications of ZnO synthesized by simple eco-friendly route.

A novel 3D structure composed of strings of hierarchical TiO{sub 2} spheres formed on TiO{sub 2} nanobelts with high photocatalytic properties

Energy Technology Data Exchange (ETDEWEB)

Jiang, Yongjian [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); Li, Meicheng, E-mail: mcli@ncepu.edu.cn [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); Suzhou Institute, North China Electric Power University, Suzhou 215123 (China); Song, Dandan; Li, Xiaodan; Yu, Yue [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China)

2014-03-15

A novel hierarchical titanium dioxide (TiO{sub 2}) composite nanostructure with strings of anatase TiO{sub 2} hierarchical micro-spheres and rutile nanobelts framework (TiO{sub 2} HSN) is successfully synthesized via a one-step hydrothermal method. Particularly, the strings of hierarchical spheres are assembled by very thin TiO{sub 2} nanosheets, which are composed of highly crystallized anatase nanocrystals. Meanwhile, the HSN has a large surface area of 191 m{sup 2}/g, which is about 3 times larger than Degussa P25. More importantly, the photocatalytic activity of HSN and P25 were evaluated by the photocatalytic oxidation decomposition of methyl orange (MO) under UV light illumination, and the TiO{sub 2} HSN shows enhanced photocatalytic activity compared with Degussa P25, as result of its continuous hierarchical structures, special conductive channel and large specific surface area. With these features, the hierarchical TiO{sub 2} may have more potential applications in the fields of dye-sensitized solar cells and lithium ion batteries. -- Graphical abstract: Novel TiO{sub 2} with anatase micro-spheres and rutile nanobelts is synthesized. Enhanced photocatalysis is attributed to hierarchical structures (3D spheres), conductive channel (1D nanobelts) and large specific surface area (2D nanosheet). Highlights: • The novel TiO{sub 2} nanostructure (HSN) is fabricated for the first time. • HSN is composed of strings of anatase hierarchical spheres and rutile nanobelt. • HSN presents a larger S{sub BET} of 191 m{sup 2}/g, 3 times larger than the Degussa P25 (59 m{sup 2}/g). • HSN owns three kinds of dimensional TiO{sub 2} (1D, 2D and 3D) simultaneously. • HSN exhibits better photocatalytic performance compared with Degussa P25.

Optical properties of Mn doped ZnO films and wires synthesized by thermal oxidation of ZnMn alloy

International Nuclear Information System (INIS)

Sima, M.; Mihut, L.; Vasile, E.; Sima, Ma.; Logofatu, C.

2015-01-01

Mn doped ZnO films and wires, having different manganese concentrations were synthesized by thermal oxidation of the corresponding ZnMn alloy films and wires electrodeposited on a gold substrate. Structural and optical properties were addressed with scanning electron microscopy, X-ray diffraction (XRD), Raman scattering and photoluminescence (PL). To estimate the manganese concentration in Mn doped ZnO films, X-ray photoelectron spectroscopy was used. XRD patterns indicate that the incorporation of Mn 2+ ions into the Zn 2+ site of ZnO lattice takes place. Quenching of the ZnO PL appears due to Mn 2+ ions in the ZnO lattice. Moreover, a significant decrease in the green emission of ZnO is reported in the case of the Mn doped ZnO wire array with a Mn concentration of 1.45%. The wurtzite ZnO has a total of 12 phonon modes, namely, one longitudinal acoustic (LA), two transverse acoustic (TA), three longitudinal optical (LO), and six transverse optical branches. Compared to the undoped ZnO, a gradual up-shift of the Raman lines assigned to the 2LA and A 1 (LO) vibrational modes, from 482 and 567 cm −1 to 532 and 580 cm −1 , respectively, takes place for the Mn doped ZnO films having a Mn concentration between 2 and 15%. Additionally, in the case of the Mn doped ZnO films with 7 and 15% Mn concentration, Raman spectra show the appearance and increase in the relative intensity of the ZnO Raman line assigned to the TA + LO vibrational mode in the 600–750 cm −1 spectral range. For the Mn-doped ZnO wires, the presence of the Raman line peaking at 527 cm −1 confirms the insertion of Mn 2+ ions in ZnO lattice. - Highlights: • Mn doped ZnO films and wires grown by thermal oxidation of ZnMn alloy • Incorporation of Mn 2+ ions into Zn 2+ site of ZnO lattice • Appearance of a strong Raman line in the spectral range 600–800 cm −1 at high Mn concentration • Compensation of the oxygen vacancy at higher Mn concentration in ZnO lattice

Influence of Mn and Co on structural and morphological characteristics of ZnO synthesized by combustion reaction

International Nuclear Information System (INIS)

Torquato, R.A.; Costa, C.F.M.; Kiminami, R.H.A.

2010-01-01

This study aims to evaluate the effect of doping of 0.2 mol of Mn and Co on structural and morphological characteristics of ZnO synthesized by combustion reaction. During the synthesis was the measurement of temperature and time of the combustion flame. The samples were characterized by XRD, SEM, particle size distribution and nitrogen adsorption (BET). The maximum temperature the reactions were 428 deg C and 436 deg C, reaction time, and 115 and 0 seconds for the samples doped with Mn and Co, respectively. The XRD data showed that for both impurities were formed only ZnO phase. For Co were formed secondary phase CoO. The crystallite size and surface area were 18 nm and 22 nm, and 52 and 38 m2/g for ZnO doped with Mn and Co, respectively. (author)

Pulsed laser deposition of Ag nanoparticles on titanium hydroxide/oxide nanobelt arrays for highly sensitive surface-enhanced Raman spectroscopy

International Nuclear Information System (INIS)

Jing, Yuting; Wang, Huanwen; Zhao, Jie; Yi, Huan; Wang, Xuefeng

2015-01-01

Highlights: • Silver nanoparticles (NPs) were deposited on Ti(OH) 4 nanobelt by pulsed laser deposition (PLD). • The highest enhancement factor of 10 6 and a maximum relative standard deviation (RSD) of 0.18. • Ag 2 O play important role for the high sensitivity Raman phenomenon. • Charge transfer from Ag NPs is also responsible for the enhancement ability. - Abstract: Surface-enhanced Raman scattering (SERS) substrate of Ti(OH) 4 nanobelt arrays (NBAs) was synthesized by a hydrothermal reaction, on which silver nanoparticles (NPs) were deposited by pulsed laser deposition (PLD). Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed the effective high specific surface area with silver NPs decorated on three-dimensional NBAs. Using rhodamine 6G (R6G) as an analyte molecule, the highest enhancement factor of 10 6 and a maximum relative standard deviation (RSD) of 0.18 were obtained. It has been found that the specific morphology of these composite nanobelt arrays and the formation of Ag 2 O play important role for the high sensitivity Raman phenomenon. In addition, the surface plasmon resonance wavelength of Ag decorated Ti(OH) 4 NBAs and the charge transfer from Ag NPs are also responsible for the enhancement ability. For comparison SERS was investigated with silver particles decorated on TiO 2 NBAs, which is much less active

Fabrication of BiOBr nanosheets@TiO{sub 2} nanobelts p–n junction photocatalysts for enhanced visible-light activity

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yang [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Huang, Xiang [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); School of Science, Tibet University, Lhasa 850000 (China); Tan, Xin [School of Science, Tibet University, Lhasa 850000 (China); Yu, Tao, E-mail: yutao@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Li, Xiangli [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China); Yang, Libin [College of Chemical Engineering and Materials Science, Tianjin University of Science & Technology, Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin 300457 (China); Wang, Shucong [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China)

2016-03-01

Graphical abstract: - Highlights: • BiOBr nanosheets@TiO{sub 2} nanobelts p–n junction photocatalysts have been synthesized. • The p–n junction photocatalysts improved water splitting and dye degradation activity. • BiOBr amount in the BiOBr@TiO{sub 2} photocatalysts was investigated. - Abstract: The construction of p–n junction structure is a smart strategy for improving the photocatalytic activity, since p–n junctions can inhibit the recombination of photo-induced charges. Herein, BiOBr nanosheets@TiO{sub 2} nanobelts p–n junction photocatalysts were prepared by assembling BiOBr nanosheets on the surface of TiO{sub 2} nanobelts via a hydrothermal route followed by a co-precipitation process. BiOBr@TiO{sub 2} p–n junction photocatalysts exhibited enhanced photocatalytic activity in photocatalytic H{sub 2} production over water splitting and photodegradation of Rhodamine B (RhB) under visible light irradiation. Mott–Schottky plots confirmed the formation of p–n junctions in the interface of BiOBr and TiO{sub 2}. The enhanced photocatalytic performance can be ascribed to the 1D nanostructure and the formation of p–n junctions. This work shows a potential application of low cost BiOBr as a substitute for noble metals in photocatalytic H{sub 2} production under visible light irradiation.

Synthesis of isotopically modified ZnO nanoparticles and their potential as nanotoxicity tracers

International Nuclear Information System (INIS)

Dybowska, Agnieszka D.; Croteau, Marie-Noele; Misra, Superb K.; Berhanu, Deborah; Luoma, Samuel N.; Christian, Paul; O'Brien, Paul; Valsami-Jones, Eugenia

2011-01-01

Understanding the behavior of engineered nanoparticles in the environment and within organisms is perhaps the biggest obstacle to the safe development of nanotechnologies. Reliable tracing is a particular issue for nanoparticles such as ZnO, because Zn is an essential element and a common pollutant thus present at elevated background concentrations. We synthesized isotopically enriched (89.6%) with a rare isotope of Zn ( 67 Zn) ZnO nanoparticles and measured the uptake of 67 Zn by L. stagnalis exposed to diatoms amended with the particles. Stable isotope technique is sufficiently sensitive to determine the uptake of Zn at an exposure equivalent to lower concentration range ( -1 ). Without a tracer, detection of newly accumulated Zn is significant at Zn exposure concentration only above 5000 μg g -1 which represents some of the most contaminated Zn conditions. Only by using a tracer we can study Zn uptake at a range of environmentally realistic exposure conditions. - ZnO nanoparticles with distinct isotopic composition can be tailor synthesized to be used as tracers of environmental fate and uptake by organisms.

Piezoelectric and opto-electrical properties of silver-doped ZnO nanorods synthesized by low temperature aqueous chemical method

Directory of Open Access Journals (Sweden)

E. S. Nour

2015-07-01

Full Text Available In this paper, we have synthesized Zn1−xAgxO (x = 0, 0.03, 0.06, and 0.09 nanorods (NRs via the hydrothermal method at low temperature on silicon substrate. The characterization and comparison between the different Zn1−xAgxO samples, indicated that an increasing Ag concentration from x = 0 to a maximum of x = 0.09; All samples show a preferred orientation of (002 direction with no observable change of morphology. As the quantity of the Ag dopant was changed, the transmittances, as well as the optical band gap were decreased. X-ray photoelectron spectroscopy data clearly indicate the presence of Ag in ZnO crystal lattice. A nanoindentation-based technique was used to measure the effective piezo-response of different concentrations of Ag for both direct and converse effects. The value of the piezoelectric coefficient (d33 as well as the piezo potential generated from the ZnO NRs and Zn1−xAgxO NRs was found to decrease with the increase of Ag fraction. The finding in this investigation reveals that Ag doped ZnO is not suitable for piezoelectric energy harvesting devices.

Hydrothermal growth and characterizations of dandelion-like ZnO nanostructures

Energy Technology Data Exchange (ETDEWEB)

Kale, Rohidas B., E-mail: rb_kale@yahoo.co.in [Department of Physics, The Institute of Science, Madam Cama Road, Mumbai 400 032, (M.S.) (India); Lu, Shih-Yuan, E-mail: sylu@nthu.edu.tw [Department of Chemical Engineering, National Tsing-Hua University, Hsinchu 30013, Taiwan, ROC (China)

2013-12-05

Highlights: •The simple, low cost, environmental benign hydrothermal method has been used to synthesize ZnO nanostructure. •The SEM images reveal the interesting 3D dandelion-like morphology of synthesized ZnO nanostructure. The SAED pattern and HRTEM study confirms that the ZnO nanorods are single crystalline. •Change in experimental conditions dramatically changes the morphologies of the synthesized ZnO. •The room temperature PL study reveals strong band edge emission along with much weaker defect related blue emission. •The reaction and growth mechanism of ZnO nanostructure is also discussed. -- Abstract: Three dimensional (3D) ZnO nanostructures have been synthesized by using a facile low-cost hydrothermal method under mild conditions. Aqueous alkaline ammonia solution of Zn(CH{sub 3}COO){sub 2} is used to grow 3D ZnO nanostructures. The X-ray diffraction (XRD) study reveals the well crystallized hexagonal structure of ZnO. SEM observations depict that the ZnO product grows in the form of nanorods united together to form 3D dandelion-like nanostructures. The elemental analysis using EDAX technique confirms the stoichiometry of the ZnO nanorods. The product exhibits special optical properties with red-shifts in optical absorption peak (376 nm) as compared with those of conventional ZnO nanorods. PL spectra show emission peak (396 nm) at the near band-edge and peak (464 nm) originated from defects states that are produced during the hydrothermal growth. TEM and SAED results reveal single crystalline structure of the synthesized product. The reaction and growth mechanisms on the morphological evolution of the ZnO nanostructures are discussed. The morphology of ZnO product is investigated by varying the reaction time, temperature, and type of complexing reagent.

Interface-defect-mediated photocatalysis of mesocrystalline ZnO assembly synthesized in-situ via a template-free hydrothermal approach

Science.gov (United States)

Wang, Hui; Wang, Cuicui; Chen, Qifeng; Ren, Baosheng; Guan, Ruifang; Cao, Xiaofeng; Yang, Xiaopeng; Duan, Ran

2017-08-01

Both architecture construction and defects engineering of photocatalysts are highly vital in the photocatalytic activity. We report herein that the interface-defect-mediated photocatalytic activity of pompon-like ZnO (P-ZnO) mesocrystal photocatalyst synthesized via an aqueous approach, in the presence of sodium citrate without any other organic templates. The microstructure and defects of the diverse ZnO photocatalysts were examined with various techniques. The results indicated that the P-ZnO assemblies were composed of mesocrystal nanosheets exposed high energy (002) facet with high crystallinity. More importantly, the defects located at the interfaces among the nanocrystals in ZnO mesocrystals played an important role in the photocatalytic activity than that of interstitial zinc vacancies in bulk, which was confirmed by photocatalytic degradation of organic pollutants, such as methylene blue (MB) and 2,4,6-trichlorophenol (2,4,6-TCP). The results showed that the P-ZnO exhibited higher photocatalytic activity than that of the nanosized ZnO (N-ZnO), which could be attributed to not only the unique mesocrystal structure and high energy (002) facet exposed, but also the defects located at interfaces among nanocrystals in ZnO mesocrystals. In addition, the formation mechanism of the P-ZnO was investigated via a time-dependent method. It was found that the formation of P-ZnO hierarchical architecture assembled with ZnO mesocrystals involved a nonclassical crystallization growth and Ostwald Ripening process. This study provides a perspective on the improvement in photocatalytic activity via adjusting the bulk and interface defects and construction of hierarchical architectures of semiconductors.

The effect of Ce3+ on structure, morphology and optical properties of flower-like ZnO synthesized using the chemical bath method

International Nuclear Information System (INIS)

Koao, L.F.; Dejene, F.B.; Swart, H.C.; Botha, J.R.

2013-01-01

Ce 3+ doped ZnO flower-like structures were synthesized by the chemical bath deposition method (CBD). The influence of Ce 3+ as a dopant on the crystallization, surface morphology, optical and luminescent properties of ZnO flowers-like structures were investigated. The X-ray diffraction (XRD) spectra of the ZnO:Ce 3+ nanostructures correspond to the various planes of a single hexagonal ZnO phase for the lower Ce concentration samples. The estimated grain sizes calculated using the XRD spectra were found to be in order of 42±2 nm. The grain size was found to be not dependent on the concentration of the Ce 3+ ions used up to 3 mol% of Ce. Scanning Auger electron microscopy and scanning electron micrographs indicate that the addition of Ce 3+ influence the morphology of the samples. The flower-like structures obtained for the undoped and low concentration Ce doped ZnO changed into a mixed structure with the emergence of pyramid shapes for higher concentration Ce doped samples. The solid undoped and low concentration Ce doped powder showed good optical properties with a high reflectance in the visible regions. The properties, however, diminished at higher Ce concentration. The band gap energies decreased linearly with concentration from 3.0±0.1 to 2.4±0.3 eV for ZnO:0 mol% Ce 3+ up to ZnO:10 mol% Ce 3+ . Under 248 nm excitation, the undoped and low concentration Ce doped ZnO flower-like rods exhibited a green emission, peaking at about 559 nm. The higher Ce concentration (0.3 mol% and above) was emitted at 436 and 503 nm due to the Ce transitions. The intensity of these emission spectra of the ZnO:Ce 3+ decreased with the addition of more Ce 3+ ions. -- Highlights: • Ce 3+ doped ZnO flower-like structures were synthesized by CBD. • Flower-like hexagonal ZnO:Ce 3+ nanostructures were obtained for undoped and low mol% Ce. • ZnO changed into a mixed structure with emergence of pyramid shapes for higher mol% Ce. • Good optical properties with a high reflectance

Fe-tannic acid complex dye as photo sensitizer for different morphological ZnO based DSSCs

Science.gov (United States)

Çakar, Soner; Özacar, Mahmut

2016-06-01

In this paper we have synthesized different morphological ZnO nanostructures via microwave hydrothermal methods at low temperature within a short time. We described different morphologies of ZnO at different Zn(NO3)2/KOH mole ratio. The ZnO nanostructures were characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and UV-vis spectrophotometry. All ZnO structures have hexagonal wurtzite type structures. The FESEM images showed various morphologies of ZnO such as plate, rod and nanoparticles. Dye sensitized solar cells have been assembled by these different morphological structures photo electrode and tannic acid or Fe-tannic acid complex dye as sensitizer. We have achieved at maximum efficiencies of photovoltaic cells prepared with ZnO plate in all dye systems. The conversion efficiencies of dye sensitized solar cells are 0.37% and 1.00% with tannic acid and Fe-tannic acid complex dye, respectively.

Luminescent ZnO quantum dots as an efficient sensor for free chlorine detection in water.

Science.gov (United States)

Singh, Kulvinder; Mehta, S K

2016-04-21

Highly luminescent ZnO quantum dots (QDs) synthesized via a simple and facile route are used for the preparation of an optical sensor for the detection of free chlorine. The concentration of free chlorine greatly affects the PL emission of the ZnO QDs at 525 nm. Since hypochlorite gains electrons with high efficiency, it takes electrons from the oxygen vacancies of ZnO QDs, which gives rise to defect emission in ZnO QDs. UV-vis data analysis shows that free chlorine does not affect the optical absorption spectra of ZnO QDs. The optical sensing of free chlorine using ZnO QDs has several advantages, like quick response time, good selectivity and of course high sensitivity. The pH has very little effect on the PL emission of ZnO QDs. It does not interfere in the sensing mechanism for free chlorine. After 60 s, the response of the ZnO QDs remains stable. The present sensor shows high selectivity with respect to various common cations, as well as anions.

Zinc Oxide Nano crystals Synthesized by Quenching Technique

International Nuclear Information System (INIS)

Norhayati Abu Bakar; Akrajas Ali Umar; Muhamad Mat Salleh; Muhammad Yahya

2011-01-01

This paper reports an attempt to synthesize non toxic zinc oxide (ZnO) nano crystals using a simple quenching technique. The hot zinc oxide powder was quenched in hexane solution to obtain ZnO nano crystals. As the result, diameter size of the synthesized ZnO is 200 nm. It was also exhibited a good crystalline with wurtzite phase. The nano crystals properties of ZnO were revealed from good absorbance and green luminescence under UV exposure. This may be related with oxygen vacancy ionization during the annealing process. (author)

Effect of Eu{sup 3+} on the structure, morphology and optical properties of flower-like ZnO synthesized using chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Koao, L.F. [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba ZA9866 (South Africa); Dejene, F.B., E-mail: dejenebf@qwa.ufs.ac.za [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba ZA9866 (South Africa); Kroon, R.E. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa)

2014-03-15

The chemical bath deposition (CBD) method was used to synthesize ZnO undoped and Eu{sup 3+}-doped nanostructures. The Eu{sup 3+} concentration was varied from 0.2 to 5 mol%. The X-ray diffraction (XRD) spectra of the undoped and low concentration Eu{sup 3+} doped ZnO nanostructures correspond to the various planes of a single hexagonal ZnO phase. The estimated crystalline grain size was calculated using the XRD spectra and was found to be in the order of 47±5 nm and independent on the Eu{sup 3+} ion concentration up to 4 mol%. Scanning electron microscopy (SEM) micrographs, however, indicate that the addition of Eu{sup 3+} influences the morphology of the samples. In the UV–vis study the highest band gap energy was obtained for the undoped ZnO. The effective band gap energy of the ZnO decayed exponentially with the addition of Eu{sup 3+} up to 4 mol% where impurity phases started to appear. Although weak luminescence was observed for excitation above the bandgap at 300 nm the best results were obtained by exciting the Eu{sup 3+} directly through the {sup 7}F{sub 0}→{sup 5}L{sub 6} absorption band at 395 nm. Excitation at a wavelength of 395 nm produced the highest Eu{sup 3+} luminescence intensity without any noticeable ZnO defect emissions. The maximum luminescence intensity for this excitation was obtained for ZnO:3 mol% Eu{sup 3+} ions and luminescent quenching was observed for higher Eu concentrations. -- Highlights: • CBD was used to synthesize ZnO undoped and Eu{sup 3+}-doped nanostructures. • The powders having particles with flower-like morphology with good optical properties. • Weak luminescence for excitation above the bandgap at 300 nm. • Excitation at 395 nm produced the highest pure Eu{sup 3+} luminescence.

Effect of zinc oxide nanoparticles synthesized by a precipitation

Indian Academy of Sciences (India)

ZnO nanoparticles were synthesized by a precipitation method in aqueous media from zinc nitrate hexahydrate and sodium hydroxide. The synthesized ZnO nanoparticles exhibited a crystalline structure with hexagonal structure of the wurtzite. The morphology of the synthesized ZnO nanoparticles presented a spherical ...

Optical properties of Mn doped ZnO films and wires synthesized by thermal oxidation of ZnMn alloy

Energy Technology Data Exchange (ETDEWEB)

Sima, M., E-mail: msima@infim.ro [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania); Mihut, L. [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania); Vasile, E. [University “Politehnica”of Bucharest, Faculty of Applied Chemistry and Material Science, Department of Oxide Materials and Nanomaterials, No. 1-7 Gh. Polizu Street, 011061 Bucharest (Romania); Sima, Ma.; Logofatu, C. [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania)

2015-09-01

Mn doped ZnO films and wires, having different manganese concentrations were synthesized by thermal oxidation of the corresponding ZnMn alloy films and wires electrodeposited on a gold substrate. Structural and optical properties were addressed with scanning electron microscopy, X-ray diffraction (XRD), Raman scattering and photoluminescence (PL). To estimate the manganese concentration in Mn doped ZnO films, X-ray photoelectron spectroscopy was used. XRD patterns indicate that the incorporation of Mn{sup 2+} ions into the Zn{sup 2+} site of ZnO lattice takes place. Quenching of the ZnO PL appears due to Mn{sup 2+} ions in the ZnO lattice. Moreover, a significant decrease in the green emission of ZnO is reported in the case of the Mn doped ZnO wire array with a Mn concentration of 1.45%. The wurtzite ZnO has a total of 12 phonon modes, namely, one longitudinal acoustic (LA), two transverse acoustic (TA), three longitudinal optical (LO), and six transverse optical branches. Compared to the undoped ZnO, a gradual up-shift of the Raman lines assigned to the 2LA and A{sub 1} (LO) vibrational modes, from 482 and 567 cm{sup −1} to 532 and 580 cm{sup −1}, respectively, takes place for the Mn doped ZnO films having a Mn concentration between 2 and 15%. Additionally, in the case of the Mn doped ZnO films with 7 and 15% Mn concentration, Raman spectra show the appearance and increase in the relative intensity of the ZnO Raman line assigned to the TA + LO vibrational mode in the 600–750 cm{sup −1} spectral range. For the Mn-doped ZnO wires, the presence of the Raman line peaking at 527 cm{sup −1} confirms the insertion of Mn{sup 2+} ions in ZnO lattice. - Highlights: • Mn doped ZnO films and wires grown by thermal oxidation of ZnMn alloy • Incorporation of Mn{sup 2+} ions into Zn{sup 2+} site of ZnO lattice • Appearance of a strong Raman line in the spectral range 600–800 cm{sup −1} at high Mn concentration • Compensation of the oxygen vacancy at higher

Synthesis and properties of ZnO nanorods as ethanol gas sensors

International Nuclear Information System (INIS)

Mirabbaszadeh, K; Mehrabian, M

2012-01-01

Uniform ZnO nanorods were synthesized via the sol-gel process under mild conditions in which different ZnO nanostructures have been prepared by changing the pH of growth solution. It was seen that the optimum nanorods were grown at pH 11.33. The prepared ZnO nanostructures and morphologies were characterized by x-ray diffraction and scanning electron microscopy measurements. The ZnO one-dimensional nanostructures were found to have a wurtzite hexagonal crystalline structure and grow along the [001] direction. The optimum nanorods were about 1 μm in length and less than 100 nm in diameter. The ZnO nanostructures have been tested for different concentrations and different operating temperatures for ethanol vapor in air and the surface resistance of the sensors has been evaluated as a function of different parameters. The gas sensor fabricated from ZnO nanorods grown in solution with a special pH exhibited good performance. The sensor response to 5000 ppm ethanol was up to about 2.5 at the operating temperature of 300 °C. The differences in gas-sensing performance between the sensors were analyzed based on the defects created in the nanorods during their fast growth. The correlations between material structures and the properties of the gas sensors are discussed.

Hexagonal ZnO porous plates prepared from microwave synthesized layered zinc hydroxide sulphate via thermal decomposition

Energy Technology Data Exchange (ETDEWEB)

Machovsky, Michal, E-mail: machovsky@ft.utb.cz [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, Nam. T.G. Masaryka 275, 762 72 Zlin (Czech Republic); Kuritka, Ivo, E-mail: ivo@kuritka.net [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, Nam. T.G. Masaryka 275, 762 72 Zlin (Czech Republic); Sedlak, Jakub, E-mail: j1sedlak@ft.utb.cz [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Polymer Centre, Faculty of Technology, Tomas Bata University in Zlin, Nam. T.G. Masaryka 275, 762 72 Zlin (Czech Republic); Pastorek, Miroslav, E-mail: pastorek@ft.utb.cz [Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin (Czech Republic); Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlin, Nam. T.G. Masaryka 275, 762 72 Zlin (Czech Republic)

2013-10-15

Graphical abstract: - Highlights: • Zinc hydroxy sulphate was synthesized in 3 min via microwave hydrothermal route. • Zinc hydroxy sulphate was converted into mesh like porous ZnO by calcining at 900°. • The process of transformation is topotactic. - Abstract: Layered zinc hydroxide sulphate (ZHS) was prepared by microwave-assisted hydrothermal precipitation of zinc sulphate monohydrate with hexamethylenetetramine. Under ambient conditions, the structure of ZHS determined by X-ray diffraction (XRD) was found to be a mixture of zinc hydroxide sulphate pentahydrate Zn{sub 4}SO{sub 4}(OH){sub 6}·5H{sub 2}O and tetrahydrate Zn{sub 4}SO{sub 4}(OH){sub 6}·4H{sub 2}O. Fourier transform infrared (FTIR) spectroscopy was used for characterization of the prepared materials. Based on the interpretation of ZHS's thermal decomposition profile obtained by thermogravimetric analysis, ZnO of high purity was prepared by calcination at 900 °C for 2 h. The structure of the resulting ZnO was confirmed by the XRD. The morphology examination by scanning electron microscopy revealed a porous mesh-like ZnO structure developed from the ZHS precursor at the expense of mass removal due to the release of water and sulphate during the calcination.

Optical and morphological properties of ZnO- and TiO2-derived nanostructures synthesized via a microwave-assisted hydrothermal method

CSIR Research Space (South Africa)

Moloto, N

2012-01-01

Full Text Available Corporation International Journal of Photoenergy Volume 2012, Article ID 189069, 6 pages doi:10.1155/2012/189069 Research Article Optical and Morphological Properties of ZnO- and TiO2-Derived Nanostructures Synthesized via a Microwave... International Journal of Photoenergy the sol-gel, hydrothermal process, and pulse laser deposition [22?24]. Although the sol-gel method is widely accepted for the preparation of both ZnO and TiO2 nanostructures, the calcinations process is essential and can...

Raman scattering and band-gap variations of Al-doped ZnO nanoparticles synthesized by a chemical colloid process

International Nuclear Information System (INIS)

Lo, Shih-Shou; Huang, Dison; Tu, Chun Hsiang; Hou, Chia-Hung; Chen, Chii-Chang

2009-01-01

This study synthesizes Al-doped ZnO (AZO) nanoparticles using a chemical colloid process. Raman scattering analysis shows that Al doping increases the lattice defects and induces Raman vibration modes of 651 cm -1 . The Raman shift of the active mode E 2 (high) of AZO nanoparticles shows the presence and increase in the stress in nanoparticles when the Al dopant concentration increases. Room-temperature photoluminescence (RT-PL) spectra of synthesized AZO nanoparticles exhibit strong UV emissions near the band edges. The RT-PL peak shifts to a higher photon energy region as the Al concentration increases, indicating a broadening of the band gap.

Zinc accumulation and synthesis of ZnO nanoparticles using Physalis alkekengi L

International Nuclear Information System (INIS)

Qu Jiao; Yuan Xing; Wang Xinhong; Shao Peng

2011-01-01

A field survey and greenhouse experiments were conducted using Physalis alkekengi L. to investigate strategies of phytoremediation. In addition, ZnO nanoparticles were synthesized using P. alkekengi. P. alkekengi plants grew healthily at Zn levels from 50 to 5000 mg kg -1 in soils. The plants incorporated Zn into their aerial parts (with mean dry weight values of 235-10,980 mg kg -1 ) and accumulated biomass (with a mean dry weight of 25.7 g plant -1 ) during 12 weeks. The synthesized ZnO nanoparticles showed a polydisperse behavior and had a mean size of 72.5 nm. The results indicate that P. alkekengi could be used for the remediation of zinc-contaminated soils. Moreover, the synthetic method of synthesizing ZnO nanoparticles from Zn hyperaccumulator plants constitutes a new insight into the recycling of metals in plant sources. - Highlights: → P. alkekengi plants were used to remediate the Zn-contaminated soils. → Zn in P. alkekengi plants were used as a material to synthesize ZnO nanoparticles. → P. alkekengi plants absorbed large amounts of Zn from soils into its aerial parts. → The synthesized ZnO nanoparticles were not uniform. → The mean size of synthesized ZnO nanoparticles was 72.5 nm. - ZnO nanoparticles were synthesized using P. alkekengi plants, which absorbed large amounts of Zn from contaminated soils.

Zinc accumulation and synthesis of ZnO nanoparticles using Physalis alkekengi L

Energy Technology Data Exchange (ETDEWEB)

Qu Jiao, E-mail: qujiao@bhu.edu.cn [School of Urban and Environmental Sciences, Northeast Normal University, No. 5268 Renmin street, Changchun 130024 (China); Yuan Xing, E-mail: yuanx@nenu.edu.cn [School of Urban and Environmental Sciences, Northeast Normal University, No. 5268 Renmin street, Changchun 130024 (China); Wang Xinhong; Shao Peng [School of Urban and Environmental Sciences, Northeast Normal University, No. 5268 Renmin street, Changchun 130024 (China)

2011-07-15

A field survey and greenhouse experiments were conducted using Physalis alkekengi L. to investigate strategies of phytoremediation. In addition, ZnO nanoparticles were synthesized using P. alkekengi. P. alkekengi plants grew healthily at Zn levels from 50 to 5000 mg kg{sup -1} in soils. The plants incorporated Zn into their aerial parts (with mean dry weight values of 235-10,980 mg kg{sup -1}) and accumulated biomass (with a mean dry weight of 25.7 g plant{sup -1}) during 12 weeks. The synthesized ZnO nanoparticles showed a polydisperse behavior and had a mean size of 72.5 nm. The results indicate that P. alkekengi could be used for the remediation of zinc-contaminated soils. Moreover, the synthetic method of synthesizing ZnO nanoparticles from Zn hyperaccumulator plants constitutes a new insight into the recycling of metals in plant sources. - Highlights: > P. alkekengi plants were used to remediate the Zn-contaminated soils. > Zn in P. alkekengi plants were used as a material to synthesize ZnO nanoparticles. > P. alkekengi plants absorbed large amounts of Zn from soils into its aerial parts. > The synthesized ZnO nanoparticles were not uniform. > The mean size of synthesized ZnO nanoparticles was 72.5 nm. - ZnO nanoparticles were synthesized using P. alkekengi plants, which absorbed large amounts of Zn from contaminated soils.

Ge nanobelts with high compressive strain fabricated by secondary oxidation of self-assembly SiGe rings

DEFF Research Database (Denmark)

Lu, Weifang; Li, Cheng; Lin, Guangyang

2015-01-01

Curled Ge nanobelts were fabricated by secondary oxidation of self-assembly SiGe rings, which were exfoliated from the SiGe stripes on the insulator. The Ge-rich SiGe stripes on insulator were formed by hololithography and modified Ge condensation processes of Si0.82Ge0.18 on SOI substrate. Ge...... nanobelts under a residual compressive strain of 2% were achieved, and the strain should be higher before partly releasing through bulge islands and breakage of the curled Ge nanobelts during the secondary oxidation process. The primary factor leading to compressive strain is thermal shrinkage of Ge...... nanobelts, which extrudes to Ge nanobelts in radial and tangent directions during the cooling process. This technique is promising for application in high-mobility Ge nano-scale transistors...

Sonochemical synthesis of Dy-doped ZnO nanostructures and their photocatalytic properties

Energy Technology Data Exchange (ETDEWEB)

Yayapao, Oranuch [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongtem, Titipun, E-mail: ttpthongtem@yahoo.com [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Phuruangrat, Anukorn, E-mail: phuruangrat@hotmail.com [Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Thongtem, Somchai [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2013-11-05

Highlights: •Undoped and Dy-doped ZnO used as photocatalysts. •They were synthesized by sonochemistry. •The promising materials for treatment of organic pollutants. -- Abstract: Dy-doped ZnO nanostructures were synthesized by a sonochemical method. The concentration effect of Dy on their phase, morphology, optical properties and photocatalytic activities was investigated. XRD patterns indicated that the as-synthesized 0–3% Dy-doped ZnO was hexagonal wurtzite structure. SEM and TEM show that the products were nanorods with their growth direction along the c axis. The photoluminescence spectrum of 3% Dy-doped ZnO, applied by Gaussian analysis, consists of three emission peaks at 376 nm, 448 nm and 487 nm. The photocatalytic activities of the as-synthesized products were determined from the degradation of methylene blue (C{sub 16}H{sub 18}N{sub 3}SCl) by UV radiation. In this research, the 3% Dy-doped ZnO showed the highest photocatalytic activity.

Sonochemical synthesis of Dy-doped ZnO nanostructures and their photocatalytic properties

International Nuclear Information System (INIS)

Yayapao, Oranuch; Thongtem, Titipun; Phuruangrat, Anukorn; Thongtem, Somchai

2013-01-01

Highlights: •Undoped and Dy-doped ZnO used as photocatalysts. •They were synthesized by sonochemistry. •The promising materials for treatment of organic pollutants. -- Abstract: Dy-doped ZnO nanostructures were synthesized by a sonochemical method. The concentration effect of Dy on their phase, morphology, optical properties and photocatalytic activities was investigated. XRD patterns indicated that the as-synthesized 0–3% Dy-doped ZnO was hexagonal wurtzite structure. SEM and TEM show that the products were nanorods with their growth direction along the c axis. The photoluminescence spectrum of 3% Dy-doped ZnO, applied by Gaussian analysis, consists of three emission peaks at 376 nm, 448 nm and 487 nm. The photocatalytic activities of the as-synthesized products were determined from the degradation of methylene blue (C 16 H 18 N 3 SCl) by UV radiation. In this research, the 3% Dy-doped ZnO showed the highest photocatalytic activity

Effect of temperature on structural, optical and photoluminescence studies on ZnO nanoparticles synthesized by the standard co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Raj, K. Pradeev [Research and Development Centre, Bharathiar University, Coimbatore 641046, Tamil Nadu (India); Department of Physics, CSI College of Engineering, Ooty 643215, Tamil Nadu (India); Sadayandi, K. [Department of Physics, Alagappa Government Arts College, Karaikudi, Sivagangai 630003, Tamil Nadu (India)

2016-04-15

This present study brings the synthesis of Zinc oxide (ZnO) nanoparticles (NPs) by the standard aqueous chemical route technique. The impact of calcination temperature on the extent of the ZnO nanoparticles is studied for its lattice constraints. X-ray diffraction (XRD) affirms the hexagonal Wurtzite structure of the synthesized ZnO nanoparticles. From the Williamson–Hall (W–H) plot, positive slope is inferred for pure and calcined ZnO NPs and confirms the presence of tensile strain. From the SEM images it is found that the crystallinity enhances with calcination temperature. From the optical studies, it is found that the band gap energy decreases with improved transmission. The Photoluminescence (PL) spectrum reveals the UV emission is strong near the band-edge. The emission peaks around 400–480 nm result in blue emission and the peaks around 540–560 nm result in green emission. Decrease in band gap energy and enhancement in PL studies reveal the red shift of the calcined ZnO exhibiting solid quantum confinements.

Synthesis of ZnO nanorods and observation of resistive switching memory in ZnO based polymer nanocomposites

Science.gov (United States)

Nair, Manjula G.; Malakar, Meenakshi; Mohapatra, Saumya R.; Chowdhury, Avijit

2018-05-01

This research reports the observation of bipolar resistive switching memory in ZnO nanorod based polymer nanocomposites. We synthesized ZnO nanorods by wet-chemical method and characterized them using XRD, UV-VIS spectroscopy and SEM. The synthesized materials have hexagonal ZnO phase with grain size of 24 nm and having strong orientation along (101) direction as observed from XRD. The SEM micrograph confirms the formation of ZnO nanorods with diameter in the range of 10 to 20 nm and length of the order of 1 µm. From optical absorption spectra the band gap is estimated to be 2.42 eV. ZnO nanorods were dispersed in PVDF-HFP polymer matrix to prepare the nanocomposite. This nanocomposite was used as active layer in the devices having sandwich structure of ITO/PVDF-HFP+ZnO nanorods/Al. Bipolar non-volatile memory was observed with ON-OFF resistance ratio of the order of 103 and with a wide voltage window of 2.3V. The switching mechanism could be due to the trapping and de-trapping of electrons by the ZnO nanorods in the nanocomposite during ON and OFF states respectively.

Synthesis of isotopically modified ZnO nanoparticles and their potential as nanotoxicity tracers

Energy Technology Data Exchange (ETDEWEB)

Dybowska, Agnieszka D., E-mail: a.dybowska@nhm.ac.u [Department of Mineralogy, Natural History Museum London, Cromwell Road, London, SW7 5BD (United Kingdom); Croteau, Marie-Noele [U.S. Geological Survey, 345 Middlefield Road, MS 496, Menlo Park, CA 94025 (United States); Misra, Superb K.; Berhanu, Deborah [Department of Mineralogy, Natural History Museum London, Cromwell Road, London, SW7 5BD (United Kingdom); Luoma, Samuel N. [Department of Mineralogy, Natural History Museum London, Cromwell Road, London, SW7 5BD (United Kingdom); U.S. Geological Survey, 345 Middlefield Road, MS 496, Menlo Park, CA 94025 (United States); Christian, Paul; O' Brien, Paul [School of Chemistry, University of Manchester, M13 9PL, Manchester (United Kingdom); Valsami-Jones, Eugenia [Department of Mineralogy, Natural History Museum London, Cromwell Road, London, SW7 5BD (United Kingdom)

2011-01-15

Understanding the behavior of engineered nanoparticles in the environment and within organisms is perhaps the biggest obstacle to the safe development of nanotechnologies. Reliable tracing is a particular issue for nanoparticles such as ZnO, because Zn is an essential element and a common pollutant thus present at elevated background concentrations. We synthesized isotopically enriched (89.6%) with a rare isotope of Zn ({sup 67}Zn) ZnO nanoparticles and measured the uptake of {sup 67}Zn by L. stagnalis exposed to diatoms amended with the particles. Stable isotope technique is sufficiently sensitive to determine the uptake of Zn at an exposure equivalent to lower concentration range (<15 {mu}g g{sup -1}). Without a tracer, detection of newly accumulated Zn is significant at Zn exposure concentration only above 5000 {mu}g g{sup -1} which represents some of the most contaminated Zn conditions. Only by using a tracer we can study Zn uptake at a range of environmentally realistic exposure conditions. - ZnO nanoparticles with distinct isotopic composition can be tailor synthesized to be used as tracers of environmental fate and uptake by organisms.

High efficient ZnO nanowalnuts photocatalyst: A case study

Energy Technology Data Exchange (ETDEWEB)

Yan, Feng [College of Chemistry and Chemical Engineering, Mudanjiang Normal University, Mudanjiang 157011 (China); College of Chemistry and Chemical Engineering, Harbin Normal University, Harbin 150025 (China); Zhang, Siwen; Liu, Yang [College of Chemistry and Chemical Engineering, Harbin Normal University, Harbin 150025 (China); Liu, Hongfeng [School of Basic Medical Sciences, Mudanjiang Medical University, Mudanjiang 157011 (China); Qu, Fengyu [College of Chemistry and Chemical Engineering, Harbin Normal University, Harbin 150025 (China); Cai, Xue, E-mail: xuecai@mail.sdu.edu.cn [College of Chemistry and Chemical Engineering, Mudanjiang Normal University, Mudanjiang 157011 (China); Wu, Xiang, E-mail: wuxiang@hrbnu.edu.cn [College of Chemistry and Chemical Engineering, Harbin Normal University, Harbin 150025 (China)

2014-11-15

Highlights: • Walnut-like ZnO nanostructures are synthesized through a facile hydrothermal method. • Morphologies and microstructures of the as-obtained ZnO products were investigated. • The photocatalytic results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. - Abstract: Walnut-like ZnO nanostructures are successfully synthesized through a facile hydrothermal method. The structure and morphology of the as-synthesized products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic properties of ZnO nanowalnuts are investigated by photodegradating several organic dyes, such as Congo red (CR), methyl orange (MO) and eosin red aqueous solutions under UV irradiation, respectively. The results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. In addition, eosin red and Congo red (CR) aqueous solution degradation experiments are also conducted in the same condition, respectively. It showed that ZnO nanowalnuts represent high photocatalytic activities with a degradation efficiency of 87% for CR with 115 min of irradiation and 97% for eosin red with 55 min of irradiation. The reported ZnO products may be promising candidates as the photocatalysts in waste water treatment.

