Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terep...Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terephthalic acid fluorescence probing. The photocatalytic activities of catalysts were evaluated by using ethylene oxidation studies under visible light irradiation（λ>450 nm） from 40 to 62 ℃. It is found that the platinum doping in titania caused significant absorption shift to the visible region and the surface recombination of photogenerated carriers was inhibited. The results show that ethylene was not converted on conventional TiO2 while the conversion was 90% and the complete mineralization was achieved over Pt-Pt 4+/TiO2 at 62 ℃ in our experiment. Besides the exponential increase of thermalcatalytic activity, pure photocatalytic activity of the planitized sample enhanced linearly with the increase of temperature.展开更多
A TiO2 modified with PtⅣ chloride was investigated by diffuse reflectance UV-Vis spectra（DRS）,X-ray photoelectron spectroscopy（XPS）, surface photovoltage spectroscopy（SPS） and electric field-induced surface pho...A TiO2 modified with PtⅣ chloride was investigated by diffuse reflectance UV-Vis spectra（DRS）,X-ray photoelectron spectroscopy（XPS）, surface photovoltage spectroscopy（SPS） and electric field-induced surface photovoltage spectroscopy（EFISPS）.XPS showed that a Ti-O-PtⅣClx surface complex between PtⅣ chloride and TiO2 appears to be responsible for visible light absorption.An electron transfer from the surface-complexed PtⅣClx to the conduction band of TiO2 upon absorbing visible light was confirmed by SPS and EFISPS.展开更多
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
A series of SO 2- 4/TiO 2 SiO 2 catalysts with different mass fractions of SiO 2 were prepared by sol gel method. The effect of adding SiO 2 on the crystal structure, specific surface area, oxygen adsorption, and acid...A series of SO 2- 4/TiO 2 SiO 2 catalysts with different mass fractions of SiO 2 were prepared by sol gel method. The effect of adding SiO 2 on the crystal structure, specific surface area, oxygen adsorption, and acidity of SO 2- 4/TiO 2 catalyst and its photocatalytic property for degradation of bromomethane was studied. The results showed that the specific surface area and amount of oxygen adsorption of catalyst were increased by addition of SiO 2, leading to the obvious increase on photocatalytic activity of SO 2- 4/TiO 2 SiO 2 catalysts and mineralization ratio of bromomethane. Comparing with SO 2- 4/TiO 2, the acidic strength and anti moisture ability of SO 2- 4/TiO 2 SiO 2 catalyst were decreased.展开更多
文摘Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terephthalic acid fluorescence probing. The photocatalytic activities of catalysts were evaluated by using ethylene oxidation studies under visible light irradiation（λ>450 nm） from 40 to 62 ℃. It is found that the platinum doping in titania caused significant absorption shift to the visible region and the surface recombination of photogenerated carriers was inhibited. The results show that ethylene was not converted on conventional TiO2 while the conversion was 90% and the complete mineralization was achieved over Pt-Pt 4+/TiO2 at 62 ℃ in our experiment. Besides the exponential increase of thermalcatalytic activity, pure photocatalytic activity of the planitized sample enhanced linearly with the increase of temperature.
文摘A TiO2 modified with PtⅣ chloride was investigated by diffuse reflectance UV-Vis spectra（DRS）,X-ray photoelectron spectroscopy（XPS）, surface photovoltage spectroscopy（SPS） and electric field-induced surface photovoltage spectroscopy（EFISPS）.XPS showed that a Ti-O-PtⅣClx surface complex between PtⅣ chloride and TiO2 appears to be responsible for visible light absorption.An electron transfer from the surface-complexed PtⅣClx to the conduction band of TiO2 upon absorbing visible light was confirmed by SPS and EFISPS.
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A series of SO 2- 4/TiO 2 SiO 2 catalysts with different mass fractions of SiO 2 were prepared by sol gel method. The effect of adding SiO 2 on the crystal structure, specific surface area, oxygen adsorption, and acidity of SO 2- 4/TiO 2 catalyst and its photocatalytic property for degradation of bromomethane was studied. The results showed that the specific surface area and amount of oxygen adsorption of catalyst were increased by addition of SiO 2, leading to the obvious increase on photocatalytic activity of SO 2- 4/TiO 2 SiO 2 catalysts and mineralization ratio of bromomethane. Comparing with SO 2- 4/TiO 2, the acidic strength and anti moisture ability of SO 2- 4/TiO 2 SiO 2 catalyst were decreased.
