Preparation And Simulation Of Heterojunction Composite Photocatalyst Sunlight Catalytic Hydrogen Production Photocatalyst Modified Hydrogen Storage Alloys

Doping zirconate and titanate heterojunction composite photocatalysts were prepared firstly and noble metal or metal oxide was further modified. These photocatalysts were characterized by X-ray diffraction, scanning electron microscope, fourier transform infrared, thermogravimetry and differential thermal analysis, ultraviolet visible diffuse reflectance absorption spectra, fluorescence spectra. The photocatalytic generation of hydrogen in oxalic acid solution was used as the probe reaction to evaluate the photocatalytic activity of the photocatalyst. The influencing factors of photocatalytic activity and continuous usage property of photocatalysts were investigated. We also studied the mechanism of photocatalytic activity and photo-generated carrier separation of photocatalyst. These can afford some experimental data and theoretical references for enriching the research on perovskite heterojunction composite oxides. Secondly, the photocatalytic hydrogen storage alloy (PHSA) was made by the combination of photocatalyst with hydrogen storage alloy. The electrochemical test was used as a means to evaluate their charge-discharge properties. The effect of photocatalyst modification and UV light treatment on the electrochemical property of hydrogen storage alloy was discussed.SrZr_0.95Y_0.05O₃-TiO_2-xN_x heterojunction composite photocatalyst prepared by sol coating method had high activity under simulated sunlight irradiation. The photocatalytic activity of composite particles was higher than that of pure TiO₂ and pure SrZr_0.95Y_0.05O₃. The composite catalysts prepared under different conditions were systematically investigated and the optimum conditions were obtained as follows: the concentration of electron donor was 30-70mmol/L, the pH value was 2-4, the nitrogen source regent was triethylamine, the molar ratio of N/Ti was 8:100, the content of TiO₂ in composite catalyst was 70mass%, the calcination temperature was 400℃and the calcination atmosphere was air. After further loading Pt by different methods, the photocatalytic activity of hydrogen generation was all greatly improved, and the in situ photoreduction method showed the optimized activity of hydrogen generation. The average rate of hydrogen generation was up to 2.1 mmol·g·cat^-1h^-1when the optimum loaded content was 1 mass %. Meanwhile, we also discussed the stability of Pt loaded heterojunction composite photocatalyst and possible photocatalytic mechanism. Nitrogen doped SrTiO₃ were prepared by solid sintering method under different conditions. The photocatalytic hydrogen generation activity of catalysts was discussed. The optimal preparation condition was obtained by experiments: the nitrogen source was HMT, the mass proportion of SrTiO₃ and HMT was 1:3, and the calcination temperature was 450℃. Under this condition, the photocatalytic activity of hydrogen generation was both greatly improved after losding Pt on nitrogen doped SrTiO₃ by hydrogen reduction method and photoreduction method respectively, and the photocatalytic activity of photocatalysts prepared by hydrogen reduction method was better than that prepared by photoreduction method. The average rates of hydrogen generation were respectively up to 1.15 and 0.38 mmol-g-caf'h"1 when the optimal loaded content were both 2mass%. Moreover, the good result of hydrogen generation was achieved by loading NiO, CoO and ZnO with hydrogen reduction method. The effect of different treatment methods of loading NiO on hydrogen generation activity of nitrogen doped SrTiO3 was also studied. The result demonstrated that the NiO loaded composite catalyst showed higher photocatalytic activity when NiO was loaded by hydrogen reduction treatment firstly and then oxidation treatment than NiO was loaded by direct oxidation treatment. The optimal loaded contents, the law of hydrogen generation and heterojunction mechanism of three loadings were also discussed.The nitrogen doped SrTiO₃ obtained from above further combined with TiO₂ by sol coating method to form heterojunction composite catalyst, and noble metal Pt and Pd particles were further modified by hydrogen reduction method. Photocatalytic hydrogen generation was used as the probe reaction to evaluate the photocatalytic activity of photocatalysts under simulated sunlight irradiation in detail from the aspects of different contents of TiO₂ in the composite particles, different calcination temperatures, and different contents of Pt and Pd. The result demonstrated that the average rates of hydrogen generation were respectively up to 5.1 and 5.4mmol·g·cat^-1h^-1 when the optimal loaded contents of Pt and Pd were both 2mass%.The photo-charge PHSA was made·by the modification of Pt loaded composite catalyst on hydrogen storage alloy. The electrochemical charge-discharge test demonstrated that the charge-discharge property didn't improve when the photocatalyst was modified on hydrogen storage alloy. The activation property, biggest discharge capacity, high-rate discharge property and cycle property of the PHSA with light treatment was superior to that of the PHSA without light treatment, and whereas the charge-discharge property of pure hydrogen storage alloy with light treatment was almost the same as that without light treatment. The capacity of first activation and the biggest activation capacity of PHSA with light treatment were slightly higher and the cycle property decreased when compared to pure hydrogen storage alloy.