High efficient ZnO nanowalnuts photocatalyst: A case study

International Nuclear Information System (INIS)

Yan, Feng; Zhang, Siwen; Liu, Yang; Liu, Hongfeng; Qu, Fengyu; Cai, Xue; Wu, Xiang

2014-01-01

Highlights: • Walnut-like ZnO nanostructures are synthesized through a facile hydrothermal method. • Morphologies and microstructures of the as-obtained ZnO products were investigated. • The photocatalytic results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. - Abstract: Walnut-like ZnO nanostructures are successfully synthesized through a facile hydrothermal method. The structure and morphology of the as-synthesized products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic properties of ZnO nanowalnuts are investigated by photodegradating several organic dyes, such as Congo red (CR), methyl orange (MO) and eosin red aqueous solutions under UV irradiation, respectively. The results demonstrate that methyl orange (MO) aqueous solution can be degraded over 97% after 45 min under UV light irradiation. In addition, eosin red and Congo red (CR) aqueous solution degradation experiments are also conducted in the same condition, respectively. It showed that ZnO nanowalnuts represent high photocatalytic activities with a degradation efficiency of 87% for CR with 115 min of irradiation and 97% for eosin red with 55 min of irradiation. The reported ZnO products may be promising candidates as the photocatalysts in waste water treatment

Effect of oxygen vacancy induced by pulsed magnetic field on the room-temperature ferromagnetic Ni-doped ZnO synthesized by hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Zhong, Min [Shanghai University, Laboratory for Microstructures, School of Materials Science and Engineering, 149 Yanchang Road, 200072 Shanghai (China); Li, Ying, E-mail: liying62@shu.edu.cn [Shanghai University, Laboratory for Microstructures, School of Materials Science and Engineering, 149 Yanchang Road, 200072 Shanghai (China); Tariq, Muhammad; Hu, Yemin; Li, Wenxian; Zhu, Mingyuan; Jin, Hongmin [Shanghai University, Laboratory for Microstructures, School of Materials Science and Engineering, 149 Yanchang Road, 200072 Shanghai (China); Li, Yibing [School of Chemistry, The University of New South Wales, Sydney, NSW, 2052 (Australia)

2016-08-05

Room temperature ferromagnetic 2% Ni doped ZnO rods were synthesized by high pulsed magnetic field-assisted hydrothermal method. A detailed study on the effect of high pulsed magnetic field on morphology, structural and magnetic properties of the ZnO rods has been carried out systematically by varying the intensity of field from 0 to 4 T. X-ray diffraction, Energy-dispersive spectroscopy measurements, and Raman spectra analysis suggest that all the samples have hexagonal wurtzite structure without detectable impurity. Field emission scanning electron microscopy images indicate that the particle size of samples decrease with increasing intensity of field. High resolution transmission electron microscopy observation ensures that the Ni ions addition do not change the wurtzite host matrix. X-ray photoelectron spectroscopy confirms the incorporation of Ni elements as divalent state and the dominant presence of oxygen vacancies in samples fabricated under 4 T pulsed magnetic field. Hysteresis loops demonstrate that the saturation magnetization increased regularly with the mounting magnetic field. On the framework of bound magnetic polaron model, the rising content of oxygen vacancies, as donor defect, lead to the stronger ferromagnetism in samples with pulsed magnetic field. Our findings provide a new insight for tuning the defect density by precisely controlling the intensity of field in order to get the desired magnetic behavior at room temperature. - Graphical abstract: This figure shows the magnetization versus magnetic field curves for 2%Ni doped ZnO as prepared with 0, 1, 2, 3 and 4 T pulsed magnetic field at 290 K. For 0 T sample, no ferromagnetic response is observed. But all the samples synthesized with field were well-defined hysteresis loops. The saturation magnetization estimated from the hysteresis loop come out to be ∼0.0024, 0.0023, 0.0036 and 0.0061 emu/g for 1 T, 2 T, 3 T and 4 T samples, respectively. As shown in the curves, the room

ZnO Film Photocatalysts

Directory of Open Access Journals (Sweden)

Bosi Yin

2014-01-01

Full Text Available We have synthesized high-quality, nanoscale ultrathin ZnO films at relatively low temperature using a facile and effective hydrothermal approach. ZnO films were characterized by scanning electron microscope (SEM, X-ray diffraction (XRD, Raman spectroscopy, photoluminescence spectra (PL, and UV-vis absorption spectroscopy. The products demonstrated 95% photodegradation efficiency with Congo red (CR after 40 min irradiation. The photocatalytic degradation experiments of methyl orange (MO and eosin red also were carried out. The results indicate that the as-obtained ZnO films might be promising candidates as the excellent photocatalysts for elimination of waste water.

Enhanced antibacterial activity of zinc oxide nanoparticles synthesized using Petroselinum crispum extracts

Energy Technology Data Exchange (ETDEWEB)

Stan, Manuela, E-mail: manuela.stan@itim-cj.ro; Popa, Adriana; Toloman, Dana; Silipas, Teofil-Danut [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca (Romania); Vodnar, Dan Cristian [University of Agricultural Sciences and Veterinary Medicine, Department of Food Science and Technology, 3-5 Manastur Street, 400372 Cluj-Napoca (Romania); Katona, Gabriel [Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos Street, 400028 Cluj-Napoca (Romania)

2015-12-23

The present contribution reports the synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf and root extracts of Petroselinum crispum (parsley) and characterization of as-prepared samples. ZnO NPs are subjected to X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) studies. The XRD studies reveal a hexagonal wurtzite structure without supplementary diffraction lines for all ZnO samples. TEM analysis shows that the particle size is influenced by the type of plant extract. The EPR spectra indicate the presence of Mn{sup 2+} ions in ZnO sample synthesized using P. crispum leaf extract, while zinc vacancy complexes and oxygen vacancies are evidenced in all analyzed samples. ZnO NPs synthesized using P. crispum extracts exhibit increased (2-16 times) antibacterial activity as compared to chemically synthesized ZnO NPs.

Enhanced antibacterial activity of zinc oxide nanoparticles synthesized using Petroselinum crispum extracts

International Nuclear Information System (INIS)

Stan, Manuela; Popa, Adriana; Toloman, Dana; Silipas, Teofil-Danut; Vodnar, Dan Cristian; Katona, Gabriel

2015-01-01

The present contribution reports the synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf and root extracts of Petroselinum crispum (parsley) and characterization of as-prepared samples. ZnO NPs are subjected to X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) studies. The XRD studies reveal a hexagonal wurtzite structure without supplementary diffraction lines for all ZnO samples. TEM analysis shows that the particle size is influenced by the type of plant extract. The EPR spectra indicate the presence of Mn 2+ ions in ZnO sample synthesized using P. crispum leaf extract, while zinc vacancy complexes and oxygen vacancies are evidenced in all analyzed samples. ZnO NPs synthesized using P. crispum extracts exhibit increased (2-16 times) antibacterial activity as compared to chemically synthesized ZnO NPs

Hydrolysis and ion exchange of titania nanoparticles towards large-scale titania and titanate nanobelts for gas sensing applications

International Nuclear Information System (INIS)

Bela, Somaiah; Ho, Ghim Wei; Wong, Andrew See Weng

2010-01-01

One-dimensional titanate and titania nanostructures are prepared by hydrothermal method from titania nanoparticles precursor via hydrolysis and ion exchange processes. The formation mechanism and the reaction process of the nanobelts are elucidated. The effects of the NaOH concentration, HCl leaching duration and the calcination temperature on the morphology and chemical composition of the produced nanobelts are investigated. Na + ions of the titanate nanobelts can be effectively removed by longer acid leaching and neutralization process and transformed into metastable hydrogen titanate compound. A hybrid hydrogen titanate and anatase titania nanobelts can be obtained under dehydration process of 500 0 C. The nanobelts are produced in gram quantities and easily made into nanostructure paper for the bulk study on their electrical and sensing properties. The sensing properties of the nanobelts sheet are tested and exhibited response to H 2 gas.

Resistive Switching Characteristics in Electrochemically Synthesized ZnO Films

Directory of Open Access Journals (Sweden)

Shuhan Jing

2015-04-01

Full Text Available The semiconductor industry has long been seeking a new kind of non-volatile memory technology with high-density, high-speed, and low-power consumption. This study demonstrated the electrochemical synthesis of ZnO films without adding any soft or hard templates. The effect of deposition temperatures on crystal structure, surface morphology and resistive switching characteristics were investigated. Our findings reveal that the crystallinity, surface morphology and resistive switching characteristics of ZnO thin films can be well tuned by controlling deposition temperature. A conducting filament based model is proposed to explain the switching mechanism in ZnO thin films.

Sea-Urchin-Like ZnO Nanoparticle Film for Dye-Sensitized Solar Cells

Directory of Open Access Journals (Sweden)

Cheng-Wen Ma

2015-01-01

Full Text Available We present novel sea-urchin-like ZnO nanoparticles synthesized using a chemical solution method. Solution approaches to synthesizing ZnO nanostructures have several advantages including low growth temperatures and high potential for scaling up. We investigated the influence of reaction times on the thickness and morphology of sea-urchin-like ZnO nanoparticles, and XRD patterns show strong intensity in every direction. Dye-sensitized solar cells (DSSCs were developed using the synthesized ZnO nanostructures as photoanodes. The DSSCs comprised a fluorine-doped tin oxide (FTO glass with dense ZnO nanostructures as the working electrode, a platinized FTO glass as the counter electrode, N719-based dye, and I-/I3-liquid electrolyte. The DSSC fabricated using such nanostructures yielded a high power conversion efficiency of 1.16% with an incident photo-to-current efficiency (IPCE as high as 15.32%. Electrochemical impedance spectroscopy was applied to investigate the characteristics of DSSCs. An improvement in the electron transport in the ZnO photoanode was also observed.

Synthesis, characterization and photocatalysis enhancement of Eu2O3-ZnO mixed oxide nanoparticles

Science.gov (United States)

Mohamed, W. S.; Abu-Dief, Ahmed M.

2018-05-01

Pure ZnO nanoparticles (NPs) and mixed Eu2O3 and ZnO NPs with different Eu2O3 ratios (5%, 10%, and 15%) were synthesized by a precipitation method under optimum conditions. The synthesized samples were characterized by means of X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and UV-vis diffuse reflectance spectroscopy. The as-synthesized ZnO NPs exhibit high phase purity and a highly crystalline wurtzite ZnO structure. The mixed Eu2O3 and ZnO NPs exhibit a Eu2O3 zinc blend phase in addition to the wurtzite phase of pure ZnO, confirming the high purity and good crystallinity of the as-synthesized samples. The high-purity formation of ZnO and Eu2O3 phases was confirmed by FTIR and Raman spectra. Microstructural analysis by SEM and TEM confirmed the sphere-like morphology with different particle sizes (29-40 nm) of the as-synthesized samples. The photocatalytic activities of pure ZnO NPs and mixed Eu2O3 and ZnO NPs for the degradation of methylene blue were evaluated under ultraviolet (UV) irradiation. The results show that Eu2O3 plays an important role in the enhancement of the photocatalytic properties of ZnO NPs. We found that mixed 5% Eu2O3 and ZnO NPs exhibit the highest photocatalytic activity (degradation efficiency of 96.5% after 180 min of UV irradiation) as compared with pure ZnO NPs (degradation efficiency of 80.3% after 180 min of UV irradiation). The increased photocatalytic activity of the optimum mixed Eu2O3 and ZnO NPs is due to the high crystallinity, high surface area with small particle size, and narrow energy gap.

Enhanced fluorescence imaging performance of hydrophobic colloidal ZnO nanoparticles by a facile method

International Nuclear Information System (INIS)

Zang, Zhigang; Tang, Xiaosheng

2015-01-01

Highlights: • A dual phase hydrothermal method was developed to synthesize ZnO nanoparticles. • ZnO nanoparticles show a stability and solubility in the aqueous environment. • ZnO nanoparticles with a blue emission wavelength at around 420 nm and small size (30 nm). • ZnO nanoparticles as biological labeling agent was also shown. - Abstract: A facile synthesis method for the formation of ZnO nanoparticles by using a double-phase reaction was demonstrated in this paper. The morphology of the synthesized ZnO nanoparticles shows a flower-shape. Hydrogen peroxide was used as a unique oxygenic source to promote the formation of ZnO in the presence of organic zinc precursor. The as-synthesized ZnO nanoparticles also show a stability and solubility in the aqueous environment. The structure and properties of ZnO nanoparticles were investigated by the transmission electron microscopy (TEM) and X-ray diffraction (XRD) as well as UV–vis and photoluminescence spectroscopy. The as-prepared hydrophobic colloidal ZnO nanoparticles could be modified to become water-soluble via ligand exchange with amineothanethiol⋅HCl while retaining the photoluminescence properties. In addition, the potential application for biological label of water-soluble ZnO nanoparticles were also demonstrated. These results not only have applications towards using colloidal ZnO nanoparticles effectively in biological fluorescence imaging, but also promote its application in the field of targeted drug delivery

The effect of Ce{sup 3+} on structure, morphology and optical properties of flower-like ZnO synthesized using the chemical bath method

Energy Technology Data Exchange (ETDEWEB)

Koao, L.F. [Department of Physics, University of the Free State, Qwaqwa Campus, Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, F.B., E-mail: dejenebf@qwa.ufs.ac.za [Department of Physics, University of the Free State, Qwaqwa Campus, Private Bag X13, Phuthaditjhaba 9866 (South Africa); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa); Botha, J.R. [Physics Department, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

2013-11-15

Ce{sup 3+} doped ZnO flower-like structures were synthesized by the chemical bath deposition method (CBD). The influence of Ce{sup 3+} as a dopant on the crystallization, surface morphology, optical and luminescent properties of ZnO flowers-like structures were investigated. The X-ray diffraction (XRD) spectra of the ZnO:Ce{sup 3+}nanostructures correspond to the various planes of a single hexagonal ZnO phase for the lower Ce concentration samples. The estimated grain sizes calculated using the XRD spectra were found to be in order of 42±2 nm. The grain size was found to be not dependent on the concentration of the Ce{sup 3+} ions used up to 3 mol% of Ce. Scanning Auger electron microscopy and scanning electron micrographs indicate that the addition of Ce{sup 3+} influence the morphology of the samples. The flower-like structures obtained for the undoped and low concentration Ce doped ZnO changed into a mixed structure with the emergence of pyramid shapes for higher concentration Ce doped samples. The solid undoped and low concentration Ce doped powder showed good optical properties with a high reflectance in the visible regions. The properties, however, diminished at higher Ce concentration. The band gap energies decreased linearly with concentration from 3.0±0.1 to 2.4±0.3 eV for ZnO:0 mol% Ce{sup 3+} up to ZnO:10 mol% Ce{sup 3+}. Under 248 nm excitation, the undoped and low concentration Ce doped ZnO flower-like rods exhibited a green emission, peaking at about 559 nm. The higher Ce concentration (0.3 mol% and above) was emitted at 436 and 503 nm due to the Ce transitions. The intensity of these emission spectra of the ZnO:Ce{sup 3+} decreased with the addition of more Ce{sup 3+} ions. -- Highlights: • Ce{sup 3+} doped ZnO flower-like structures were synthesized by CBD. • Flower-like hexagonal ZnO:Ce{sup 3+}nanostructures were obtained for undoped and low mol% Ce. • ZnO changed into a mixed structure with emergence of pyramid shapes for higher mol% Ce

Electrical, dielectric and photocatalytic properties of Fe-doped ZnO nanomaterials synthesized by sol gel method

Directory of Open Access Journals (Sweden)

Yacine Cherif

2016-09-01

Full Text Available Fe-doped ZnO nanoparticles were synthesized by sol gel technique. Fine-scale and single phase hexagonal wurtzite structure in all samples were confirmed by SEM and XRD, respectively. The band gap energy depends on the amount of Fe and was found to be in the range of 3.11–2.53 eV. The electric and dielectric properties were investigated using complex impedance spectroscopy. AC conductivity data were correlated with the barrier hopping (CBH model to evaluate the binding energy (Wm, the minimum hopping distance (Rmin and the density of states at Fermi level, N(EF. Fe doping in ZnO also improved the photocatalytic activity. Thus, the sample Zn0.95Fe0.05O showed high degradation potential towards methylene blue (MB, i.e. it degrades 90% of BM in 90 min under UV light.

Effect of solvent medium on the structural, morphological and optical properties of ZnO nanoparticles synthesized by the sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Ungula, J., E-mail: ungulaj@qwa.ufs.ac.za; Dejene, B.F.

2016-01-01

ZnO nanoparticles were synthesized using a sol–gel method. The effect of solvent medium on the structural, morphological and optical properties of ZnO nanoparticles were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectroscopy (PL), UV–vis spectroscopy (UV–vis) and Energy-dispersive X-ray spectroscopy ( EDS). The XRD patterns showed single phase hexagonal structure. The crystallite size of as prepared ZnO nanoparticles was found to decrease from 28.1 nm to 10.8 nm with the increase in volume ratio of ethanol in the solvent as peak intensities and sharpness increase with corresponding increase in volume ratio of water. SEM micrographs showed that samples prepared in water medium are fairly spherical which turned to tiny rods with increasing volume ratios of ethanol. A sharp ultraviolet (UV) emission peak centred about 385 nm and a broad green–yellow emission at about 550 nm are observed with PL measurements. The band gap of ZnO decreased from 3.31 to 3.17 eV with an increase in the ethanol composition in the solvent, implying that the optical properties of these materials are clearly affected by the synthesis medium.

Template-free sonochemical synthesis of flower-like ZnO nanostructures

International Nuclear Information System (INIS)

Yu, Huawa; Fan, Huiqing; Wang, Xin; Wang, Jing; Cheng, Pengfei; Zhang, Xiaojun

2014-01-01

Flower-like ZnO nanostructures have been successfully synthesized via a facile and template-free sonochemical method, using zinc acetate and potassium hydroxide as reactants only. The as-synthesized flower-like ZnO nanostructures were composed of nanorods with the width of ∼300–400 nm and the length of ∼2–3 μm. The structures, morphologies and optical properties of the as-prepared products were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscopy, UV-Vis spectrophotometry and Raman-scattering spectroscopy. A plausible formation mechanism of flower-like ZnO nanostructures was studied by SEM which monitors an intermediate morphology transformation of the product at the different ultrasonic time (t=80,90,95,105, and 120 min). - Highlights: • A facile and template-free sonochemical method to fabricate flower-like ZnO nanostructures was proposed. • The flower-like ZnO nanostructures follow the ingrowth of ZnO from the matrix of Zn(OH) 2 crystals. • The flower-like ZnO nanostructures are also expected to explore their application in the field of nano-electronic devices

Synthesis of 1-D ZnO nanorods and polypyrrole/1-D ZnO ...

Indian Academy of Sciences (India)

1-D ZnO nanorods and PPy/1-D ZnO nanocomposites were prepared by the surfactant-assisted precipitation and in situ polymerization method, respectively. The synthesized nanorods and nanocomposites were characterized by UV–Vis spectrophotometer, Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction ...

Synthesis, optical, structural, and electrical properties of single-crystalline CdS nanobelts

Energy Technology Data Exchange (ETDEWEB)

Alqahtani, Mohammed S. [King Saud University, Department of Physics and Astronomy, Riyadh (Saudi Arabia); Hadia, N.M.A.; Mohamed, S.H. [Sohag University, Physics Department, Faculty of Science, Sohag (Egypt)

2017-04-15

CdS nanobelts (NBs) were synthesized by vapor transport of CdS powders. The growth was carried out without any catalyst on quartz and Si (100) substrates. The synthesized CdS NBs were examined by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD), energy dispersion analysis of X-ray (EDAX), spectrophotometer, and photoluminescence spectroscopy. CdS NBs were indexed as hexagonal wurtzite structure. The growth was via vapor-solid growth mechanism and along the [100] direction. The refractive index was evaluated in the transparent region, as suggested by Swanepoel, using the envelope method. The refractive index values and the extinction coefficient were decreased by increasing the wavelength. The calculated optical band gap was 2.50 eV. The photoluminescence (PL) spectrum of the synthesized CdS NBs exhibited a green emission peak at 510 nm and a broad red emission peak at 696 nm. The conductivity measurements were achieved, in the temperature range from 300 to 600 K, using the conventional two-probe technique. Two different slopes with different activation energies of 0.618 and 0.215 eV were obtained. The CdS NBs are likely being novel functional materials. Thus, they can be used in the manufacture of innovative optoelectronic nanodevices. (orig.)

Photocatalytic activity of Ag3PO4 nanoparticle/TiO2 nanobelt heterostructures

Science.gov (United States)

Liu, Ruoyu; Hu, Peiguang; Chen, Shaowei

2012-10-01

Heterostructures based on Ag3PO4 nanoparticles and TiO2 nanobelts were prepared by a coprecipitation method. The crystalline structures were characterized by X-ray diffraction measurements. Electron microscopic studies showed that the Ag3PO4 nanoparticles and TiO2 nanobelts were in intimate contact which might be exploited to facilitate charge transfer between the two semiconductor materials. In fact, the heterostructures exhibited markedly enhanced photocatalytic activity as compared with unmodified TiO2 nanobelts or commercial TiO2 colloids in the photodegradation of methyl orange under UV irradiation. This was accounted for by the improved efficiency of interfacial charge separation thanks to the unique alignments of their band structures. Remarkably, whereas the photocatalytic activity of the heterostructure was comparable to that of Ag3PO4 nanoparticles alone, the heterostructures exhibited significantly better stability and reusability in repeated tests than the Ag3PO4 nanoparticles.

Synthesis, characterization and optical properties of sheet-like ZnO

International Nuclear Information System (INIS)

Liu, Changzhen; Meng, Dawei; Wu, Xiuling; Wang, Yongqian; Yu, Xiaohong; Zhang, Zhengjie; Liu, Xiaoyang

2011-01-01

Highlights: → Sheet-like ZnO with regular hexagon shape was synthesized with a two-step method. → Sheet-like ZnO predecessor was synthesized at low temperature in open system. → The diameter and thickness of ZnO sheet can be controlled conveniently. → This low-cost and environmentally benign approach is controllable and reproducible. → Sheet-like ZnO may have potential application in optical and electrical devices. -- Abstract: Sheet-like ZnO with regular hexagon shape and uniform diameter has been successfully synthesized through a two-step method without any metal catalyst. First, the sheet-like ZnO precursor was synthesized in a weak alkaline carbamide environment with stirring in a constant temperature water-bath by the homogeneous precipitation method, then sheet-like ZnO was obtained by calcining at 600 o C for 2 h. The structures and optical properties of sheet-like ZnO have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) and UV-vis-NIR spectrophotometer. The results reveal that the product is highly crystalline with hexagonal wurtzite phase and has appearance of hexagon at (0 0 0 1) plane. The HRTEM images confirm that the individual sheet-like ZnO is single crystal. The PL spectrum exhibits a narrow ultraviolet emission at 397 nm and a broad visible emission centering at 502 nm. The band gap of sheet-like ZnO is about 3.15 eV.

Preparation of ZnO nanocrystals via ultrasonic irradiation

DEFF Research Database (Denmark)

Qian, D.; Jiang, Jianzhong; Hansen, P. L.

2003-01-01

A simple and rapid process has been developed for the preparation of nanometer-sized ZnO crystals via ultrasonic irradiation, by which pure ZnO nanocrystals with an average size of 6 nm and narrow size distribution can be synthesized in a short time and without using any solvents for the precipit......A simple and rapid process has been developed for the preparation of nanometer-sized ZnO crystals via ultrasonic irradiation, by which pure ZnO nanocrystals with an average size of 6 nm and narrow size distribution can be synthesized in a short time and without using any solvents...

Nanotubes, nanobelts, nanowires, and nanorods of silicon carbide from the wheat husks

Energy Technology Data Exchange (ETDEWEB)

Qadri, S. B.; Rath, B. B.; Gorzkowski, E. P.; Feng, J.; Qadri, S. N.; Caldwell, J. D. [Materials Science and Component Technology Directorate, Naval Research Laboratory, Washington, District of Columbia 20375 (United States)

2015-09-14

Nanotubes, nanowires, nanobelts, and nanorods of SiC were synthesized from the thermal treatment of wheat husks at temperatures in excess of 1450 °C. From the analysis based on x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy, it has been found that the processed samples of wheat husk consisted of 2H and 3C polytypes of SiC exhibiting the nanostructure shapes. These nanostructures of silicon carbide formed from wheat husks are of technological importance for designing advance composites, applications in biotechnology, and electro-optics. The thermodynamics of the formation of SiC is discussed in terms of the rapid solid state reaction between hydrocarbons and silica on the molecular scale, which is inherently present in the wheat husks.

Nanosheet-Assembled ZnO Microflower Photocatalysts

Directory of Open Access Journals (Sweden)

Siwen Zhang

2014-01-01

Full Text Available Large scale ZnO microflowers assembled by numerous nanosheets are synthesized through a facile and effective hydrothermal route. The structure and morphology of the resultant products are characterized by X-ray diffraction (XRD and scanning electron microscope (SEM. Photocatalytic properties of the as-synthesized products are also investigated. The results demonstrate that eosin red aqueous solution can be degraded over 97% after 110 min under UV light irradiation. In addition, methyl orange (MO and Congo red (CR aqueous solution degradation experiments also are conducted in the same condition, respectively. It showed that nanosheet-assembled ZnO microflowers represent high photocatalytic activities with a degradation efficiency of 91% for CR with 90 min of irradiation and 90% for MO with 60 min of irradiation. The reported ZnO products may be promising candidates as the photocatalysts in waste water treatment.

Enhanced field emission of ZnO nanoneedle arrays via solution etching at room temperature

DEFF Research Database (Denmark)

Ma, Huanming; Qin, Zhiwei; Wang, Zaide

2017-01-01

ZnO nanoneedle arrays (ZnO nns) were synthesized by a facile two-step solution-phase method based on the etching of pre-synthesized ZnO nanowire arrays (ZnO nws) with flat ends at room temperature. Field emission measurement results showed that the turn-on electronic fields of ZnO nns and nws wer...

Effect of indium on photovoltaic property of n-ZnO/p-Si heterojunction device prepared using solution-synthesized ZnO nanowire film

Science.gov (United States)

Kathalingam, Adaikalam; Kim, Hyun-Seok; Park, Hyung-Moo; Valanarasu, Santiyagu; Mahalingam, Thaiyan

2015-01-01

Preparation of n-ZnO/p-Si heterostructures using solution-synthesized ZnO nanowire films and their photovoltaic characterization is reported. The solution-grown ZnO nanowire film is characterized using scanning electron microscope, electron dispersive x-ray, and optical absorption studies. Electrical and photovoltaic properties of the fabricated heterostructures are studied using e-beam-evaporated aluminum as metal contacts. In order to use transparent contact and to simultaneously collect the photogenerated carriers, sandwich-type solar cells were fabricated using ZnO nanorod films grown on p-silicon and indium tin oxide (ITO) coated glass as ITO/n-ZnO NR/p-Si. The electrical properties of these structures are analyzed from current-voltage (I-V) characteristics. ZnO nanowire film thickness-dependent photovoltaic properties are also studied. Indium metal was also deposited over the ZnO nanowires and its effects on the photovoltaic response of the devices were studied. The results demonstrated that all the samples exhibit a strong rectifying behavior indicating the diode nature of the devices. The sandwich-type ITO/n-ZnO NR/p-Si solar cells exhibit improved photovoltaic performance over the Al-metal-coated n-ZnO/p-Si structures. The indium deposition is found to show enhancement in photovoltaic behavior with a maximum open-circuit voltage (Voc) of 0.3 V and short-circuit current (Isc) of 70×10-6 A under ultraviolet light excitation.

Synthesis of {alpha}-Fe{sub 2}O{sub 3} nanobelts and nanoflakes by thermal oxidation and study to their magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Su Xinghua [School of Materials Science and Engineering, Chang' an University, Xi' an 710061 (China); Yu Chengshou [Department of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Qiang Chengwen, E-mail: qiangchw04@gmail.com [Department of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China)

2011-08-15

{alpha}-Fe{sub 2}O{sub 3} nanobelts and nanoflakes have been successfully synthesized by oxidation of iron-coated ITO glass in air. The X-ray diffraction, Raman spectrum and scanning electron microscopy are carried out to characterize the nanobelts and nanoflakes. The formation mechanism has been presented. Significantly, the magnetic investigations show that the magnetic properties are strongly shape-dependent. The magnetization measurements of belt-like and flake-like {alpha}-Fe{sub 2}O{sub 3} in perpendicular exhibit ferromagnetic feature with the coercivity (H{sub c}) and saturation magnetization (M{sub s}) of 334.5 Oe and 1.35 emu/g, 239.5 Oe and 0.12 emu/g, respectively. For the parallel, belt-like and flake-like {alpha}-Fe{sub 2}O{sub 3} also exhibit ferromagnetic feature with the H{sub c} and M{sub s} of 205.5 Oe and 1.44 emu/g, 159.6 Oe and 0.15 emu/g, respectively.

Template-free sonochemical synthesis of flower-like ZnO nanostructures

Energy Technology Data Exchange (ETDEWEB)

Yu, Huawa [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi' an 710072 (China); School of Science, Xi' an Polytechnic University, Xi' an 710048 (China); Fan, Huiqing, E-mail: hqfan3@163.com [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi' an 710072 (China); Wang, Xin [Shaanxi Province Thin Film Technology and Optical Test Open Key Laboratory, School of Photoelectrical Engineering, Xi' an Technological University, Xi' an 710032 (China); Wang, Jing [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi' an 710072 (China); Cheng, Pengfei; Zhang, Xiaojun [School of Science, Xi' an Polytechnic University, Xi' an 710048 (China)

2014-10-03

Flower-like ZnO nanostructures have been successfully synthesized via a facile and template-free sonochemical method, using zinc acetate and potassium hydroxide as reactants only. The as-synthesized flower-like ZnO nanostructures were composed of nanorods with the width of ∼300–400 nm and the length of ∼2–3 μm. The structures, morphologies and optical properties of the as-prepared products were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscopy, UV-Vis spectrophotometry and Raman-scattering spectroscopy. A plausible formation mechanism of flower-like ZnO nanostructures was studied by SEM which monitors an intermediate morphology transformation of the product at the different ultrasonic time (t=80,90,95,105, and 120 min). - Highlights: • A facile and template-free sonochemical method to fabricate flower-like ZnO nanostructures was proposed. • The flower-like ZnO nanostructures follow the ingrowth of ZnO from the matrix of Zn(OH){sub 2} crystals. • The flower-like ZnO nanostructures are also expected to explore their application in the field of nano-electronic devices.

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

International Nuclear Information System (INIS)

Miao Tingting; Guo Yuanru; Pan Qingjiang

2013-01-01

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

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

Science.gov (United States)

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

2013-06-01

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

On the origin of blue emission from ZnO quantum dots synthesized by a sol–gel route

International Nuclear Information System (INIS)

Han, Li-Li; Cui, Lan; Du, Xi-Wen; Wang, Wei-Hua; Wang, Jiang-Long

2012-01-01

ZnO quantum dots (QDs) with blue emission were synthesized by a sol–gel method. A series of control experiments were conducted to explore the origin of the blue emission. It is found that the blue emission arises from neither the quantum confinement nor intermediate products, and it can be achieved only in the presence of Li + cations and excessive OH − anions. Moreover, the long decay time of the blue emission suggests a defect-related de-excitation process. On the basis of the experimental and calculation results, possible de-excitation paths for light emission were discussed, and the origin of the blue emission was determined as the electron transition from the conduction band to interstitial oxygen defects. Excessive OH − anions are responsible for the formation of interstitial oxygen defects, and Li + ions can stabilize the defects by substituting for Zn atoms. Besides, Li + ions can block the growth of ZnO QDs, broaden their band gap and cause a blue shift of the blue emission. (paper)

Trioctylphosphine-assisted morphology control of ZnO nanoparticles

Science.gov (United States)

Hong, Yun-Kun; Cho, GeonHee; Park, YoonSu; Oh, Soong Ju; Ha, Don-Hyung

2018-06-01

This study investigates the morphological change in colloidal ZnO nanoparticles (NPs) synthesized with trioctylphosphine (TOP). The addition of TOP to the synthesis causes an evolution in the shape of ZnO NPs to tadpole-like particles from quasi-spherical particles at 300 °C. The total length of the tadpole-like ZnO NPs can be modified by controlling the molar ratio of TOP to oleylamine (OLAM). The tadpole-like particles are elongated as the concentration of TOP increased but decreased when the addition of TOP is excessive. These tadpole-like ZnO NPs transform to quasi-spherical NPs regardless of the amount of TOP at a reaction time of 3 h at 300 °C. At 200 °C, the effect of TOP on the ZnO NP synthesis differs from that at 300 °C. The ZnO NPs synthesized by controlling the molar ratios of surfactant ligands (TOP:OLAM = 2:100 and 70:100) at 200 °C share similar amorphous structures, while a crystalline ZnO phase is formed when the reaction time is 3 h. X-ray photoelectron spectroscopy analysis shows that TOP influences the oxidation of ZnO and suggests that a combination of OLAM and TOP plays a role in controlling the shape of ZnO NPs. These results provide critical insights to the utilization of TOP for a shape controlling ligand in ZnO NPs and suggest a new route to design oxide NPs.

Zn doped MoO3 nanobelts and the enhanced gas sensing properties to ethanol

Science.gov (United States)

Yang, Shuang; Liu, Yueli; Chen, Tao; Jin, Wei; Yang, Tingqiang; Cao, Minchi; Liu, Shunshun; Zhou, Jing; Zakharova, Galina S.; Chen, Wen

2017-01-01

Zn doped MoO3 nanobelts with the thickness of 120-275 nm, width of 0.3-1.4 μm and length of more than 100 μm are prepared by hydrothermal reaction. The operating temperature of sensors based on Zn doped MoO3 nanobelts is 100-380 °C with a better response to low concentration of ethanol. The highest response value of sensors based on Zn doped MoO3 to 1000 ppm ethanol at 240 °C is 321, which is about 15 times higher than that of pure MoO3 nanobelts. The gas sensors based on Zn doped MoO3 nanobelts possess good selectivity to ethanol compared with methanol, ammonia, acetone and toluene, which implies that it would be a good candidate in the potential application. The improvement of gas sensing properties may be attributed to the increasing absorbed ethanol, the decreasing probability of ethoxy recombination, the promoted dehydrogenation progress at lower temperature, and the narrowed band gap by Zn doping.

Magnetic properties of sol-gel synthesized C-doped ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Dung, Nguyen Duc, E-mail: dung.nguyenduc@hust.edu.vn [Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology, No.1 Dai Co Viet, Hanoi (Viet Nam); Son, Cao Thai; Loc, Pham Vu; Cuong, Nguyen Huu; Kien, Pham The; Huy, Pham Thanh [Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology, No.1 Dai Co Viet, Hanoi (Viet Nam); Ha, Ngo Ngoc [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No.1 Dai Co Viet, Hanoi (Viet Nam)

2016-05-25

ZnO doping with Carbon (C-doped ZnO) materials were prepared by sol-gel technique following with a heat treatment process. Single phase of Wurtzite crystal structure of ZnO was concluded via x-ray diffraction (XRD) with a large amount of excess C tracking by energy dispersive X-ray spectroscopy (EDX) analysis. Two types of ZnO crystals (twinning particles) with different grain sizes and shapes were identified via scanning electron microscopy (FE-SEM). The first type has a smaller grain size of about 20 nm and hexagonal shape. And the second type has a larger grain size of about 80–120 nm and round shape. C substitutions of both Zn and O sites to form C–O and C–Zn bonds were conclusively confirmed via x-ray photoelectron spectroscope (XPS). Experimental evidences for the co-existence of different ferromagnetic phases in the materials are reported and discussed. Two Curie points at high temperatures (>500 °C) are presented. A metamagnetic transition was observed at magnetic field H = 19.2 kOe which was related to the co-existence of ferromagnetic phases. These involve in the formation of twinning C-doped ZnO nanoparticles. - Highlights: • Formation of sol-gel prepared single phase wurtzite ZnO nanoparticles. • Two morphological C-doped ZnO nanoparticles of different grain sizes. • The room temperature ferromagnetism. • An abnormal metamagnetic transition at magnetic field H = 19.2 kOe. • Two different Curie points (T{sub C}) at 500–600 °C.

Positron annihilation spectroscopic studies of solvothermally synthesized ZnO nanobipyramids and nanoparticles

Science.gov (United States)

Ghoshal, Tandra; Biswas, Subhajit; Kar, Soumitra; Chaudhuri, Subhadra; Nambissan, P. M. G.

2008-02-01

Zinc oxide (ZnO) samples in the form of hexagonal-based bipyramids and particles of nanometer dimensions were synthesized through solvothermal route and characterized by x-ray diffraction and transmission electron microscopy. Positron annihilation experiments were performed to study the structural defects such as vacancies and surfaces in these nanosystems. From coincidence Doppler broadening measurements, the positron trapping sites were identified as Zn vacancies or Zn-O-Zn trivacancy clusters. The positron lifetimes, their relative intensities, and the Doppler broadened lineshape parameter S all showed characteristic changes across the nanobipyramid size corresponding to the thermal diffusion length of positrons. In large nanobipyramids, vacancies within the crystallites also trapped positrons and the effects of agglomeration of such vacancies due to increased temperatures of synthesis were reflected in the variation of the annihilation parameters with their base diameters. The sizes of the nanoparticles used were all in the limit of thermal diffusion length of positrons and the annihilation characteristics were in accordance with the decreasing contribution from surfaces with increasing particle size.

Size control synthesis and characterization of ZnO nanoparticles and its application as ZnO-water based nanofluid in heat transfer enhancement in light water nuclear reactor

Energy Technology Data Exchange (ETDEWEB)

Sharma, Deepak; Pandey, Krishna Murari [National Institute of Technology Silchar, Assam (India). Dept. of Mechanical Engineering

2017-03-15

A novel and facile approach for size-tunable synthesis of ZnO nanoparticle (NPs) is reported. Size-tuning was attained by using PEG (polyethylene glycol) of molecular weights 400 and 4000. ZnO NPs was synthesized using homogeneous chemical precipitation followed by hydrothermal. Here triethylamine (TEA) was used as a hydroxylating agent. As-synthesized ZnO NPs were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Energy Dispersive Spectroscopy (EDS) analysis. Synthesized ZnO nanoparticle was used for the preparation of ZnO-water based nanofluid and its application in heat transfer enhancement in light water nuclear reactor. In this work, ZnO-water based nanofluid of different volume concentration (1%, 2% and 3%) and particle size of 10 nm and 20 nm is used for enhancement in heat transfer in annular channel by using two phase approach. The particle size of 10 nm gives better result for enhancing the heat transfer rate in comparison to 20 nm particle size in nuclear reactor.

Growth of vertically aligned ZnO nanorods using textured ZnO films

Directory of Open Access Journals (Sweden)

Meléndrez Manuel

2011-01-01

Full Text Available Abstract A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100 substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.

A review on bio-synthesized zinc oxide nanoparticles using plant extracts as reductants and stabilizing agents.

Science.gov (United States)

Basnet, Parita; Inakhunbi Chanu, T; Samanta, Dhrubajyoti; Chatterjee, Somenath

2018-06-01

In the age of technology, nanoparticles have proven to be one of the essential needs for development. These nanoparticles have the potential to be used for a wide variety of applications, thereby, development in improving the quality of nanoparticles, to make them more application specific, is still under research. In this regard, an important point to note is that the procedures employed in synthesizing nanoparticles require to be cost-effective and less-steps involved and have an additional advantage, i.e. they should be eco-friendly. This means that the synthesis procedure needs avoiding the use of harmful chemicals, and negligible generation of any noxious by-products. The green synthesis (biosynthesis) method employs simple procedures, easily available raw materials and ambiance for the synthesis process, where the precursors used are safe, with minute possibility for the production of harmful by-products. Considering these advantages, the current review includes a brief description on the various chemical and physical synthesis method of zinc oxide (ZnO) nanoparticles with emphasis on the biosynthesis of ZnO nanoparticles using plant extracts (and briefly microbes), the phytochemicals present in the plant extracts, the plausible mechanisms involved in the formation of ZnO nanoparticles and applications of the as-synthesized ZnO nanoparticles as photocatalysts and microbial inhibitors. Copyright © 2018 Elsevier B.V. All rights reserved.

Construction of 3D Arrays of Cylindrically Hierarchical Structures with ZnO Nanorods Hydrothermally Synthesized on Optical Fiber Cores

Directory of Open Access Journals (Sweden)

Weixuan Jing

2014-01-01

Full Text Available With ZnO nanorods hydrothermally synthesized on manually assembled arrays of optical fiber cores, 3D arrays of ZnO nanorod-based cylindrically hierarchical structures with nominal pitch 250 μm or 375 μm were constructed. Based on micrographs of scanning electron microscopy and image processing operators of MATLAB software, the 3D arrays of cylindrically hierarchical structures were quantitatively characterized. The values of the actual diameters, the actual pitches, and the parallelism errors suggest that the process capability of the manual assembling is sufficient and the quality of the 3D arrays of cylindrically hierarchical structures is acceptable. The values of the characteristic parameters such as roughness, skewness, kurtosis, correlation length, and power spectrum density show that the surface morphologies of the cylindrically hierarchical structures not only were affected significantly by Zn2+ concentration of the growth solution but also were anisotropic due to different curvature radii of the optical fiber core at side and front view.

Electrochemical investigation of the properties of Co doped ZnO nanoparticle as a corrosion inhibitive pigment for modifying corrosion resistance of the epoxy coating

International Nuclear Information System (INIS)

Rostami, M.; Rasouli, S.; Ramezanzadeh, B.; Askari, A.

2014-01-01

Highlights: • Corrosion inhibitive pigment based on ZnOCo was synthesized through combustion method. • Doping ZnO nanoparticle with Co enhanced its inhibition properties considerably. • ZnOCo nanoparticle could enhance corrosion protective performance of epoxy coating. • Co doped ZnO nanoparticles behaved as efficient barrier and inhibitive pigment. - Abstract: Co doped ZnO nanoparticles were synthesized by combustion method. Then, the epoxy nanocomposites were prepared using various amounts of nanoparticles. Salt spray and electrochemical impedance spectroscopy (EIS) were used in order to investigate the corrosion inhibition effects of nanoparticles on the steel substrate. The morphology and composition of the films precipitated on the steel surface were investigated by scanning electron microscope (SEM) and energy dispersive spectroscopy. Results revealed that the corrosion inhibition properties of ZnO nanoparticle were significantly enhanced after doping with Co. Moreover, Co doped ZnO nanoparticles enhanced the corrosion resistance of the epoxy coating effectively

ZnO nanostructure fabrication in different solvents transforms physio-chemical, biological and photodegradable properties

Energy Technology Data Exchange (ETDEWEB)

Ali, Attarad; Ambreen, Sidra; Javed, Rabia; Tabassum, Saira [Department of Biotechnology, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Ul Haq, Ihsan [Department of Pharmacy, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Zia, Muhammad, E-mail: ziachaudhary@gmail.com [Department of Biotechnology, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2017-05-01

Zinc oxide (ZnO) nanostructures are synthesized in various organic solvents (acetone, chloroform, ethyl acetate, ethanol and methanol) and water via coprecipitation process using zinc acetate as precursor. The resultant ZnO nanoparticles, nano rods and nano sheets are characterized by UV–vis spectrophotometric analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). The variable size and geometry of nanoparticles depend upon medium used for synthesis. The synthesized ZnO nanostructures exhibit minor to moderate antioxidative (DPPH based free radical scavenging activity, total antioxidative potential and total reducing power) response. Mild to moderate antibacterial and antifungal activities, excellent antileishmanial potential (IC50 up to 3.76), and good cytotoxic perspective (LD50 up to 49.4) is also observed by the synthesized ZnO NPs. The nanoparticles also exhibit moderate α-amylase inhibition response. Furthermore the nanostructures are evaluated for methylene blue photodegradation response within 60 min time period. It is found that organic solvent alters shape, size and other physio-chemical properties of ZnO that ultimately modulate the biological, chemical, and environmental properties. - Highlights: • Zinc oxide nanoparticles are fabricated in different solvents using co-precipitation method • SEM, XRD and FTIR analysis confirms variation in physical and chemical characteristics of synthesized ZnO NPs • The synthesized ZnO demonstrates variation in biological, phytochemical and photodegradable properties.

