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RISS 인기검색어
- 검색키워드
- 저자 : Yuewei Zhang (검색결과 2 건)
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Preparation of highly efficient Al-doped ZnO photocatalyst by combustion synthesis
M. Ahmad,E. Ahmed,Yuewei Zhang,N.R. Khalid,Jianfeng Xu,M. Ullah,Zhanglian Hong 한국물리학회 2013 Current Applied Physics Vol.13 No.4
Novel Al-doped ZnO (AZO) photocatalysts with different Al concentrations (0.5e6.0 mol%) were prepared through a facile combustion method and followed by calcination at 500 ℃ for 3 h. The obtained nanopowders were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) combined with EDX, transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UVevis spectroscopy and photoluminescence spectroscopy. The XRD patterns of AZO nanopowders were assigned to wurtzite structure of ZnO with the smallest crystallite size about 11 nm consistent with the results from TEM. The doping of Al in ZnO crystal structure successfully suppressed the growth of ZnO nanoparticles confirmed by XRD patterns. The absorption spectra analysis showed that the optical band gap energy (Eg) for the AZO nanopowders were in the range of 3.12-3.21 eV and decreased with increasing of Al dopant. The photocatalytic activities of the samples were evaluated by photocatalytic degradation of methyl orange under visible light (λ≥ 420 nm) and sunlight irradiation. The results showed that the AZO photocatalyst doped with 4.0 mol% Al exhibited five times enhanced photocatalytic activity compared to pure ZnO. The enhanced photocatalytic activity could be attributed to extended visible light absorption, inhibition of the electronehole pair’s recombination and enhanced adsorptivity of MO dye molecule on the surface of AZO nanopowders.
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Nitrogen doped TiO2 nanoparticles decorated on graphene sheets for photocatalysis applications
N.R. Khalid,E. Ahmed,Zhanglian Hong,Yuewei Zhang,M. Ahmad 한국물리학회 2012 Current Applied Physics Vol.12 No.6
Nitrogen doped TiO2 nanoparticles decorated on graphene sheets are successfully synthesized by a lowtemperature hydrothermal method. The resulting GR-N/TiO2 composites are characterized by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-Ray photoelectron spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The optical properties are studied using UVevisible diffuse reflectance spectroscopy (DRS), which confirms that the spectral responses of the composite catalysts are extended to the visible-light region and show a significant reduction in band gap energy from 3.18 to 2.64 eV. Photoluminescence emission spectra verify that GR-N/TiO2 composites possess better charge separation capability than pure TiO2. The photocatalytic activity is tested by degradation of methyl orange (MO) dye under visible light irradiation. The results demonstrate that GR-N/TiO2composites can effectively photodegrade MO, showing an impressive photocatalytic enhancement over pure TiO2. The dramatically enhanced activity of composite photocatalysts can be attributed to great adsorption of dyes, enhanced visible light absorption and efficient charge separation and transfer processes. This work may provide new insights into the design of novel composite photocatalysts system with efficient visible light activity.
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