The samples of nano-size ZnO were pre pared by precipitation,hydrolysis,sol-gel method and characterized b y X-ray diffraction,Uv-Vis diffuse r eflection spectrum,and time resolv ed luminescent spectrum.The results sh...The samples of nano-size ZnO were pre pared by precipitation,hydrolysis,sol-gel method and characterized b y X-ray diffraction,Uv-Vis diffuse r eflection spectrum,and time resolv ed luminescent spectrum.The results showed that the crystallite dimensions of a ll ZnO samples were coarsening with i ncreasing annealing temperature an d the grain sizes prepared by sol-gel meth od were obviously smaller than the others prepared by precipitation and h y-drolysis method.Under excitation o f monochromatic light of wavelength300nm,a strong and broad photolumin es-cence(PL)emissions were observed in the wavelength range of 420～780nm.As the grain size decreased,the PL peak positions moved to shorter wavelengths.And as the annealing temperature increased,the peak intensity de-creased.The photoluminescence dec ay profile of ZnO was well described b y three decay components of 46ns,330ns and 1630ns.展开更多
The Gd3+-doped TiO2 photocatalyst was prepared by the sol-gel and impregnation method. The effect of Gd3+ doping on crystalline size, BET surface area and photocatalytic activity was studied by XRD, FTIR, BET, UV-Vis ...The Gd3+-doped TiO2 photocatalyst was prepared by the sol-gel and impregnation method. The effect of Gd3+ doping on crystalline size, BET surface area and photocatalytic activity was studied by XRD, FTIR, BET, UV-Vis diffuse reflection spectroscopy, surface photovoltage spectroscopy (SPS). The activities of TiO2 and Gd3+-doped TiO2 catalysts for photocatalytic degradation of ethylene were studied by means of in situ FTIR. The photocatalytic reaction rate constant of ethylene becomes larger through Gd3+ doping. The rate constant of TiO2 was k1=8.51×10-4 min-1, while that of Gd/TiO2 was k2=1.85×10-3 min-1. At the same time, the yield of CO2 increased with Gd3+ doping. The enhancement in photocatalytic activity is probably due to the increase of light absorption, higher content of anatase, smaller crystal line size and higher specific surface area. In addition, the higher photocatalytic activity of Gd3+-doped TiO2 might be attributed to the effective separation of photo-generated electron-hole pairs.展开更多
文摘The samples of nano-size ZnO were pre pared by precipitation,hydrolysis,sol-gel method and characterized b y X-ray diffraction,Uv-Vis diffuse r eflection spectrum,and time resolv ed luminescent spectrum.The results showed that the crystallite dimensions of a ll ZnO samples were coarsening with i ncreasing annealing temperature an d the grain sizes prepared by sol-gel meth od were obviously smaller than the others prepared by precipitation and h y-drolysis method.Under excitation o f monochromatic light of wavelength300nm,a strong and broad photolumin es-cence(PL)emissions were observed in the wavelength range of 420～780nm.As the grain size decreased,the PL peak positions moved to shorter wavelengths.And as the annealing temperature increased,the peak intensity de-creased.The photoluminescence dec ay profile of ZnO was well described b y three decay components of 46ns,330ns and 1630ns.
文摘The Gd3+-doped TiO2 photocatalyst was prepared by the sol-gel and impregnation method. The effect of Gd3+ doping on crystalline size, BET surface area and photocatalytic activity was studied by XRD, FTIR, BET, UV-Vis diffuse reflection spectroscopy, surface photovoltage spectroscopy (SPS). The activities of TiO2 and Gd3+-doped TiO2 catalysts for photocatalytic degradation of ethylene were studied by means of in situ FTIR. The photocatalytic reaction rate constant of ethylene becomes larger through Gd3+ doping. The rate constant of TiO2 was k1=8.51×10-4 min-1, while that of Gd/TiO2 was k2=1.85×10-3 min-1. At the same time, the yield of CO2 increased with Gd3+ doping. The enhancement in photocatalytic activity is probably due to the increase of light absorption, higher content of anatase, smaller crystal line size and higher specific surface area. In addition, the higher photocatalytic activity of Gd3+-doped TiO2 might be attributed to the effective separation of photo-generated electron-hole pairs.