ZnO nanostructure fabrication in different solvents transforms physio-chemical, biological and photodegradable properties

International Nuclear Information System (INIS)

Ali, Attarad; Ambreen, Sidra; Javed, Rabia; Tabassum, Saira; Ul Haq, Ihsan; Zia, Muhammad

2017-01-01

Zinc oxide (ZnO) nanostructures are synthesized in various organic solvents (acetone, chloroform, ethyl acetate, ethanol and methanol) and water via coprecipitation process using zinc acetate as precursor. The resultant ZnO nanoparticles, nano rods and nano sheets are characterized by UV–vis spectrophotometric analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). The variable size and geometry of nanoparticles depend upon medium used for synthesis. The synthesized ZnO nanostructures exhibit minor to moderate antioxidative (DPPH based free radical scavenging activity, total antioxidative potential and total reducing power) response. Mild to moderate antibacterial and antifungal activities, excellent antileishmanial potential (IC50 up to 3.76), and good cytotoxic perspective (LD50 up to 49.4) is also observed by the synthesized ZnO NPs. The nanoparticles also exhibit moderate α-amylase inhibition response. Furthermore the nanostructures are evaluated for methylene blue photodegradation response within 60 min time period. It is found that organic solvent alters shape, size and other physio-chemical properties of ZnO that ultimately modulate the biological, chemical, and environmental properties. - Highlights: • Zinc oxide nanoparticles are fabricated in different solvents using co-precipitation method • SEM, XRD and FTIR analysis confirms variation in physical and chemical characteristics of synthesized ZnO NPs • The synthesized ZnO demonstrates variation in biological, phytochemical and photodegradable properties.

Wafer-Scale High-Throughput Ordered Growth of Vertically Aligned ZnO Nanowire Arrays

KAUST Repository

Wei, Yaguang; Wu, Wenzhuo; Guo, Rui; Yuan, Dajun; Das, Suman; Wang, Zhong Lin

2010-01-01

-synthesized morphology. The development of textured ZnO seed layers for replacing single crystalline GaN and ZnO substrates extends the large-scale fabrication of vertically aligned ZnO NW arrays on substrates of other materials, such as polymers, Si, and glass

Capacitive and photocatalytic performance of Bi_2S_3 nanostructures synthesized by solvothermal method

International Nuclear Information System (INIS)

Liang, Kangqiang; Wang, Chenggang; Xu, Xijin; Leng, Jiancai; Ma, Hong

2017-01-01

Different Bi_2S_3 nanoarchitectures (nanorods and nanobelts) were successfully synthesized with a facile solvothermal method at different temperature. The nanobelts transformed into nanorods when the temperature was 200 °C increased from 150 °C. The nanorod-morphology was kept even the temperature was further increased. The galvanostatic charge/discharge performance showed that the prepared Bi_2S_3 nanorods had good performance of discharge efficiency at current density from 1 A g"−"1 to 4 A g"−"1. The specific capacitance was 270 F g"−"1 at a current density of 1 A g"−"1. Furthermore, the nanorods were also used as the efficient UV-light photocatalysts for the degradation of Rhodamine B (RhB), which showed almost complete degradation (∼87%) of RhB dye at 100 min. - Highlights: • Bi_2S_3 nanorods were successfully synthesized with a facile solvothermal method. • The specific capacitance can be 270 F g"−"1 at a current density of 1 A g"−"1. • 87% of RhB dye can be degraded at 100 min.

Low Temperature Ferromagnetism and Optical Properties of Fe Doped ZnO Nanoparticles Synthesized by Sol-Gel Method

Directory of Open Access Journals (Sweden)

B. Sathya

2017-06-01

Full Text Available In this present investigation, pure and Fe doped Zinc oxide nanoparticles were successfully synthesized by sol gel method.The structural and optical properties were examined by using X-ray diffraction (XRD, Scanning electron microscope (SEM, Transmission electron microscope (TEM, Ultraviolet spectroscopy and Photoluminescence (PL techniques.The structural characterization of XRD analysis confirmed the phase purity of the samples and crystallite size can be decreased with increasing doping concentrations.SEM image show that nanoparticles in spherical shape. The optical band gap calculated through UV-visible spectroscopy is found to be increasing from 3.48 to 3.57eV. TEM analysis depicted the crystallinity of nanoparticles prepared and chemical composition conformed the EDAX analysis. The PL spectra reveal that, Fe doped ZnO exhibit a decrease in intensity of the band edge emission peak while the intensity of the deep level emission peak increases.The enhancement of low temperature ferromagnetism in ZnO: Fe was achieved.

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

International Nuclear Information System (INIS)

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

2015-01-01

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

A self-seeded, surfactant-directed hydrothermal growth of single crystalline lithium manganese oxide nanobelts from the commercial bulky particles.

Science.gov (United States)

Zhang, Lizhi; Yu, Jimmy C; Xu, An-Wu; Li, Quan; Kwong, Kwan Wai; Wu, Ling

2003-12-07

Single crystalline lithium manganese oxide nanobelts were obtained through a self-seeded, surfactant-directed growth process from the commercial bulky particles under hydrothermal treatment. A possible mechanism was proposed to explain the growth of the nanobelts. This new process could be extended to prepare other one-dimensional nanomaterials such as Se nanorods, Te nanotubes, and MnO2 nanowires.

Microstructure, electronic structure and optical properties of combustion synthesized Co doped ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Srinatha, N. [Department of Physics, JB Campus, Bangalore University, Bangalore 560056 (India); Nair, K.G.M. [UGC-DAE-CSR, Kalpakkam Node, Kalpakkam, Kokilamedu 603102 (India); Angadi, Basavaraj, E-mail: brangadi@gmail.com [Department of Physics, JB Campus, Bangalore University, Bangalore 560056 (India)

2015-10-01

We report on the microstructure, electronic structure and optical properties of nanocrystalline Zn{sub 1−x}Co{sub x}O (x=0, 0.01, 0.03, 0.05 and 0.07) particles prepared by solution combustion technique using L-Valine as fuel. The detailed structural and micro-structural studies were carried out by XRD, HRTEM and TEM-SAED respectively, which confirms the formation of single phased, nano-sized particles. The electronic structure was determined through NEXAFS and atomic multiplet calculations/simulations performed for various symmetries and valence states of ‘Co’ to determine the valance state, symmetry and crystal field splitting. The correlations between the experimental NEXAFS spectra and atomic multiplet simulations, confirms that, ‘Co’ present is in the 2+ valence state and substituted at the ‘Zn’ site in tetrahedral symmetry with crystal field splitting, 10Dq =−0.6 eV. The optical properties and ‘Co’ induced defect formation of as-synthesized materials were examined by using diffuse reflectance and Photoluminescence spectroscopy, respectively. Red-shift of band gap energy (E{sub g}) was observed in Zn{sub 1−x}Co{sub x}O samples due to Co (0.58 Å) substitution at Zn (0.60 Å) site of the host ZnO. Also, in PL spectra, a prominent pre-edge peak corresponds to ultraviolet (UV) emission around 360–370 nm was observed with Co concentration along with near band edge emission (NBE) of the wide band gap ZnO and all samples show emission in the blue region.

Microstructural, chemical and textural characterization of ZnO nanorods synthesized by aerosol assisted chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Fuentes-Cobas, L.; Pizá-Ruiz, P.; Antúnez-Flores, W.; Ornelas-Gutiérrez, C. [Centro de Investigación en Materiales Avanzados, S.C., Chihuahua, Chihuahua 31109 (Mexico); Pérez-García, S.A. [Centro de Investigación en Materiales Avanzados, S.C., Unidad Monterrey, Apodaca, Nuevo León 66600 (Mexico); Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx [Centro de Investigación en Materiales Avanzados, S.C., Chihuahua, Chihuahua 31109 (Mexico)

2014-12-15

ZnO nanorods were synthesized by aerosol assisted chemical vapor deposition onto TiO{sub 2} covered borosilicate glass substrates. Deposition parameters were optimized and kept constant. Solely the effect of different nozzle velocities on the growth of ZnO nanorods was evaluated in order to develop a dense and uniform structure. The crystalline structure was characterized by conventional X-ray diffraction in grazing incidence and Bragg–Brentano configurations. In addition, two-dimensional grazing incidence synchrotron radiation diffraction was employed to determine the preferred growth direction of the nanorods. Morphology and growth characteristics analyzed by electron microscopy were correlated with diffraction outcomes. Chemical composition was established by X-ray photoelectron spectroscopy. X-ray diffraction results and X-ray photoelectron spectroscopy showed the presence of wurtzite ZnO and anatase TiO{sub 2} phases. Morphological changes noticed when the deposition velocity was lowered to the minimum, indicated the formation of relatively vertically oriented nanorods evenly distributed onto the TiO{sub 2} buffer film. By coupling two-dimensional X-ray diffraction and computational modeling with ANAELU it was proved that a successful texture determination was achieved and confirmed by scanning electron microscopy analysis. Texture analysis led to the conclusion of a preferred growth direction in [001] having a distribution width Ω = 20° ± 2°. - Highlights: • Uniform and pure single-crystal ZnO nanorods were obtained by AACVD technique. • Longitudinal and transversal axis parallel to the [001] and [110] directions, respectively. • Texture was determined by 2D synchrotron diffraction and electron microscopy analysis. • Nanorods have its [001] direction distributed close to the normal of the substrate. • Angular spread about the preferred orientation is 20° ± 2°.

Random laser based on Rhodamine 6G (Rh6G doped poly(methyl methacrylate (PMMA films coating on ZnO nanorods synthesized by hydrothermal oxidation

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Hua Zhang

Full Text Available Random laser based on Rh6G doped PMMA thin films coating on ZnO nanorods synthesized by a simple hydrothermal oxidation method has been demonstrated. This kind of random laser medium is based on waveguide structure consisting of ZnO nanorods, Rh6G doped PMMA film and air. By controlling the time of hydrothermal oxidation reaction, wheat-like and hexagonal prism ZnO nanorods have been successfully fabricated. The emission spectra of these gain mediums based on different ZnO nanorods are different. The one based on wheat-like ZnO nanorods mainly exhibits amplified spontaneous emission, and the other one based on hexagonal prism ZnO nanorods shows random laser emission. The threshold of the random laser medium is about 73.8 μJ/pulse, and the full width at half maximum (FWHM is around 2.1 nm. The emission spectra measured at different detecting angles reveal that the output direction is strongly confined in ±30° by the waveguide effect. Our experiments demonstrate a promising method to achieve organic random laser medium. Keywords: Random laser, ZnO nanorods, Hydrothermal oxidation, Rhodamine 6G (Rh6G, Poly(methyl methacrylate (PMMA

In vitro antibacterial activity of ZnO and Nd doped ZnO nanoparticles against ESBL producing Escherichia coli and Klebsiella pneumoniae

Science.gov (United States)

Hameed, Abdulrahman Syedahamed Haja; Karthikeyan, Chandrasekaran; Ahamed, Abdulazees Parveez; Thajuddin, Nooruddin; Alharbi, Naiyf S.; Alharbi, Sulaiman Ali; Ravi, Ganasan

2016-04-01

Pure ZnO and Neodymium (Nd) doped ZnO nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure. From FESEM studies, ZnO and Nd doped ZnO NPs showed nanorod and nanoflower like morphology respectively. The FT-IR spectra confirmed the Zn-O stretching bands at 422 and 451 cm-1 for ZnO and Nd doped ZnO NPs respectively. From the UV-VIS spectroscopic measurement, the excitonic peaks were found around 373 nm and 380 nm for the respective samples. The photoluminescence measurements revealed that the broad emission was composed of ten different bands due to zinc vacancies, oxygen vacancies and surface defects. The antibacterial studies performed against extended spectrum β-lactamases (ESBLs) producing strains of Escherichia coli and Klebsiella pneumoniae showed that the Nd doped ZnO NPs possessed a greater antibacterial effect than the pure ZnO NPs. From confocal laser scanning microscopic (CLSM) analysis, the apoptotic nature of the cells was confirmed by the cell shrinkage, disorganization of cell wall and cell membrane and dead cell of the bacteria. SEM analysis revealed the existence of bacterial loss of viability due to an impairment of cell membrane integrity, which was highly consistent with the damage of cell walls.

Electromechanical Characterization of Single GaN Nanobelt Probed with Conductive Atomic Force Microscope

Science.gov (United States)

Yan, X. Y.; Peng, J. F.; Yan, S. A.; Zheng, X. J.

2018-04-01

The electromechanical characterization of the field effect transistor based on a single GaN nanobelt was performed under different loading forces by using a conductive atomic force microscope (C-AFM), and the effective Schottky barrier height (SBH) and ideality factor are simulated by the thermionic emission model. From 2-D current image, the high value of the current always appears on the nanobelt edge with the increase of the loading force less than 15 nN. The localized (I-V) characteristic reveals a typical rectifying property, and the current significantly increases with the loading force at the range of 10-190 nN. The ideality factor is simulated as 9.8 within the scope of GaN nano-Schottky diode unity (6.5-18), therefore the thermionic emission current is dominant in the electrical transport of the GaN-tip Schottky junction. The SBH is changed through the piezoelectric effect induced by the loading force, and it is attributed to the enhanced current. Furthermore, a single GaN nanobelt has a high mechanical-induced current ratio that could be made use of in a nanoelectromechanical switch.

In-situ PXRD studies of ZnO nanoparticle growth: How do various salts influence the hydrothermal growth of ZnO?

DEFF Research Database (Denmark)

Bøjesen, Espen Drath

ZnO is a material of great scientific and everyday relevance; it is used widely in all sorts of application. Synthesis of ZnO nanoparticles can be performed by a wide assortment of methods and a tremendous variety of sizes and shapes, it has been suggested that ZnO is the one known compound showing...... the broadest range of nanostructures. Previously many different in-situ characterization methods have been used to investigate the ZnO formation under various synthesis conditions; these include UV-VIS and SAXS. These methods were primarily used to give information on particle size of ZnO formed using soft...... chemical methods and non-aqueous solvents. In our work we have studied the formation of ZnO during hydrothermal syntheses using in-situ powder X-ray diffraction, thus enabling us to extract crystallographic as well as microstructural information. The data was analyzed using Rietveld refinement and whole...

ROS-dependent anticandidal activity of zinc oxide nanoparticles synthesized by using egg albumen as a biotemplate

International Nuclear Information System (INIS)

Shoeb, M; Singh, Braj R; Khan, Javed A; Khan, Wasi; Naqvi, Alim H; Singh, Brahma N; Singh, Harikesh B

2013-01-01

Zinc oxide nanoparticles (ZnO NPs) have attracted great attention because of their superior optical properties and wide application in biomedical science. However, little is known about the anticandidal activity of ZnO NPs against Candida albicans (C. albicans). This study was designed to develop the green approach to synthesize ZnO NPs using egg white (denoted as EtZnO NPs) and investigated its possible mechanism of antimicrobial activity against C. albicans 077. It was also notable that anticandidal activity of EtZnO NPs is correlated with reactive oxygen species (ROS) production in a dose dependent manner. Protection of histidine against ROS clearly suggests the implication of ROS in anticandidal activity of EtZnO NPs. This green approach based on egg white-mediated synthesis of ZnO NPs paves the way for developing cost effective, eco-friendly and promising antimicrobial nanomaterial for applications in medicine. (paper)

Synthesis of Cu Doped ZnO Nanostructures for Ultra Violet Sensing

OpenAIRE

Nazar Abbas SHAH; Muhammad ABID; Muhammad AMIN; Rahat AFRIN; Syed Zafar ILYAS

2015-01-01

This paper mainly focused on the synthesis of zinc oxide nanostructures, their characterization and their ultra violet light sensing response at room temperature. Nanowires, nanobelts and nanosheets were synthesized by varying doping material copper by using vapor transport technique governed by the vapor-liquid-solid or vapor-solid mechanisms. The structural, morphological and optical characterization was carried out using X-ray diffraction, scanning electron microscopy, energy dispersive X-...

Synthesis and optical properties of flower-like ZnO nanorods by thermal evaporation method

International Nuclear Information System (INIS)

Zheng, J.H.; Jiang, Q.; Lian, J.S.

2011-01-01

Flower-like ZnO nanorods have been synthesized by heating a mixture of ZnO/graphite powders using the thermal evaporation and vapor transport on Si (1 0 0) substrates without any catalyst. The structures, morphologies and optical properties of the products were characterized in detail by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and Raman spectroscopy. The synthesized products consisted of large quantities of flower-like ZnO nanostructures in the form of uniform nanorods. The flower-like ZnO nanorods had high purity and well crystallized wurtzite structure, whose high crystalline quality was proved by Raman spectroscopy. The as-synthesized flower-like ZnO nanorods showed a strong ultraviolet emission at 386 nm and a weak and broad yellow-green emission in visible spectrum in its room temperature photoluminescence (PL) spectrum. In addition, the growth mechanism of the flower-like ZnO nanorods was discussed based on the reaction conditions.

Chemical Sensing Applications of ZnO Nanomaterials

Science.gov (United States)

Chaudhary, Savita; Umar, Ahmad; Bhasin, K. K.

2018-01-01

Recent advancement in nanoscience and nanotechnology has witnessed numerous triumphs of zinc oxide (ZnO) nanomaterials due to their various exotic and multifunctional properties and wide applications. As a remarkable and functional material, ZnO has attracted extensive scientific and technological attention, as it combines different properties such as high specific surface area, biocompatibility, electrochemical activities, chemical and photochemical stability, high-electron communicating features, non-toxicity, ease of syntheses, and so on. Because of its various interesting properties, ZnO nanomaterials have been used for various applications ranging from electronics to optoelectronics, sensing to biomedical and environmental applications. Further, due to the high electrochemical activities and electron communication features, ZnO nanomaterials are considered as excellent candidates for electrochemical sensors. The present review meticulously introduces the current advancements of ZnO nanomaterial-based chemical sensors. Various operational factors such as the effect of size, morphologies, compositions and their respective working mechanisms along with the selectivity, sensitivity, detection limit, stability, etc., are discussed in this article. PMID:29439528

Evolution of the zinc compound nanostructures in zinc acetate single-source solution

International Nuclear Information System (INIS)

Wang Ying; Li Yinhua; Zhou Zhengzhi; Zu Xihong; Deng Yulin

2011-01-01

A series of nanostructured zinc compounds with different nanostructures such as nanobelts, flake-like, flower-like, and twinning crystals was synthesized using zinc acetate (Zn(Ac) 2 ) as a single-source. The evolution of the zinc compounds from layered basic zinc acetate (LBZA) to bilayered basic zinc acetate (BLBZA) and twinned ZnO nano/microcrystal was studied. The low-angle X-ray diffraction spectra indicate the layered spacing is 1.34 and 2.1 nm for LBZA and BLBZA, respectively. The Fourier transform infrared (FTIR) spectra results confirmed that the bonding force of acetate anion with zinc cations decreases with the phase transformation from Zn(Ac) 2 to BLBZA, and finally to LBZA. The OH − groups gradually replaced the acetate groups coordinated to the matrix zinc cation, and the acetate groups were released completely. Finally, the Zn(OH) 2 and ZnO were formed at high temperature. The conversion process from Zn(Ac) 2 to ZnO with release of acetate anions can be described as Zn(Ac) 2 → BLBZA → LBZA → Zn(OH) 2 → ZnO.

Synthesis, characteristics and antimicrobial activity of ZnO nanoparticles

Science.gov (United States)

Janaki, A. Chinnammal; Sailatha, E.; Gunasekaran, S.

2015-06-01

The utilization of various plant resources for the bio synthesis of metallic nano particles is called green technology and it does not utilize any harmful protocols. Present study focuses on the green synthesis of ZnO nano particles by Zinc Carbonate and utilizing the bio-components of powder extract of dry ginger rhizome (Zingiber officinale). The ZnO nano crystallites of average size range of 23-26 nm have been synthesized by rapid, simple and eco friendly method. Zinc oxide nano particles were characterized by using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX). FTIR spectra confirmed the adsorption of surfactant molecules at the surface of ZnO nanoparticles and the presence of ZnO bonding. Antimicrobial activity of ZnO nano particles was done by well diffusion method against pathogenic organisms like Klebsiella pneumonia, Staphylococcus aureus and Candida albicans and Penicillium notatum. It is observed that the ZnO synthesized in the process has the efficient antimicrobial activity.

Facile fabrication of p-n heterojunctions for Cu2O submicroparticles deposited on anatase TiO2 nanobelts

International Nuclear Information System (INIS)

Li, Li; Lei, Jingguo; Ji, Tianhao

2011-01-01

Graphical abstract: Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via two-step preparation process, and their visible-light photodegradation activities of Rhodamine B were investigated in detail. Highlights: → Cu 2 O particle-deposited TiO 2 nanobelts mainly with diameters in a range of 200-400 nm were successfully prepared. → The amount of Cu 2 O particles deposited on TiO 2 nanobelts can be tuned. → The composite structure with Cu 2 O particles and TiO 2 nanobelts exhibits p-n semiconductor heterojunction performance. → Photocatalytic properties of such composites. -- Abstract: In this paper, Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via a two-step preparation process to investigate electron-transfer performance between p-type Cu 2 O and n-type TiO 2 . Various measurement results confirm that the amount of pure Cu 2 O submicroparticles, with diameters within the range of 200-400 nm and deposited on the surface of TiO 2 nanobelts, can be controlled, and that the purity of Cu 2 O is heavily affected by reaction time. Visible-light photodegradation activities of Rhodamine B show that photocatalysts have little or no photocatalytic activities mainly due to their p-n heterojunction structure, indicating that there hardly appears any electron-transfer from Cu 2 O to TiO 2 .

Investigation of the Optimal Parameters in Hydrothermal Method for the Synthesis of ZnO Nanorods

Directory of Open Access Journals (Sweden)

Ying-Chung Chen

2014-01-01

Full Text Available We investigated a two-step method to deposit the ZnO-based nanostructure films, including nanorods and nanoflowers. In the first step, sputtering method was used to deposit the ZnO films on SiO2/Si substrates as the seed layer. In the second step, Zn(NO32–6H2O and C6H12N4 were used as precursors and hydrothermal process was used as the method to synthesize the ZnO films. After that, the ZnO films were measured by an X-ray diffraction pattern and a FESEM to analyze their crystallization and morphology. We had found that the ZnO films had three different morphologies synthesized on ZnO/SiO2/Si substrates, including irregular-plate structure films, nanorod films, and beautiful chrysanthemum-like clusters (nanoflower films. We would prove that the face direction of ZnO/SiO2/Si substrates in the hydrothermal bottle and deposition time were two important factors to influence the synthesized results of the ZnO films.

ZnO/SnO{sub 2} nanoflower based ZnO template synthesized by thermal chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Sin, N. D. Md., E-mail: diyana0366@johor.uitm.edu.my; Amalina, M. N., E-mail: amalina0942@johor.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Fakulti Kejuruteraan Elektrik, Universiti Teknologi MARA Cawangan Johor, Kampus Pasir Gudang, 81750 Masai, Johor (Malaysia); Ismail, Ahmad Syakirin, E-mail: kyrin-samaxi@yahoo.com; Shafura, A. K., E-mail: shafura@ymail.com; Ahmad, Samsiah, E-mail: samsiah.ahmad@johor.uitm.edu.my; Mamat, M. H., E-mail: mhmamat@salam.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Rusop, M., E-mail: rusop@salam.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia)

2016-07-06

The ZnO/SnO{sub 2} nanoflower like structures was grown on a glass substrate deposited with seed layer using thermal chemical vapor deposition (CVD) with combining two source materials. The ZnO/SnO{sub 2} nanoflower like structures had diameter in the range 70 to 100 nm. The atomic percentage of ZnO nanoparticle , SnO{sub 2} nanorods and ZnO/SnO{sub 2} nanoflower was taken using EDS. Based on the FESEM observations, the growth mechanism is applied to describe the growth for the synthesized nanostructures.

Photoluminescent ZnO Nanoparticles and Their Biological Applications

Directory of Open Access Journals (Sweden)

Zheng-Yong Zhang

2015-05-01

Full Text Available During the past decades, numerous achievements concerning luminescent zinc oxide nanoparticles (ZnO NPs have been reported due to their improved luminescence and good biocompatibility. The photoluminescence of ZnO NPs usually contains two parts, the exciton-related ultraviolet (UV emission and the defect-related visible emission. With respect to the visible emission, many routes have been developed to synthesize and functionalize ZnO NPs for the applications in detecting metal ions and biomolecules, biological fluorescence imaging, nonlinear multiphoton imaging, and fluorescence lifetime imaging. As the biological applications of ZnO NPs develop rapidly, the toxicity of ZnO NPs has attracted more and more attention because ZnO can produce the reactive oxygen species (ROS and release Zn2+ ions. Just as a coin has two sides, both the drug delivery and the antibacterial effects of ZnO NPs become attractive at the same time. Hence, in this review, we will focus on the progress in the synthetic methods, luminescent properties, and biological applications of ZnO NPs.

Electrosynthesis and characterization of ZnO nanoparticles as inorganic component in organic thin-film transistor active layers

International Nuclear Information System (INIS)

Picca, Rosaria Anna; Sportelli, Maria Chiara; Hötger, Diana; Manoli, Kyriaki; Kranz, Christine; Mizaikoff, Boris; Torsi, Luisa; Cioffi, Nicola

2015-01-01

Highlights: • PSS-capped ZnO NPs were synthesized via a green electrochemical-thermal method • The influence of electrochemical conditions and temperature was studied • Spectroscopic data show that PSS functionalities are retained in the annealed NPs • Nanostructured ZnO improved the performance of P3HT-based thin film transistors - Abstract: ZnO nanoparticles have been prepared via a green electrochemical synthesis method in the presence of a polymeric anionic stabilizer (poly-sodium-4-styrenesulfonate, PSS), and then applied as inorganic component in poly-3-hexyl-thiophene thin-film transistor active layers. Different parameters (i.e. current density, electrolytic media, PSS concentration, and temperature) influencing nanoparticle synthesis have been studied. The resulting nanomaterials have been investigated by transmission electron microscopy (TEM) and spectroscopic techniques (UV-Vis, infrared, and x-ray photoelectron spectroscopies), assessing the most suitable conditions for the synthesis and thermal annealing of nanostructured ZnO. The proposed ZnO nanoparticles have been successfully coupled with a poly-3-hexyl-thiophene thin-film resulting in thin-film transistors with improved performance.

Preparation, structural and optical characterization of ZnO, ZnO: Al nanopowder

Energy Technology Data Exchange (ETDEWEB)

Mohan, R. Raj [Department of ECE, Gojan School of Business and Technology, Chennai (India); Rajendran, K. [Department of Electronics, Government Arts College for Women, Ramanathapuram, TN (India); Sambath, K. [Department of ECS, Sri Krishna Arts and Science College, Coimbatore, TN (India)

2014-01-28

In this paper, ZnO and ZnO:Al nanopowders have been synthesized by low cost hydrothermal method. Zinc nitrate, hexamethylenetetramine (HMT) and aluminium nitrate are used as precursors for ZnO and AZO with different molar ratios. The structural and optical characterization of doped and un-doped ZnO powders have been investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX), photoluminescence (PL) and ultra violet visible (UV-Vis) absorption studies. The SEM results show that the hydrothermal synthesis can be used to obtain nanoparticles with different morphology. It is observed that the grain size of the AZO nanoparticles increased with increasing of Al concentration. The PL measurement of AZO shows that broad range of green emission around 550nm with high intensity. The green emission resulted mainly because of intrinsic defects.

Growth and characterization of ZnO nanowires for optical applications

International Nuclear Information System (INIS)

AlSalhi, M S; Atif, M; Ansari, A A; Khun, K; Ibupoto, Z H; Willander, M

2013-01-01

In the present work, cerium oxide CeO 2 nanoparticles were synthesized by the sol–gel method and used for the growth of ZnO nanorods. The synthesized nanoparticles were studied by x-ray diffraction (XRD) and Raman spectroscopic techniques. Furthermore, these nanoparticles were used as the seed layer for the growth of ZnO nanorods by following the hydrothermal growth method. The structural study of ZnO nanorods was carried out by means of field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and XRD techniques. This study demonstrated that the grown ZnO nanorods are well aligned, uniform, of good crystal quality and have diameters of less than 200 nm. Energy dispersive x-ray (EDX) analysis revealed that the ZnO nanorods are composed only of zinc, cerium as the seed atom, and oxygen atoms, with no other impurities in the grown nanorods. Moreover, a photoluminescence (PL) approach was applied for the optical characterization, and it was observed that the near-band-edge (NBE) emission was the same as that of the zinc acetate seed layer, however the green and orange/red emission peaks were slightly raised due to possibly higher levels of defects in the cerium oxide seeded ZnO nanorods. This study provides an alternative approach for the controlled synthesis of ZnO nanorods using cerium oxide nanoparticles as the seed nucleation layer, improving both the morphology of the nanorods and the performance of devices based upon them. (paper)

Directed batch assembly of three-dimensional helical nanobelts through angular winding and electroplating

International Nuclear Information System (INIS)

Bell, D J; Bauert, T E; Zhang, L; Dong, L X; Sun, Y; Gruetzmacher, D; Nelson, B J

2007-01-01

This paper presents a new technique for the directed batch assembly of rolled-up three-dimensional helical nanobelts. The wet etch time is controlled in order for the loose end of the self-formed SiGe/Si/Cr nanobelts to be located over an electrode by taking advantage of the additional angular winding motion in the lateral direction. In a subsequent Au electroplating step, contacts are electroformed and the batch assembly is completed, while at the same time the conductance of the structures is increased

Capacitive and photocatalytic performance of Bi{sub 2}S{sub 3} nanostructures synthesized by solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Liang, Kangqiang, E-mail: liang_kangqiang@126.com [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Wang, Chenggang, E-mail: ujnsps_wangchg@163.com [School of Physics and Technology, University of Jinan, 336 West Road of Nan Xinzhuang, Jinan, 250022, Shandong Province (China); Xu, Xijin, E-mail: sps_xuxj@ujn.edu.cn [School of Physics and Technology, University of Jinan, 336 West Road of Nan Xinzhuang, Jinan, 250022, Shandong Province (China); Key Laboratory for Photonic and Electric Bandgap Materials, Ministry of Education, Harbin Normal University, Harbin, 150025 (China); Leng, Jiancai, E-mail: jiancaileng@qlu.edu.cn [School of Science, Qilu University of Technology, Jinan 250353 (China); Ma, Hong, E-mail: mahong@sdnu.edu.cn [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China)

2017-02-12

Different Bi{sub 2}S{sub 3} nanoarchitectures (nanorods and nanobelts) were successfully synthesized with a facile solvothermal method at different temperature. The nanobelts transformed into nanorods when the temperature was 200 °C increased from 150 °C. The nanorod-morphology was kept even the temperature was further increased. The galvanostatic charge/discharge performance showed that the prepared Bi{sub 2}S{sub 3} nanorods had good performance of discharge efficiency at current density from 1 A g{sup −1} to 4 A g{sup −1}. The specific capacitance was 270 F g{sup −1} at a current density of 1 A g{sup −1}. Furthermore, the nanorods were also used as the efficient UV-light photocatalysts for the degradation of Rhodamine B (RhB), which showed almost complete degradation (∼87%) of RhB dye at 100 min. - Highlights: • Bi{sub 2}S{sub 3} nanorods were successfully synthesized with a facile solvothermal method. • The specific capacitance can be 270 F g{sup −1} at a current density of 1 A g{sup −1}. • 87% of RhB dye can be degraded at 100 min.

Tragacanth gum biopolymer as reducing and stabilizing agent in biosonosynthesis of urchin-like ZnO nanorod arrays: A low cytotoxic photocatalyst with antibacterial and antifungal properties.

Science.gov (United States)

Ghayempour, Soraya; Montazer, Majid; Mahmoudi Rad, Mahnaz

2016-01-20

Tragacanth, a natural gum, has been used for centuries as emulsifier, thickener, stabilizer and binder in various fields such as food, medical and cosmetic industries. In this study, Tragacanth gum was used as a clean and natural reducing and stabilizing agent for preparation of urchin-like ZnO nanorod arrays at low-temperature using ultrasonic irradiation. The morphology and structure of urchin-like ZnO nanorod arrays was investigated by XRD, FESEM images, EDX, UV-vis and FT-IR spectroscopy. The hexagonal zinc oxide nanorods were synthesized with the average diameter of 55-80 nm and length of 240 nm. The peak appeared in 447 cm(-1) in FTIR spectra and the peak around 362.3 nm in UV-vis spectra of ZnO nanorods confirmed the successful synthesis of ZnO nanorods. The urchin-like ZnO nanorod arrays indicated a good photocatalytic activity through degradation of methylene blue with 92.2% efficiency and rate constant of 0.0027 min(-1) at 120 min. Finally, the synthesized urchin-like ZnO nanorod arrays indicated 100% antibacterial activity against S. aureus and E. coli and 93% antifungal activity against C. albicans with a low cytotoxicity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis of ZnO nanopowders by DC thermal plasma for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Lee, Soo-Jung; Choi, Jinsub [Department of Chemical Engineering, Inha University, 253 Yonghyun-dong, Nam-gu, Incheon 402-751 (Korea, Republic of); Park, Dong-Wha, E-mail: dwpark@inha.ac.kr [Department of Chemical Engineering, Inha University, 253 Yonghyun-dong, Nam-gu, Incheon 402-751 (Korea, Republic of)

2013-05-01

Highlights: ► ZnO nanopowders were synthesized using DC thermal plasma process. ► Type and flow rate of reaction gas were controlled as experimental variables. ► Various morphologies were identified by changing the reaction gas. ► The photovoltaic performances were promoted by removing the unreacted precursors. ► DSSCs based on 1D nanostructure ZnO show the enhanced energy conversion efficiency. -- Abstract: Zinc oxide (ZnO) nanopowders were synthesized from commercially available micro-sized zinc powders (Aldrich Co., 98%, 10 μm) by a DC thermal plasma process at atmospheric pressure. The micro-sized zinc powders were vaporized in the plasma region, after which the plasma processing equipment was rapidly quenched, resulting in the formation of ZnO nanopowders with a size of less than 300 nm. Two different reaction gases of oxygen and carbon dioxide were used as the oxygen source and each gas flow rate was controlled as a process variable. The obtained ZnO nanopowders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). All synthesized ZnO nanopowders showed high crystalline wurtzite structures and the differences in their morphologies were strongly dependent on the operating variables. The photocurrent–voltage (J–V) curve of the ZnO nanopowders with a dye of ruthenium (II) 535 bis-TBA (N719, Solaronix) in redox electrolyte showed an overall energy conversion efficiency (η) of 2.54%, demonstrating that the application of the mass-producible ZnO nanopowders by thermal plasma processing to DSSC was feasible.

Topotactic conversion route to mesoporous quasi-single-crystalline Co{sub 3}O{sub 4} nanobelts with optimizable electrochemical performance

Energy Technology Data Exchange (ETDEWEB)

Tian, Li [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry State Key Laboratory of Optoelectronic Materials and Technology School of Chemistry and Chemical Engineering School of Physics and Engineering Sun Yat-Sen University Guangzhou, 510275 (China); School of Chemistry and Chemical Engineering, Hunan University of Science and Technology Xiangtan, 411201 (China); Zou, Hongli; Fu, Junxiang; Yang, Xianfeng; Wang, Yi; Fu, Xionghui; Liang, Chaolun; Wu, Mingmei; Shen, Pei Kang [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry State Key Laboratory of Optoelectronic Materials and Technology School of Chemistry and Chemical Engineering School of Physics and Engineering Sun Yat-Sen University Guangzhou, 510275 (China); Guo, Hongliang; Gao, Qiuming [State Key Laboratory of High Performance Ceramics and Superfine Microstructures Shanghai Institute of Ceramics, Graduate School, Chinese Academy of Sciences 1295 Dingxi Rd., Shanghai 200050 (China)

2010-02-22

The growth of mesoporous quasi-single-crystalline Co{sub 3}O{sub 4} nanobelts by topotactic chemical transformation from {alpha}-Co(OH){sub 2} nanobelts is realized. During the topotactic transformation process, the primary {alpha}-Co(OH){sub 2} nanobelt frameworks can be preserved. The phases, crystal structures, morphologies, and growth behavior of both the precursory and resultant products are characterized by powder X-ray diffraction (XRD), electron microscopy - scanning electron (SEM) and transmission electron (TEM) microscopy, and selected area electron diffraction (SAED). Detailed investigation of the formation mechanism of the porous Co{sub 3}O{sub 4} nanobelts indicates topotactic nucleation and oriented growth of textured spinel Co{sub 3}O{sub 4} nanowalls (nanoparticles) inside the nanobelts. Co{sub 3}O{sub 4} nanocrystals prefer [0001] epitaxial growth direction of hexagonal {alpha}-Co(OH){sub 2} nanobelts due to the structural matching of [0001] {alpha}-Co(OH){sub 2}//[111] Co{sub 3}O{sub 4}. The surface-areas and pore sizes of the spinel Co{sub 3}O{sub 4} products can be tuned through heat treatment of {alpha}-Co(OH){sub 2} precursors at different temperatures. The galvanostatic cycling measurement of the Co{sub 3}O{sub 4} products indicates that their charge-discharge performance can be optimized. In the voltage range of 0.0-3.0 V versus Li{sup +}/Li at 40 mA g{sup -1}, reversible capacities of a sample consisting of mesoporous quasi-single-crystalline Co{sub 3}O{sub 4} nanobelts can reach up to 1400 mA h g{sup -1}, much larger than the theoretical capacity of bulk Co{sub 3}O{sub 4} (892 mA h g{sup -1}). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

ZnO nanoparticles based fiber optic gas sensor

Energy Technology Data Exchange (ETDEWEB)

Narasimman, S.; Sivacoumar, R.; Alex, Z. C. [MEMS and Sensor Division, School of Electronics Engineering, VIT University, Vellore 632 014 (India); Balakrishnan, L., E-mail: bslv85@gmail.com; Meher, S. R. [Materials Physics Division, School of Advanced Sciences, VIT University, Vellore 632 014 (India)

2016-05-23

In this work, ZnO nanoparticles were synthesized by simple aqueous chemical route method. The synthesized ZnO nanoparticles were characterized by X-ray diffraction and scanning electron microscope. The sensitivity of the nanoparticles was studied for different gases like acetone, ammonia and ethanol in terms of variation in spectral light intensity. The XRD and SEM analysis confirms the formation of hexagonal wurtzite structure with the grain size of 11.2 nm. The small cladding region of the optical fiber was replaced with the synthesized nanoparticles. The light spectrum was recorded for different gas concentrations. The synthesized nanoparticles showed high sensitivity towards ammonia in low ppm level and acetone in high ppm level.

The effect of strontium doping on structural and morphological properties of ZnO nanofilms synthesized by ultrasonic spray pyrolysis method

Directory of Open Access Journals (Sweden)

A. Ouhaibi

2018-03-01

Full Text Available Pristine and strontium doped ZnO nanometric films were successfully synthesized on heated glass substrates by the ultrasonic spray pyrolysis technique. The samples were characterized by means of X-ray diffraction (XRD, Atomic Force Microscope (AFM, UV–visible spectroscopy and photoluminescence (PL. X-ray diffraction patterns confirmed the hexagonal (wurtzite structure, where the most pronounced (002 peak indicates the preferential orientation along the c-axis perpendicular to the sample surface. The intensity of this peak was increased rapidly from the first doping of 1% and its position was shifted toward higher angles under Sr-doping effect. For the used doping range of 1–5%, the Sr-doping at 3% attracted an especial attention. At this concentration, the particular transformation in the surface morphology of doped ZnO films was observed. The surface became granular and rough by expanding the crystallites' size. From optical measurements, transmittance and PL spectra were found to be sensitive to Sr-doping, where two different behaviors were observed before and after 3% of Sr-doping. Keywords: Ultrasonic spray pyrolysis, Sr-doped ZnO, Morphology study, Optical properties

Orthorhombic MoO{sub 3} nanobelts based NO{sub 2} gas sensor

Energy Technology Data Exchange (ETDEWEB)

Mane, A.A. [Thin Film Nanomaterials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India); General Science and Humanities Department, Sant Gajanan Maharaj College of Engineering, Mahagaon, 416 503 (India); Moholkar, A.V., E-mail: avmoholkar@gmail.com [Thin Film Nanomaterials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India)

2017-05-31

Highlights: • The effect of thickness on physicochemical and NO{sub 2} gas sensing properties of sprayed MoO{sub 3} nanobelts has been reported. • The sprayed MoO{sub 3} nanobelts show the NO{sub 2} gas response of 68% for 100 ppm concentration at an operating temperature of 200 °C. • The lower detection limit of MoO{sub 3} nanobelts based NO{sub 2} sensor is found to be half of the IDLH value (20 ppm). - Abstract: Molybdenum trioxide (MoO{sub 3}) nanobelts have been deposited onto the glass substrates using chemical spray pyrolysis (CSP) deposition method. The XRD patterns reveal that films are polycrystalline having an orthorhombic crystal structure. Raman spectra confirm that the films are orthorhombic in phase. The XPS study shows the presence of two well resolved spectral lines of Mo-3d core levels appearing at the binding energy values of 232.82 eV and 235.95 eV corresponding to Mo-3d{sub 5/2} and Mo-3d{sub 3/2}, respectively. These binding energy values are assigned to Mo{sup 6+} oxidation state of fully oxidized MoO{sub 3}. The FE-SEM micrographs show the formation of nanobelts-like morphology. The AFM micrographs reveal that the RMS surface roughness increases from 16.5 nm to 17.5 nm with increase in film thickness from 470 nm to 612 nm and then decreases to 16 nm for 633 nm film thickness. The band gap energy is found to be decreased from 3.40 eV to 3.38 eV. To understand the electronic transport phenomenon in MoO{sub 3} thin films, dielectric properties are studied. For 612 nm film thickness, the highest NO{sub 2} gas response of 68% is obtained at an operating temperature of 200 °C for 100 ppm concentration with response and recovery times of 15 s and 150 s, respectively. The lower detection limit is found to be 10 ppm which is half of the immediately dangerous to life or health (IDLH) value of 20 ppm. Finally, NO{sub 2} gas sensing mechanism in an orthorhombic MoO{sub 3} crystal structure is discussed in detail.

Improvement of inverted organic solar cells using acetic acid as an additive for ZnO layer processing

Directory of Open Access Journals (Sweden)

Yang Li

2018-02-01

Full Text Available In this work, we used acetic acid as an additive for the preparation of ZnO layers and improved the performance of poly{4,8-bis[(2-ethylhexyl-oxy]benzo[1,2-b:4,5-b’] dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexylcarbonyl]thieno[3,4-b]thiophene- 4,6-diyl} (PTB7-based inverted organic solar cells. The addition of acetic acid to the ZnO precursor solution improved the transparency and conductivity of the sol-gel-synthesized ZnO film, by increasing the grain size of the film. Accordingly, the power conversion efficiency (PCE of the organic solar cells was improved from 6.42% to 7.55%, which was mainly caused by the enhanced current density and fill factor. The best sample demonstrated a high PCE of 7.85% with negligible hysteresis and good stability. Our results indicate that using acetic acid as an additive for the preparation of ZnO is a simple and effective way of fabricating high-performance inverted organic solar cells.

Improvement of inverted organic solar cells using acetic acid as an additive for ZnO layer processing

Science.gov (United States)

Li, Yang; Liu, Yawen; Liu, Zhihai; Xie, Xiaoyin; Lee, Eun-Cheol

2018-02-01

In this work, we used acetic acid as an additive for the preparation of ZnO layers and improved the performance of poly{4,8-bis[(2-ethylhexyl)-oxy]benzo[1,2-b:4,5-b'] dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene- 4,6-diyl} (PTB7)-based inverted organic solar cells. The addition of acetic acid to the ZnO precursor solution improved the transparency and conductivity of the sol-gel-synthesized ZnO film, by increasing the grain size of the film. Accordingly, the power conversion efficiency (PCE) of the organic solar cells was improved from 6.42% to 7.55%, which was mainly caused by the enhanced current density and fill factor. The best sample demonstrated a high PCE of 7.85% with negligible hysteresis and good stability. Our results indicate that using acetic acid as an additive for the preparation of ZnO is a simple and effective way of fabricating high-performance inverted organic solar cells.

Facile combustion synthesis of ZnO nanoparticles using Cajanus cajan (L.) and its multidisciplinary applications

Energy Technology Data Exchange (ETDEWEB)

Manjunath, K.; Ravishankar, T.N. [Centre for Nano and Material Sciences, Jain University, Jakkasandra, Kanakapura Talluk (India); Kumar, Dhanith [Department of Chemistry, B.M.S. Instsitute of Technology, Yelahanka, Bangalore (India); Priyanka, K.P; Varghese, Thomas [Nanoscience Research Centre, Department of Physics, Nirmala College, Muvattupuzha, Kerala (India); Naika, H.Raja [Department of Studies and Research in Environmental Science, Tumkur University, Tumkur (India); Nagabhushana, H. [CNR Rao Center for Advanced Materials, Tumkur University, Tumkur (India); Sharma, S.C. [Chattisgarh Swami Vivekananda Technical University, Bhilai (India); Dupont, J. [Institute of Chemistry, Laboratory of Molecular Catalysis, UFRGS, Porto Alegre (Brazil); Ramakrishnappa, T. [Centre for Nano and Material Sciences, Jain University, Jakkasandra, Kanakapura Talluk (India); Nagaraju, G., E-mail: nagarajugn@rediffmail.com [Department of Chemistry, B.M.S. Instsitute of Technology, Yelahanka, Bangalore (India)

2014-09-15

Graphical abstract: Facile combustion synthesis of ZnO nanoparticles using Cajanuscajan (L.) and its multidisciplinary applications.Zinc oxide nanoparticles were successfully synthesized by solution combustion method (SCM) using pigeon pea as a combustible fuel for the first time. The as-prepared product shows good photocatalytic, dielectric, antibacterial, electrochemical properties. - Highlights: • ZnO Nps were synthesized via combustion method using pigeon pea as a fuel. • The structure of the product was confirmed by XRD technique. • The morphology was confirmed by SEM and TEM images. • The as-prepared product shown good photocatalytic activity, dielectric property. • It has also shown good antibacterial and electrochemical properties. - Abstract: Zinc oxide nanoparticles (ZnO Nps) were successfully synthesized by solution combustion method (SCM) using pigeon pea as a fuel for the first time. X-Ray diffraction pattern reveals that the product belongs to hexagonal system. FTIR spectrum of ZnO Nps shows the band at 420 cm{sup −1} associated with the characteristic vibration of Zn–O. TEM images show that the nanoparticles are found to be ∼40–80 nm. Furthermore, the as-prepared ZnO Nps exhibits good photocatalytic activity for the photodegradation of methylene blue (MB), indicating that they are indeed a promising photocatalytic semiconductor. The antibacterial properties of ZnO nanopowders were investigated by their bactericidal activity against four bacterial strains.

Facile combustion synthesis of ZnO nanoparticles using Cajanus cajan (L.) and its multidisciplinary applications

International Nuclear Information System (INIS)

Manjunath, K.; Ravishankar, T.N.; Kumar, Dhanith; Priyanka, K.P; Varghese, Thomas; Naika, H.Raja; Nagabhushana, H.; Sharma, S.C.; Dupont, J.; Ramakrishnappa, T.; Nagaraju, G.

2014-01-01

Graphical abstract: Facile combustion synthesis of ZnO nanoparticles using Cajanuscajan (L.) and its multidisciplinary applications.Zinc oxide nanoparticles were successfully synthesized by solution combustion method (SCM) using pigeon pea as a combustible fuel for the first time. The as-prepared product shows good photocatalytic, dielectric, antibacterial, electrochemical properties. - Highlights: • ZnO Nps were synthesized via combustion method using pigeon pea as a fuel. • The structure of the product was confirmed by XRD technique. • The morphology was confirmed by SEM and TEM images. • The as-prepared product shown good photocatalytic activity, dielectric property. • It has also shown good antibacterial and electrochemical properties. - Abstract: Zinc oxide nanoparticles (ZnO Nps) were successfully synthesized by solution combustion method (SCM) using pigeon pea as a fuel for the first time. X-Ray diffraction pattern reveals that the product belongs to hexagonal system. FTIR spectrum of ZnO Nps shows the band at 420 cm −1 associated with the characteristic vibration of Zn–O. TEM images show that the nanoparticles are found to be ∼40–80 nm. Furthermore, the as-prepared ZnO Nps exhibits good photocatalytic activity for the photodegradation of methylene blue (MB), indicating that they are indeed a promising photocatalytic semiconductor. The antibacterial properties of ZnO nanopowders were investigated by their bactericidal activity against four bacterial strains

Mesoporous ZnO microcube derived from a metal-organic framework as photocatalyst for the degradation of organic dyes

Science.gov (United States)

Ban, Jin-jin; Xu, Guan-cheng; Zhang, Li; Lin, He; Sun, Zhi-peng; Lv, Yan; Jia, Dian-zeng

2017-12-01

A cube-like porous ZnO architecture was synthesized by direct two-step thermolysis of a zinc-based metal-organic framework [(CH3)2NH2][Zn(HCOO)3]. The obtained ZnO microcube was characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption and desorption isotherms. The mesoporous ZnO microcube was comprised by many nanoparticles, and inherited the cube shape from [(CH3)2NH2][Zn(HCOO)3] precursor. With large surface area and mesoporous structure, the ZnO microcube exhibits excellent photocatalytic activities against methyl orange (MO) and rhodamine B (RhB) under UV irradiation, and the degradation rates reached 99.7% and 98.1% within 120 min, respectively.

Biogenic ZnO nanoparticles synthesized using L. aculeata leaf ...

Indian Academy of Sciences (India)

The antifungal activity of ZnO nanoparticles were determined using the well diffusion method. All the ... 1. Introduction. Nanoparticles have gained increasing importance because ... The synthesis of nanoparticles by conventional physical.

Reducing ZnO nanoparticles toxicity through silica coating

Directory of Open Access Journals (Sweden)

Sing Ling Chia

2016-10-01

Full Text Available ZnO NPs have good antimicrobial activity that can be utilized as agents to prevent harmful microorganism growth in food. However, the use of ZnO NPs as food additive is limited by the perceived high toxicity of ZnO NPs in many earlier toxicity studies. In this study, surface modification by silica coating was used to reduce the toxicity of ZnO NPs by significantly reducing the dissolution of the core ZnO NPs. To more accurately recapitulate the scenario of ingested ZnO NPs, we tested our as synthesized ZnO NPs in ingestion fluids (synthetic saliva and synthetic gastric juice to determine the possible forms of ZnO NPs in digestive system before exposing the products to colorectal cell lines. The results showed that silica coating is highly effective in reducing toxicity of ZnO NPs through prevention of the dissociation of ZnO NPs to zinc ions in both neutral and acidic condition. The silica coating however did not alter the desired antimicrobial activity of ZnO NPs to E. coli and S. aureus. Thus, silica coating offered a potential solution to improve the biocompatibility of ZnO NPs for applications such as antimicrobial agent in foods or food related products like food packaging. Nevertheless, caution remains that high concentration of silica coated ZnO NPs can still induce undesirable cytotoxicity to mammalian gut cells. This study indicated that upstream safer-by-design philosophy in nanotechnology can be very helpful in a product development.

Controllable synthesis of ZnO nanograss with different morphologies and enhanced performance in dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Zhu Shibu; Chen Xiangnan; Zuo Feibiao; Jiang Man [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Zhou Zuowan, E-mail: zwzhou@at-c.net [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Hui, David [Department of Mechanical Engineering, University of New Orleans, New Orleans, LA 70148 (United States)

2013-01-15

A series of ZnO nanograss films grown on fluorine-doped tin oxide coated glass substrates were synthesized via hydrothermal method by using polyethyleneimine (PEI) as adjusting agent. The films were characterized by field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD). It was found that the PEI not only affected the aspect ratios of ZnO nanograss but also changed the geometrical shape of ZnO nanograss. A possible mechanism based on PEI adsorbed on the non-polar facets of ZnO that governed the growth rate of different directions were proposed to elucidate the effect of PEI on morphology of ZnO. The ZnO nanograss films were applied to dye-sensitized solar cells (DSSCs). The results showed that the photocurrent density significantly enhanced, and the power conversion efficiency increased by 55% based on ZnO nanograss synthesized in a growth solution containing 7 mmol/L PEI, resulting from the dye loading properties related to the different morphologies. - Graphical abstract: Effect of PEI on ZnO nanograss: controlling the aspect ratio and morphology of ZnO and enhancing their photovoltaic performance. Highlights: Black-Right-Pointing-Pointer ZnO nanograss with different aspect ratios were synthesized by adjusting PEI content. Black-Right-Pointing-Pointer PEI affects both on the aspect ratios and geometrical shapes of ZnO nanograss. Black-Right-Pointing-Pointer ZnO nanograss with high aspect ratio and needle-like tip was advantageous for improved photovoltaic conversion performance.

Ag nanodots decorated SiO2 coated ZnO core-shell nanostructure with enhanced luminescence property as potential imaging agent

Science.gov (United States)

Gupta, Jagriti; Barick, K. C.; Hassan, P. A.; Bahadur, Dhirendra

2018-04-01

Ag decorated silica coated ZnO nanocomposite (Ag@SiO2@ZnO NCs) has been synthesized by soft chemical approach. The physico-chemical properties of Ag@SiO2@ZnO NCs are investigated by various sophisticated characterization techniques such as X-ray diffraction, Transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible absorption and photoluminescent spectroscopy. X-ray diffraction confirms the phase formation of ZnO and Ag in nanocomposite. TEM micrograph clearly shows that Ag nanodots are well decorated over silica coated ZnO NCs. The photoluminescent study reveals the enhancement in the photoluminance property when the Ag nanodots are decorated over silica coated ZnO nanocomposite due to an electromagnetic coupling between excitons and plasmons. Furthermore, the photoluminescent property is an important tool for bio-imaging application, reveal that NCs give green and red emission after excitation with 488 and 535 nm. Therefore, low cytotoxicity and excellent fluorescence stability in vitro makes it a more suitable material for both cellular imaging and therapy for biomedical applications.

Exfoliated β-Ga2O3 nano-belt field-effect transistors for air-stable high power and high temperature electronics.

Science.gov (United States)

Kim, Janghyuk; Oh, Sooyeoun; Mastro, Michael A; Kim, Jihyun

2016-06-21

This study demonstrated the exfoliation of a two-dimensional (2D) β-Ga2O3 nano-belt and subsequent processing into a thin film transistor structure. This mechanical exfoliation and transfer method produces β-Ga2O3 nano-belts with a pristine surface as well as a continuous defect-free interface with the SiO2/Si substrate. This β-Ga2O3 nano-belt based transistor displayed an on/off ratio that increased from approximately 10(4) to 10(7) over the operating temperature range of 20 °C to 250 °C. No electrical breakdown was observed in our measurements up to VDS = +40 V and VGS = -60 V between 25 °C and 250 °C. Additionally, the electrical characteristics were not degraded after a month-long storage in ambient air. The demonstration of high-temperature/high-voltage operation of quasi-2D β-Ga2O3 nano-belts contrasts with traditional 2D materials such as transition metal dichalcogenides that intrinsically have limited temperature and power operational envelopes owing to their narrow bandgap. This work motivates the application of 2D β-Ga2O3 to high power nano-electronic devices for harsh environments such as high temperature chemical sensors and photodetectors as well as the miniaturization of power circuits and cooling systems in nano-electronics.

Optical Properties of ZnO Nanoparticles Capped with Polymers

Directory of Open Access Journals (Sweden)

Atsushi Noguchi

2011-06-01

Full Text Available Optical properties of ZnO nanoparticles capped with polymers were investigated. Polyethylene glycol (PEG and polyvinyl pyrrolidone (PVP were used as capping reagents. ZnO nanoparticles were synthesized by the sol-gel method. Fluorescence and absorption spectra were measured. When we varied the timing of the addition of the polymer to the ZnO nanoparticle solution, the optical properties were drastically changed. When PEG was added to the solution before the synthesis of ZnO nanoparticles, the fluorescence intensity increased. At the same time, the total particle size increased, which indicated that PEG molecules had capped the ZnO nanoparticles. The capping led to surface passivation, which increased fluorescence intensity. However, when PEG was added to the solution after the synthesis of ZnO nanoparticles, the fluorescence and particle size did not change. When PVP was added to the solution before the synthesis of ZnO nanoparticles, aggregation of nanoparticles occurred. When PVP was added to the solution after the synthesis of ZnO nanoparticles, fluorescence and particle size increased. This improvement of optical properties is advantageous to the practical usage of ZnO nanoparticles, such as bioimaging

Room-temperature ferromagnetic properties of Cu-doped ZnO rod ...

Indian Academy of Sciences (India)

We have investigated properties of the Cu-doped ZnO crystalline film synthesized by the hydrothermal method. X-ray diffraction and X-ray ... DMSs are semiconducting alloys whose lattice is made up in part of substitutional magnetic ... investigate Cu-doped ZnO system (Hou et al 2007a, b), as. Cu is a potential magnetic ion ...

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.

Synthesis and characterization of Mn-doped ZnO column arrays

International Nuclear Information System (INIS)

Yang Mei; Guo Zhixing; Qiu Kehui; Long Jianping; Yin Guangfu; Guan Denggao; Liu Sutian; Zhou Shijie

2010-01-01

Mn-doped ZnO column arrays were successfully synthesized by conventional sol-gel process. Effect of Mn/Zn atomic ratio and reaction time were investigated, and the morphology, tropism and optical properties of Mn-doped ZnO column arrays were characterized by SEM, XRD and photoluminescence (PL) spectroscopy. The result shows that a Mn/Zn atomic ratio of 0.1 and growth time of 12 h are the optimal condition for the preparation of densely distributed ZnO column arrays. XRD analysis shows that Mn-doped ZnO column arrays are highly c-axis oriented. As for Mn-doped ZnO column arrays, obvious increase of photoluminescence intensity is observed at the wavelength of ∼395 nm and ∼413 nm, compared to pure ZnO column arrays.

Y-Doped ZnO Nanorods by Hydrothermal Method and Their Acetone Gas Sensitivity

Directory of Open Access Journals (Sweden)

Peng Yu

2013-01-01

Full Text Available Pure and yttrium- (Y- doped (1 at%, 3 at%, and 7 at% ZnO nanorods were synthesized using a hydrothermal process. The crystallography and microstructure of the synthesized samples were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and energy dispersive X-ray spectroscopy (EDX. Comparing with pure ZnO nanorods, Y-doped ZnO exhibited improved acetone sensing properties. The response of 1 at% Y-doped ZnO nanorods to 100 ppm acetone is larger than that of pure ZnO nanorods. The response and recovery times of 1 at% Y-doped ZnO nanorods to 100 ppm acetone are about 30 s and 90 s, respectively. The gas sensor based on Y-doped ZnO nanorods showed good selectivity to acetone in the interfere gases of ammonia, benzene, formaldehyde, toluene, and methanol. The formation mechanism of the ZnO nanorods was briefly analyzed.

Influence of doping of Mn{sup +2} and Co{sup +2} in ZnO synthesized by combustion reaction for use in DMS; Influencia da dopagem do Mn{sup +2} e Co{sup +2} no ZnO sintetizado por reacao de combustao para uso em SMD

Energy Technology Data Exchange (ETDEWEB)

Torquato, R.; Costa, A.C.F.M. [Universidade Federal de Campina Grande (UFCG), Campina Grande, PB (Brazil). Departamento de Engenharia de Materiais; Shirsath, S.E. [Department of Physics, Vivekanand College, Aurangabad, MS (India); Kiminami, R.H.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

2011-07-01

ZnO is a semiconducting ceramics used for development of electrical devices such as varistors, chemical sensors, piezoelectric transducers and diluted magnetic semiconductors. So this paper proposes to investigate the influence of doping of 0.1 mol of Mn{sup +2} and Co{sup +2} on the structure, morphology and magnetic measurements of ZnO synthesized by combustion reaction in DMS applications. The resulting samples were characterized by XRD, SEM, BET, VSM. The combustion temperature for samples doped with Mn and Co were 512 deg C and 397 °C, respectively. XRD results for both samples showed the formation of ZnO as the major phase, with crystallite size of 21nm and 23nm and a surface area of 59 and 17 m2/g for samples doped with Mn{sup +2} and Co{sup +2}, respectively. The magnetic measurements showed values of saturation magnetization and coercive force of 12 and 3 emu/g, and 94 and 237Oe, respectively. (author)

A novel hierarchical ZnO disordered/ordered bilayer nanostructured film for dye sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Feng, Yamin, E-mail: yaminfengccnuphy@outlook.com; Wu, Fei; Jiang, Jian; Zhu, Jianhui; Fodjouong, Ghislain Joel; Meng, Gaoxiang; Xing, Yanmin; Wang, Wenwu; Huang, Xintang, E-mail: xthuang@phy.ccnu.edu.cn

2013-12-25

Graphical abstract: A novel hierarchical disordered/ordered bilayer ZnO nanostructured film in the length of 18 μm have been successfully synthesized on the FTO substrate; the hierarchical ZnO nanostructured film electrodes applied in DSSCs exhibit photoelectric conversion efficiency as high as 5.16%. Highlights: •A novel hierarchical ZnO structure film was fabricated on a FTO substrate. •Hierarchical ZnO film is applied as the electrodes for dye sensitized solar cells. •The film possess high specific surface area and fast electron transport effect. •The light-scattering effect of the hierarchical film is pronounced. •The energy conversion efficiency of hierarchical ZnO electrode reaches to 5.16%. -- Abstract: A novel hierarchical ZnO nanostructured film is synthesized via a chemical bath deposition (CBD) method followed by a treatment of thermal decomposition onto a fluorine-doped tin oxide (FTO) substrate. This hierarchical film is composed of disordered ZnO nanorods (NRs) (top layer) and ordered ZnO nanowires (NWs) (bottom layer). The products possess the following features such as high specific surface area, fast electron transport, and pronounced light-scattering effect, which are quite suitable for dye sensitized solar cells (DSSCs) applications. A light-to-electricity conversion efficiency of 5.16% is achieved when the hierarchical ZnO nanostructured film is used as the photoanode under 100 mW cm{sup −2} illumination. This efficiency is found to be much higher than that of the DSSCs with pure ordered ZnO NWs (1.45%) and disordered ZnO NRs (3.31%) photoanodes.

A novel hierarchical ZnO disordered/ordered bilayer nanostructured film for dye sensitized solar cells

International Nuclear Information System (INIS)

Feng, Yamin; Wu, Fei; Jiang, Jian; Zhu, Jianhui; Fodjouong, Ghislain Joel; Meng, Gaoxiang; Xing, Yanmin; Wang, Wenwu; Huang, Xintang

2013-01-01

Graphical abstract: A novel hierarchical disordered/ordered bilayer ZnO nanostructured film in the length of 18 μm have been successfully synthesized on the FTO substrate; the hierarchical ZnO nanostructured film electrodes applied in DSSCs exhibit photoelectric conversion efficiency as high as 5.16%. Highlights: •A novel hierarchical ZnO structure film was fabricated on a FTO substrate. •Hierarchical ZnO film is applied as the electrodes for dye sensitized solar cells. •The film possess high specific surface area and fast electron transport effect. •The light-scattering effect of the hierarchical film is pronounced. •The energy conversion efficiency of hierarchical ZnO electrode reaches to 5.16%. -- Abstract: A novel hierarchical ZnO nanostructured film is synthesized via a chemical bath deposition (CBD) method followed by a treatment of thermal decomposition onto a fluorine-doped tin oxide (FTO) substrate. This hierarchical film is composed of disordered ZnO nanorods (NRs) (top layer) and ordered ZnO nanowires (NWs) (bottom layer). The products possess the following features such as high specific surface area, fast electron transport, and pronounced light-scattering effect, which are quite suitable for dye sensitized solar cells (DSSCs) applications. A light-to-electricity conversion efficiency of 5.16% is achieved when the hierarchical ZnO nanostructured film is used as the photoanode under 100 mW cm −2 illumination. This efficiency is found to be much higher than that of the DSSCs with pure ordered ZnO NWs (1.45%) and disordered ZnO NRs (3.31%) photoanodes

Cu-implanted ZnO nanorods array film: An aqueous synthetic approach

Energy Technology Data Exchange (ETDEWEB)

Singh, Ajaya Kumar, E-mail: ajayaksingh_au@yahoo.co.in [Department of Chemistry, Govt. VYT PG. Autonomous College Durg, Chhattisgarh (India); Thool, Gautam Sheel [Department of Chemistry, Govt. VYT PG. Autonomous College Durg, Chhattisgarh (India); Singh, R.S. [Department of Physics, Govt. D.T. College, Utai, Durg, Chhattisgarh (India); Singh, Surya Prakash, E-mail: spsingh@iict.res.in [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Uppal road, Tarnaka, Hyderabad 500007 (India)

2015-01-05

Highlights: • Cu doped ZnO nanorods were synthesized using low temperature aqueous solution method. • We demonstrated the capping action of TEA via theoretical simulation. • Raman analysis revealed the presence of tensile strain in Cu doped ZnO nanorods. • Growth rate was found to be high in Cu doped ZnO nanorods. - Abstract: Pure and Cu doped ZnO nanorods array are synthesized via two step chemical bath deposition method. The seed layer is prepared by successive ionic layer adsorption reaction (SILAR) method. The synthesized materials have been systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy and photoluminescence (PL) spectroscopy. SEM pictures show the existence of vertically well aligned hexagonal ZnO nanorods. EDAX spectrum confirms the presence of Cu in ZnO nanorods. High intense peak of (0 0 2) plane and E{sub 2}{sup high} mode for XRD and Raman spectrum respectively, suggest the ZnO nanorods are adopted c-axis orientation perpendicular to substrate. XRD and Raman analysis shows the presence of tensile strain in Cu doped ZnO nanorods. Effect of Cu doping on lattice constants, unit cell volume and Zn–O bond length of ZnO nanorods have also been studied. Room temperature PL measurement exhibits two luminescence bands in the spectra i.e. UV emission centered at 3.215 eV and a broad visible band. Theoretical investigation for capping action of triethanolamine is done by Hartree–Fock (HF) method with 3-21G basis set using Gaussian 09 program package.

Influence of Codoping on the Optical Properties of ZnO Thin Films Synthesized on Glass Substrate by Chemical Bath Deposition Method

Directory of Open Access Journals (Sweden)

G. Shanmuganathan

2014-01-01

Full Text Available Fe and K simultaneously doped ZnO thin films Zn0.99 K0.01 (Fex O (x=1, 2, 3, and 4% were synthesized by chemical bath deposition method. The XRD investigation reveals that all the doped ZnO thin films are in hexagonal wurtzite crystal structure without impurity phases. With increase in Fe concentration, the growth of thin films along c axis is evident from the XRD which indicates the increase in intensity along (002 direction. The same is visible from the surface morphology which shows the formation of hexagonal structure for higher Fe concentration. The topography shows gradual variation with Fe incorporation. The optical energy band gap obtained from the transmittance spectrum decreases from 3.42 to 3.06 eV with increase in Fe concentration indicating the red shift and this trend is consistent with the earlier experimental results. The UV emission is centered around 3.59 eV. The optical constants such as refractive index, extinction coefficient, and absorption coefficient which are essential for the optoelectronic applications were also determined.

Enhanced antimicrobial activity in biosynthesized ZnO nanoparticles

Science.gov (United States)

Kumari, Niraj; Kumari, Priti; Jha, Anal K.; Prasad, K.

2018-05-01

Biological synthesis of different metallic and/or oxide nanoparticles and their applications especially in agriculture and biomedical sciences are gaining prominence nowadays due to their handy and reproducible synthetic protocols which are cost-effective and eco-friendly. In this work, green synthesis of zinc oxide nanoparticles (ZnO NPs) using the alcoholic extract of Azadirachta indica as a reducing and stabilizing agent has been presented. Formation of ZnO NPs was confirmed by X-ray diffraction, scanning and transmission electron microscopy techniques. The phytochemicals responsible for nano-transformation were principally alkaloids, flavanoids, terpenoids, tannins and organic acids present in the Azadirachta indica leaves. The synthesized ZnO NPs were used for antimicrobial assays by disc diffusion method against Staphylococcus aureus and Candida albicans. Results showed that ZnO NPs may act as antimicrobial agent especially against skin infections.

Formation of ZnO Nanocrystalline via Facile Non-Hydrolytic Route

International Nuclear Information System (INIS)

Ooi, M. D. Johan; Aziz, A. Abdul; Abdullah, M. J.

2011-01-01

Zinc oxide (ZnO) nanocrystalline were synthesized via oxidizing Zn powder in non-aqueous solvent with addition of Diethanolamine (DEA) as a stabilizing agent. The influence of DEA on the structural, optical properties and the formation of ZnO nanocrystalline were studied. The synthesized ZnO were polycrystalline in structures where sample without the addition of DEA shows high intensity peak of (002) phase compared with sample in the presence of DEA which preferred to grow in (101) direction. SEM micrograph displays the morphology of ZnO nanocrystalline for both of the samples which shows micron size and non-uniform particles for sample without DEA whereas for sample with DEA exhibit smaller size (∼110 nm) and nearly spherical in shape despite of some agglomeration occurs at the interparticle separation. The photoluminescence (PL) spectra shows UV emission peak for both of the samples where sample with the absence of DEA possess lower intensity of UV emission peak compared to samples with DEA which demonstrate stronger intensity despite of having very weak visible secondary emission peak at 530 nm.

Optimization of CVD parameters for long ZnO NWs grown on ITO

Indian Academy of Sciences (India)

The optimization of chemical vapour deposition (CVD) parameters for long and vertically aligned (VA) ZnO nanowires (NWs) were investigated. Typical ZnO NWs as a single crystal grown on indium tin oxide (ITO)-coated glass substrate were successfully synthesized. First, the conducted side of ITO–glass substrate was ...

ZnO doped SnO2 nanoparticles heterojunction photo-catalyst for environmental remediation

International Nuclear Information System (INIS)

Lamba, Randeep; Umar, Ahmad; Mehta, S.K.; Kansal, Sushil Kumar

2015-01-01

ZnO doped SnO 2 nanoparticles were synthesized by facile and simple hydrothermal technique and used as an effective photocatalyst for the photocatalytic degradation of harmful and toxic organic dye. The prepared nanoparticles were characterized in detail using different techniques for morphological, structural and optical properties. The characterization results revealed that the synthesized nanoparticles possess both crystal phases of tetragonal rutile phase of pure SnO 2 and wurtzite hexagonal phase of ZnO. In addition, the nanoparticles were synthesized in very high quantity with good crystallinity. The photocatalytic activity of prepared nanoparticles was evaluated by the photocatalytic degradation of methylene blue (MB) dye. Detailed photocatalytic experiments based on the effects of irradiation time, catalyst dose and pH were performed and presented in this paper. The detailed photocatalytic experiments revealed that the synthesized ZnO doped SnO 2 nanoparticles heterojunction photocatalyst exhibit best photocatalytic performance when the catalyst dose was 0.25 g/L and pH = 10. ZnO doped SnO 2 nanoparticles heterojunction photocatalyst was also compared with commercially available TiO 2 (PC-50), TiO 2 (PC-500) and SnO 2 and interestingly ZnO doped SnO 2 nanoparticles exhibited superior photocatalytic performance. The presented work demonstrates that the prepared ZnO doped SnO 2 nanoparticles are promising material for the photocatalytic degradation of organic dyes and toxic chemicals. - Highlights: • Synthesis of well-crystalline ZnO-doped SnO 2 nanoparticles. • Excellent morphological, crystalline and photoluminescent properties. • Efficient environmental remediation using ZnO-doped SnO 2 nanoparticles.

Hydrodynamic fabrication of structurally gradient ZnO nanorods.

Science.gov (United States)

Kim, Hyung Min; Youn, Jae Ryoun; Song, Young Seok

2016-02-26

We studied a new approach where structurally gradient nanostructures were fabricated by means of hydrodynamics. Zinc oxide (ZnO) nanorods were synthesized in a drag-driven rotational flow in a controlled manner. The structural characteristics of nanorods such as orientation and diameter were determined by momentum and mass transfer at the substrate surface. The nucleation of ZnO was induced by shear stress which plays a key role in determining the orientation of ZnO nanorods. The nucleation and growth of such nanostructures were modeled theoretically and analyzed numerically to understand the underlying physics of the fabrication of nanostructures controlled by hydrodynamics. The findings demonstrated that the precise control of momentum and mass transfer enabled the formation of ZnO nanorods with a structural gradient in diameter and orientation.

Gel-combustion-synthesized ZnO nanoparticles for visible light ...

Indian Academy of Sciences (India)

diet in Africa [19], consumed by 500 million people around the world [20] and is ... water splitting by ZnO involves ZnO/Zn redox mechanism where the conversion of .... important tool to study the crystal quality and the vibrations occuring due to ...

Raman selection rule of surface optical phonon in ZnS nanobelts

KAUST Repository

Ho, Chih-Hsiang

2016-02-18

We report Raman scattering results of high-quality wurtzite ZnS nanobelts (NBs) grown by chemical vapor deposition. In Raman spectrum, the ensembles of ZnS NBs exhibit first order phonon modes at 274 cm-1 and 350 cm-1, corresponding to A1/E1 transverse optical and A1/E1 longitudinal optical phonons, in addition with strong surface optical (SO) phonon mode at 329 cm-1. The existence of SO band is confirmed by its shift with different surrounding dielectric media. Polarization dependent Raman spectrum was performed on a single ZnS NB and for the first time SO phonon band has been detected on a single nanobelt. Different selection rules of SO phonon modeshown from their corresponding E1/A1 phonon modeswere attributed to the anisotropic translational symmetry breaking on the NB surface.

Raman selection rule of surface optical phonon in ZnS nanobelts

KAUST Repository

Ho, Chih-Hsiang; Varadhan, Purushothaman; Wang, Hsin-Hua; Chen, Cheng-Ying; Fang, Xiaosheng; He, Jr-Hau

2016-01-01

We report Raman scattering results of high-quality wurtzite ZnS nanobelts (NBs) grown by chemical vapor deposition. In Raman spectrum, the ensembles of ZnS NBs exhibit first order phonon modes at 274 cm-1 and 350 cm-1, corresponding to A1/E1 transverse optical and A1/E1 longitudinal optical phonons, in addition with strong surface optical (SO) phonon mode at 329 cm-1. The existence of SO band is confirmed by its shift with different surrounding dielectric media. Polarization dependent Raman spectrum was performed on a single ZnS NB and for the first time SO phonon band has been detected on a single nanobelt. Different selection rules of SO phonon modeshown from their corresponding E1/A1 phonon modeswere attributed to the anisotropic translational symmetry breaking on the NB surface.

Room temperature ferromagnetism in Mg-doped ZnO nanoparticles

International Nuclear Information System (INIS)

Singh, Jaspal; Vashihth, A.; Gill, Pritampal Singh; Verma, N. K.

2015-01-01

Zn 1-x Mg x O (x = 0, 0,10) nanoparticles were successfully synthesized using sol-gel method. X-ray diffraction (XRD) confirms that the synthesized nanoparticles possess wurtzite phase having hexagonal structure. Morphological analysis was carried out using transmission electron microscopy (TEM) which depicts the spherical morphology of ZnO nanoparticles. Energy dispersive spectroscopy (EDS) showed the presence of Mg in ZnO nanoparticles. Electron spin resonance (ESR) signal was found to be decreasing with increasing of Mg-doping concentration. The room temperature ferromagnetism was observed in undoped and Mg-doped ZnO nanoparticles. The increase of Mg-doping concentration resulted in decrease of saturation magnetization value which could be attributed to decrease of oxygen vacancies present in host nanoparticles

Morphological transition of ZnO nanostructures influenced by magnesium doping

International Nuclear Information System (INIS)

Premkumar, T.; Zhou, Y.S.; Gao, Y.; Baskar, K.; Jiang, L.; Lu, Y.F.

2012-01-01

Wurtzite zinc oxide (ZnO) nanochains have been synthesized through high-pressure pulsed laser deposition. The chain-like ZnO nanostructures were obtained from magnesium (Mg) doped ZnO targets, whereas vertically aligned nanorods were obtained from primitive ZnO targets. The Mg doping has influenced the morphological transition of ZnO nanostructures from nanorods to nanochains. The field emission scanning electron microscope images revealed the growth of beaded ZnO nanochains. The ZnO nanochains of different diameters 40 and 120 nm were obtained. The corresponding micro-Raman spectra showed strong E 2H mode of ZnO, which confirmed the good crystallinity of the nanochains. In addition to near band edge emission at 3.28 eV, ZnO nanochains show broad deep level emission at 2.42 eV than that of ZnO nanorods.

Surface potential driven dissolution phenomena of [0 0 0 1]-oriented ZnO nanorods grown from ZnO and Pt seed layers

Science.gov (United States)

Seo, Youngmi; Kim, Jung Hyeun

2011-06-01

Highly oriented ZnO nanorods are synthesized hydrothermally on ZnO and Pt seed layers, and they are dissolved in KOH solution. The rods grown on ZnO seed layer show uniform dissolution, but those grown on Pt seed layer are rod-selectively dissolved. The ZnO nanorods from both seed layers show the same crystalline structure through XRD and Raman spectrometer data. However, the surface potential analysis reveals big difference for ZnO and Pt seed cases. The surface potential distribution is very uniform for the ZnO seed case, but it is much fluctuated on the Pt seed case. It suggests that the rod-selective dissolution phenomena on Pt seed case are likely due to the surface energy difference.

Diameter Control and Photoluminescence of ZnO Nanorods from Trialkylamines

Directory of Open Access Journals (Sweden)

Tamar Andelman

2007-01-01

Full Text Available A novel solution method to control the diameter of ZnO nanorods is reported. Small diameter (2-3 nm nanorods were synthesized from trihexylamine, and large diameter (50–80 nm nanorods were synthesized by increasing the alkyl chain length to tridodecylamine. The defect (green emission of the photoluminescence (PL spectra of the nanorods varies with diameter, and can thus be controlled by the diameter control. The small ZnO nanorods have strong green emission, while the large diameter nanorods exhibit a remarkably suppressed green band. We show that this observation supports surface oxygen vacancies as the defect that gives rise to the green emission.

Magnetic and optical properties of Mn-doped ZnO vertically aligned nanorods synthesized by hydrothermal technique

Energy Technology Data Exchange (ETDEWEB)

Panda, J.; Sasmal, I.; Nath, T. K., E-mail: tnath@phy.iitkgp.ernet.in, E-mail: tapnath@gmail.com [Department of Physics, Indian Institute Technology Kharagpur, West Bengal, 721302 (India)

2016-03-15

In this paper we have reported the synthesis of high quality vertically aligned undoped and Mn-doped ZnO single crystalline nanorods arrays on Si (100) substrates using two steps process, namely, initial slow seed layer formation followed by solution growth employing wet chemical hydrothermal method. The shapes of the as grown single crystalline nanorods are hexagonal. The diameter and length of the as grown undoped ZnO nanorods varies in the range of 80-150 nm and 1.0 - 1.4 μm, respectively. Along with the lattice parameters of the hexagonal crystal structure, the diameter and length of Mn doped ZnO nanorods are found to increase slightly as compared to the undoped ZnO nanorods. The X-ray photoelectron spectroscopy confirms the presence of Mn atoms in Mn{sup 2+} state in the single crystalline ZnO nanorods. The recorded photoluminescence spectrum contains two emissions peaks having UV exciton emissions along with a green-yellow emission. The green-yellow emissions provide the evidence of singly ionized oxygen vacancies. The magnetic field dependent magnetization measurements [M (H)] and zero field cooled (ZFC) and field cooled (FC) magnetization [M(T)] measurements have been carried out at different isothermal conditions in the temperature range of 5-300 K. The Mn doped ZnO nanorods clearly show room temperature ferromagnetic ordering near room temperature down to 5 K. The observed magnetization may be attributed to the long range ferromagnetic interaction between bound magnetic polarons led by singly charged oxygen vacancies.

Carbon doped ZnO: Synthesis, characterization and interpretation

International Nuclear Information System (INIS)

Mishra, D.K.; Mohapatra, J.; Sharma, M.K.; Chattarjee, R.; Singh, S.K.; Varma, Shikha; Behera, S.N.; Nayak, Sanjeev K.; Entel, P.

2013-01-01

A novel thermal plasma in-flight technique has been adopted to synthesize nanocrystalline ZnO and carbon doped nanocrystalline ZnO matrix. Transmission electron microscopy (TEM) studies on these samples show the average particle sizes to be around 32 nm for ZnO and for carbon doped ZnO. An enhancement of saturation magnetization in nanosized carbon doped ZnO matrix by a factor of 3.8 has been found in comparison to ZnO nanoparticles at room temperature. Raman measurement clearly indicates the presence of Zn–C complexes surrounded by ZnO matrix in carbon doped ZnO. This indicates that the ferromagnetic signature in carbon doped ZnO arises from the creation of defects or the development of oxy-carbon clusters, in the carbon doped ZnO system. Theoretical studies based on density functional theory also support the experimental analyses. - Highlights: ► Synthesis of nanocrystalline ZnO and carbon doped ZnO matrix by inflight thermal plasma reactor. ► Enhancement of ferromagnetism in nanosized carbon doped ZnO in comparison to ZnO nanoparticles. ► Raman measurement indicates the presence of Zn–C complexes surrounded by ZnO matrix. ► Ferromagnetic signature in carbon doped ZnO arises from the development of oxy-carbon clusters. ► DFT supports experimental evidence of ferromagnetism in C doped ZnO nanoparticles.

Green method for producing hierarchically assembled pristine porous ZnO nanoparticles with narrow particle size distribution

International Nuclear Information System (INIS)

Escobedo-Morales, A.; Téllez-Flores, D.; Ruiz Peralta, Ma. de Lourdes; Garcia-Serrano, J.; Herrera-González, Ana M.; Rubio-Rosas, E.; Sánchez-Mora, E.; Olivares Xometl, O.

2015-01-01

A green method for producing pristine porous ZnO nanoparticles with narrow particle size distribution is reported. This method consists in synthesizing ZnO 2 nanopowders via a hydrothermal route using cheap and non-toxic reagents, and its subsequent thermal decomposition at low temperature under a non-protective atmosphere (air). The morphology, structural and optical properties of the obtained porous ZnO nanoparticles were studied by means of powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and nitrogen adsorption–desorption measurements. It was found that after thermal decomposition of the ZnO 2 powders, pristine ZnO nanoparticles are obtained. These particles are round-shaped with narrow size distribution. A further analysis of the obtained ZnO nanoparticles reveals that they are hierarchical self-assemblies of primary ZnO particles. The agglomeration of these primary particles at the very early stage of the thermal decomposition of ZnO 2 powders provides to the resulting ZnO nanoparticles a porous nature. The possibility of using the synthesized porous ZnO nanoparticles as photocatalysts has been evaluated on the degradation of rhodamine B dye. - Highlights: • A green synthesis method for obtaining porous ZnO nanoparticles is reported. • The obtained ZnO nanoparticles have narrow particle size distribution. • This method allows obtaining pristine ZnO nanoparticles avoiding unintentional doping. • A growth mechanism for the obtained porous ZnO nanoparticles is proposed

A sol-gel method for preparing ZnO quantum dots with strong blue emission

International Nuclear Information System (INIS)

Chen Zhong; Li Xiaoxia; Du Guoping; Chen Nan; Suen, Andy Y.M.

2011-01-01

ZnO quantum dots (QDs) with strong blue emission have been successfully synthesized by sol-gel method, and their crystal structures, sizes, and photoluminescence properties were characterized by X-ray diffractometer, scanning electron microscope, and ultraviolet-visible spectroscopy. It has been found that ZnO QDs had a hexagonal wurtzite crystal structure, and their average diameter was about 16.0-32.2 nm. Both the reaction time and temperature were found to have a strong influence on the average size and photoluminescence properties of ZnO QDs. Longer reaction time and higher reaction temperature resulted in larger average size for ZnO QDs. It has been shown that at reaction temperature 60 deg. C the emission intensity for ZnO QDs increased first with reaction time before 7 h and then decreased after 7 h. For the same reaction time 7 h, ZnO QDs synthesized at 60 deg. C showed the strongest emission intensity. It was found that annealing in nitrogen, vacuum, and air all resulted in an increase of the size of ZnO QDs and a reduction in their photoluminescence. The dependence of the size and properties of ZnO QDs on the reaction parameters as well as the annealing conditions has been discussed. - Highlights: → ZnO quantum dots (QDs) with strong blue emission were prepared by sol-gel method. → ZnO QDs had a pure spectral blue with the chromaticity coordinates (0.166, 0.215). → Optimal reaction time and temperature were 7 h and 60 deg. C, respectively.

Structure-controlled synthesis and electrochemical properties of NH_4V_3O_8 as cathode material for Lithium ion batteries

International Nuclear Information System (INIS)

Cheng, Yayi; Huang, Jianfeng; Li, Jiayin; Cao, Liyun; Xu, Zhanwei; Wu, Jianpeng; Cao, Shanshan; Hu, Hailing

2016-01-01

NH_4V_3O_8 flower, nanobelt, lath and sheet were synthesized using a facile microwave hydrothermal method. The formation mechanism of NH_4V_3O_8 with various structures was proposed. As an cathode in Li-ion battery, the NH_4V_3O_8 nanobelt with one-dimensional structure as well as nanosized morphology, presents excellent cycling stability and enhanced rate capability when comparing with other NH_4V_3O_8 structures. Further study finds that the NH_4V_3O_8 nanobelt could provide high Li ion diffusion, excellent structural stability and good reversibility during the charge/discharge process, indicating a strong connection between the morphology and the electrochemical performance of NH_4V_3O_8 cathode.

Shape-selective dependence of room temperature ferromagnetism induced by hierarchical ZnO nanostructures

CSIR Research Space (South Africa)

Motaung, DE

2014-05-01

Full Text Available . These materials were synthesized in a shape-selective manner using simple microwave assisted hydrothermal synthesis. Thermogravimetric analyses demonstrated the as-synthesized ZnO nanostructures to be stable and of high purity. Structural analyses showed...

Structure and photoluminescence properties of Ag-coated ZnO nano-needles

Energy Technology Data Exchange (ETDEWEB)

Li Xiaozhu, E-mail: Lixiaozhu1019@21cn.com [Department of Physics, Shaoguan University, Shaoguan, Guangdong 512005 (China) and Department of Physics and Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Wuhan University, Wuhan, Hubei 430072 (China); Wang Yongqian [Engineering Research Center of Nano-Geomaterials of Ministry of Education (China University of Geosciences), Wuhan, Hubei 430074 (China)

2011-05-12

Highlights: > ZnO nano-needles were synthesized by thermal oxidation. > Their surfaces were coated with Ag by pulse electro-deposition technique. > The uncoated and coated ZnO nano-needles were characterized. > The results showed that the prepared ZnO nano-needles have been coated with Ag successfully. > The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the Ag-coated ZnO nano-needles can increase the absorption of UV light. - Abstract: A large number of zinc oxide (ZnO) nano-needles were synthesized by thermal oxidation of pure zinc. The surfaces of ZnO nano-needles were coated with a layer of Ag by pulse electro-deposition technique. The uncoated and coated ZnO nano-needles were characterized by using the X-ray diffraction and the scanning electron microscope (SEM). The results showed that the uncoated samples were close-packed hexagonal structure, which showed needle-like morphology. Their average diameter is about 40 nm, lengths up to 5 {mu}m. At the same time we observed that the prepared ZnO nano-needles have been coated with Ag successfully. The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the uncoated ZnO nano-needles have two fluorescence peaks at 388 nm and 470.8 nm, respectively, the relative intensity of 143.4 and 93.61; and the Ag-coated ZnO nano-needles showed a pair of strong peaks at 387.4 nm and 405.2 nm, the relative intensity of 1366 and 1305, respectively, indicating that the Ag-coated ZnO nano-needles can increase the absorption of UV light.

Synthesis of isotopically modified ZnO nanoparticles and their potential as nanotoxicity tracers.

Science.gov (United States)

Dybowska, Agnieszka D; Croteau, Marie-Noele; Misra, Superb K; Berhanu, Deborah; Luoma, Samuel N; Christian, Paul; O'Brien, Paul; Valsami-Jones, Eugenia

2011-01-01

Understanding the behavior of engineered nanoparticles in the environment and within organisms is perhaps the biggest obstacle to the safe development of nanotechnologies. Reliable tracing is a particular issue for nanoparticles such as ZnO, because Zn is an essential element and a common pollutant thus present at elevated background concentrations. We synthesized isotopically enriched (89.6%) with a rare isotope of Zn (67Zn) ZnO nanoparticles and measured the uptake of 67Zn by L. stagnalis exposed to diatoms amended with the particles. Stable isotope technique is sufficiently sensitive to determine the uptake of Zn at an exposure equivalent to lower concentration range (<15 μg g(-1)). Without a tracer, detection of newly accumulated Zn is significant at Zn exposure concentration only above 5000 μg g(-1) which represents some of the most contaminated Zn conditions. Only by using a tracer we can study Zn uptake at a range of environmentally realistic exposure conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

Synthesis of isotopically modified ZnO nanoparticles and their potential as nanotoxicity tracers

Science.gov (United States)

Dybowska, A.D.; Croteau, M.-N.; Misra, S.K.; Berhanu, D.; Luoma, S.N.; Christian, P.; O'Brien, P.; Valsami-Jones, E.

2011-01-01

Understanding the behavior of engineered nanoparticles in the environment and within organisms is perhaps the biggest obstacle to the safe development of nanotechnologies. Reliable tracing is a particular issue for nanoparticles such as ZnO, because Zn is an essential element and a common pollutant thus present at elevated background concentrations. We synthesized isotopically enriched (89.6%) with a rare isotope of Zn (67Zn) ZnO nanoparticles and measured the uptake of 67Zn by L. stagnalis exposed to diatoms amended with the particles. Stable isotope technique is sufficiently sensitive to determine the uptake of Zn at an exposure equivalent to lower concentration range (<15 ??g g-1). Without a tracer, detection of newly accumulated Zn is significant at Zn exposure concentration only above 5000 ??g g-1 which represents some of the most contaminated Zn conditions. Only by using a tracer we can study Zn uptake at a range of environmentally realistic exposure conditions. ?? 2010 Elsevier Ltd. All rights reserved.

Red luminescence from hydrothermally synthesized Eu-doped ZnO ...

Indian Academy of Sciences (India)

Administrator

turally characterized by X-ray diffraction, transmission electron microscopy ... II–VI compound semiconductor with large exciton binding .... ions occupy a site with inversion symmetry and 617 nm ... TEM image of Eu-doped ZnO nanoparticles with (a) 1⋅2 at. .... Jacquier B, Lebrasseur E, Guy S, Belarouci A and Menchini F.

Three-dimensional carbon cloth-supported ZnO nanorod arrays as a binder-free anode for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Huang, Lanyan; Wang, Xin, E-mail: wangxin@scnu.edu.cn [South China Normal University, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics (China); Yin, Fuxing [Synergy Innovation Institute of GDUT (China); Zhang, Chengwei [Hebei University of Technology, Research Institute for Energy Equipment Materials, Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology (China); Gao, Jinwei; Liu, Junming [South China Normal University, Institute of Advanced Materials, South China Academy of Advanced Optoelectronics (China); Zhou, Guofu [South China Normal University, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics (China); Zhang, Yongguang, E-mail: yongguangzhang@hebut.edu.cn; Bakenov, Zhumabay [Synergy Innovation Institute of GDUT (China)

2017-02-15

Three-dimensional ZnO nanorod arrays on flexible high surface area carbon cloth were successfully synthesized and directly used as negative electrodes for lithium-ion batteries without using any binder additive. The structure and morphology of the as-prepared hybrid ZnO electrode were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). When tested as anodes in a lithium cell, the hybrid electrode demonstrated a high discharge capacity along with excellent rate capability and good cycling stability, delivering a reversible capacity of 891 mAh g{sup −1} at the second cycle and retaining a capacity of 469 mAh g{sup −1} after 100 cycles.

Performance of Cr-doped ZnO for acetone sensing

Energy Technology Data Exchange (ETDEWEB)

Al-Hardan, N.H., E-mail: naif_imen@ukm.my [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Abdullah, M.J.; Aziz, A. Abdul [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia)

2013-04-01

Zinc oxide (ZnO) doped with chromium (Cr) was synthesized by reactive co-sputtering for gas sensing applications. The effect of varying the contents of Cr (from 1 to 4 at%) on the ZnO gas sensor response was studied. X-ray diffraction analysis reveals the high orientation of c-axis of the prepared films. The optimum operating temperature of the undoped ZnO was 400 °C and shifted to 300 °C for the Cr-doped ZnO under the acetone vapour. The 1% Cr doping ZnO gas sensor was most sensitive for the acetone vapour. The ability of the 1% Cr-doped ZnO to produce repeatable results under different acetone vapour concentrations was tested. The timing properties of the doped Cr ZnO gas sensor were 70 and 95 s for the rise and recovery time respectively.

ZnO Nanowires Synthesized by Vapor Phase Transport Deposition on Transparent Oxide Substrates

Directory of Open Access Journals (Sweden)

Taylor Curtis

2010-01-01

Full Text Available Abstract Zinc oxide nanowires have been synthesized without using metal catalyst seed layers on fluorine-doped tin oxide (FTO substrates by a modified vapor phase transport deposition process using a double-tube reactor. The unique reactor configuration creates a Zn-rich vapor environment that facilitates formation and growth of zinc oxide nanoparticles and wires (20–80 nm in diameter, up to 6 μm in length, density <40 nm apart at substrate temperatures down to 300°C. Electron microscopy and other characterization techniques show nanowires with distinct morphologies when grown under different conditions. The effect of reaction parameters including reaction time, temperature, and carrier gas flow rate on the size, morphology, crystalline structure, and density of ZnO nanowires has been investigated. The nanowires grown by this method have a diameter, length, and density appropriate for use in fabricating hybrid polymer/metal oxide nanostructure solar cells. For example, it is preferable to have nanowires no more than 40 nm apart to minimize exciton recombination in polymer solar cells.

Fabrication and Characterization of Vertically Aligned ZnO Nanorod Arrays via Inverted Monolayer Colloidal Crystals Mask

Science.gov (United States)

Chen, Cheng; Ding, Taotao; Qi, Zhiqiang; Zhang, Wei; Zhang, Jun; Xu, Juan; Chen, Jingwen; Dai, Jiangnan; Chen, Changqing

2018-04-01

The periodically ordered ZnO nanorod (NR) arrays have been successfully synthesized via a hydrothermal approach on the silicon substrates by templating of the TiO2 ring deriving from the polystyrene (PS) nanosphere monolayer colloidal crystals (MCC). With the inverted MCC mask, sol-gel-derived ZnO seeds could serve as the periodic nucleation positions for the site-specific growth of ZnO NRs. The large-scale patterned arrays of single ZnO NR with good side-orientation can be readily produced. According to the experimental results, the as-integrated ZnO NR arrays showed an excellent crystal quality and optical property, very suitable for optoelectronic applications such as stimulated emitters and ZnO photonic crystal devices.

Recent advances in ZnO nanostructures and thin films for biosensor applications: Review

International Nuclear Information System (INIS)

Arya, Sunil K.; Saha, Shibu; Ramirez-Vick, Jaime E.; Gupta, Vinay; Bhansali, Shekhar; Singh, Surinder P.

2012-01-01

Graphical abstract: ZnO nanostructures have shown binding of biomolecules in desired orientation with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, their compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes them suitable candidate for future small integrated biosensor devices. This review highlights various approaches to synthesize ZnO nanostructures and thin films, and their applications in biosensor technology. Highlights: ► This review highlights various approaches to synthesize ZnO nanostructures and thin films. ► Article highlights the importance of ZnO nanostructures as biosensor matrix. ► Article highlights the advances in various biosensors based on ZnO nanostructures. ► Article describes the potential of ZnO based biosensor for new generation healthcare devices. - Abstract: Biosensors have shown great potential for health care and environmental monitoring. The performance of biosensors depends on their components, among which the matrix material, i.e., the layer between the recognition layer of biomolecule and transducer, plays a crucial role in defining the stability, sensitivity and shelf-life of a biosensor. Recently, zinc oxide (ZnO) nanostructures and thin films have attracted much interest as materials for biosensors due to their biocompatibility, chemical stability, high isoelectric point, electrochemical activity, high electron mobility, ease of synthesis by diverse methods and high surface-to-volume ratio. ZnO nanostructures have shown the binding of biomolecules in desired orientations with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes ZnO nanostructures suitable candidate for future small integrated biosensor devices. This review

Recent advances in ZnO nanostructures and thin films for biosensor applications: Review

Energy Technology Data Exchange (ETDEWEB)

Arya, Sunil K., E-mail: sunilarya333@gmail.com [Bioelectronics Program, Institute of Microelectronics, A-Star 11 Science Park Road, Singapore Science Park II, Singapore 117685 (Singapore); Saha, Shibu [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Ramirez-Vick, Jaime E. [Engineering Science and Materials Department, University of Puerto Rico, Mayaguez, PR 00681 (United States); Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Bhansali, Shekhar [Department of Electrical and Computer Engineering, Florida International University, Miami, FL (United States); Singh, Surinder P., E-mail: singh.uprm@gmail.com [National Physical Laboratory, Dr K.S. Krishnan Marg, New Delhi 110012 (India)

2012-08-06

Graphical abstract: ZnO nanostructures have shown binding of biomolecules in desired orientation with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, their compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes them suitable candidate for future small integrated biosensor devices. This review highlights various approaches to synthesize ZnO nanostructures and thin films, and their applications in biosensor technology. Highlights: Black-Right-Pointing-Pointer This review highlights various approaches to synthesize ZnO nanostructures and thin films. Black-Right-Pointing-Pointer Article highlights the importance of ZnO nanostructures as biosensor matrix. Black-Right-Pointing-Pointer Article highlights the advances in various biosensors based on ZnO nanostructures. Black-Right-Pointing-Pointer Article describes the potential of ZnO based biosensor for new generation healthcare devices. - Abstract: Biosensors have shown great potential for health care and environmental monitoring. The performance of biosensors depends on their components, among which the matrix material, i.e., the layer between the recognition layer of biomolecule and transducer, plays a crucial role in defining the stability, sensitivity and shelf-life of a biosensor. Recently, zinc oxide (ZnO) nanostructures and thin films have attracted much interest as materials for biosensors due to their biocompatibility, chemical stability, high isoelectric point, electrochemical activity, high electron mobility, ease of synthesis by diverse methods and high surface-to-volume ratio. ZnO nanostructures have shown the binding of biomolecules in desired orientations with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes ZnO

Solution precursor plasma deposition of nanostructured ZnO coatings

International Nuclear Information System (INIS)

Tummala, Raghavender; Guduru, Ramesh K.; Mohanty, Pravansu S.

2011-01-01

Highlights: → The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. → It is highly capable of developing tailorable nanostructures. → This technique can be employed to spray the coatings on any kind of substrates including polymers. → The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains. -- Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol-gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10-40 nm. Observed optical transmittance (∼65-80%) and reflectivity (∼65-70%) in the visible spectrum, and electrical resistivity (48.5-50.1 mΩ cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

Solution precursor plasma deposition of nanostructured ZnO coatings

Energy Technology Data Exchange (ETDEWEB)

Tummala, Raghavender [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Guduru, Ramesh K., E-mail: rkguduru@umich.edu [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Mohanty, Pravansu S. [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States)

2011-08-15

Highlights: {yields} The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. {yields} It is highly capable of developing tailorable nanostructures. {yields} This technique can be employed to spray the coatings on any kind of substrates including polymers. {yields} The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains. -- Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol-gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10-40 nm. Observed optical transmittance ({approx}65-80%) and reflectivity ({approx}65-70%) in the visible spectrum, and electrical resistivity (48.5-50.1 m{Omega} cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

Starch assisted growth of dumbbell-shaped ZnO microstructures

Energy Technology Data Exchange (ETDEWEB)

Baranwal, V., E-mail: vikasphy@gmail.com [Nanotechnology Application Centre, University of Allahabad, Allahabad 21002 (India); Zahra, Abeer [Department of Physics, Integral University, Lucknow 226026 (India); Singh, Prashant K.; Pandey, Avinash C. [Nanotechnology Application Centre, University of Allahabad, Allahabad 21002 (India)

2015-10-15

We present an experimental study on evolution of dumbbell-shaped ZnO microstructures. Structure, shape, size and optical properties were monitored by means of scanning electron microscopy, x-ray diffraction, and photoluminescence spectroscopy, respectively. Our results show that a crystalline phase of ZnO is formed. A uniform distribution of randomly oriented dumbbell-shaped ZnO microstructures is observed. Near band edge as well as deep level visible emissions confirmed that there are intrinsic defects present in the system. Emissions extending from UV region to visible region show that these microstructures are good quality optical material which can be used in photocatalytic field. - Highlights: • Dumbbell-shaped ZnO micro-rods were synthesized by starch assisted hydrothermal process. • Micro-rods were of crystalline nature, confirmed by x-ray diffraction. • UV-emission as well as deep level visible emissions were observed. • Broad absorption band is observed which can be utilized in photocatalytic field.

Structure and photoluminescence properties of Ag-coated ZnO nano-needles

International Nuclear Information System (INIS)

Li Xiaozhu; Wang Yongqian

2011-01-01

Highlights: → ZnO nano-needles were synthesized by thermal oxidation. → Their surfaces were coated with Ag by pulse electro-deposition technique. → The uncoated and coated ZnO nano-needles were characterized. → The results showed that the prepared ZnO nano-needles have been coated with Ag successfully. → The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the Ag-coated ZnO nano-needles can increase the absorption of UV light. - Abstract: A large number of zinc oxide (ZnO) nano-needles were synthesized by thermal oxidation of pure zinc. The surfaces of ZnO nano-needles were coated with a layer of Ag by pulse electro-deposition technique. The uncoated and coated ZnO nano-needles were characterized by using the X-ray diffraction and the scanning electron microscope (SEM). The results showed that the uncoated samples were close-packed hexagonal structure, which showed needle-like morphology. Their average diameter is about 40 nm, lengths up to 5 μm. At the same time we observed that the prepared ZnO nano-needles have been coated with Ag successfully. The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the uncoated ZnO nano-needles have two fluorescence peaks at 388 nm and 470.8 nm, respectively, the relative intensity of 143.4 and 93.61; and the Ag-coated ZnO nano-needles showed a pair of strong peaks at 387.4 nm and 405.2 nm, the relative intensity of 1366 and 1305, respectively, indicating that the Ag-coated ZnO nano-needles can increase the absorption of UV light.

Hierarchical nanoflowers assembled with Au nanoparticles decorated ZnO nanosheets toward enhanced photocatalytic properties

DEFF Research Database (Denmark)

Yu, Cuiyan; Yu, Yanlong; Xu, Tao

2017-01-01

Hierarchical nanoflowers assembled with Au nanoparticles (NPs) decorated ZnO nanosheets (Au-ZnO nanosheet flowers, AZNSFs) were successful synthesized. The AZNSFs showed more efficient activity to photodegradation of RhB than that of pure ZnO nanosheet flowers and commercial ZnO nanopowders. The ...

Growth and photoluminescence of vertically aligned ZnO nanowires/nanowalls

Energy Technology Data Exchange (ETDEWEB)

Fang Fang; Zhao Dongxu; Li Binghui; Zhang Zhenzhong; Zhang Jiying; Shen Dezhen, E-mail: dxzhao2000@yahoo.com.c [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone Changchun 130033 (China)

2009-07-07

By controlling the incoming gas flow, vertically aligned ZnO nanowires and nanowalls have been successfully synthesized on a Si (1 0 0) substrate by the simple physical vapour deposition method. The growth process of the ZnO nanowalls was observed by adjusting the growth time. The probable growth mechanisms of the ZnO nanowires and nanowalls were discussed in detail. In contrast to the photoluminescence results of nanowires, an enhancement of the LO phonon signal was observed in ZnO nanowalls, which was attributed to an additional channel of electron-phonon coupling induced by the residual strains in the ZnO nanowalls during the coalescence growth process.

One-step synthesis of bird cage-like ZnO and other controlled morphologies: Structural, growth mechanism and photocatalytic properties

International Nuclear Information System (INIS)

Yang, Shuo; Wang, Jian; Li, Xiuyan; Zhai, Hongju; Han, Donglai; Wei, Bing; Wang, Dandan; Yang, Jinghai

2014-01-01

Highlights: • ZnO nanocage arrays were synthesized by a one-step etching route. • ZnO nanocage exhibit higher photocatalytic activity than other samples. • The different photocatalytic activities of different samples were analyzed. • The formation mechanism of ZnO nanocages was proposed. - Abstract: ZnO nanocages and other nanostructures have been synthesized via a simple one-pot hydrothermal method with different reaction times. It is worth mentioning that this is a completely green method which does not require any other chemicals except that Zn foil served as Zn source in the experiment. X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) and UV–Vis diffuse reflection spectra were used to characterize the crystallinity, morphology and optical property of ZnO structures. Growth mechanisms of ZnO were proposed based on these results. Furthermore, ZnO films with different morphologies and crystal growth habits exhibited different activities to rhodamine B degradation. The influence of the reaction time on the morphology of ZnO films and the effect of the morphologies on the photocatalytic activity are discussed

Biosynthesis and characterization of ZnO nanoparticles using the aqueous leaf extract of Imperata cylindrica L.

Science.gov (United States)

Saputra, I. S.; Yulizar, Y.

2017-04-01

ZnO nanoparticles (ZnO NPs) were biosynthesized.The growth was observed by a sol-gel method. ZnO were successfully formed through the reaction of zinc nitrate tetrahydrate Zn(NO3)2.4H2O precursor with aqueous leaf extract of Imperata cylindrica L (ICL). The structural and optical properties of ZnO were investigated. The as-synthesized products were characterized by UV-Visible (UV-Vis), UV diffuse reflectance spectroscopy (UV-DRS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). UV-Vis absorption data showed hydrolysis and characteristic of absorption peak at 300 nm of Zn(OH)2. UV-DRS confirmed that ZnO NPs has the indirect band gap at 3.13 eV. FTIR spectrum revealed the functional groups and indicated the presence of protein as the capping and stabilizing agent on the ZnO surface. Powder XRD studies indicated the formation of pure wurtzite hexagonal structure with particle size of 11.9 nm. The detailed morphological and structural characterizations revealed that the synthesized products were hexagonal nanochip.

Influence of solvents on the changes in structure, purity, and in vitro characteristics of green-synthesized ZnO nanoparticles from Costus igneus

Science.gov (United States)

Nandhini, G.; Suriyaprabha, R.; Maria Sheela Pauline, W.; Rajendran, V.; Aicher, Wilhelm Karl; Awitor, Oscar Komla

2018-05-01

The present study is intended to produce high-purity zinc oxide nanoparticles from the leaves of Costus igneus and zinc acetate precursor via sustainable methods by the tribulation with three different solvents (hot water, methanol, and acetone) for the extraction of plant compounds. While examining the physico-chemical characteristics of ZnO nanoparticles incurred by the catalysis of plant bioactive compounds extracted from different solvents, the hot water extract-based green synthesis process yields higher purity (99.89%) and smaller particle size (94 nm) than other solvents. The optimization of the solvents used for the green synthesis of nanoparticles renders key identification in appropriate extraction of bioactive compounds suitable for the nucleation/production of nanoparticles in addition to annealing temperature. The impregnable usage of ZnO nanoparticles in clinical applications is further confirmed based on the treatment of particles (1-10 mg ml-1) against Gram-positive (S. aureus and S. epidermis) and Gram-negative bacteria (E. coli and K. pneumoniae) with respect to their growth inhibition. An in-force growth inhibition against particular S. aureus and S. epidermis imparted by the low concentration of ZnO nanoparticles signifies the utilization and consumption of green-synthesized high-purity nanoparticles for therapeutic and cosmetic applications.

Synthesis of High Crystalline Al-Doped ZnO Nanopowders from Al2O3 and ZnO by Radio-Frequency Thermal Plasma

Directory of Open Access Journals (Sweden)

Min-Kyeong Song

2015-01-01

Full Text Available High crystalline Al-doped ZnO (AZO nanopowders were prepared by in-flight treatment of ZnO and Al2O3 in Radio-Frequency (RF thermal plasma. Micron-sized (~1 μm ZnO and Al2O3 powders were mixed at Al/Zn ratios of 3.3 and 6.7 at.% and then injected into the RF thermal plasma torch along the centerline at a feeding rate of 6.6 g/min. The RF thermal plasma torch system was operated at the plate power level of ~140 kVA to evaporate the mixture oxides and the resultant vapor species were condensed into solid particles by the high flow rate of quenching gas (~7000 slpm. The FE-SEM images of the as-treated powders showed that the multipod shaped and the whisker type nanoparticles were mainly synthesized. In addition, these nanocrystalline structures were confirmed as the single phase AZO nanopowders with the hexagonal wurtzite ZnO structure by the XRD patterns and FE-TEM results with the SAED image. However, the composition changes of 0.3 and 1.0 at.% were checked for the as-synthesized AZO nanopowders at Al/Zn ratios of 3.3 and 6.7 at.%, respectively, by the XRF data, which can require the adjustment of Al/Zn in the mixture precursors for the applications of high Al doping concentrations.

MoS2-modified ZnO quantum dots nanocomposite: Synthesis and ultrafast humidity response

International Nuclear Information System (INIS)

Ze, Lu; Yueqiu, Gong; Xujun, Li; Yong, Zhang

2017-01-01

Highlights: • MoS 2 @ZnO QDs composite structure was synthesized by two-steps methods. • Ultrafast humidity sensing response is achieved by MoS 2 @ZnO QDs humidity sensor. • Sensor performs excellent cycle stability from 11% to 95% RH. • Humidity sensor could detect wide humidity range (11–95%). - Abstract: In this work, ZnO quantum dots (QDs), layered MoS 2 and MoS 2 -modified ZnO QDs (MoS 2 @ZnO QDs) nanocomposite were synthesized and then applied as humidity sensor. The crystal structure, morphology and element distribution of ZnO QDs, MoS 2 and MoS 2 @ZnO QDs were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectrometry, respectively. The humidity sensing characteristics of the MoS 2 and MoS 2 @ZnO QDs against various relative humidity were measured at room temperature. The results show that the MoS 2 @ZnO QDs sensor exhibits high sensitivity with an impedance variation of three or four orders of magnitude to relative humidity range of 11–95% and it exhibits a short response-recovery time (1 s for adsorption and 20 s for desorption) and excellent repeatability. The mechanisms of the excellent performance for humidity sensing of MoS 2 @ZnO QDs sensor were discussed based on its impedance properties. Our work could offer guidelines to design higher performance especially ultrafast humidity response sensor utilizing the nanocomposite structure with two dimensional material and QDs.

Effect of Eosin Y Dye on Electrical Properties of ZnO Film Synthesized by Sol-Gel Technique

Science.gov (United States)

Rani, Mamta; Tripathi, S. K.

2014-02-01

This paper presents preparation of zinc oxide (ZnO) nanoparticles by the sol-gel technique. ZnO films were prepared by the doctor-blade method, and the resulting films were sensitized with eosin Y (EY) by immersing them in a solution of EY dye in ethanol. The prepared samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transmission infrared spectroscopy, and ultraviolet (UV)-visible spectroscopy. The monodispersed ZnO nanocrystals possess a wurtzite hexagonal structure with diameter of ˜7 nm to 17 nm as observed by XRD and TEM analyses. The absorption spectrum of EY-dye-sensitized ZnO (ZnO/EY) film is slightly broadened, with a red-shift in the peak position compared with the absorbance spectrum of the dye in ethanol. Measurements of electrical parameters such as dark conductivity and photoconductivity were carried out at different temperatures. Transient photoconductivity was also studied at different temperatures to investigate the photoconduction mechanism. The photosensitivity of the ZnO/EY film is higher than that of the ZnO film. Hall measurements show n-type behavior for both samples. The visible absorption spectrum and high photosensitivity of the ZnO/EY films support their potential use as photoanode materials in dye-sensitized solar cells and optoelectronic devices.

Green method for producing hierarchically assembled pristine porous ZnO nanoparticles with narrow particle size distribution

Energy Technology Data Exchange (ETDEWEB)

Escobedo-Morales, A., E-mail: alejandro.escobedo@correo.buap.mx [Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, C.P. 72570 Puebla, Pue. (Mexico); Téllez-Flores, D.; Ruiz Peralta, Ma. de Lourdes [Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, C.P. 72570 Puebla, Pue. (Mexico); Garcia-Serrano, J.; Herrera-González, Ana M. [Centro de Investigaciones en Materiales y Metalurgia, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca Tulancingo Km 4.5, Pachuca, Hidalgo (Mexico); Rubio-Rosas, E. [Centro Universitario de Vinculación y Transferencia de Tecnología, Benemérita Universidad Autónoma de Puebla, C.P. 72570 Puebla, Pue. (Mexico); Sánchez-Mora, E. [Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, 72570 Puebla, Pue. (Mexico); Olivares Xometl, O. [Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, C.P. 72570 Puebla, Pue. (Mexico)

2015-02-01

A green method for producing pristine porous ZnO nanoparticles with narrow particle size distribution is reported. This method consists in synthesizing ZnO{sub 2} nanopowders via a hydrothermal route using cheap and non-toxic reagents, and its subsequent thermal decomposition at low temperature under a non-protective atmosphere (air). The morphology, structural and optical properties of the obtained porous ZnO nanoparticles were studied by means of powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and nitrogen adsorption–desorption measurements. It was found that after thermal decomposition of the ZnO{sub 2} powders, pristine ZnO nanoparticles are obtained. These particles are round-shaped with narrow size distribution. A further analysis of the obtained ZnO nanoparticles reveals that they are hierarchical self-assemblies of primary ZnO particles. The agglomeration of these primary particles at the very early stage of the thermal decomposition of ZnO{sub 2} powders provides to the resulting ZnO nanoparticles a porous nature. The possibility of using the synthesized porous ZnO nanoparticles as photocatalysts has been evaluated on the degradation of rhodamine B dye. - Highlights: • A green synthesis method for obtaining porous ZnO nanoparticles is reported. • The obtained ZnO nanoparticles have narrow particle size distribution. • This method allows obtaining pristine ZnO nanoparticles avoiding unintentional doping. • A growth mechanism for the obtained porous ZnO nanoparticles is proposed.

UV and humidity sensing properties of ZnO nanorods prepared by the arc discharge method

International Nuclear Information System (INIS)

Fang, F; Futter, J; Markwitz, A; Kennedy, J

2009-01-01

The UV and humidity sensing properties of ZnO nanorods prepared by arc discharge have been studied. Scanning electron microscopy and photoluminescence spectroscopy were carried out to analyze the morphology and optical properties of the as-synthesized ZnO nanorods. Proton induced x-ray emission was used to probe the impurities in the ZnO nanorods. A large quantity of high purity ZnO nanorod structures were obtained with lengths of 0.5-1 μm. The diameters of the as-synthesized ZnO nanorods were found to be between 40 and 400 nm. The nanorods interlace with each other, forming 3D networks which make them suitable for sensing application. The addition of a polymeric film-forming agent (BASF LUVISKOL VA 64) improved the conductivity, as it facilitates the construction of conducting networks. Ultrasonication helped to separate the ZnO nanorods and disperse them evenly through the polymeric agent. Improved photoconductivity was measured for a ZnO nanorod sensor annealed in air at 200 deg. C for 30 min. The ZnO nanorod sensors showed a UV-sensitive photoconduction, where the photocurrent increased by nearly four orders of magnitude from 2.7 x 10 -10 to 1.0 x 10 -6 A at 18 V under 340 nm UV illumination. High humidity sensitivity and good stability were also measured. The resistance of the ZnO nanorod sensor decreased almost linearly with increasing relative humidity (RH). The resistance of the ZnO nanorods changed by approximately five orders of magnitude from 4.35 x 10 11 Ω in dry air (7% RH) to about 4.95 x 10 6 Ω in 95% RH air. It is experimentally demonstrated that ZnO nanorods obtained by the arc discharge method show excellent performance and promise for applications in both UV and humidity sensors.

Anchoring ZnO Nanoparticles in Nitrogen-Doped Graphene Sheets as a High-Performance Anode Material for Lithium-Ion Batteries

Directory of Open Access Journals (Sweden)

Guanghui Yuan

2018-01-01

Full Text Available A novel binary nanocomposite, ZnO/nitrogen-doped graphene (ZnO/NG, is synthesized via a facile solution method. In this prepared ZnO/NG composite, highly-crystalline ZnO nanoparticles with a size of about 10 nm are anchored uniformly on the N-doped graphene nanosheets. Electrochemical properties of the ZnO/NG composite as anode materials are systematically investigated in lithium-ion batteries. Specifically, the ZnO/NG composite can maintain the reversible specific discharge capacity at 870 mAh g−1 after 200 cycles at 100 mA g−1. Besides the enhanced electronic conductivity provided by interlaced N-doped graphene nanosheets, the excellent lithium storage properties of the ZnO/NG composite can be due to nanosized structure of ZnO particles, shortening the Li+ diffusion distance, increasing reaction sites, and buffering the ZnO volume change during the charge/discharge process.

High mobility ZnO nanowires for terahertz detection applications

International Nuclear Information System (INIS)

Liu, Huiqiang; Peng, Rufang; Chu, Shijin; Chu, Sheng

2014-01-01

An oxide nanowire material was utilized for terahertz detection purpose. High quality ZnO nanowires were synthesized and field-effect transistors were fabricated. Electrical transport measurements demonstrated the nanowire with good transfer characteristics and fairly high electron mobility. It is shown that ZnO nanowires can be used as building blocks for the realization of terahertz detectors based on a one-dimensional plasmon detection configuration. Clear terahertz wave (∼0.3 THz) induced photovoltages were obtained at room temperature with varying incidence intensities. Further analysis showed that the terahertz photoresponse is closely related to the high electron mobility of the ZnO nanowire sample, which suggests that oxide nanoelectronics may find useful terahertz applications.

Tungsten-doped ZnO nanocomposite: Synthesis, characterization, and highly active photocatalyst toward dye photodegradation

Energy Technology Data Exchange (ETDEWEB)

Moafi, Hadi Fallah, E-mail: Fallah.m@guilan.ac.ir [Department of Chemistry, Faculty of Science, University of Guilan, P.O. Box 1914, Rasht (Iran, Islamic Republic of); Zanjanchi, Mohammad Ali; Shojaie, Abdollah Fallah [Department of Chemistry, Faculty of Science, University of Guilan, P.O. Box 1914, Rasht (Iran, Islamic Republic of)

2013-05-15

A series of W-doped ZnO nanocomposite with different W contents were synthesized by sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP) and BET surface area measurement. The XRD results revealed that all the W-doped samples showed a hexagonal wurtzite structure. The results of EDS and XPS revealed that W was doped into ZnO structure. The particle size of doped ZnO is much smaller as compared to that of pure ZnO. The photocatalytic activity of undoped ZnO and W-doped ZnO was evaluated by the photodegradation of methylene blue in aqueous solution. The results show that the photocatalytic activity of the W-doped ZnO is much higher than that of undoped ZnO and the optimum percentage of doped W is 4 mol%. The enhanced photocatalytic activity of the W-ZnO samples may be related to the narrowing of the band gap, increase in the charge separation efficiency, particle size reduction and increase of the surface area. Highlights: ► W-doped ZnO nanocomposites were synthesized by a sol–gel method. ► The XRD results revealed that all the materials consisting of wurtzite structure. ► The sizes of the W-ZnO nanocomposite are 5–10 nm, obtained from TEM image. ► With W doping into ZnO photoinduced charge separation rate has been enhanced. ► Photocatalytic activity of the W-ZnO is much higher than that of undoped ZnO.

Tungsten-doped ZnO nanocomposite: Synthesis, characterization, and highly active photocatalyst toward dye photodegradation

International Nuclear Information System (INIS)

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

2013-01-01

A series of W-doped ZnO nanocomposite with different W contents were synthesized by sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP) and BET surface area measurement. The XRD results revealed that all the W-doped samples showed a hexagonal wurtzite structure. The results of EDS and XPS revealed that W was doped into ZnO structure. The particle size of doped ZnO is much smaller as compared to that of pure ZnO. The photocatalytic activity of undoped ZnO and W-doped ZnO was evaluated by the photodegradation of methylene blue in aqueous solution. The results show that the photocatalytic activity of the W-doped ZnO is much higher than that of undoped ZnO and the optimum percentage of doped W is 4 mol%. The enhanced photocatalytic activity of the W-ZnO samples may be related to the narrowing of the band gap, increase in the charge separation efficiency, particle size reduction and increase of the surface area. Highlights: ► W-doped ZnO nanocomposites were synthesized by a sol–gel method. ► The XRD results revealed that all the materials consisting of wurtzite structure. ► The sizes of the W-ZnO nanocomposite are 5–10 nm, obtained from TEM image. ► With W doping into ZnO photoinduced charge separation rate has been enhanced. ► Photocatalytic activity of the W-ZnO is much higher than that of undoped ZnO

Carbon-coated ZnO mat passivation by atomic-layer-deposited HfO2 as an anode material for lithium-ion batteries.

Science.gov (United States)

Jung, Mi-Hee

2017-11-01

ZnO has had little consideration as an anode material in lithium-ion batteries compared with other transition-metal oxides due to its inherent poor electrical conductivity and large volume expansion upon cycling and pulverization of ZnO-based electrodes. A logical design and facile synthesis of ZnO with well-controlled particle sizes and a specific morphology is essential to improving the performance of ZnO in lithium-ion batteries. In this paper, a simple approach is reported that uses a cation surfactant and a chelating agent to synthesize three-dimensional hierarchical nanostructured carbon-coated ZnO mats, in which the ZnO mats are composed of stacked individual ZnO nanowires and form well-defined nanoporous structures with high surface areas. In order to improve the performance of lithium-ion batteries, HfO 2 is deposited on the carbon-coated ZnO mat electrode via atomic layer deposition. Lithium-ion battery devices based on the carbon-coated ZnO mat passivation by atomic layer deposited HfO 2 exhibit an excellent initial discharge and charge capacities of 2684.01 and 963.21mAhg -1 , respectively, at a current density of 100mAg -1 in the voltage range of 0.01-3V. They also exhibit cycle stability after 125 cycles with a capacity of 740mAhg -1 and a remarkable rate capability. Copyright © 2017 Elsevier Inc. All rights reserved.

Positron annihilation studies of vacancy-type defects and room temperature ferromagnetism in chemically synthesized Li-doped ZnO nanocrystals

International Nuclear Information System (INIS)

Ghosh, S.; Khan, Gobinda Gopal; Mandal, K.; Thapa, Samudrajit; Nambissan, P.M.G.

2014-01-01

Highlights: • Evidence of zinc vacancy-induced intrinsic ferromagnetism in Li-doped ZnO. • Modification of defects and properties through alkali metal substitution. • Study of defect-modification using positron annihilation spectroscopy. • New way to prepare ZnO-based magnetic semiconductor for spintronic applications. -- Abstract: In this article, we have investigated the effects of Li incorporation on the lattice defects and room-temperature d 0 ferromagnetic behaviour in ZnO nanocrystals by correlating X-ray photoelectron, photoluminescence and positron annihilation spectroscopic study in details. It is found that at low doping level ( 1+ is an effective substituent of Zn site, but it prefers to occupy the interstitial positions when Li-doping exceeds 7 at.% resulting in lattice expansion and increase of particle sizes. The pristine ZnO nanocrystals exhibit ferromagnetic behaviour which is further enhanced significantly after few percentage of Li-doping in ZnO. The magnitude of both saturation magnetizations (M S ) as well as the Curie temperature (T C ) are found to increase considerably up to Li concentration of 10 at.% and then started to decrease on further Li-doping. The gradual enhancement of Zn vacancy (V Zn ) defects in ZnO nanocrystals due to Li substitution as confirmed from photoluminescence and positron annihilation spectroscopy measurements might be responsible to induce paramagnetic moments within ZnO host. The ferromagnetic exchange interaction between the localised moments of V Zn defects can be mediated though the holes arising due to Li-substitutional (Li Zn ) acceptor defects within ZnO. Hence, Li doping in ZnO favours in stabilizing considerable V Zn defects and thus helps to sustain long-range high-T C ferromagnetism in ZnO which can be a promising material in future spintronics

Positron annihilation studies of vacancy-type defects and room temperature ferromagnetism in chemically synthesized Li-doped ZnO nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Ghosh, S., E-mail: sghoshphysics@gmail.com [S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Khan, Gobinda Gopal [Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, Technology Campus, Block JD2, Sector III, Salt Lake City, Kolkata 700098 (India); Mandal, K. [S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Thapa, Samudrajit; Nambissan, P.M.G. [Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, Technology Campus, Block JD2, Sector III, Salt Lake City, Kolkata 700098 (India); Saha Institute of Nuclear Physics, Sector 1, Block AF, Bidhannagar, Kolkata 700064 (India)

2014-03-25

Highlights: • Evidence of zinc vacancy-induced intrinsic ferromagnetism in Li-doped ZnO. • Modification of defects and properties through alkali metal substitution. • Study of defect-modification using positron annihilation spectroscopy. • New way to prepare ZnO-based magnetic semiconductor for spintronic applications. -- Abstract: In this article, we have investigated the effects of Li incorporation on the lattice defects and room-temperature d{sup 0} ferromagnetic behaviour in ZnO nanocrystals by correlating X-ray photoelectron, photoluminescence and positron annihilation spectroscopic study in details. It is found that at low doping level (<7 at.%), Li{sup 1+} is an effective substituent of Zn site, but it prefers to occupy the interstitial positions when Li-doping exceeds 7 at.% resulting in lattice expansion and increase of particle sizes. The pristine ZnO nanocrystals exhibit ferromagnetic behaviour which is further enhanced significantly after few percentage of Li-doping in ZnO. The magnitude of both saturation magnetizations (M{sub S}) as well as the Curie temperature (T{sub C}) are found to increase considerably up to Li concentration of 10 at.% and then started to decrease on further Li-doping. The gradual enhancement of Zn vacancy (V{sub Zn}) defects in ZnO nanocrystals due to Li substitution as confirmed from photoluminescence and positron annihilation spectroscopy measurements might be responsible to induce paramagnetic moments within ZnO host. The ferromagnetic exchange interaction between the localised moments of V{sub Zn} defects can be mediated though the holes arising due to Li-substitutional (Li{sub Zn}) acceptor defects within ZnO. Hence, Li doping in ZnO favours in stabilizing considerable V{sub Zn} defects and thus helps to sustain long-range high-T{sub C} ferromagnetism in ZnO which can be a promising material in future spintronics.

Room temperature synthesis and optical properties of small diameter (5 nm) ZnO nanorod arrays.

Science.gov (United States)

Cho, Seungho; Jang, Ji-Wook; Lee, Jae Sung; Lee, Kun-Hong

2010-10-01

We report a simple wet-chemical synthesis of ∼5 nm diameter ZnO nanorod arrays at room temperature (20 °C) and normal atmospheric pressure (1 atm) and their optical properties. They were single crystalline in nature, and grew in the [001] direction. These small diameter ZnO nanorod arrays can also be synthesized at 0 °C. Control experiments were also conducted. On the basis of the results, we propose a mechanism for the spontaneous growth of the small diameter ZnO structures. The optical properties of the 5 nm diameter ZnO nanorod arrays synthesized using this method were probed by UV-Visible diffuse reflectance spectroscopy. A clear blue-shift, relative to the absorption band from 50 nm diameter ZnO nanorod arrays, was attributed to the quantum confinement effects caused by the small nanocrystal size in the 5 nm diameter ZnO nanorods.

A vanadium-doped ZnO nanosheets-polymer composite for flexible piezoelectric nanogenerators

Science.gov (United States)

Shin, Sung-Ho; Kwon, Yang Hyeog; Lee, Min Hyung; Jung, Joo-Yun; Seol, Jae Hun; Nah, Junghyo

2016-01-01

We report high performance flexible piezoelectric nanogenerators (PENGs) by employing vanadium (V)-doped ZnO nanosheets (NSs) and the polydimethylsiloxane (PDMS) composite structure. The V-doped ZnO NSs were synthesized to overcome the inherently low piezoelectric properties of intrinsic ZnO. Ferroelectric phase transition induced in the V-doped ZnO NSs contributed to significantly improve the performance of the PENGs after the poling process. Consequently, the PENGs exhibited high output voltage and current up to ~32 V and ~6.2 μA, respectively, under the applied strain, which are sufficient to directly turn on a number of light emitting diodes (LEDs). The composite approach for PENG fabrication is scalable, robust, and reproducible during periodic bending/releasing over extended cycles. The approach introduced here extends the performance limits of ZnO-based PENGs and demonstrates their potential as energy harvesting devices.We report high performance flexible piezoelectric nanogenerators (PENGs) by employing vanadium (V)-doped ZnO nanosheets (NSs) and the polydimethylsiloxane (PDMS) composite structure. The V-doped ZnO NSs were synthesized to overcome the inherently low piezoelectric properties of intrinsic ZnO. Ferroelectric phase transition induced in the V-doped ZnO NSs contributed to significantly improve the performance of the PENGs after the poling process. Consequently, the PENGs exhibited high output voltage and current up to ~32 V and ~6.2 μA, respectively, under the applied strain, which are sufficient to directly turn on a number of light emitting diodes (LEDs). The composite approach for PENG fabrication is scalable, robust, and reproducible during periodic bending/releasing over extended cycles. The approach introduced here extends the performance limits of ZnO-based PENGs and demonstrates their potential as energy harvesting devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07185b

Self-Reconstructed Formation of a One-Dimensional Hierarchical Porous Nanostructure Assembled by Ultrathin TiO2 Nanobelts for Fast and Stable Lithium Storage.

Science.gov (United States)

Liu, Yuan; Yan, Xiaodong; Xu, Bingqing; Lan, Jinle; Yu, Yunhua; Yang, Xiaoping; Lin, Yuanhua; Nan, Cewen

2018-06-06

Owing to their unique structural advantages, TiO 2 hierarchical nanostructures assembled by low-dimensional (LD) building blocks have been extensively used in the energy-storage/-conversion field. However, it is still a big challenge to produce such advanced structures by current synthetic techniques because of the harsh conditions needed to generate primary LD subunits. Herein, a novel one-dimensional (1D) TiO 2 hierarchical porous fibrous nanostructure constructed by TiO 2 nanobelts is synthesized by combining a room-temperature aqueous solution growth mechanism with the electrospinning technology. The nanobelt-constructed 1D hierarchical nanoarchitecture is evolves directly from the amorphous TiO 2 /SiO 2 composite fibers in alkaline solutions at ambient conditions without any catalyst and other reactant. Benefiting from the unique structural features such as 1D nanoscale building blocks, large surface area, and numerous interconnected pores, as well as mixed phase anatase-TiO 2 (B), the optimum 1D TiO 2 hierarchical porous nanostructure shows a remarkable high-rate performance when tested as an anode material for lithium-ion batteries (107 mA h g -1 at ∼10 A g -1 ) and can be used in a hybrid lithium-ion supercapacitor with very stable lithium-storage performance (a capacity retention of ∼80% after 3000 cycles at 2 A g -1 ). The current work presents a scalable and cost-effective method for the synthesis of advanced TiO 2 hierarchical materials for high-power and stable energy-storage/-conversion devices.

Ultra-high sensitive hydrazine chemical sensor based on low-temperature grown ZnO nanoparticles

International Nuclear Information System (INIS)

Mehta, S.K.; Singh, Kulvinder; Umar, Ahmad; Chaudhary, G.R.; Singh, Sukhjinder

2012-01-01

Graphical abstract: Systematic representation of the fabricated amperometric hydrazine chemical sensor based on ZnO NPs/Au modified electrode. Highlights: ► Synthesis of well-crystalline ZnO NPs has been achieved in aqueous solution. ► ZnO NPs act as efficient electron mediators for hydrazine sensor. ► Extremely high sensitivity and low-detection limit have been obtained. - Abstract: Using well-crystalline ZnO nanoparticles (NPs), an ultra high sensitive hydrazine amperometric sensor has been fabricated and reported in this paper. The ZnO NPs have been synthesized by very simple aqueous solution process at 90 °C and characterized in detail in terms of their morphological, compositional, structural and optical properties. The detailed investigations reveal that the synthesized products are well-crystalline NPs, possessing wurtzite hexagonal phase and exhibit good optical properties. The fabricated amperometric hydrazine sensor exhibits ultra-high sensitivity of ∼97.133 μA cm −2 μM −1 and very low-detection limit of 147.54 nM. To the best of our knowledge, this is the first report in which an ultra-high sensitivity and low-detection limit have been obtained for the hydrazine chemical sensor based on ZnO nanostructures.

Static susceptibility and heat capacity studies on V{sub 3}O{sub 7}.H{sub 2}O{sub 7} nanobelts

Energy Technology Data Exchange (ETDEWEB)

Hellmann, I., E-mail: i.hellmann@ifw-dresden.d [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Zakharova, G.S.; Volkov, V.L. [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620219 (Russian Federation); Taeschner, C.; Leonhardt, A.; Buechner, B.; Klingeler, R. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

2010-04-15

V{sub 3}O{sub 7}.H{sub 2}O nanobelts were prepared by a hydrothermal method at 190 deg. C using V{sub 2}O{sub 5}.nH{sub 2}O gel and H{sub 2}C{sub 2}O{sub 4}.2H{sub 2}O as starting agents. The obtained nanobelts have diameters ranging from 40 to 70 nm with lengths up to several micrometers. Measurements of the static magnetic susceptibility and the specific heat show a discontinuous phase transition at around T=145 K, which separates two regions of paramagnetic behavior.

Photoluminescence quenching and enhanced spin relaxation in Fe doped ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ovhal, Manoj M.; Santhosh Kumar, A. [Department of Materials Engineering, Defence Institute of Advanced Technology, Girinagar, Pune 411025 (India); Khullar, Prerna [School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Kumar, Manjeet [Department of Materials Engineering, Defence Institute of Advanced Technology, Girinagar, Pune 411025 (India); Abhyankar, A.C., E-mail: ashutoshabhyankar@gmail.com [Department of Materials Engineering, Defence Institute of Advanced Technology, Girinagar, Pune 411025 (India)

2017-07-01

Cost-effective ultrasonically assisted precipitation method is utilized to synthesize Zinc oxide (ZnO) nanoparticles (NPs) at room temperature and the effect of Iron (Fe) doping on structural, optical and spin relaxation properties also presented. As-synthesized pure and Fe doped ZnO NPs possess a perfect hexagonal growth habit of wurtzite zinc oxide, along the (101) direction of preference. With Fe doping, ‘c/a’ ratio and compressive lattice strain in ZnO NPs are found to reduce and increase, respectively. Raman studies demonstrate that the E{sub 1} longitudinal optical (LO) vibrational mode is very weak in pure which remarkably enhanced with Fe doping into ZnO NPs. The direct band gap energy (E{sub g}) of the ZnO NPs has been increased from 3.02 eV to 3.11 eV with Fe doping. A slight red-shift observed with strong green emission band, in photoluminescence spectra, is strongly quenched in 6 wt.% Fe doped ZnO NPs. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) reveals spherical shape of ZnO NPs with 60–70 nm, which reduces substantially on Fe doping. The energy dispersive X-ray spectrum and elemental mapping confirms the homogeneous distribution of Fe in ZnO NPs. Moreover, the specific relaxation rate (R{sub 2sp} = 1/T{sub 2}) has been measured using Carr-Purcell-Meiboom-Gill (CPMG) method and found to be maximum in 6 wt.% Fe doped ZnO NPs. Further, the correlation of structural, optical and dynamic properties is proposed. - Highlights: • Pure ZnO and Fe doped ZnO NPs were successfully prepared by cost effective ultrasonically assisted precipitation method. • The optical band gap of ZnO has been enhanced form 3.02–3.11 eV with Fe doping. • PL quenching behaviour has been observed with Fe{sup 3+} ions substitution in ZnO lattice. • Specific relaxation rate (R{sub 2sp} = 1/T{sub 2}) has been varied with Fe doping and found to be maximum in 6 wt.% Fe doped ZnO NPs.

Synthesis of ZnO decorated graphene nanocomposite for enhanced photocatalytic properties

Science.gov (United States)

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

2014-05-01

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

A dual-colored bio-marker made of doped ZnO nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Wu, Y L; Zeng, X T [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, 638075 (Singapore); Fu, S; Kwek, L C [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, 637616 (Singapore); Tok, A I Y; Boey, F C Y [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Lim, C S [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

2008-08-27

Bio-compatible ZnO nanocrystals doped with Co, Cu and Ni cations, surface capped with two types of aminosilanes and titania are synthesized by a soft chemical process. Due to the small particle size (2-5 nm), surface functional groups and the high photoluminescence emissions at the UV and blue-violet wavelength ranges, bio-imaging on human osteosarcoma (Mg-63) cells and histiocytic lymphoma U-937 monocyte cells showed blue emission at the nucleus and bright turquoise emission at the cytoplasm simultaneously. This is the first report on dual-color bio-images labeled by one semiconductor nanocrystal colloidal solution. Bright green emission was detected on mung bean seedlings labeled by all the synthesized ZnO nanocrystals. Cytotoxicity tests showed that the aminosilanes capped nanoparticles are non-toxic. Quantum yields of the nanocrystals varied from 79% to 95%. The results showed the potential of the pure ZnO and Co-doped ZnO nanocrystals for live imaging of both human cells and plant systems.

Hierarchical ZnO with twinned structure: Morphology evolution, formation mechanism and properties

International Nuclear Information System (INIS)

Shi, Ruixia; Song, Xueling; Li, Jia; Yang, Ping

2015-01-01

Various hierarchical ZnO architectures constructed by twinned structures have been synthesized via a trisodium citrate assisted hydrothermal method on a large scale. The probable formation mechanisms of hierarchical ZnO structures with twinned structure were proposed and discussed. The hierarchical ZnO with twinned structures are composed of two hemispheres with a center concave junction to join them together at their waists. The ZnO microspheres with rough surfaces were obtained when the concentration of trisodium citrate is 0.1 M. However, the football-like microspheres consisted of hexagonal nanosheets were formed when adding glycerol into the water, which should be attributed to the slower nucleation and growth rate of nanocrystals. The hamburger-like ZnO with different aspect ratio and nonuniform ZnO microspheres were generated due to the different quantity of initial nuclei and growth units when simply modulating the concentration of trisodium citrate. The surface area of football-like ZnO is about 3.51 times of microspheres composed of irregular particles. However their photocatalytic performances are similar under UV light irradiation, which indicates that pore sizes of the sample have more important influences on the photocatalytic activity. - Highlights: • Hierarchical ZnO constructed by twinned structures have been synthesized. • The formation mechanisms of ZnO with twinned structure were discussed. • Football-like microspheres were obtained due to the slower nucleation and growth. • Hamburger-like ZnO was formed due to the amount of initial nuclei and growth units. • Pore sizes have important effects on the photocatalytic activity of sample

Hierarchical ZnO with twinned structure: Morphology evolution, formation mechanism and properties

Energy Technology Data Exchange (ETDEWEB)

Shi, Ruixia; Song, Xueling; Li, Jia; Yang, Ping, E-mail: mse_yangp@ujn.edu.cn

2015-04-15

Various hierarchical ZnO architectures constructed by twinned structures have been synthesized via a trisodium citrate assisted hydrothermal method on a large scale. The probable formation mechanisms of hierarchical ZnO structures with twinned structure were proposed and discussed. The hierarchical ZnO with twinned structures are composed of two hemispheres with a center concave junction to join them together at their waists. The ZnO microspheres with rough surfaces were obtained when the concentration of trisodium citrate is 0.1 M. However, the football-like microspheres consisted of hexagonal nanosheets were formed when adding glycerol into the water, which should be attributed to the slower nucleation and growth rate of nanocrystals. The hamburger-like ZnO with different aspect ratio and nonuniform ZnO microspheres were generated due to the different quantity of initial nuclei and growth units when simply modulating the concentration of trisodium citrate. The surface area of football-like ZnO is about 3.51 times of microspheres composed of irregular particles. However their photocatalytic performances are similar under UV light irradiation, which indicates that pore sizes of the sample have more important influences on the photocatalytic activity. - Highlights: • Hierarchical ZnO constructed by twinned structures have been synthesized. • The formation mechanisms of ZnO with twinned structure were discussed. • Football-like microspheres were obtained due to the slower nucleation and growth. • Hamburger-like ZnO was formed due to the amount of initial nuclei and growth units. • Pore sizes have important effects on the photocatalytic activity of sample.

Vegetable Peel Waste for the Production of ZnO Nanoparticles and its Toxicological Efficiency, Antifungal, Hemolytic, and Antibacterial Activities

Science.gov (United States)

Surendra, T. V.; Roopan, Selvaraj Mohana; Al-Dhabi, Naif Abdullah; Arasu, Mariadhas Valan; Sarkar, Gargi; Suthindhiran, K.

2016-12-01

Zinc oxide (ZnO) nanoparticles (NPs) are important materials when making different products like sun screens, textiles, and paints. In the current study, the photocatalytic effect of prepared ZnO NPs from Moringa oleifera ( M. oleifera) was evaluated on degradation of crystal violet (CV) dye, which is largely released from textile industries and is harmful to the environment. Preliminarily, ZnO NP formation was confirmed using a double beam ultraviolet visible (UV-Vis) spectrophotometer; further, the NP size was estimated using XRD analysis and the functional group analysis was determined using Fourier transform infrared (FT-IR) spectroscopy. The morphology of the synthesized NPs was found to be a hexagonal shape using SEM and TEM analysis and elemental screening was analyzed using EDX. ZnO NPs were shown sized 40-45 nm and spherical in shape. The degradation percentage of ZnO NPs was calculated as 94% at 70 min and the rate of the reaction -k = 0.0282. The synthesized ZnO NPs were determined for effectiveness on biological activities such as antifungal, hemolytic, and antibacterial activity. ZnO NPs showed good antifungal activity against Alternaria saloni and Sclerrotium rolfii strains. Further, we have determined the hemolytic and antibacterial activity of ZnO NPs and we got successive results in antibacterial and hemolytic activities.

The structural properties of flower-like ZnO nanostructures on porous silicon

Science.gov (United States)

Eswar, Kevin Alvin; Suhaimi, Mohd Husairi Fadzillah; Guliling, Muliyadi; Mohamad, Maryam; Khusaimi, Zuraida; Rusop, M.; Abdullah, Saifollah

2018-05-01

The flower-like zinc oxide (ZnO) were successfully synthesized on porous silicon (PSi) via hydrothermal method. The characteristic of ZnO nanostructures was investigated using field emission scanning microscopy (FESEM) and X-ray diffraction (X-Ray). The FESEM images show the flower-like ZnO nanostructures composed ZnO nanoparticles. The X-ray diffraction shows that strong intensity of (100), (002) and (101) peaks. The structural analysis revealed that the peaks angles were shifted due to the stress or imperfection of the crystalline of ZnO nanostructures. The crystalline sizes in range of 42.60 to 54.09 nm were produced.

Growth of Fe2O3/SnO2 nanobelt arrays on iron foil for efficient photocatalytic degradation of methylene blue

Science.gov (United States)

Lei, Rui; Ni, Hongwei; Chen, Rongsheng; Zhang, Bowei; Zhan, Weiting; Li, Yang

2017-04-01

Tin(IV) oxide has been intensively employed in optoelectronic devices due to its excellent electrical and optical properties. But the high recombination rates of the photogenerated electron-hole pairs of SnO2 nanomaterials often results in low photocatalytic efficiency. Herein, we proposed a facile route to prepare a novel Fe2O3/SnO2 heterojunction structure. The nanobelt arrays grown on iron foil naturally form a Schottky-type contact and provide a direct pathway for the photogenerated excitons. Hence, the Fe2O3/SnO2 nanobelt arrays exhibit much improved photocatalytic performance with the degradation rate constant on the Fe2O3/SnO2 film of approximately 12 times to that of α-Fe2O3 nanobelt arrays.

Integrated ZnO nanotube arrays as efficient dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Xi, Y., E-mail: yxi6@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Wu, W.Z.; Fang, H. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Hu, C.G. [Department of Applied Physics, Chongqing University, Chongqing 400044 (China)

2012-07-15

Highlights: Black-Right-Pointing-Pointer Tuning the reaction parameters, we got the best reaction conditions on ITO glass. Black-Right-Pointing-Pointer Introduce ZnO NTs design of photoanode featuring high aspect ratio structure. Black-Right-Pointing-Pointer The design strategy integrates the optical fibers or ITO with ZnO NTs grown. - Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material and has been considered as an alternative material in dye-sensitized solar cell (DSSC) applications. A high-performance nanotube (NT) photoanode must have a large surface area for dye adsorption in order to enhance conversion efficiency. In this work, the way of hydrothermally grown ZnO NT arrays on the indium tin oxide (ITO) substrate is presented by utilizing a systematic study. By adjusting the hydrothermal reaction parameters, we attained the optimizing reaction conditions on the ITO substrate. Moreover, ZnO NT arrays are introduced as a photoanode on various substrates, such as optical fiber and ITO glass, for DSSCs applications. We took the contrast test with conversion efficiency of the DSSC based on ZnO NT arrays versus ZnO nanowire arrays on the ITO substrate, which the DSSC based on ZnO NT arrays shows significantly enhanced power conversion efficiency. Furthermore, the conversion efficiency of DSSC based on the ZnO NT arrays grown on an optical fiber substrate is enhanced up to 1.44%.

Transport and structural characterization of solution-processable doped ZnO nanowires

KAUST Repository

Noriega, Rodrigo

2009-08-18

The use of ZnO nanowires has become a widespread topic of interest in optoelectronics. In order to correctly assess the quality, functionality, and possible applications of such nanostructures it is important to accurately understand their electrical and optical properties. Aluminum- and gallium-doped crystalline ZnO nanowires were synthesized using a low-temperature solution-based process, achieving dopant densities of the order of 1020 cm-3. A non-contact optical technique, photothermal deflection spectroscopy, is used to characterize ensembles of ZnO nanowires. By modeling the free charge carrier absorption as a Drude metal, we are able to calculate the free carrier density and mobility. Determining the location of the dopant atoms in the ZnO lattice is important to determine the doping mechanisms of the ZnO nanowires. Solid-state NMR is used to distinguish between coordination environments of the dopant atoms.

Structural, spectroscopic and anti-microbial inspection of PEG capped ZnO nanoparticles for biomedical applications

Science.gov (United States)

Meshram, J. V.; Koli, V. B.; Kumbhar, S. G.; Borde, L. C.; Phadatare, M. R.; Pawar, S. H.

2018-04-01

Zinc oxide (ZnO) nanoparticles (NPs) have a wide range of biomedical applications. Present study demonstrates the new methodology in sol-gel technology for synthesizing Polyethylene glycol (PEG) capped ZnO NPs and its size effect on anti-microbial activity. The reaction time was increased from 1 h to 5 h for the synthesis of ZnO NPs at 130 °C. The size of PEG capped ZnO NPs is increased from 10 to 84 nm by increasing the reaction upto 5 h. The x-ray diffraction studies and transmission electron microscopy analysis reveals the phase purity and hexagonal wurtzite crystal structure with uniform PEG capping on the surface of ZnO NPs. UV–visible spectroscopy exhibits the peak at 366 nm which is attributed to ZnO NPs. No adverse effect is observed in case of absorbance spectroscopy. Further, Fourier transforms infrared spectroscopy and thermo gravimetric analysis depicts the adsorption of PEG molecules on the ZnO NPs surface. The anti-microbial activities for both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria were studied by optical density (OD) mesurement. The remarkable anti-microbial activity was observed for PEG capped ZnO NPs synthesized at 1 h reaction time showing higher activity in comparison with that synthesized from 2 h to 5 h reaction time. The microbial growth was found to be inhibited after 10 h OD measurement for both the bacteria. The anti-microbial activity may be attributed to the generation of ROS and H2O2. However, these generated species plays a vital role in inhibition of microbial growth. Hence, PEG capped ZnO NPs has promising biomedical applications.

Effect of shallow donors on Curie–Weiss temperature of Co-doped ZnO

Energy Technology Data Exchange (ETDEWEB)

Guo, Shuxia, E-mail: gsx0391@sina.com [Department of Physics, Jiaozuo Teachers College, Jiaozuo 454001 (China); Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China); Li, Jiwu [Department of Physics, Jiaozuo Teachers College, Jiaozuo 454001 (China); Du, Zuliang [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China)

2014-12-15

Co-doped ZnO and Al, Co co-doped ZnO polycrystalline powders were synthesized by co-precipitation method. The magnetization curves measured at 2 K show no hysteresis neither remanence for all samples. ZnO:Co grown at low temperature has a positive Curie–Weiss temperature Θ, and ZnO:Co grown at high temperature has a negative Θ. But Al-doped ZnO:Co grown at high temperature has a positive Θ. Positive Curie–Weiss temperature Θ was considered to have relation to the presence of shallow donors in the samples. - Highlights: • Co-doped ZnO and Al, Co co-doped ZnO polycrystalline powders were synthesized. • No hysteresis is observed for all samples. • The Curie–Weiss temperature Θ changes its sign by Al doping. • Positive Θ should be related to shallow donors.

Physical properties and heterojunction device demonstration of aluminum-doped ZnO thin films synthesized at room ambient via sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Karaagac, Hakan, E-mail: hkaraagac@ucdavis.edu [Department of Electrical and Computer Engineering, University of California at Davis, Davis, CA 95616 (United States); Yengel, Emre; Saif Islam, M. [Department of Electrical and Computer Engineering, University of California at Davis, Davis, CA 95616 (United States)

2012-04-25

Highlights: Black-Right-Pointing-Pointer Undoped and Al doped ZnO (AZO) thin films were successfully prepared using sol-gel technique. Black-Right-Pointing-Pointer Structural analysis has revealed that Al doping has a significant influence on preferential orientation. Black-Right-Pointing-Pointer It has been observed that wrinkles forms on the surface of films when annealed with a fast heat ramp up rate. Black-Right-Pointing-Pointer Optical analysis has revealed that that the band gap energy of ZnO thin film increases with increasing Al doping concentration. Black-Right-Pointing-Pointer The lowest resistivity is observed for 1% Al ZnO thin film, which is 2.2 Multiplication-Sign 10{sup -2} ({Omega} cm). - Abstract: ZnO and some of its ternary wide-bandgap alloys offer interesting opportunities for designing materials with tunable band gaps, strong piezoresistivity and controlled electrical conductance with high optical transparency. Synthesizing these materials on arbitrary substrates using low-cost and unconventional techniques can help in integrating semiconductors with different physical, electrical, and optical characteristics on a single substrate for heterogeneous integration of multifunctional devices. Here we report the successful synthesis of aluminum (Al) doped ZnO (AZO) thin films on soda-lime glass, silicon and fluorine doped tin oxide (FTO) pre-coated glass substrates by using sol-gel deposition method at ambient condition. X-ray diffraction (XRD) analysis revealed that varying degree of Al doping significantly impacts the crystal orientation, semiconductor bandgap and optical transparency of the film. Crystal structure of the film is also found to be strongly correlated to the characteristics of the substrate material. The impact of heating rate during post annealing process is studied and optimized in order to improve the surface morphology of the deposited films. Optical characterizations have revealed that bandgap energy of AZO films can be tuned

Ultra-Fast Microwave Synthesis of ZnO Nanorods on Cellulose Substrates for UV Sensor Applications

Directory of Open Access Journals (Sweden)

Ana Pimentel

2017-11-01

Full Text Available In the present work, tracing and Whatman papers were used as substrates to grow zinc oxide (ZnO nanostructures. Cellulose-based substrates are cost-efficient, highly sensitive and environmentally friendly. ZnO nanostructures with hexagonal structure were synthesized by hydrothermal under microwave irradiation using an ultrafast approach, that is, a fixed synthesis time of 10 min. The effect of synthesis temperature on ZnO nanostructures was investigated from 70 to 130 °C. An Ultra Violet (UV/Ozone treatment directly to the ZnO seed layer prior to microwave assisted synthesis revealed expressive differences regarding formation of the ZnO nanostructures. Structural characterization of the microwave synthesized materials was carried out by scanning electron microscopy (SEM and X-ray diffraction (XRD. The optical characterization has also been performed. The time resolved photocurrent of the devices in response to the UV turn on/off was investigated and it has been observed that the ZnO nanorod arrays grown on Whatman paper substrate present a responsivity 3 times superior than the ones grown on tracing paper. By using ZnO nanorods, the surface area-to-volume ratio will increase and will improve the sensor sensibility, making these types of materials good candidates for low cost and disposable UV sensors. The sensors were exposed to bending tests, proving their high stability, flexibility and adaptability to different surfaces.

Acceptor Type Vacancy Complexes In As-Grown ZnO

International Nuclear Information System (INIS)

Zubiaga, A.; Tuomisto, F.; Zuniga-Perez, J.

2010-01-01

One of the many technological areas that ZnO is interesting for is the construction of opto-electronic devices working in the blue-UV range as its large band gap (∼3.4 eV at 10 K) makes them suitable for that purpose. As-grown ZnO shows generally n-type conductivity partially due to the large concentration of unintentional shallow donors, like H, but impurities can also form complexes with acceptor type defects (Zn vacancy) leading to the creation of compensating defects. Recently, Li Zn and Na Zn acceptors have been measured and H could form similar type of defects. Doppler Broadening Positron Annihilation spectroscopy experimental results on the observation of Zn related vacancy complexes in ZnO thin films, as-grown, O implanted and Al doped will be presented. Results show that as-grown ZnO film show small Zn vacancy related complexed that could be related to presence of H as a unintentional doping element.

Acceptor Type Vacancy Complexes In As-Grown ZnO

Science.gov (United States)

Zubiaga, A.; Tuomisto, F.; Zuñiga-Pérez, J.

2010-11-01

One of the many technological areas that ZnO is interesting for is the construction of opto-electronic devices working in the blue-UV range as its large band gap (˜3.4 eV at 10 K) makes them suitable for that purpose. As-grown ZnO shows generally n-type conductivity partially due to the large concentration of unintentional shallow donors, like H, but impurities can also form complexes with acceptor type defects (Zn vacancy) leading to the creation of compensating defects. Recently, LiZn and NaZn acceptors have been measured and H could form similar type of defects. Doppler Broadening Positron Annihilation spectroscopy experimental results on the observation of Zn related vacancy complexes in ZnO thin films, as-grown, O implanted and Al doped will be presented. Results show that as-grown ZnO film show small Zn vacancy related complexed that could be related to presence of H as a unintentional doping element.

Green synthesis of ZnO nanoparticles by Aspalathus linearis: Structural & optical properties

International Nuclear Information System (INIS)

Diallo, A.; Ngom, B.D.; Park, E.; Maaza, M.

2015-01-01

This contribution reports for the 1st time on the synthesis and the main physical properties of ZnO nanoparticles synthesized by an entirely green physical-chemistral process using Aspalathus linearis's natural extract as an efficient reduction/oxidizing agent. Their structural and optical properties by electron microscopy, X-rays diffraction, Raman and X-rays photoemission spectroscopies as well as room temperature photoluminescence are reported. - Highlights: • 1st time report on synthesis of ZnO nanoparticles by a green process via Aspalathus linearis extract. • A. linearis's natural extract was used as an effective reduction/oxidizing agent. • Wurtzite nature of ZnO nanoparticles was confirmed via XRD, Raman, XPS and PL

Green synthesis of ZnO nanoparticles by Aspalathus linearis: Structural & optical properties

Energy Technology Data Exchange (ETDEWEB)

Diallo, A.; Ngom, B.D. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); Park, E. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); Nelson Mandela African Institute for Science & Technology, Arusha (Tanzania, United Republic of); Maaza, M., E-mail: Maaza@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa)

2015-10-15

This contribution reports for the 1st time on the synthesis and the main physical properties of ZnO nanoparticles synthesized by an entirely green physical-chemistral process using Aspalathus linearis's natural extract as an efficient reduction/oxidizing agent. Their structural and optical properties by electron microscopy, X-rays diffraction, Raman and X-rays photoemission spectroscopies as well as room temperature photoluminescence are reported. - Highlights: • 1st time report on synthesis of ZnO nanoparticles by a green process via Aspalathus linearis extract. • A. linearis's natural extract was used as an effective reduction/oxidizing agent. • Wurtzite nature of ZnO nanoparticles was confirmed via XRD, Raman, XPS and PL.

Rapid green synthesis of ZnO nanoparticles using a hydroelectric cell without an electrolyte

Science.gov (United States)

Shah, Jyoti; Kumar Kotnala, Ravinder

2017-09-01

In this study, zinc oxide (ZnO) nanoparticles were synthesized using a novel environmentally friendly hydroelectric cell without an electrolyte or external current source. The hydroelectric cell comprised a nanoporous Li substituted magnesium ferrite pellet in contact with two electrodes, with zinc as the anode and silver as an inert cathode. The surface unsaturated cations and oxygen vacancies in the nanoporous ferrite dissociated water molecules into hydronium and hydroxide ions when the hydroelectric cell was dipped into deionized water. Hydroxide ions migrated toward the zinc electrode to form zinc hydroxide and the hydronium ions were evolved as H2 gas at the silver electrode. The zinc hydroxide collected as anode mud was converted into ZnO nanoparticles by heating at 250 °C. Structural analysis using Raman spectroscopy indicated the good crystallinity of the ZnO nanoparticles according to the presence of a high intensity E2-(high) mode. The nanoparticle size distribution was 5-20 nm according to high resolution transmission electron microscopy. An indirect band gap of 2.75 eV was determined based on the Tauc plot, which indicated the existence of an interstitial cation level in ZnO. Near band edge and blue emissions were detected in photoluminescence spectral studies. The blue emissions obtained from the ZnO nanoparticles could potentially have applications in blue lasers and LEDs. The ZnO nanoparticles synthesized using this method had a high dielectric constant value of 5 at a frequency of 1 MHz, which could be useful for fabricating nano-oscillators. This facile, clean, and cost-effective method obtained a significant yield of 0.017 g for ZnO nanoparticles without applying an external current source.

Direct Precipitation and Characterization of ZnO Nanoparticles

Directory of Open Access Journals (Sweden)

A. H. Moharram

2014-01-01

Full Text Available ZnO nanoparticles are prepared through hydrolysis and condensation of zinc acetate dihydrate by potassium hydroxide in alcoholic medium at low temperatures. Thermal gravimetric analysis (TGA of the precursor is made in order to specify the temperature range over which the weight loss and thermal effect are significant. X-ray diffraction of the as-prepared specimens shows that the hexagonal (a=3.2459 Å, c=5.1999 Å structure is the predominant crystallographic structure. According to Scherer’s formula, the average size of the nanoparticles is 22.4 ± 0.6 nm. The structural properties of the synthesized ZnO nanoparticles have been confirmed using the TEM micrographs. The optical energy gap of the ZnO nanoparticles, as obtained from applying Tauc’s equation, is equal to 3.52 eV, which is higher than that of the bulk material. Absorption peak of the as-prepared sample is 298 nm which is highly blue shifted as compared to the bulk (360 nm. Large optical energy gap and highly blue shifted absorption edge confirm that the prepared ZnO nanoparticle exhibits strong quantum confinement effect.

Anodized ZnO nanostructures for photoelectrochemical water splitting

Energy Technology Data Exchange (ETDEWEB)

Huang, Mao-Chia [Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan (China); Wang, TsingHai [Department of Biomedical Engineering and Environment Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Wu, Bin-Jui [Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan (China); Lin, Jing-Chie, E-mail: jclin4046@gmail.com [Institute of Materials Science and Engineering, National Central University, Taoyuan 32001, Taiwan (China); Wu, Ching-Chen [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 310, Taiwan (China)

2016-01-01

Highlights: • ZnO nanostructures were synthesized by electrochemical anodic process. • The parameter of ZnO nanostructure was anodic potential. • The model of growth of ZnO nanostructure was investigated. - Abstract: Zinc oxide (ZnO) nanostructures were fabricated on the polished zinc foil by anodic deposition in an alkaline solution containing 1.0 M NaOH and 0.25 M Zn(NO{sub 3}){sub 2}. Potentiostatic anodization was conducted at two potentials (−0.7 V in the passive region and −1.0 V in the active region vs. SCE) which are higher than the open circuit potential (−1.03 V vs. SCE) and as-obtained ZnO nanostrcutures were investigated focusing on their structural, optical, electrical and photoelectrochemical (PEC) characteristics. All samples were confirmed ZnO by X-ray photoelectron spectroscopy and Raman spectra. Observations in the SEM images clearly showed that ZnO nanostructures prepared at −0.7 V vs. SCE were composed of nanowires at while those obtained at −1.0 V vs. SCE possessed nanosheets morphology. Result from transmission electron microscope and X-ray diffraction patterns suggested that the ZnO nanowires belonged to single crystalline with a preferred orientation of (0 0 2) whereas the ZnO nanosheets were polycrystalline. Following PEC experiments indicated that ZnO nanowires had higher photocurrent density of 0.32 mA/cm{sup 2} at 0.5 V vs. SCE under 100 mW/cm{sup 2} illumination. This value was about 1.9 times higher than that of ZnO nanosheets. Observed higher photocurrent was likely due to the single crystalline, preferred (0 0 2) orientation, higher carrier concentration and lower charge transfer resistance.

Synthesis of ZnO nanorods by spray pyrolysis for H2S gas sensor

International Nuclear Information System (INIS)

Shinde, S.D.; Patil, G.E.; Kajale, D.D.; Gaikwad, V.B.; Jain, G.H.

2012-01-01

Highlights: ► Hexagonal pillar shaped ZnO nanorods with different sizes have been successfully synthesized by spray pyrolysis technique. ► ZnO nanorods thin films showed much better sensitivity and stability than the conventional materials to H 2 S gas (100 ppm) at 50 °C. ► This ZnO thin film has potential in application of room temperature H 2 S gas sensing. - Abstract: Hexagonal pillar shaped ZnO nanorods with different sizes have been successfully synthesized by spray pyrolysis technique (SPT). The equal amount of methanol and water is used as a solvent to dissolve the AR grade Zinc acetate for precursor solution. This solution is sprayed on to the glass substrate heated at 350 °C. The films were characterized by ultra-violet spectroscopy (UV), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The deposition of thin films results in a layer comprising well-shaped hexagonal ZnO nanorods with diameter of 90–120 nm and length of up to 200 nm. The gas sensing properties of these films have been investigated for various interfering gases such as CO 2 , CO, ethanol, NH 3 and H 2 S, etc. at operating temperature from 30° (room temperature) to 450 °C. The results indicate that the ZnO nanorods thin films showed much better sensitivity and stability than the conventional materials to H 2 S gas (100 ppm) at 50 °C. The hexagonal pillar shaped ZnO nanorods can improve the sensitivity and selectivity of the sensors.

Hydrothermal temperature effect on crystal structures, optical properties and electrical conductivity of ZnO nanostructures

Science.gov (United States)

Dhafina, Wan Almaz; Salleh, Hasiah; Daud, Mohd Zalani; Ghazali, Mohd Sabri Mohd; Ghazali, Salmah Mohd

2017-09-01

ZnO is an wide direct band gap semiconductor and possess rich family of nanostructures which turned to be a key role in the nanotechnology field of applications. Hydrothermal method was proven to be simple, robust and low cost among the reported methods to synthesize ZnO nanostructures. In this work, the properties of ZnO nanostructures were altered by varying temperatures of hydrothermal process. The changes in term of morphological, crystal structures, optical properties and electrical conductivity were investigated. A drastic change of ZnO nanostructures morphology and decreases of 002 diffraction peak were observed as the hydrothermal temperature increased. The band gap of samples decreased as the size of ZnO nanostructure increased, whereas the electrical conductivity had no influence on the band gap value but more on the morphology of ZnO nanostructures instead.

Antibacterial effect of novel synthesized sulfated β-cyclodextrin crosslinked cotton fabric and its improved antibacterial activities with ZnO, TiO2 and Ag nanoparticles coating.

Science.gov (United States)

Selvam, S; Rajiv Gandhi, R; Suresh, J; Gowri, S; Ravikumar, S; Sundrarajan, M

2012-09-15

Sulfated β-cyclodextrin was synthesized from sulfonation of β-cyclodextrin and sulfated polymer was crosslinked with cotton fabric using ethylenediaminetetraacetic acid as crosslinker. ZnO, TiO(2) and Ag nanoparticles were prepared and characterized by XRD, UV, DLS, SEM and PSA. The prepared nanoparticles were coated on crosslinked cotton fabric. The crosslinking and nanoparticles coating effects of cotton fabrics were studied by FTIR and SEM analysis. The antibacterial test was done against gram positive Staphylococcus aureus and gram negative Escherichia coli bacterium. Copyright © 2012 Elsevier B.V. All rights reserved.

MoS{sub 2}-modified ZnO quantum dots nanocomposite: Synthesis and ultrafast humidity response

Energy Technology Data Exchange (ETDEWEB)

Ze, Lu [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Yueqiu, Gong, E-mail: yqgong@xtu.edu.cn [School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105 (China); Xujun, Li; Yong, Zhang [School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105 (China)

2017-03-31

Highlights: • MoS{sub 2}@ZnO QDs composite structure was synthesized by two-steps methods. • Ultrafast humidity sensing response is achieved by MoS{sub 2}@ZnO QDs humidity sensor. • Sensor performs excellent cycle stability from 11% to 95% RH. • Humidity sensor could detect wide humidity range (11–95%). - Abstract: In this work, ZnO quantum dots (QDs), layered MoS{sub 2} and MoS{sub 2}-modified ZnO QDs (MoS{sub 2}@ZnO QDs) nanocomposite were synthesized and then applied as humidity sensor. The crystal structure, morphology and element distribution of ZnO QDs, MoS{sub 2} and MoS{sub 2}@ZnO QDs were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectrometry, respectively. The humidity sensing characteristics of the MoS{sub 2} and MoS{sub 2}@ZnO QDs against various relative humidity were measured at room temperature. The results show that the MoS{sub 2}@ZnO QDs sensor exhibits high sensitivity with an impedance variation of three or four orders of magnitude to relative humidity range of 11–95% and it exhibits a short response-recovery time (1 s for adsorption and 20 s for desorption) and excellent repeatability. The mechanisms of the excellent performance for humidity sensing of MoS{sub 2}@ZnO QDs sensor were discussed based on its impedance properties. Our work could offer guidelines to design higher performance especially ultrafast humidity response sensor utilizing the nanocomposite structure with two dimensional material and QDs.

Effect of morphology on the non-ohmic conduction in ZnO nanostructures

Science.gov (United States)

Praveen, E.; Jayakumar, K.

2016-05-01

Nanostructures of ZnO is synthesized with nanoflower like morphology by simple wet chemical method. The structural, morphological and electrical characterization have been carried out. The temperature dependent electrical characterization of ZnO pellets of thickness 1150 µm is made by the application of 925MPa pressure. The morphological dependence of non-ohmic conduction beyond some arbitrary tunneling potential and grain boundary barrier thickness is compared with the commercially available bulk ZnO. Our results show the suitability of nano-flower like ZnO for the devices like sensors, rectifiers etc.

Solar-assisted synthesis of ZnO nanoparticles using lime juice: a green approach

Science.gov (United States)

Hinge, Shruti P.; Pandit, Aniruddha B.

2017-12-01

Zinc oxide (ZnO) nanoparticles are those nanoparticles which have been synthesized in various morphologies and shapes. Their size and shape dependent properties and their applications in vivid sectors of science and technology make them interesting to synthesize. Present work reports a green method for ZnO nanoparticle synthesis using lime juice and sunlight. ZnO nanoparticles were also synthesized by conventionally used methods like heating, stirring or no heating and/or stirring. The nanoparticles were characterized using different techniques like UV-vis spectroscopy, scanning electron microscopy (SEM), x-ray diffraction (XRD) and dynamic light scattering (DLS). Thermo gravimetric analysis (TGA) was also carried out for the intermediate product to select the calcination temperature. Stoichiometric study reveals that the intermediate product formed is zinc citrate dihydrate. The synthesized calcined nanoparticles have good crystallinity, uniform shape, and high purity and were in the size range of 20-30 nm. These nanoparticles formed agglomerates of various shapes in the size range of 200-750 nm. This process is ecofriendly and is amiable for easy scale up.

Characterization of structural and electrical properties of ZnO tetrapods

Science.gov (United States)

Gu, Yu-Dong; Mai, Wen-Jie; Jiang, Peng

2011-12-01

ZnO tetrapods were synthesized by a typical thermal vapor-solid deposition method in a horizontal tube furnace. Structural characterization was carried out by transmission electron microscopy (TEM) and select-area electron diffraction (SAED), which shows the presence of zinc blende nucleus in the center of tetrapods while the four branches taking hexagonal wurtzite structure. The electrical transport property of ZnO tetrapods was investigated through an in-situ nanoprobe system. The three branches of a tetrapod serve as source, drain, and "gate", respectively; while the fourth branch pointing upward works as the force trigger by vertically applying external force downward. The conductivity of each branch of ZnO-tetrapods increases 3-4 times under pressure. In such situation, the electrical current through the branches of ZnO tetrapods can be tuned by external force, and therefore a simple force sensor based on ZnO tetrapods has been demonstrated for the first time.

The Applications of Morphology Controlled ZnO in Catalysis

Directory of Open Access Journals (Sweden)

Yuhai Sun

2016-11-01

Full Text Available Zinc oxide (ZnO, with the unique chemical and physical properties of high chemical stability, broad radiation absorption range, high electrochemical coupling coefficient, and high photo-stability, is an attractive multifunctional material which has promoted great interest in many fields. What is more, its properties can be tuned by controllable synthesized morphologies. Therefore, after the success of the abundant morphology controllable synthesis, both the morphology-dependent ZnO properties and their related applications have been extensively investigated. This review concentrates on the properties of morphology-dependent ZnO and their applications in catalysis, mainly involved reactions on green energy and environmental issues, such as CO2 hydrogenation to fuels, methanol steam reforming to generate H2, bio-diesel production, pollutant photo-degradation, etc. The impressive catalytic properties of ZnO are associated with morphology tuned specific microstructures, defects or abilities of electron transportation, etc. The main morphology-dependent promotion mechanisms are discussed and summarized.

Electron paramagnetic resonance in Cu-doped ZnO

Science.gov (United States)

Buchheit, R.; Acosta-Humánez, F.; Almanza, O.

2016-04-01

In this work, ZnO and Cu-doped ZnO nanoparticles (Zn1-xCuxO, x = 3%), with a calcination temperature of 500∘C were synthesized using the sol-gel method. The particles were analyzed using atomic absorption spectroscopy (AAS), X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) at X-band, measurement in a temperature range from 90 K to room temperature. AAS confirmed a good correspondence between the experimental doping concentration and the theoretical value. XRD reveals the presence of ZnO phase in hexagonal wurtzite structure and a nanoparticle size for the samples synthesized. EPR spectroscopy shows the presence of point defects in both samples with g-values of g = 1.959 for shallow donors and g = 2.004 for ionized vacancies. It is important when these materials are required have been used as catalysts, as suggested that it is not necessary prepare them at higher temperature. A simulation of the Cu EPR signal using an anisotropic spin Hamiltonian was performed and showed good coincidence with the experimental spectra. It was shown that Cu2+ ions enter interstitial octahedral sites of orthorhombic symmetry in the wurtzite crystal structure. Temperature dependence of the EPR linewidth and signal intensity shows a paramagnetic behavior of the sample in the measurement range. A Néel temperature TN = 78 ± 19 K was determined.

Synthesis and characterization of nanocomposites ZnO / polypyrrole for anti corrosive application

International Nuclear Information System (INIS)

Valenca, D.P.; Bouchonneau, N.; Vieira, M.R.S.; Alves, K.G.B.; Melo, C.P. de; Urtiga Filho, S.L.

2014-01-01

Nanoparticles of metal oxides and conductive polymers have been investigated as alternative additives in corrosion protection of oxidizable metals. In this hybrid nanocomposites work Polypyrrole-ZnO were synthesized and characterized as a potential application as industrial paint anti corrosive additive. The different steps of the synthesis and characterization of nanocomposites are described. The nanocomposites were obtained from the emulsion polymerization of aqueous solutions of pyrrole and sodium dodecyl sulfate containing ZnO nanoparticles dispersed in the mass. The nanoparticles were characterized by scanning electron microscopy and transmission, dynamic light scattering, diffraction of X-rays and techniques of infrared spectroscopy. From the characterization techniques, it was possible to determine the average size of nanoparticles of ZnO and ZnO-Polypyrrole. The peaks in the diffraction pattern of X-rays observed in the nanocomposite were the same as in ZnO, confirming the presence of ZnO in the composite. (author)

ZNO and AG-ZNO crystals: synthesis, characterization, and application in heterogeneous photocatalysis

Directory of Open Access Journals (Sweden)

Adriana Campano Lucilha

2016-05-01

Full Text Available ZnO and Ag-ZnO were synthesized in a simple and efficient manner by thermal decomposition of zinc oxalate and silver/zinc mixed oxalate. The influence of the addition of metallic silver on ZnO particles and the effect of temperature in the thermal treatment were investigated. The samples were characterized by thermogravimetric analysis, Raman, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, specific surface area (Brunauer-Emmett-Teller and diffuse reflectance spectroscopy. The photocatalytic activity of these materials in the decolorization of direct red 23 diazo dye was studied. The complete conversion into oxides from oxalates at lower temperatures was determinant in the photocatalytic efficiency of both the oxides. The presence of silver in zinc oxide, treated at 400 °C, more than doubled the rate constant of diazo dye decolorization (6.87×10-3 min-1 with respect to ZnO, treated at 600 °C, resulting in 3.07×10-3 min-1 under UV irradiation at 30 °C.

Theoretical prediction of low-density hexagonal ZnO hollow structures

Energy Technology Data Exchange (ETDEWEB)

Tuoc, Vu Ngoc, E-mail: tuoc.vungoc@hust.edu.vn [Institute of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hanoi (Viet Nam); Huan, Tran Doan [Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269-3136 (United States); Thao, Nguyen Thi [Institute of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hanoi (Viet Nam); Hong Duc University, 307 Le Lai, Thanh Hoa City (Viet Nam); Tuan, Le Manh [Hong Duc University, 307 Le Lai, Thanh Hoa City (Viet Nam)

2016-10-14

Along with wurtzite and zinc blende, zinc oxide (ZnO) has been found in a large number of polymorphs with substantially different properties and, hence, applications. Therefore, predicting and synthesizing new classes of ZnO polymorphs are of great significance and have been gaining considerable interest. Herein, we perform a density functional theory based tight-binding study, predicting several new series of ZnO hollow structures using the bottom-up approach. The geometry of the building blocks allows for obtaining a variety of hexagonal, low-density nanoporous, and flexible ZnO hollow structures. Their stability is discussed by means of the free energy computed within the lattice-dynamics approach. Our calculations also indicate that all the reported hollow structures are wide band gap semiconductors in the same fashion with bulk ZnO. The electronic band structures of the ZnO hollow structures are finally examined in detail.

Use of Nanostructured ZnO for Production of Antimicrobial Textiles

International Nuclear Information System (INIS)

Chit Ko Ko Htwe

2011-12-01

An awareness of general sanitation, contact disease transmission, and personal protection has led to the development of antimicrobial textiles. The development of antimicrobial fabrics using nanostructure ZnO has been investigated in this present work. The nanostructure ZnO were produced using a microwave irradiation without any other calcinations and were directly applied on to the fabric using pad-dry-cure method.Synthesized nanostructure ZnO were characterized by XRD and SEM for ZnO purification and particle size examination. The antibacterial activity of the finished fabrics was assessed qualitatively by agar diffusion method. The results show that the finished fabric demonstrated significant antibacterial activity against Staphylococcus aureus and Escherichia coli in qualitative test.

Visible light photocatalytic activities of ZnFe_2O_4/ZnO nanoparticles for the degradation of organic pollutants

International Nuclear Information System (INIS)

Rameshbabu, R.; Kumar, Niraj; Karthigeyan, A.; Neppolian, B.

2016-01-01

ZnFe_2O_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_2O_4 and hexagonal ZnO were identified in accordance with different molar concentrations of Fe"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"3"+ ions were analyzed from diffuse reflectance spectra (DRS). Superparamagnetic property was observed for synthesized ZnFe_2O_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_2O_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.

Structural, optical and magnetic characterization of Ru doped ZnO nanorods

International Nuclear Information System (INIS)

Kumar, Sanjeev; Kaur, Palvinder; Chen, C.L.; Thangavel, R.; Dong, C.L.; Ho, Y.K.; Lee, J.F.; Chan, T.S.; Chen, T.K.; Mok, B.H.; Rao, S.M.; Wu, M.K.

2014-01-01

Graphical abstract: Ruthenium (Ru = 0%, 1% and 2%) doped nano-crystalline zinc oxide (ZnO) nanorods were synthesized by using well-known sol–gel technique. X-ray diffraction (XRD) results show that Ru (0%, 1% and 2%) doped ZnO nanorods crystallized in the wurtzite structure having space group C 3v (P6 3 mc). Williamson and Hall plot reveal that in the nanoscale dimensions, incorporation of Ru induced the tensile strain in ZnO host matrix. Photoluminescence (PL) and Raman studies of Ru doped ZnO nanorods show the formation of singly ionized oxygen vacancies which may account for the observed room temperature ferromagnetism (RTFM) in 2% Ru doped ZnO. X-ray absorption spectroscopy (XAS) reveals that Ru replace the Zn atoms in the host lattice and maintain the crystal symmetry with slightly lattice distortion. Highlights: • Ru doped ZnO nanorods crystallized in the wurtzite structure having space group C 3v (P6 3 mc). • PL and Raman studies show the formation of singly ionized oxygen vacancies in 2% Ru doped ZnO. • XAS reveals that Ru replace the Zn atoms in the host lattice with slightly lattice distortion. • Doping of Ru in ZnO nanostructures gives rise to RTFM ordering. -- Abstract: Ruthenium (Ru = 0%, 1% and 2%) doped nano-crystalline zinc oxide (ZnO) nanorods were synthesized by using well-known sol–gel technique. X-ray diffraction (XRD) results show that Ru (0%, 1% and 2%) doped ZnO nanorods crystallized in the wurtzite structure having space group C 3v (P6 3 mc). Williamson and Hall plot reveal that in the nanoscale dimensions, incorporation of Ru induced the tensile strain in ZnO host matrix. Photoluminescence (PL) and Raman studies of Ru doped ZnO nanorods show the formation of singly ionized oxygen vacancies which may account for the observed room temperature ferromagnetism (RTFM) in 2% Ru doped ZnO. X-ray absorption spectroscopy (XAS) reveals that Ru replace the Zn atoms in the host lattice and maintain the crystal symmetry with slightly lattice

Lattice location of implanted As in ZnO

CERN Document Server

Wahl, U; Correia, J G; Marques, A C; Alves, E; Soares, J C

2007-01-01

Radioactive 73As ions were implanted into a ZnO single crystal at room temperature with 60 keV up to a fluence of 2×1013 cm−2. Subsequently, the angular emission channeling patterns of emitted conversion electrons were recorded by means of a position-sensitive detector in the as-implanted state and following annealing up to 900 C, and were compared to simulated emission yields for a variety of different lattice sites. We find that As does not occupy substitutional O sites, but mainly occupies the substitutional Zn sites. The fraction of As on O sites was at most a few per cent. Arsenic in ZnO is thus an interesting example of an impurity in a semiconductor where the major impurity lattice site is determined by atomic size and electronegativity rather than its position in the periodic system. Possible consequences with respect to the role of arsenic as a p-type dopant in ZnO are being discussed.

Synthesis of vertical arrays of ultra long ZnO nanowires on noncrystalline substrates

International Nuclear Information System (INIS)

Kwon, Bong Jun; Lee, Kyung Moon; Shin, Hae-Young; Kim, Jinwoong; Liu, Jinzhang; Yoon, Seokhyun; Lee, Soonil; Ahn, Y.H.; Park, Ji-Yong

2012-01-01

Highlights: ► Arrays of vertical ultra-long ZnO nanowires with lengths upto 300 μm. ► Controls of lengths and diameters of vertical arrays of ZnO nanowires on SiO 2 substrates. ► Luminescent and electrical properties of ZnO nanowires prepared with different growth conditions. - Abstract: Vertically aligned arrays of ultralong ZnO nanowires were synthesized on SiO 2 substrates with carbothermal vapor phase transport method with Au seeding layer. High density of vertically aligned ZnO nanowires with lengths from a few to ∼300 μm could be grown by controlling growth conditions. Supply of high concentration of Zn vapor and control of the ratio between Zn vapor and oxygen are found to have the most significant effects on the growth of long ZnO nanowires in the vapor–solid growth mechanism. The nanowires are of high crystalline quality as confirmed by various structural, compositional, and luminescent measurements. Luminescent and electrical properties of ZnO nanowires with different growth conditions were also investigated.

Wafer-Scale High-Throughput Ordered Growth of Vertically Aligned ZnO Nanowire Arrays

KAUST Repository

Wei, Yaguang

2010-09-08

This article presents an effective approach for patterned growth of vertically aligned ZnO nanowire (NW) arrays with high throughput and low cost at wafer scale without using cleanroom technology. Periodic hole patterns are generated using laser interference lithography on substrates coated with the photoresist SU-8. ZnO NWs are selectively grown through the holes via a low-temperature hydrothermal method without using a catalyst and with a superior control over orientation, location/density, and as-synthesized morphology. The development of textured ZnO seed layers for replacing single crystalline GaN and ZnO substrates extends the large-scale fabrication of vertically aligned ZnO NW arrays on substrates of other materials, such as polymers, Si, and glass. This combined approach demonstrates a novel method of manufacturing large-scale patterned one-dimensional nanostructures on various substrates for applications in energy harvesting, sensing, optoelectronics, and electronic devices. © 2010 American Chemical Society.

Synthesis of assembled ZnO structures by precipitation method in aqueous media

International Nuclear Information System (INIS)

Sepulveda-Guzman, S.; Reeja-Jayan, B.; Rosa, E. de la; Torres-Castro, A.; Gonzalez-Gonzalez, V.; Jose-Yacaman, M.

2009-01-01

In this work, arrays of submicron ZnO structures were successfully synthesized using a one-step aqueous precipitation method. Snowflake-like and flower-like morphologies were obtained by changing the reaction temperature. X-ray diffraction (XRD) patterns indicated that the ZnO arrays have a wurtzite crystal structure. A possible growth mechanism based on the analysis done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and high-angle annular dark field (HAADF) is proposed. Our findings suggest that the growth mechanism of the ZnO arrays is by self-aggregation, and that such an oriented aggregation is enhanced by increasing the reaction temperature. The results also revealed that the aggregation process introduces several structural defects such as differences in mass distribution and crystalline structure. In order to study the surface chemical composition the samples were also characterized by XPS. The results showed the presence of Zn(OH) 2 and absorbed carbon species on the ZnO surface. In addition, the photoluminescence characterization showed that on UV excitation (λ = 360 nm) all samples present the characteristic UV emission centered at 390 nm, and for the sample synthesized at 60 deg. C, a visible emission was also observed

Synthesis of assembled ZnO structures by precipitation method in aqueous media

Energy Technology Data Exchange (ETDEWEB)

Sepulveda-Guzman, S. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, UANL Km. 10 de la nueva carretera al Aeropuerto Internacional de Monterrey, PIIT Monterrey, Apodaca NL (Mexico); Facultad de Ingenieria Mecanica y Electrica de la UANL, Ciudad Universitaria San Nicolas de los Garza, Nuevo Leon C.P. 66451 (Mexico)], E-mail: ssepulveda@mail.uanl.mx; Reeja-Jayan, B. [Texas Materials Institute, University of Texas at Austin, 1 University Station C0803 (United States); Rosa, E. de la [Centro de Investigaciones en Optica, A.C. Loma del Bosque 115 Col. Lomas del Campestre, Leon Gto. C.P. 37150 (Mexico); Torres-Castro, A.; Gonzalez-Gonzalez, V. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, UANL Km. 10 de la nueva carretera al Aeropuerto Internacional de Monterrey, PIIT Monterrey, Apodaca NL (Mexico); Facultad de Ingenieria Mecanica y Electrica de la UANL, Ciudad Universitaria San Nicolas de los Garza, Nuevo Leon C.P. 66451 (Mexico); Jose-Yacaman, M. [Physics and Astronomy Department, University of Texas at San Antonio, 1604 Campus San Antonio, TX 78249 (United States)

2009-05-15

In this work, arrays of submicron ZnO structures were successfully synthesized using a one-step aqueous precipitation method. Snowflake-like and flower-like morphologies were obtained by changing the reaction temperature. X-ray diffraction (XRD) patterns indicated that the ZnO arrays have a wurtzite crystal structure. A possible growth mechanism based on the analysis done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and high-angle annular dark field (HAADF) is proposed. Our findings suggest that the growth mechanism of the ZnO arrays is by self-aggregation, and that such an oriented aggregation is enhanced by increasing the reaction temperature. The results also revealed that the aggregation process introduces several structural defects such as differences in mass distribution and crystalline structure. In order to study the surface chemical composition the samples were also characterized by XPS. The results showed the presence of Zn(OH){sub 2} and absorbed carbon species on the ZnO surface. In addition, the photoluminescence characterization showed that on UV excitation ({lambda} = 360 nm) all samples present the characteristic UV emission centered at 390 nm, and for the sample synthesized at 60 deg. C, a visible emission was also observed.

A flexible UV nanosensor based on reduced graphene oxide decorated ZnO nanostructures

Science.gov (United States)

Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Muhammad, Safdar; Huang, Ying; He, Jun

2012-03-01

A low-cost, compatible with flexible electronics, high performance UV sensor has been achieved from a reduced graphene oxide (RGO) decorated hydrangea-like ZnO film on a PDMS substrate. The hydrangea-like ZnO UV sensor has the best UV sensing performance among devices made of three kinds of ZnO nanostructures synthesized by a hydrothermal method, and demonstrated a dramatic enhancement in on/off ratio and photoresponse current by introducing an appropriate weight ratio of RGO. The on/off ratio of the 0.05% RGO/ZnO sensor increases almost one order of magnitude compared to that of a pristine hydrangea-like ZnO UV sensor. While for the 5% RGO decorated ZnO sensor, the photoresponse current reaches as high as ~1 μA and exceeds 700 times that of a ZnO UV sensor. These results indicate that RGO is an appropriate material to enhance the performance of ZnO nanostructure UV sensors based on its unique features, especially the high optical transparency and excellent electronic conductivity. Our findings will make RGO/ZnO nanohybrids extraordinarily promising in optoelectronics, flexible electronics and sensor applications.

Synthesis, effect of capping agents, structural, optical and photoluminescence properties of ZnO nanoparticles

International Nuclear Information System (INIS)

Singh, A.K.; Viswanath, V.; Janu, V.C.

2009-01-01

Zinc oxide nanoparticles were synthesized using chemical method in alcohol base. During synthesis three capping agents, i.e. triethanolamine (TEA), oleic acid and thioglycerol, were used and the effect of concentrations was analyzed for their effectiveness in limiting the particle growth. Thermal stability of ZnO nanoparticles prepared using TEA, oleic acid and thioglycerol capping agents, was studied using thermogravimetric analyzer (TGA). ZnO nanoparticles capped with TEA showed maximum weight loss. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for structural and morphological characterization of ZnO nanoparticles. Particle size was evaluated using effective mass approximation method from UV-vis spectroscopy and Scherrer's formula from XRD patterns. XRD analysis revealed single crystal ZnO nanoparticles of size 12-20 nm in case of TEA capping. TEA, oleic acid and thioglycerol capped synthesized ZnO nanoparticles were investigated at room temperature photoluminescence for three excitation wavelengths i.e. 304, 322 and 325 nm, showing strong peaks at about 471 nm when excited at 322 and 325 nm whereas strong peak was observed at 411 for 304 nm excitation.

Role of nickel doping on structural, optical, magnetic properties and antibacterial activity of ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Vijayaprasath, G.; Murugan, R. [School of Physics, Alagappa University, Karaikudi 630 004, Tamil Nadu (India); Palanisamy, S.; Prabhu, N.M. [Department of Animal Health and Management, Alagappa University, Karaikudi 630 004, Tamil Nadu (India); Mahalingam, T. [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of); Hayakawa, Y. [Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8011 (Japan); Ravi, G., E-mail: gravicrc@gmail.com [School of Physics, Alagappa University, Karaikudi 630 004, Tamil Nadu (India)

2016-04-15

Highlights: • The XRD analyses revealed that the synthesizes nickel doped ZnO (Zn{sub 1−x}Ni{sub x}O, x = 0.0, 0.03, 0.06 and 0.09) nanostructures have hexagonal wurtzite structure. • The photoluminescence measurements revealed that the broad emission was composed of different bands due to zinc and oxygen vacancies. • X-ray photoelectron spectroscopy (XPS) confirmed the Ni incorporation in ZnO lattice as Ni{sup 2+} ions. • Room temperature ferromagnetism was observed due to the oxygen vacancies and zinc interstitials are the main reasons for ferromagnetism in Ni doped ZnO NPs. - Abstract: Zn{sub 1−x}Ni{sub x}O nanoparticles were synthesized by co-precipitation method. The crystallite sizes of the synthesized samples found to decrease from 38 to 26 nm with increase in nickel concentration. FTIR spectra confirmed the presence of Zn−O stretching bands at 577, 573, 569 and 565 cm{sup −1} in the respective ZnO NPs. Optical absorption spectra revealed the red shifted and estimated band gap is found to decrease with increase of Ni doping concentration. The PL spectra of all the samples exhibited a broad emission at 390 nm in the visible range. The carriers (donors) bounded on the Ni sites were observed from the micro Raman spectroscopic studies. Pure and Ni doped ZnO NPs showed significant changes in the M–H loop, especially the diamagnetic behavior changed into ferromagnetic nature for Ni doped samples. The antiferromagnetic super-exchange interactions between Ni{sup 2+} ions is increased in higher Ni doped ZnO NPs and also their antibacterial activity has been studied.

Synthesis of TCPP/ZnFe{sub 2}O{sub 4}@ZnO nanohollow sphere composite for degradation of methylene blue and 4-nitrophenol under visible light

Energy Technology Data Exchange (ETDEWEB)

Rabbani, Mahboubeh, E-mail: m_rabani@iust.ac.ir; Heidari-Golafzani, Mahdi; Rahimi, Rahmatollah

2016-08-15

In this study, ZnFe{sub 2}O{sub 4} nanohallow spheres were synthesized by hydrothermal method, then ZnFe{sub 2}O{sub 4}@ZnO core-shell was prepared by forming of ZnO nanoshell onto magnetic microspheres via sol–gel route. Finally, TCPP/ZnFe{sub 2}O{sub 4}@ZnO composite was synthesized through the immobilization of the meso-tetrakis(4-carboxyphenyl)porphyrin on ZnFe{sub 2}O{sub 4}@ZnO core-shell. The prepared photocatalysts were characterized by different techniques such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray fluorescence analysis (XRF), vibration sample magnetometery (VSM), Brunauer–Emmett–Teller (BET) model, UV–visible diffuse reflectance spectroscopy (DRS) and dynamic light scattering (DLS). The photocatalytic activity of prepared photocatalysts was evaluated for degradation of methylene blue, as an organic dye and 4-nitrophenol as an organic pollutant under visible LED light irradiation. The results illustrated that TCPP/ZnFe{sub 2}O{sub 4}@ZnO composite show better photodegradating behavior vs. methylene blue and 4-nitrophenol compared to ZnFe{sub 2}O{sub 4}@ZnO, pure ZnFe{sub 2}O{sub 4} and pure ZnO. - Highlights: • ZnFe{sub 2}O{sub 4} nanohallow spheres were synthesized by hydrothermal method. • ZnFe{sub 2}O{sub 4}@ZnO core-shell was prepared by forming of ZnO nanoshell. • ZnFe{sub 2}O{sub 4}@ZnO spheres was modified by immobilization of TCPP on their surface. • Photocatalytic activity of catalysts was tested for degradation of MB and 4-NP. • TCPP/ZnFe{sub 2}O{sub 4}@ZnO composite show better photodegradating behavior.

Graphene-wrapped ZnO nanospheres as a photocatalyst for high performance photocatalysis

International Nuclear Information System (INIS)

Chen, Da; Wang, Dongfang; Ge, Qisheng; Ping, Guangxing; Fan, Meiqiang; Qin, Laishun; Bai, Liqun; Lv, Chunju; Shu, Kangying

2015-01-01

In this work, graphene-wrapped ZnO nanospheres (ZnO–graphene nanocomposites) were prepared by a simple facile lyophilization method, followed by thermal treatment process. ZnO nanospheres with the size of about 100–400 nm, composed of numerous nanocrystals with hexagonal wurtzite structure, were well separated from each other and wrapped with transparent graphene sheets. Compared to ZnO nanospheres, the ZnO–graphene nanocomposites showed a significant enhancement in the photodegradation of methylene blue. This enhanced photocatalytic activity could be attributed to their favorable dye-adsorption affinity and increased optical absorption as well as the efficient charge transfer of the photogenerated electrons in the conduction band of ZnO to graphene. Thus, this work could provide a facile and low-cost method for the development of graphene-based nanocomposites with promising applications in photocatalysis, solar energy conversion, sensing, and so on. - Highlights: • Graphene-wrapped ZnO nanospheres were prepared by a facile lyophilization method. • ZnO nanospheres were separated from each other and wrapped with 2D graphene sheets. • Graphene-wrapped ZnO nanospheres exhibited superior photocatalytic activities. • The photocatalytic mechanisms of graphene-wrapped ZnO nanospheres were discussed

Graphene-wrapped ZnO nanospheres as a photocatalyst for high performance photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Chen, Da, E-mail: dchen_80@hotmail.com [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China); Wang, Dongfang; Ge, Qisheng; Ping, Guangxing [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China); Fan, Meiqiang, E-mail: fanmeiqiang@126.com [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China); Qin, Laishun [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China); Bai, Liqun [School of Sciences, Zhejiang Agriculture and Forestry University, Hangzhou 311300 (China); Lv, Chunju; Shu, Kangying [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China)

2015-01-01

In this work, graphene-wrapped ZnO nanospheres (ZnO–graphene nanocomposites) were prepared by a simple facile lyophilization method, followed by thermal treatment process. ZnO nanospheres with the size of about 100–400 nm, composed of numerous nanocrystals with hexagonal wurtzite structure, were well separated from each other and wrapped with transparent graphene sheets. Compared to ZnO nanospheres, the ZnO–graphene nanocomposites showed a significant enhancement in the photodegradation of methylene blue. This enhanced photocatalytic activity could be attributed to their favorable dye-adsorption affinity and increased optical absorption as well as the efficient charge transfer of the photogenerated electrons in the conduction band of ZnO to graphene. Thus, this work could provide a facile and low-cost method for the development of graphene-based nanocomposites with promising applications in photocatalysis, solar energy conversion, sensing, and so on. - Highlights: • Graphene-wrapped ZnO nanospheres were prepared by a facile lyophilization method. • ZnO nanospheres were separated from each other and wrapped with 2D graphene sheets. • Graphene-wrapped ZnO nanospheres exhibited superior photocatalytic activities. • The photocatalytic mechanisms of graphene-wrapped ZnO nanospheres were discussed.

Self-aligned nanocrystalline ZnO hexagons by facile solid-state and co-precipitation route

International Nuclear Information System (INIS)

Thorat, J. H.; Kanade, K. G.; Nikam, L. K.; Chaudhari, P. D.; Panmand, R. P.; Kale, B. B.

2012-01-01

In this study, we report the synthesis of well-aligned nanocrystalline hexagonal zinc oxide (ZnO) nanoparticles by facile solid-state and co-precipitation method. The co-precipitation reactions were performed using aqueous and ethylene glycol (EG) medium using zinc acetate and adipic acid to obtain zinc adipate and further decomposition at 450 °C to confer nanocrystalline ZnO hexagons. XRD shows the hexagonal wurtzite structure of the ZnO. Thermal study reveals complete formation of ZnO at 430 °C in case of solid-state method, whereas in case of co-precipitation method complete formation was observed at 400 °C. Field emission scanning electron microscope shows spherical morphology for ZnO synthesized by solid-state method. The aqueous-mediated ZnO by co-precipitation method shows rod-like morphology. These rods are formed via self assembling of spherical nanoparticles, however, uniformly dispersed spherical crystallites were seen in EG-mediated ZnO. Transmission electron microscope (TEM) investigations clearly show well aligned and highly crystalline transparent and thin hexagonal ZnO. The particle size was measured using TEM and was observed to be 50–60 nm in case of solid-state method and aqueous-mediated co-precipitation method, while 25–50 nm in case of EG-mediated co-precipitation method. UV absorption spectra showed sharp absorption peaks with a blue shift for EG-mediated ZnO, which demonstrate the mono-dispersed lower particle size. The band gap of the ZnO was observed to be 3.4 eV which is higher than the bulk, implies nanocrystalline nature of the ZnO. The photoluminescence studies clearly indicate the strong violet and weak blue emission in ZnO nanoparticles which is quite unique. The process investigated may be useful to synthesize other oxide semiconductors and transition metal oxides.

Self-aligned nanocrystalline ZnO hexagons by facile solid-state and co-precipitation route

Energy Technology Data Exchange (ETDEWEB)

Thorat, J. H. [Mahatma Phule College, Department of Chemistry (India); Kanade, K. G. [Annasaheb Awate College (India); Nikam, L. K. [B.G. College (India); Chaudhari, P. D.; Panmand, R. P.; Kale, B. B., E-mail: kbbb1@yahoo.com [Center for Materials for Electronics Technology (C-MET) (India)

2012-02-15

In this study, we report the synthesis of well-aligned nanocrystalline hexagonal zinc oxide (ZnO) nanoparticles by facile solid-state and co-precipitation method. The co-precipitation reactions were performed using aqueous and ethylene glycol (EG) medium using zinc acetate and adipic acid to obtain zinc adipate and further decomposition at 450 Degree-Sign C to confer nanocrystalline ZnO hexagons. XRD shows the hexagonal wurtzite structure of the ZnO. Thermal study reveals complete formation of ZnO at 430 Degree-Sign C in case of solid-state method, whereas in case of co-precipitation method complete formation was observed at 400 Degree-Sign C. Field emission scanning electron microscope shows spherical morphology for ZnO synthesized by solid-state method. The aqueous-mediated ZnO by co-precipitation method shows rod-like morphology. These rods are formed via self assembling of spherical nanoparticles, however, uniformly dispersed spherical crystallites were seen in EG-mediated ZnO. Transmission electron microscope (TEM) investigations clearly show well aligned and highly crystalline transparent and thin hexagonal ZnO. The particle size was measured using TEM and was observed to be 50-60 nm in case of solid-state method and aqueous-mediated co-precipitation method, while 25-50 nm in case of EG-mediated co-precipitation method. UV absorption spectra showed sharp absorption peaks with a blue shift for EG-mediated ZnO, which demonstrate the mono-dispersed lower particle size. The band gap of the ZnO was observed to be 3.4 eV which is higher than the bulk, implies nanocrystalline nature of the ZnO. The photoluminescence studies clearly indicate the strong violet and weak blue emission in ZnO nanoparticles which is quite unique. The process investigated may be useful to synthesize other oxide semiconductors and transition metal oxides.

H2O2 sensing using HRP modified catalyst-free ZnO nanorods synthesized by RF sputtering

Science.gov (United States)

Srivastava, Amit; Kumar, Naresh; Singh, Priti; Singh, Sunil Kumar

2017-06-01

Catalyst-free ( 00 l) oriented ZnO nanorods (NRs) -based biosensor for the H2O2 sensing has been reported. The (002) oriented ZnO NRs as confirmed by X-ray diffraction were successfully grown on indium tin oxide (ITO) coated glass substrate by radio frequency (RF) sputtering technique without using any catalyst. Horseradish peroxidase (HRP) enzyme was immobilized on ZnO NRs by physical adsorption technique to prepare the biosensor. In this HRP/ZnO NR/ITO bioelectrode, nafion solution was added to form a tight membrane on surface. The prepared bioelectrode has been used for biosensing measurements by electrochemical analyzer. The electrochemical studies reveal that the prepared HRP/ZnO NR/ITO biosensor is highly sensitive to the detection of H2O2 over a linear range of 0.250-10 μM. The ZnO NR-based biosensor showed lower value of detection limit (0.125 μM) and higher sensitivity (13.40 µA/µM cm2) towards H2O2. The observed value of higher sensitivity attributed to larger surface area of ZnO nanostructure for effective loading of HRP besides its high electron communication capability. In addition, the biosensor also shows lower value of enzyme's kinetic parameter (Michaelis-Menten constant, K m) of 0.262 μM which indicates enhanced enzyme affinity of HRP to H2O2. The reported biosensor may be useful for various applications in biosensing, clinical, food, and beverage industry.

Soft-solution route to ZnO nanowall array with low threshold power density

Science.gov (United States)

Jang, Eue-Soon; Chen, Xiaoyuan; Won, Jung-Hee; Chung, Jae-Hun; Jang, Du-Jeon; Kim, Young-Woon; Choy, Jin-Ho

2010-07-01

ZnO nanowall array (ZNWA) has been directionally grown on the buffer layer of ZnO nanoparticles dip-coated on Si-wafer under a soft solution process. Nanowalls on substrate are in most suitable shape and orientation not only as an optical trap but also as an optical waveguide due to their unique growth habit, V[011¯0]≫V[0001]≈V[0001¯]. Consequently, the stimulated emission at 384 nm through nanowalls is generated by the threshold power density of only 25 kW/cm2. Such UV lasing properties are superior to those of previously reported ZnO nanorod arrays. Moreover, there is no green (defect) emission due to the mild procedure to synthesize ZNWA.

A High-Sensitivity Gas Sensor Toward Methanol Using ZnO Microrods: Effect of Operating Temperature

Science.gov (United States)

Sinha, M.; Mahapatra, R.; Mondal, B.; Ghosh, R.

2017-04-01

In the present work, zinc oxide (ZnO) microrods with the average diameter of 350 nm have been synthesized on fluorine doped tin oxide (FTO) substrate using a hydrothermal reaction process at a low temperature of 90°C. The methanol gas sensing behaviour of as-synthesized ZnO microrods have been studied at different operating temperatures (100-300°C). The gas sensing results show that the ZnO microrods exhibit excellent sensitivity, selectivity, and stability toward methanol gas at 300°C. The as-grown ZnO microrods sensor also shows the good sensitivity for methanol even at a low operating temperature of 100°C. The ultra-high sensitivity of 4.41 × 104% [gas sensitivity, S g = ( I g - I a)/ I a × 100%] and 5.11 × 102% to 100 ppm methanol gas at a temperature of 300°C and 100°C, respectively, has been observed. A fast response time of 200 ms and 270 ms as well as a recovery time of 120 ms and 1330 ms to methanol gas have also been found at an operating temperature of 300°C and 100°C, respectively. The response and recovery time decreases with increasing operation temperature of the sensor.

Schottky nanocontact of one-dimensional semiconductor nanostructures probed by using conductive atomic force microscopy

Science.gov (United States)

Lee, Jung Ah; Rok Lim, Young; Jung, Chan Su; Choi, Jun Hee; Im, Hyung Soon; Park, Kidong; Park, Jeunghee; Kim, Gyu Tae

2016-10-01

To develop the advanced electronic devices, the surface/interface of each component must be carefully considered. Here, we investigate the electrical properties of metal-semiconductor nanoscale junction using conductive atomic force microscopy (C-AFM). Single-crystalline CdS, CdSe, and ZnO one-dimensional nanostructures are synthesized via chemical vapor transport, and individual nanobelts (or nanowires) are used to fabricate nanojunction electrodes. The current-voltage (I -V) curves are obtained by placing a C-AFM metal (PtIr) tip as a movable contact on the nanobelt (or nanowire), and often exhibit a resistive switching behavior that is rationalized by the Schottky (high resistance state) and ohmic (low resistance state) contacts between the metal and semiconductor. We obtain the Schottky barrier height and the ideality factor through fitting analysis of the I-V curves. The present nanojunction devices exhibit a lower Schottky barrier height and a higher ideality factor than those of the bulk materials, which is consistent with the findings of previous works on nanostructures. It is shown that C-AFM is a powerful tool for characterization of the Schottky contact of conducting channels between semiconductor nanostructures and metal electrodes.

Synthesis and Characterization of CNT/TiO2/ZnO Composites with High Photocatalytic Performance

Directory of Open Access Journals (Sweden)

Yanzhen Huang

2018-04-01

Full Text Available Novel carbon nanotubes (CNTs/titanium dioxide (TiO2/zinc oxide (ZnO composites have been successfully synthesized via a two-step solution method using titanyl sulfate as the titanium precursor. Its structural performances were researched by various characterization methods, such as X-ray powder diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM and UV-vis diffuse reflectance spectroscopy (UV-vis DRS. The performance of the composites was tested by degrading rhodamine B (RhB under UV-vis illumination and found to strongly rely on the content of ZnO. The experimental results showed that the CNT/TiO2/ZnO-90 wt % expressed more outstanding photocatalytic performance compared to the corresponding binary composites and the CNT/TiO2/ZnO-85 wt %, CNT/TiO2/ZnO-95 wt % materials. The improved photocatalytic activity was attributed to synergistic effect of CNT, TiO2 and ZnO, in which ZnO can absorb photons to produce electrons and holes, whereas TiO2 and CNT can reduce the electron-hole recombination.

Single and couple doping ZnO nanocrystals characterized by positron techniques

Science.gov (United States)

Pasang, Tenzin; Namratha, Keerthiraj; Guagliardo, Paul; Byrappa, Kullaiah; Ranganathaiah, Chikkakuntappa; Samarin, S.; Williams, J. F.

2015-04-01

Zinc oxide (ZnO) nanocrystals have been synthesized using a mild hydrothermal process using low temperatures and pressures with the advantages of free growth catalyst, low cost and alternative technology. Positron annihilation lifetime spectroscopy and coincidence Doppler broadening (CDB) spectroscopic methods have been used to investigate the roles of single- and co-dopants and native defects of the ZnO nanocrystals controlled by the synthesis process. It is shown that single Ag1+ and Pd2+ dopants occupy interstitial sites of the ZnO lattice and single Ru3+ doping replaces Zn vacancies substitutionally with a significant effect on the CDB momentum ratio curves when compared using ZnO as the reference spectrum. The co-doping of the ZnO lattice with (Sn4+ + Co2+) shows similar CDB ratios as Ru3+ single-doping. Also co-doping with (Ag1+ + Pd2+) or (Ag1+ + W6+) shows significant decreases in the band gap energy up to about 12.6% compared to single doping. The momentum ratio curves, referenced to undoped ZnO, indicate dopants in interstitial and substitutional sites. The presence of transition metal ions interstitially will trap electrons which resist the recombination of electrons and in turn affect the conductivity of the material.

Single and couple doping ZnO nanocrystals characterized by positron techniques

International Nuclear Information System (INIS)

Pasang, Tenzin; Namratha, Keerthiraj; Byrappa, Kullaiah; Guagliardo, Paul; Ranganathaiah, Chikkakuntappa; Samarin, S; Williams, J F

2015-01-01

Zinc oxide (ZnO) nanocrystals have been synthesized using a mild hydrothermal process using low temperatures and pressures with the advantages of free growth catalyst, low cost and alternative technology. Positron annihilation lifetime spectroscopy and coincidence Doppler broadening (CDB) spectroscopic methods have been used to investigate the roles of single- and co-dopants and native defects of the ZnO nanocrystals controlled by the synthesis process. It is shown that single Ag 1+ and Pd 2+ dopants occupy interstitial sites of the ZnO lattice and single Ru 3+ doping replaces Zn vacancies substitutionally with a significant effect on the CDB momentum ratio curves when compared using ZnO as the reference spectrum. The co-doping of the ZnO lattice with (Sn 4+ + Co 2+ ) shows similar CDB ratios as Ru 3+ single-doping. Also co-doping with (Ag 1+ + Pd 2+ ) or (Ag 1+ + W 6+ ) shows significant decreases in the band gap energy up to about 12.6% compared to single doping. The momentum ratio curves, referenced to undoped ZnO, indicate dopants in interstitial and substitutional sites. The presence of transition metal ions interstitially will trap electrons which resist the recombination of electrons and in turn affect the conductivity of the material. (paper)

Synthesis of ZnO nanorods by spray pyrolysis for H{sub 2}S gas sensor

Energy Technology Data Exchange (ETDEWEB)

Shinde, S.D.; Patil, G.E. [Materials Research Lab., K.T.H.M. College, Nashik 422 005 (India); Kajale, D.D. [Materials Research Lab., Arts, Commerce and Science College, Nandgaon 423 106 (India); Gaikwad, V.B. [Materials Research Lab., K.T.H.M. College, Nashik 422 005 (India); Jain, G.H., E-mail: gotanjain@rediffmail.com [Materials Research Lab., K.T.H.M. College, Nashik 422 005 (India)

2012-07-05

Highlights: Black-Right-Pointing-Pointer Hexagonal pillar shaped ZnO nanorods with different sizes have been successfully synthesized by spray pyrolysis technique. Black-Right-Pointing-Pointer ZnO nanorods thin films showed much better sensitivity and stability than the conventional materials to H{sub 2}S gas (100 ppm) at 50 Degree-Sign C. Black-Right-Pointing-Pointer This ZnO thin film has potential in application of room temperature H{sub 2}S gas sensing. - Abstract: Hexagonal pillar shaped ZnO nanorods with different sizes have been successfully synthesized by spray pyrolysis technique (SPT). The equal amount of methanol and water is used as a solvent to dissolve the AR grade Zinc acetate for precursor solution. This solution is sprayed on to the glass substrate heated at 350 Degree-Sign C. The films were characterized by ultra-violet spectroscopy (UV), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The deposition of thin films results in a layer comprising well-shaped hexagonal ZnO nanorods with diameter of 90-120 nm and length of up to 200 nm. The gas sensing properties of these films have been investigated for various interfering gases such as CO{sub 2}, CO, ethanol, NH{sub 3} and H{sub 2}S, etc. at operating temperature from 30 Degree-Sign (room temperature) to 450 Degree-Sign C. The results indicate that the ZnO nanorods thin films showed much better sensitivity and stability than the conventional materials to H{sub 2}S gas (100 ppm) at 50 Degree-Sign C. The hexagonal pillar shaped ZnO nanorods can improve the sensitivity and selectivity of the sensors.

Magnetic and optical properties of manganese doped ZnO nanoparticles synthesized by sol-gel technique

KAUST Repository

Omri, Karim; El Ghoul, Jaber; Lemine, O. M.; Bououdina, M.; Zhang, Bei; El Mir, Lassaad

2013-01-01

Mn doped ZnO nanoparticles with different doping concentration (1, 2, 3, 4, 5 at.%) were prepared by sol-gel method using supercritical drying conditions of ethyl alcohol. The structural, morphological, optical and magnetic properties of the as-prepared nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV measurements and superconducting quantum interference device (SQUID). The structural properties showed that the undoped and Mn doped ZnO nanoparticles exhibit hexagonal wurtzite structure. From the optical studies, the transmittance in UV region was decreased with the increase of Mn concentration. For Mn doped ZnO nanoparticles the optical band gap varies between 3.34 eV and 3.22 eV. It was found that the doping Mn 2+ ions have a significant influence on the optical properties. The magnetic characterization of the samples with 1% and 5% Mn concentrations reveal diamagnetic behavior for the first one and the presence of both paramagnetic and ferromagnetic behavior for the second. The room ferromagnetic component is due to the presence of the secondary phase ZnOMn3 which is confirmed by XRD study. © 2013 Elsevier Ltd. All rights reserved.

Magnetic and optical properties of manganese doped ZnO nanoparticles synthesized by sol-gel technique

KAUST Repository

Omri, Karim

2013-08-01

Mn doped ZnO nanoparticles with different doping concentration (1, 2, 3, 4, 5 at.%) were prepared by sol-gel method using supercritical drying conditions of ethyl alcohol. The structural, morphological, optical and magnetic properties of the as-prepared nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV measurements and superconducting quantum interference device (SQUID). The structural properties showed that the undoped and Mn doped ZnO nanoparticles exhibit hexagonal wurtzite structure. From the optical studies, the transmittance in UV region was decreased with the increase of Mn concentration. For Mn doped ZnO nanoparticles the optical band gap varies between 3.34 eV and 3.22 eV. It was found that the doping Mn 2+ ions have a significant influence on the optical properties. The magnetic characterization of the samples with 1% and 5% Mn concentrations reveal diamagnetic behavior for the first one and the presence of both paramagnetic and ferromagnetic behavior for the second. The room ferromagnetic component is due to the presence of the secondary phase ZnOMn3 which is confirmed by XRD study. © 2013 Elsevier Ltd. All rights reserved.

Three-dimensional mesoscale heterostructures of ZnO nanowire arrays epitaxially grown on CuGaO2 nanoplates as individual diodes.

Science.gov (United States)

Forticaux, Audrey; Hacialioglu, Salih; DeGrave, John P; Dziedzic, Rafal; Jin, Song

2013-09-24

We report a three-dimensional (3D) mesoscale heterostructure composed of one-dimensional (1D) nanowire (NW) arrays epitaxially grown on two-dimensional (2D) nanoplates. Specifically, three facile syntheses are developed to assemble vertical ZnO NWs on CuGaO2 (CGO) nanoplates in mild aqueous solution conditions. The key to the successful 3D mesoscale integration is the preferential nucleation and heteroepitaxial growth of ZnO NWs on the CGO nanoplates. Using transmission electron microscopy, heteroepitaxy was found between the basal planes of CGO nanoplates and ZnO NWs, which are their respective (001) crystallographic planes, by the observation of a hexagonal Moiré fringes pattern resulting from the slight mismatch between the c planes of ZnO and CGO. Careful analysis shows that this pattern can be described by a hexagonal supercell with a lattice parameter of almost exactly 11 and 12 times the a lattice constants for ZnO and CGO, respectively. The electrical properties of the individual CGO-ZnO mesoscale heterostructures were measured using a current-sensing atomic force microscopy setup to confirm the rectifying p-n diode behavior expected from the band alignment of p-type CGO and n-type ZnO wide band gap semiconductors. These 3D mesoscale heterostructures represent a new motif in nanoassembly for the integration of nanomaterials into functional devices with potential applications in electronics, photonics, and energy.

Direct evidence for As as a Zn-site impurity in ZnO

CERN Document Server

Wahl, Ulrich; Correia, J G; Lourenço-Santana-Marques, Ana Claudia; Alves, E; Carvalho-Soares, José

2005-01-01

Arsenic has been reported in the literature as one of the few p-type dopants in the technologically promising II-VI semiconductor ZnO. However, there is an ongoing debate whether the p-type character is due to As simply replacing O atoms or to the formation of more complicated defect complexes, possibly involving As on Zn sites. We have determined the lattice location of implanted As in ZnO by means of conversion electron emission channeling from radioactive $^{73}$As. In contrast to what one might expect from its nature as a group V element, we find that As does not occupy substitutional O sites but in its large majority substitutional Zn sites. Arsenic in ZnO (and probably also in GaN) is thus an interesting example for an impurity in a semiconductor where the major impurity lattice site is determined by atomic size and electronegativity rather than its position in the periodic system.

Enhancing the numerical aperture of lenses using ZnO nanostructure-based turbid media

International Nuclear Information System (INIS)

Khokhra, Richa; Barman, Partha Bir; Kumar, Rajesh; Kumar, Manoj; Rawat, Nitin; Jang, Hwanchol; Lee, Heung-No

2013-01-01

Nanosheets, nanoparticles, and microstructures of ZnO were synthesized via a wet chemical method. ZnO films with a thickness of 44–46 μm were fabricated by spray coating, and these have been investigated for their potential use in turbid lens applications. A morphology-dependent comparative study of the transmittance of ZnO turbid films was conducted. Furthermore, these ZnO turbid films were used to enhance the numerical aperture (NA) of a Nikon objective lens. The variation in NA with different morphologies was explained using size-dependent scattering by the fabricated films. A maximum NA of around 1.971 of the objective lens with a turbid film of ZnO nanosheets was achieved. (paper)

Effect of growth temperature on photoluminescence and piezoelectric characteristics of ZnO nanowires

Energy Technology Data Exchange (ETDEWEB)

Water, Walter [Institute of Electro-Optical and Materials Science, National Formosa University, Yunlin 632, Taiwan (China); Fang, T.-H. [Institute of Electro-Optical and Materials Science, National Formosa University, Yunlin 632, Taiwan (China); Institute of Mechanical and Electromechanical Engineering, National Formosa University, Yunlin 632, Taiwan (China)], E-mail: fang.tehua@msa.hinet.net; Ji, L.-W.; Lee, C.-C. [Institute of Electro-Optical and Materials Science, National Formosa University, Yunlin 632, Taiwan (China)

2009-02-25

ZnO nanowire arrays were synthesized on Au-coated silicon (1 0 0) substrates by using vapour-liquid-solid process in this work. The effect of growth temperatures on the crystal structure and the surface morphology of ZnO nanowires were investigated by X-ray diffraction and scanning electron microscope. The absorption and optical characteristics of the nanowires were examined by Ultraviolet/Visible spectroscopy, and photoluminescence, respectively. The photoluminescence results exhibited ZnO nanowires had an ultraviolet and blue emission at 383 and 492 nm. Then a nanogenerator with ZnO nanowire arrays was fabricated and demonstrated Schottky-like current-voltage characteristics.

Synthesis of ZnO thin film by sol-gel spin coating technique for H2S gas sensing application

Science.gov (United States)

Nimbalkar, Amol R.; Patil, Maruti G.

2017-12-01

In this present work, zinc oxide (ZnO) thin film synthesized by a simple sol-gel spin coating technique. The structural, morphology, compositional, microstructural, optical, electrical and gas sensing properties of the film were studied by using XRD, FESEM, EDS, XPS, HRTEM, Raman, FTIR and UV-vis techniques. The ZnO thin film shows hexagonal wurtzite structure with a porous structured morphology. Gas sensing performance of synthesized ZnO thin film was tested initially for H2S gas at different operating temperatures as well as concentrations. The maximum gas response is achieved towards H2S gas at 300 °C operating temperature, at 100 ppm gas concentration as compared to other gases like CH3OH, Cl2, NH3, LPG, CH3COCH3, and C2H5OH with a good stability.

Microwave assisted biosynthesis of rice shaped ZnO nanoparticles using Amorphophallus konjac tuber extract and its application in dye sensitized solar cells

Directory of Open Access Journals (Sweden)

Naresh Kumar P.

2017-02-01

Full Text Available Rice shaped ZnO nanoparticles have been synthesized for the first time by a biological process using Amorphophallus konjac tuber extract and used as a photoanode in a dye sensitized solar cell. The glucomannan present in aqueous tuber extract acted as a reducing agent in the synthesis process, further it also acted as a template which modified and controlled the shape of the nanoparticles. The synthesized nanoparticles were dried by microwave irradiation followed by annealing at 400 °C. The FESEM and TEM images confirmed that the synthesized ZnO nanoparticles had rice shaped morphology. Furthermore, the X-ray diffraction studies revealed that the prepared ZnO nanoparticles exhibited wurtzite phase with average particle size of 17.9 nm. The UV-Vis spectroscopy studies confirmed the value of band gap energy of biosynthesized ZnO nanoparticles as 3.11 eV. The photoelectrodes for dye sensitized solar cells were prepared with the biosynthesized ZnO nanoparticles using doctor blade method. The photoelectrode was sensitized using the fruit extract of Terminalia catappa, flower extracts of Callistemon citrinus and leaf extracts of Euphorbia pulcherrima. The dye sensitized solar cells were fabricated using the sensitized photoelectrode and their open circuit voltages and short circuit current densities were found to be in the range of 0.45 V to 0.55 V and 5.6 mA/cm2 to 6.8 mA/cm2, respectively. Thus, the photovoltaic performances of all the natural dye sensitized ZnO solar cells show better conversion efficiencies due to the morphology and preparation technique.

A Novel Sensor for VOCs Using Nanostructured ZnO and MEMS Technologies

Directory of Open Access Journals (Sweden)

H. J. Pandya

2012-03-01

Full Text Available A sensor for detection of vapors of volatile organic compounds (VOCs incorporating nanostructured zinc oxide film and silicon micromachining is reported. One of the key features of the sensor is the use of nanostructured ZnO material which has been synthesized using a novel low cost process. Considerable reduction in the operating temperature of the sensor has been achieved due to the use of nanostructured ZnO material as compared to a sensor having ZnO thin film as the sensing layer. The sensor is formed on a micromachined silicon platform thereby reducing the heat loss. This resulted in reduction in power consumption. The sensor has been tested for a variety of VOCs such as: ethanol, iso-propyl alcohol and acetone. The maximum sensitivity of sensor was observed for ethanol vapors.

Influence of High-Energy Proton Irradiation on β-Ga2O3 Nanobelt Field-Effect Transistors.

Science.gov (United States)

Yang, Gwangseok; Jang, Soohwan; Ren, Fan; Pearton, Stephen J; Kim, Jihyun

2017-11-22

The robust radiation resistance of wide-band gap materials is advantageous for space applications, where the high-energy particle irradiation deteriorates the performance of electronic devices. We report on the effects of proton irradiation of β-Ga 2 O 3 nanobelts, whose energy band gap is ∼4.85 eV at room temperature. Back-gated field-effect transistor (FET) based on exfoliated quasi-two-dimensional β-Ga 2 O 3 nanobelts were exposed to a 10 MeV proton beam. The proton-dose- and time-dependent characteristics of the radiation-damaged FETs were systematically analyzed. A 73% decrease in the field-effect mobility and a positive shift of the threshold voltage were observed after proton irradiation at a fluence of 2 × 10 15 cm -2 . Greater radiation-induced degradation occurs in the conductive channel of the β-Ga 2 O 3 nanobelt than at the contact between the metal and β-Ga 2 O 3 . The on/off ratio of the exfoliated β-Ga 2 O 3 FETs was maintained even after proton doses up to 2 × 10 15 cm -2 . The radiation-induced damage in the β-Ga 2 O 3 -based FETs was significantly recovered after rapid thermal annealing at 500 °C. The outstanding radiation durability of β-Ga 2 O 3 renders it a promising building block for space applications.

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.

Fabrication of novel Ag−TiO_2 nanobelts as a photoanode for enhanced photovoltage performance in dye sensitized solar cells

International Nuclear Information System (INIS)

Wang, Yang; Li, Zhen; Cao, Ya; Li, Fei; Zhao, Wen; Liu, Xueqin; Yang, Jianbo

2016-01-01

TiO_2 nanobelts (TiO_2NBs) were successfully prepared using a solvothermal route via Ti foil as substrate in large scales. The morphology evolution process and formation mechanism of the as-obtained products were investigated in detail. On the basis of this novel structure, chemical sensitive Ag modified TiO_2NBs nanocomposites (Ag−TiO_2NBs) were fabricated. It was found that Ag−TiO_2NBs exhibit strong light absorption and efficient electron transport. According to Mott-Schottky analysis, Ag−TiO_2NBs show less surface trapping sites compared with TiO_2NBs. The Ag−TiO_2NBs photoanode fabricated in 0.01 M AgNO_3 demonstrates the best performance with a short-circuit current of 11.9 mA cm"−"2 corresponding to a photoelectric conversion efficiency of 4.89%, which is higher than that of pure TiO_2NBs based solar cell by 60%. - Graphical abstract: J-V curves of DSSCs based on TiO_2NPs, TiO_2NBs and Ag−TiO_2NBs—X under AM 1.5 conditions (100 mW cm"−"2). Ag−TiO_2NBs nanocomposites were prepared via a simple and effective method. Owing to strong light absorption and efficient electron transport, Ag−TiO_2NBs—0.01 M shows a PCE of 4.89% when prepared as a photoanode in DSSCs. - Highlights: • A facile route was adopted to construct well-dispersed Ag nanoparticles on TiO_2 nanobelts (Ag—TiO_2NBs). • Structure and photoelectrochemical properties of Ag—TiO_2NBs were studied. • Ag nanoparticles were found to modify the defects of TiO_2NBs. • Enhanced photovoltaic property of Ag—TiO_2NBs, compared to TiO_2NBs.

Structural transformation of MoO3 nanobelts into MoS2 nanotubes

International Nuclear Information System (INIS)

Deepak, Francis Leonard; Mayoral, Alvaro; Yacaman, Miguel Jose

2009-01-01

The structural transformation of MoO 3 nanobelts into MoS 2 nanotubes using a simple sulfur source has been reported. This transformation has been extensively investigated using electron microscopic and spectroscopic techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), and energy-dispersive X-ray analysis (SEM-EDAX and TEM-EDX). The method described in this report will serve as a generic route for the transformation of other oxide nanostructures into the chalcogenide nanostructures. (orig.)

Synthesis and characterization of Mg-doped ZnO hollow spheres

International Nuclear Information System (INIS)

Hammad, Talaat M.; Salem, Jamil K.

2011-01-01

Mg-doped ZnO nanoparticles were synthesized by a simple chemical method at low temperature with Mg:Zn atomic ratio from 0 to 7%. The synthesis process is based on the hydrolysis of zinc acetate dihydrate and magnesium acetate tetrahydrate were heated under refluxing at 65 °C using methanol as a solvent. X-ray diffraction analysis reveals that the Mg-doped ZnO crystallizes in a wurtzite structure with crystal size of 5–12 nm. These nanocrystals self-aggregated themselves into hollow spheres of size of 800–1100 nm. High resolution transmission electron microscopy images show that each sphere is made up of numerous nanoparticles of average diameter 5–11 nm. The XRD patterns, SEM and TEM micrographs of doping of Mg in ZnO confirmed the formation of hollow spheres indicating that the Mg 2+ is successfully substituted into the ZnO host structure of the Zn 2+ site. Furthermore, the UV–Vis spectra and photoluminescence (PL) spectra of the ZnO nanoparticles were also investigated. The band gap of the nanoparticles can be tuned in the range of 3.36–3.55 eV by the use of the dopants.

Surface nanostructuring of thin film composite membranes via grafting polymerization and incorporation of ZnO nanoparticles

Science.gov (United States)

Isawi, Heba; El-Sayed, Magdi H.; Feng, Xianshe; Shawky, Hosam; Abdel Mottaleb, Mohamed S.

2016-11-01

A new approach for modification of polyamid thin film composite membrane PA(TFC) using synthesized ZnO nanoparticles (ZnO NPs) was shown to enhance the membrane performances for reverse osmosis water desalination. First, active layer of synthesis PA(TFC) membrane was activated with an aqueous solution of free radical graft polymerization of hydrophilic methacrylic acid (MAA) monomer onto the surface of the PA(TFC) membrane resulting PMAA-g-PA(TFC). Second, the PA(TFC) membrane has been developed by incorporation of ZnO NPs into the MAA grafting solution resulting the ZnO NPs modified PMAA-g-PA(TFC) membrane. The surface properties of the synthesized nanoparticles and prepared membranes were investigated using the FTIR, XRD and SEM. Morphology studies demonstrated that ZnO NPs have been successfully incorporated into the active grafting layer over PA(TFC) composite membranes. The zinc leaching from the ZnO NPs modified PMAA-g-PA(TFC) was minimal, as shown by batch tests that indicated stabilization of the ZnO NPs on the membrane surfaces. Compared with the a pure PA(TFC) and PMAA-g-PA(TFC) membranes, the ZnO NPs modified PMAA-g-PA(TFC) was more hydrophilic, with an improved water contact angle (∼50 ± 3°) over the PMAA-g-PA(TFC) (63 ± 2.5°). The ZnO NPs modified PMAA-g-PA(TFC) membrane showed salt rejection of 97% (of the total groundwater salinity), 99% of dissolved bivalent ions (Ca2+, SO42-and Mg2+), and 98% of mono valent ions constituents (Cl- and Na+). In addition, antifouling performance of the membranes was determined using E. coli as a potential foulant. This demonstrates that the ZnO NPs modified PMAA-g-PA(TFC) membrane can significantly improve the membrane performances and was favorable to enhance the selectivity, permeability, water flux, mechanical properties and the bio-antifouling properties of the membranes for water desalination.

Improve the open-circuit voltage of ZnO solar cells with inserting ZnS layers by two ways

International Nuclear Information System (INIS)

Sun, Yunfei; Yang, Jinghai; Yang, Lili; Cao, Jian; Gao, Ming; Zhang, Zhiqiang; Wang, Zhe; Song, Hang

2013-01-01

ZnS NPs layers were deposited on ZnO NRs by two different ways. One is spin coating; the other is successive ionic layer adsorption and reaction (SILAR) method. The ZnO NRs/ZnS NPs composites were verified by X-ray diffraction, X-ray photoelectron spectroscopy, and UV–visible spectrophotometer; their morphologies and thicknesses were examined by scanning electron microscopic and transmission electron microscopic images. The CdS quantum dot sensitized solar cells (QDSSCs) were constructed using ZnO NRs/ZnS NPs composites as photoanode and their photovoltaic characteristic was studied by J–V curves. The results indicated that the way of SILAR is more beneficial for retarding the back transfer of electrons to CdS and electrolyte than spin coating method. The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method. When ZnS NPs layer was deposited for 10 times on ZnO NRs, the conversion efficiency of QDSSC shows ∼3.3 folds increments of as-synthesized ZnO solar cell. - Graphical abstract: When ZnO nanorods were deposited by ZnS for 10 times, the conversion efficiency of QDSSC shows ∼3.3 folds increments of as-synthesized ZnO solar cell. Highlights: ► ZnS layers were deposited with two different ways. ► The way of SILAR is more beneficial for retarding the back transfer of electrons. ► The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method

Improve the open-circuit voltage of ZnO solar cells with inserting ZnS layers by two ways

Energy Technology Data Exchange (ETDEWEB)

Sun, Yunfei [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Yang, Jinghai, E-mail: jhyang1@jlnu.edu.cn [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Yang, Lili; Cao, Jian [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Gao, Ming [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Zhang, Zhiqiang; Wang, Zhe [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Song, Hang [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

2013-04-15

ZnS NPs layers were deposited on ZnO NRs by two different ways. One is spin coating; the other is successive ionic layer adsorption and reaction (SILAR) method. The ZnO NRs/ZnS NPs composites were verified by X-ray diffraction, X-ray photoelectron spectroscopy, and UV–visible spectrophotometer; their morphologies and thicknesses were examined by scanning electron microscopic and transmission electron microscopic images. The CdS quantum dot sensitized solar cells (QDSSCs) were constructed using ZnO NRs/ZnS NPs composites as photoanode and their photovoltaic characteristic was studied by J–V curves. The results indicated that the way of SILAR is more beneficial for retarding the back transfer of electrons to CdS and electrolyte than spin coating method. The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method. When ZnS NPs layer was deposited for 10 times on ZnO NRs, the conversion efficiency of QDSSC shows ∼3.3 folds increments of as-synthesized ZnO solar cell. - Graphical abstract: When ZnO nanorods were deposited by ZnS for 10 times, the conversion efficiency of QDSSC shows ∼3.3 folds increments of as-synthesized ZnO solar cell. Highlights: ► ZnS layers were deposited with two different ways. ► The way of SILAR is more beneficial for retarding the back transfer of electrons. ► The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method.

ZnO nanofluids for the improved cytotoxicity and cellular uptake of doxorubicin

Directory of Open Access Journals (Sweden)

Safoura Soleymani

2018-01-01

Full Text Available Objective(s: Combination anticancer therapy holds promise for improving the therapeutic efficacy of chemotherapy drugs such as doxorubicin (DOX as well as decreasing their dose-limiting side effects. Overcoming the side effects of doxorubicin (DOX is a major challenge to the effective treatment of cancer. Zinc oxide nanoparticles (ZnO NPs are emerging as potent tools for a wide variety of biomedical applications. The aim of this study was to develop a combinatorial approach for enhancing the anticancer efficacy and cellular uptake of DOX. Materials and Methods: ZnO NPs were synthesized by the solvothermal method and were characterized by X-ray diffraction (XRD, dynamic light scattering (DLS and transmission electron microscopy (TEM. ZnO NPs were dispersed in 10% bovine serum albumin (BSA and the cytotoxic effect of the resulting ZnO nanofluids was evaluated alone and in combination with DOX on DU145 cells. The influence of ZnO nanofluids on the cellular uptake of DOX and DOX-induced catalase mRNA expression were investigated by fluorescence microscopy and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR, respectively. Results: The MTT results revealed that ZnO nanofluids decreased the cell viability of DU145 cells in a timeand dose-dependent manner. Simultaneous combination treatment of DOX and ZnO nanofluid showed a significant increase in anticancer activity and the cellular uptake of DOX compared to DOX alone. Also, a time-dependent reduction of catalase mRNA expression was observed in the cells treated with ZnO nanofluids and DOX, alone and in combination with each other. Conclusion: These results indicate the role of ZnO nanofluid as a growth-inhibitory agent and a drug delivery system for DOX in DU145 cells. Thus, ZnO nanofluid could be a candidate for combination chemotherapy.

Effect of capping agents: Structural, optical and biological properties of ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Javed, Rabia [Department of Biotechnology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Usman, Muhammad, E-mail: uk_phy@yahoo.com [Department of Physics, Faculty of Natural Sciences, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Department of Physics, School of Science and Engineering, Lahore University of Management Sciences, Lahore 54729 (Pakistan); Tabassum, Saira; Zia, Muhammad [Department of Biotechnology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2016-11-15

Highlights: • ZnO nanoparticles have been effectively capped with polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) shown by the data of XRD, FTIR and UV–visible spectroscopy. • Reduction in size occurred from 34 nm to 26 nm due to capping agent and band gap energy increases with the decrease in the particle size. • Antibacterial activity against Gram-positive bacteria is greater than the Gram-negative bacteria. • All biological assays reveal highest activities in capped ZnO nanoparticles as compared to the uncapped ZnO nanoparticles. • Highest antibacterial activity has been exhibited by ZnO-PVP while highest antioxidant and antidiabetic activities have been conferred by ZnO- PEG. - Abstract: Different biological activities of capped and uncapped ZnO nanoparticles were investigated, and the effects of potential capping agents on these biological activities were studied. ZnO nanoparticles were synthesized and capped by polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) using a simple chemical method of co-precipitation. Characterization by X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR) and UV–vis spectroscopy confirmed the crystallinity, size, functional group, and band gap of synthesized nanoparticles. Reduction in size occurred from 34 nm to 26 nm due to surfactant. Results of all biological activities indicated significantly higher values in capped as compared to uncapped nanoparticles. Antibacterial activity against Staphylococcus aureus (ATCC 6538), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC15224), and Acetobacter was obtained. This activity was more prominent against Gram-positive bacteria, and ZnO-PVP nanoparticles elucidated highest antibacterial activity (zone of inhibition 17 mm) against Gram-positive, Bacillus subtilis species. Antioxidant activities including total flavonoid content, total phenolic content, total antioxidant capacity, total reducing power and %age inhibition of DPPH, and

Effect of capping agents: Structural, optical and biological properties of ZnO nanoparticles

International Nuclear Information System (INIS)

Javed, Rabia; Usman, Muhammad; Tabassum, Saira; Zia, Muhammad

2016-01-01

Highlights: • ZnO nanoparticles have been effectively capped with polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) shown by the data of XRD, FTIR and UV–visible spectroscopy. • Reduction in size occurred from 34 nm to 26 nm due to capping agent and band gap energy increases with the decrease in the particle size. • Antibacterial activity against Gram-positive bacteria is greater than the Gram-negative bacteria. • All biological assays reveal highest activities in capped ZnO nanoparticles as compared to the uncapped ZnO nanoparticles. • Highest antibacterial activity has been exhibited by ZnO-PVP while highest antioxidant and antidiabetic activities have been conferred by ZnO- PEG. - Abstract: Different biological activities of capped and uncapped ZnO nanoparticles were investigated, and the effects of potential capping agents on these biological activities were studied. ZnO nanoparticles were synthesized and capped by polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) using a simple chemical method of co-precipitation. Characterization by X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR) and UV–vis spectroscopy confirmed the crystallinity, size, functional group, and band gap of synthesized nanoparticles. Reduction in size occurred from 34 nm to 26 nm due to surfactant. Results of all biological activities indicated significantly higher values in capped as compared to uncapped nanoparticles. Antibacterial activity against Staphylococcus aureus (ATCC 6538), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC15224), and Acetobacter was obtained. This activity was more prominent against Gram-positive bacteria, and ZnO-PVP nanoparticles elucidated highest antibacterial activity (zone of inhibition 17 mm) against Gram-positive, Bacillus subtilis species. Antioxidant activities including total flavonoid content, total phenolic content, total antioxidant capacity, total reducing power and %age inhibition of DPPH, and

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

Science.gov (United States)

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

2018-05-01

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

Structural and optical properties of Co-doped ZnO nanocrystallites prepared by a one-step solution route

International Nuclear Information System (INIS)

Li Ping; Wang Sha; Li Jibiao; Wei Yu

2012-01-01

Zinc oxide (ZnO) nanocrystallites with different Co-doping levels were successfully synthesized by a simple one-step solution route at low temperature (95 deg. C) in this study. The structure and morphology of the samples thus obtained were characterized by XRD, EDS, XPS and FESEM. Results show that cobalt ions, in the oxidation state of Co 2+ , replace Zn 2+ ions in the ZnO lattice without changing its wurtzite structure. The dopant content varies from 0.59% to 5.39%, based on Co-doping levels. The pure ZnO particles exhibit well-defined 3D flower-like morphology with an average size of 550 nm, while the particles obtained after Co-doping are mostly cauliflower-like nanoclusters with an average size of 120 nm. Both the flower-like pure ZnO and the cauliflower-like Co:ZnO nanoclusters are composed of densely arrayed nanorods. The optical properties of the ZnO nanocrystallites following Co-doping were also investigated by UV-Visible absorption and Photoluminescence spectra. Our results indicate that Co-doping can change the energy-band structure and effectively adjust the luminescence properties of ZnO nanocrystallites. - Highlights: → Co-doped ZnO nanocrystallites were synthesized via a simple one-step solution route. → Co 2+ ions incorporated into the ZnO lattice without changing its wurtzite structure. → Co-doping changed the energy band structure of ZnO. → Co-doping effectively adjusted the luminescence properties of ZnO nanocrystallites.

Structural and optical properties of Co-doped ZnO nanocrystallites prepared by a one-step solution route

Energy Technology Data Exchange (ETDEWEB)

Li Ping, E-mail: lipingchina@yahoo.com.cn [Provincial Key Laboratory of Inorganic Nanomaterials, School of Chemistry and Materials Science, Hebei Normal University, 113 Yuhua Road, Shijiazhuang 050016, Hebei (China); Wang Sha; Li Jibiao; Wei Yu [Provincial Key Laboratory of Inorganic Nanomaterials, School of Chemistry and Materials Science, Hebei Normal University, 113 Yuhua Road, Shijiazhuang 050016, Hebei (China)

2012-01-15

Zinc oxide (ZnO) nanocrystallites with different Co-doping levels were successfully synthesized by a simple one-step solution route at low temperature (95 deg. C) in this study. The structure and morphology of the samples thus obtained were characterized by XRD, EDS, XPS and FESEM. Results show that cobalt ions, in the oxidation state of Co{sup 2+}, replace Zn{sup 2+} ions in the ZnO lattice without changing its wurtzite structure. The dopant content varies from 0.59% to 5.39%, based on Co-doping levels. The pure ZnO particles exhibit well-defined 3D flower-like morphology with an average size of 550 nm, while the particles obtained after Co-doping are mostly cauliflower-like nanoclusters with an average size of 120 nm. Both the flower-like pure ZnO and the cauliflower-like Co:ZnO nanoclusters are composed of densely arrayed nanorods. The optical properties of the ZnO nanocrystallites following Co-doping were also investigated by UV-Visible absorption and Photoluminescence spectra. Our results indicate that Co-doping can change the energy-band structure and effectively adjust the luminescence properties of ZnO nanocrystallites. - Highlights: > Co-doped ZnO nanocrystallites were synthesized via a simple one-step solution route. > Co{sup 2+} ions incorporated into the ZnO lattice without changing its wurtzite structure. > Co-doping changed the energy band structure of ZnO. > Co-doping effectively adjusted the luminescence properties of ZnO nanocrystallites.

Tri-functional Fe2O3-encased Ag-doped ZnO nanoframework: magnetically retrievable antimicrobial photocatalyst

Science.gov (United States)

Karunakaran, Chockalingam; Vinayagamoorthy, Pazhamalai

2016-11-01

Fe2O3-encased ZnO nanoframework was obtained by hydrothermal method and was doped with Ag through photoreduction process. Energy dispersive x-ray spectroscopy, transmission electron microscopy (TEM), high resolution TEM, selected area electron diffractometry, x-ray diffractometry and Raman spectroscopy were employed for the structural characterization of the synthesized material. While the charge transfer resistance of the prepared nanomaterial is larger than those of Fe2O3 and ZnO the coercivity of the nanocomposite is less than that of hydrothermally obtained Fe2O3 nanostructures. Although Fe2O3/Ag-ZnO exhibits weak visible light absorption its band gap energy does not differ from that of ZnO. The photoluminescence of the fabricated nanoframework is similar to that of ZnO. The radiative recombination of charge carriers is slightly slower in Fe2O3/Ag-ZnO than in ZnO. The synthesized Fe2O3-encased Ag-doped ZnO, under UV A light, exhibits sustainable photocatalytic activity to degrade dye and is magnetically recoverable. Also, the Fe2O3/Ag-ZnO nanocomposite disinfects bacteria effectively in absence of direct illumination.

Different valence Sn doping - A simple way to detect oxygen concentration variation of ZnO quantum dots synthesized under ultrasonic irradiation.

Science.gov (United States)

Yang, Weimin; Zhang, Bing; Zhang, Qitu; Wang, Lixi; Song, Bo; Wu, Fan; Wong, C P

2017-09-01

An ultrasonic method is employed to synthesize the Sn doped Zn 0.95 Sn 0.05 O quantum dots with green light emission. Sn 2+ and Sn 4+ ions are used to create different optical defects inside Zn 0.95 Sn 0.05 O quantum dots and the changing trend of oxygen concentration under different ultrasonic irradiation power are investigated. The photoluminescence spectra are employed to characterize the optical defects of Zn 0.95 Sn 0.05 O quantum dots. The UV-vis spectra are used to study the band gap of Zn 0.95 Sn 0.05 O quantum dots, which is influenced by their sizes. The results indicate that ultrasonic power would influence the size of Zn 0.95 Sn 0.05 O quantum dots as well as the type and quantity of defects in ZnO quantum dots. Changing trends in size of Sn 2+ and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots are quite similar with each other, while the changing trends in optical defects types and concentration of Sn 2+ and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots are different. The difference of the optical defects concentration changing between Sn 2+ doped Zn 0.95 Sn 0.05 O quantum dots (V O defects) and Sn 4+ doped Zn 0.95 Sn 0.05 O quantum dots (O Zn and O i defects) shows that the formation process of ZnO under ultrasonic irradiation wiped oxygen out. Copyright © 2017 Elsevier B.V. All rights reserved.

Eosin-Y sensitized core-shell TiO2-ZnO nano-structured photoanodes for dye-sensitized solar cell applications.

Science.gov (United States)

Manikandan, V S; Palai, Akshaya K; Mohanty, Smita; Nayak, Sanjay K

2018-06-01

In the current investigation, TiO 2 and TiO 2 -ZnO (core-shell) spherical nanoparticles were synthesized by simple combined hydrolysis and refluxing method. A TiO 2 core nanomaterial on the shell material of ZnO was synthesized by utilizing variable ratios of ZnO. The structural characterization of TiO 2 -ZnO core/shell nanoparticles were done by XRD analysis. The spherical structured morphology of the TiO 2 -ZnO has been confirmed through field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) studies. The UV-visible spectra of TiO 2 -ZnO nanostructures were also compared with the pristine TiO 2 to investigate the shift of wavelength. The TiO 2 -ZnO core/shell nanoparticles at the interface efficiently collect the photogenarated electrons from ZnO and also ZnO act a barrier for reduced charge recombination of electrolyte and dye-nanoparticles interface. This combination improved the light absorption which induced the charge transfer ability and dye loading capacity of core-shell nanoparticles. An enhancement in the short circuit current (J sc ) from 1.67 mA/cm 2 to 2.1 mA/cm 2 has been observed for TiO 2 -ZnObased photoanode (with platinum free counter electrode), promises an improvement in the energy conversion efficiency by 57% in comparison with that of the DSSCs based on the pristine TiO 2 . Henceforth, TiO 2 -ZnO photoelectrode in ZnO will effectively act as barrier at the interface of TiO 2 -ZnO and TiO 2 , ensuring the potential for DSSC application. Copyright © 2018 Elsevier B.V. All rights reserved.

High electro-catalytic activities of glucose oxidase embedded one-dimensional ZnO nanostructures

International Nuclear Information System (INIS)

Sarkar, Nirmal K; Bhattacharyya, Swapan K

2013-01-01

One-dimensional ZnO nanorods and nanowires are separately synthesized on Zn substrate by simple hydrothermal processes at low temperatures. Electro-catalytic responses of glucose oxidase/ZnO/Zn electrodes using these two synthesized nanostructures of ZnO are reported and compared with others available in literature. It is apparent the Michaelis–Menten constant, K M app , for the present ZnO nanowire, having a greater aspect ratio, is found to be the lowest when compared with others. This sensor shows lower oxidation peak potential with a long detection range of 6.6 μM–380 mM and the highest sensitivity of ∼35.1 μA cm −2 mM −1 , among the reported values in the literature. Enzyme catalytic efficiency and turnover numbers are also found to be remarkably high. (paper)

Efficient solution route to transparent ZnO semiconductor films using colloidal nanocrystals

Directory of Open Access Journals (Sweden)

Satoshi Suehiro

2016-09-01

Full Text Available ZnO nanocrystals (NCs were synthesized by heating Zn (II acetylacetonate in oleic acid/oleylamine in the presence of 1,2-hexadecanediol at 220 °C. Transmission electron microscopy (TEM and dynamic light scattering (DLS measurements revealed the formation of monodispersed ZnO NCs of ca. 7 nm. ZnO NC assembled films were fabricated on a glass substrate by deposition with the colloidal ZnO NCs dispersed in toluene. The film composed of the NCs showed good optical transparency in the visible to near-infrared region. A device coupling the ZnO NC film with a p-type Cu2ZnSnS4 (CZTS NC film exhibited an obvious diode-like current–voltage behavior. The results suggest that the transparent ZnO film has a potentiality to be used for an n-type window layer in some optoelectronic applications.

Gum Tragacanth-Mediated Synthesis of Nanocrystalline ZnO Powder for Use in Varistors

Science.gov (United States)

Liu, Ting-Ting; Wang, Mao-Hua; Su, Hang; Chen, Xi; Chen, Chao; Zhang, Ruo-Chen

2015-10-01

Zinc oxide nanopowders were synthesized by a sol-gel method with gum tragacanth and zinc nitrate as raw materials. Gum tragacanth was used as stabilizer to control the mobility of zinc cations and the growth of the nanopowders. Thermo-gravimetric analysis, x-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, and scanning electron microscopy were used to characterize the as-prepared samples. Zinc oxide (ZnO) nanoparticles calcined at different temperatures had a hexagonal wurtzite structure with average particle size ranging from 32.29 nm to 42.83 nm. The crystallinity of ZnO nanoparticles was improved by increasing the calcination temperature. The density of ZnO varistor ceramics sintered at 1150°C for 2 h in air was 5.46 g/cm3, which was 97.5% of the theoretical density, their breakdown voltage was 4572 V/cm, and their nonlinear coefficient was ~16.8. This method can be used as an excellent alternative method for synthesis of ZnO nanoparticles with a plant extract as a raw material. Our experimental results show our method had the advantage of improving the electrical performance of ZnO varistors.

Microwave synthesis and photocatalytic activities of ZnO bipods with different aspect ratios

Energy Technology Data Exchange (ETDEWEB)

Sun, Fazhe; Zhao, Zengdian [Analysis and Testing Center, Shandong University of Technology, Zibo 255100 (China); Qiao, Xueliang, E-mail: xuelqiao@163.com [State Key Laboratory of Plastic Forming Simulation and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Tan, Fatang; Wang, Wei [State Key Laboratory of Plastic Forming Simulation and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China)

2016-02-15

Highlights: • We synthesized linked ZnO nanorods by a facile microwave method. • The effect of reaction parameters on ZnO was investigated. • ZnO bipods with different aspect ratios were prepared. • The photocatalytic performance of ZnO bipods was evaluated. - Abstract: Linked ZnO nanorods have been successfully prepared via a facile microwave method without any post-synthesis treatment. The X-ray diffraction (XRD) patterns indicated the precursor had completely transformed into the pure ZnO crystal. The images of field emitting scanning electron microscope (FESEM) and transmission electron microscope (TEM) showed that linked ZnO nanorods consisted predominantly of ZnO bipods. The formation process of the ZnO bipods was clearly discussed. ZnO bipods with different aspect ratios have been obtained by tuning the concentrations of reagents and microwave power. Moreover, the photocatalytic performance of ZnO bipods with different aspect ratios for degradation of methylene blue was systematically evaluated. The results of photocatalytic experiments showed that the photocatalytic activity increased with the aspect ratios of ZnO bipods increased. The reason is that ZnO bipods with larger aspect ratio have higher surface area, which can absorb more MB molecules to react with ·OH radicals.

Photoluminescence study of novel phosphorus-doped ZnO nanotetrapods synthesized by chemical vapour deposition

International Nuclear Information System (INIS)

Yu Dongqi; Hu Lizhong; Qiao Shuangshuang; Zhang Heqiu; Fu Qiang; Chen Xi; Sun Kaitong; Len, Song-En Andy; Len, L K

2009-01-01

Novel phosphorus-doped and undoped single crystal ZnO nanotetrapods were fabricated on sapphire by a simple chemical vapour deposition method, using phosphorus pentoxide (P 2 O 5 ) as the dopant source. The optical properties of the samples were investigated by photoluminescence (PL) spectroscopy. Low-temperature PL measurements of phosphorus-doped and undoped samples were compared, and the results indicated a decrease in deep level defects due to the incorporation of a phosphorus acceptor dopant. The PL spectrum of the phosphorus-doped sample at 10 K exhibited several acceptor-bound exciton related emission peaks. The effect of phosphorus doping on the optical characteristics of the samples was investigated by excitation intensity and temperature dependent PL spectra. The acceptor-binding energies of the phosphorus dopant were estimated to be about 120 meV, in good agreement with the corresponding theoretical and experimental values in phosphorus-doped ZnO films and nanowires.

Enhanced luminescence properties of hybrid Alq{sub 3}/ZnO (organic/inorganic) composite films

Energy Technology Data Exchange (ETDEWEB)

Cuba, M.; Muralidharan, G., E-mail: muraligru@gmail.com

2014-12-15

Pristine tris-(8-hydroxyquionoline)aluminum(Alq{sub 3}) and (Alq{sub 3}/ZnO hybrid) composites containing different weight percentages (5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt%) of ZnO in Alq{sub 3} were synthesized and coated on to a glass substrate using the dip coating method. The optimum concentration of ZnO in Alq{sub 3} films to get the best luminescence yield has been identified. XRD pattern reveals the amorphous nature of pure Alq{sub 3} film. The Alq{sub 3} films containing different weight percentages of ZnO show the presence of crystalline ZnO in Alq{sub 3}/ZnO composite films. The FTIR spectrum confirms the formation of quinoline with absorption in the region 600−800 cm{sup −1}. The hybrid Alq{sub 3}/ZnO composite films indicate the presence of Zn−O vibration band along with the corresponding Alq{sub 3} band. The band gap (HOMO–LUMO) of Alq{sub 3} film was calculated using absorption spectra and it is 2.87 eV for pristine films while it is 3.26 eV, 3.21 eV, 3.14 eV, 3.10 eV, 3.13 eV and 3.20 eV for the composite films containing 5–50 wt% of ZnO. The photoluminescence (PL) spectra of Alq{sub 3} films show a maximum PL intensity at 514 nm when excited at 390 nm. The ZnO incorporated composite films (Alq{sub 3}/ZnO) exhibit an emission in 485 nm and 514 nm. The composite films containing 30 wt% of ZnO exhibit maximum luminescence yield. - Highlights: • The pure Alq{sub 3} and Alq{sub 3}/ZnO composite were synthesized and coated on to a glass substrate using dip coating method. • Alq{sub 3}/ZnO composite film containing 30 wt% of ZnO exhibits two fold increases in luminescence intensity. • The shielding effect of ZnO on the Alq{sub 3} material suppresses the interactions among the host molecules in the excited state. • This leads to enhance the luminescence intensity in composite films.

Synthesis of well-dispersed ZnO nanomaterials by directly calcining zinc stearate

International Nuclear Information System (INIS)

Guo Guangsheng; Shi Chen; Tao Dongliang; Qian Weizhong; Han Dongmei

2009-01-01

Well-dispersed ZnO nanomaterials were synthesized by direct calcination of zinc stearate. Results from Fourier transform infrared (FT-IR) spectra and X-ray diffraction (XRD) indicated both the decomposition degree of organic ligand and the purity of calcined products were increased with the calcination temperature. The influence of decomposition temperature on the morphology of ZnO nanomaterials was investigated by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The experimental results revealed the morphology of ZnO transformed from nanosheets to hexagonal nanopyramids and then to nanoparticles at 573, 673 and 773 K respectively. Finally, a morphology evolution model of ZnO nanomaterials under different temperatures was proposed

Dynamic recovery and optical properties changes in He-implanted ZnO nanoparticles

International Nuclear Information System (INIS)

Lee, J.-K.; Harriman, T.A.; Lucca, D.A.; Jung, H.S.; Ryan, D.B.; Nastasi, M.

2007-01-01

A study of the effects of ion-implanted He + on the photoluminescence (PL) of ZnO nanoparticles is presented. This investigation is motivated by the need to further understand the effects of damage resulting from the implantation process on the luminescence response of the nanoparticles. ZnO nanoparticles were synthesized by reacting zinc acetate with lithium hydroxide. The nanoparticle suspension was then dip coated on SiO 2 substrates producing thin films of ZnO nanoparticles, which were then implanted with He + ions at either room temperature or 400 deg. C. Following implantation, the PL spectrum of the ZnO nanoparticles was investigated and compared to that obtained from He-implanted bulk ZnO. Change in the overall luminescence efficiency was found to depend on both the size of the nanoparticles and the implantation temperature, and is attributed to the dynamic recovery of collision cascades in the ZnO nanoparticles. In addition, a comparison of He + -implanted ZnO nanoparticles with He + -implanted ZnO single crystals indicates that the origin of the green luminescence occurring from the ZnO nanoparticles is near-surface complex defects

Enhanced ethanol gas sensing performance of the networked Pd, In2O3-codecorated ZnO nanorod sensor

Science.gov (United States)

Lee, Sangmin; Sun, Gun-Joo; Lee, Jae Kyung; Hyun, Soong Keun; Lee, Chongmu

2017-10-01

ZnO nanorods codecorated with Pd and In2O3 nanoparticles were synthesized by thermal evaporation of a mixture of ZnO and graphite powders in an oxidizing atmosphere and followed by solvothermal deposition of Pd and In2O3 and their ethanol gas sensing properties were examined. Pristine ZnO nanorods, Pd-decorated ZnO nanorods and In2O3-decorated ZnO nanorods were also prepared in a similar manner. The codecorated ZnO nanorod sensor showed significantly stronger response to ethanol than the other three sensors, suggesting a synergistic effect of Pd and In2O3 codecoration. The former also showed faster response and recovery than the latter. The pristine and codecorated ZnO nanorod sensors exhibited selectivity toward ethanol over other gases such as acetone, CO, benzene, and toluene. The underlying mechanism for the enhanced sensing performance of the Pd, In2O3-codecorated ZnO nanorod sensor toward ethanol is discussed.

Synergistic effect of indium and gallium co-doping on the properties of RF sputtered ZnO thin films

Science.gov (United States)

Shaheera, M.; Girija, K. G.; Kaur, Manmeet; Geetha, V.; Debnath, A. K.; Karri, Malvika; Thota, Manoj Kumar; Vatsa, R. K.; Muthe, K. P.; Gadkari, S. C.

2018-04-01

ZnO thin films were synthesized using RF magnetron sputtering, with simultaneous incorporation of Indium (In) and Gallium (Ga). The structural, optical, chemical composition and surface morphology of the pure and co-doped (IGZO) thin films were characterized by X-Ray diffraction (XRD), UV-visible spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), and Raman spectroscopy. XRD revealed that these films were oriented along c-axis with hexagonal wurtzite structure. The (002) diffraction peak in the co-doped sample was observed at 33.76° with a slight shift towards lower 2θ values as compared to pure ZnO. The surface morphology of the two thin films was observed to differ. For pure ZnO films, round grains were observed and for IGZO thin films round as well as rod type grains were observed. All thin films synthesized show excellent optical properties with more than 90% transmission in the visible region and band gap of the films is observed to decrease with co-doping. The co doping of In and Ga is therefore expected to provide a broad range optical and physical properties of ZnO thin films for a variety of optoelectronic applications.

Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases

Directory of Open Access Journals (Sweden)

Elena Dilonardo

2016-01-01

Full Text Available A one-step electrochemical method based on sacrificial anode electrolysis (SAE was used to deposit stabilized gold nanoparticles (Au NPs directly on the surface of nanostructured ZnO powders, previously synthesized through a sol–gel process. The effect of thermal annealing temperatures (300 and 550 °C on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au@ZnO was investigated. Transmission and scanning electron microscopy (TEM and SEM, as well as X-ray photoelectron spectroscopy (XPS, revealed the successful deposition of nanoscale gold on the surface of spherical and rod-like ZnO nanostructures, obtained after annealing at 300 and 550 °C, respectively. The pristine ZnO and Au@ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 °C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the gas-sensing properties.

Solvothermal synthesis of nanorods of ZnO, N-doped ZnO and CdO

International Nuclear Information System (INIS)

Varghese, Neenu; Panchakarla, L.S.; Hanapi, M.; Govindaraj, A.; Rao, C.N.R.

2007-01-01

ZnO nanorods with diameters in the 80-800 nm range are readily synthesized by the reaction of zinc acetate, ethanol and ethylenediamine under solvothermal conditions. The best products are obtained at 330 deg. C with a slow heating rate. Addition of the surfactant Triton -X 100 gave nanorods of uniform (300 nm) diameter. By adding a small amount of liquid NH 3 to the reaction mixture, N-doped ZnO nanorods, with distinct spectroscopic features are obtained. CdO nanorods of 80 nm diameter have been prepared under solvothermal conditions using a mixture of cadmium cupferronate, ethylenediamine and ethanol at 330 deg. C. Similarly, Zn 1-x Cd x O nanorods of a 70 nm diameter are obtained under solvothermal conditions starting with a mixture of zinc acetate, cadmium cupferronate, ethanol and ethylenediamine

Biodiesel synthesis by TiO2-ZnO mixed oxide nanocatalyst catalyzed palm oil transesterification process.

Science.gov (United States)

Madhuvilakku, Rajesh; Piraman, Shakkthivel

2013-12-01

Biodiesel is a promising alternating environmentally benign fuel to mineral diesel. For the development of easier transesterification process, stable and active heterogeneous mixed metal oxide of TiO2-ZnO and ZnO nanocatalysts were synthesized and exploited for the palm oil transesterification process. The synthesized catalysts were characterized by XRD, FT-IR, and FE-SEM studies for their structural and morphological characteristics. It was found that TiO2-ZnO nanocatalyst exhibits good catalytic activity and the catalytic performance was greatly depends on (i) catalyst concentration (ii) methanol to oil molar ratio (iii) reaction temperature and (iv) reaction time. A highest 98% of conversion was obtained at the optimum reaction parameters with 200 mg of catalyst loading and the biodiesel was analyzed by TLC and (1)H NMR techniques. The TiO2-ZnO nanocatalyst shows good catalytic performance over the ZnO catalyst, which could be a potential candidate for the large-scale biodiesel production from palm oil at the reduced temperature and time. Copyright © 2013. Published by Elsevier Ltd.

UV irradiation assisted growth of ZnO nanowires on optical fiber surface

Energy Technology Data Exchange (ETDEWEB)

Gong, Bo; Shi, Tielin; Liao, Guanglan; Li, Xiaoping; Huang, Jie; Zhou, Temgyuan; Tang, Zirong, E-mail: zirong@mail.hust.edu.cn

2017-06-01

Highlights: • A new fabrication process combined a hydrothermal process with UV irradiation from optical fiber is developed. • The growth of ZnO nanowires is efficient in the utilization of UV light. • A novel hybrid structure which integrates ZnO nanowires on optical fiber surface is synthesized. • The UV assisted growth of ZnO nanowires shows preferred orientation and better quality. • A mechanism of growing ZnO nanowires under UV irradiation is proposed. - Abstract: In this paper, a novel approach was developed for the enhanced growth of ZnO nanowires on optical fiber surface. The method combined a hydrothermal process with the efficient UV irradiation from the fiber core, and the effects of UV irradiation on the growth behavior of ZnO nanowires were investigated. The results show that UV irradiation had great effects on the preferred growth orientation and the quality of the ZnO nanowires. The crystallization velocity along the c-axis would increase rapidly with the increase of the irradiation power, while the growth process in the lateral direction was marginally affected by the irradiation. The structure of ZnO nanowires also shows less oxygen vacancy with UV irradiation of higher power. The developed approach is applicable for the efficient growth of nanowires on the fiber surface, and the ZnO nanowires/optical fiber hybrid structures have great potentials for a wide variety of applications such as optical fiber sensors and probes.

Function of NaOH hydrolysis in electrospinning ZnO nanofibers via using polylactide as templates

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