Study On The Combustion Synthesis Of CuCrO₂ With Combined Combustion Agent And Its Photocatalytic Hydrogen Prouduction Performance After Composited WO₃

Hydrogen is regarded as the most desirable clean energy in the future to cut the emissions of green-house gases associated with fossil fuels,and to address the issues of sustainability.However,the conventional hydrogen-production processes are of high cost and not environmentally friendly.Production hydrogen by photo-induced water splitting is one of the green and benign processes.Therefore,it is of great importance to further research this technology.The key technology among this is to design and fabricate high performance catalysts.In this work,a semiconducting oxide CuCrO₂ with p-type conductivity was synthesized via solution combustion method using copper nitrate and chromium nitrate as the precursors,glycine-citric acid and glycine-urea as compound combustion agents.The synthesized CuCrO₂ was characterized by X-ray diffraction（XRD）,scanning electron microscope（SEM）,ultraviolet-visible diffuse reflectance（UV-Vis-DR）and Brunner-Emmet-Teller（BET）.A photocatalyst CuCrO₂-WO₃ was prepared by combining the synthesized CuCrO₂ with n-type conductivity WO₃,and its photocatalytic performance was tested in photo-induced water splitting for H₂generation.In the glycine-citric acid system,the molar ratio of glycine to metal ion was set as 1.4.Several preparation conditions were investigated,such as the ratio of combustion agents,the amount of ammonia and sodium chloride,gelation temperature and the calcination temperature and time.The results indicated that higher dispersion of CuCrO₂ was achieved at the condition of 0.10 molar ratio of citric acid to glycine,0.01 mol ammonia,1.1 g sodium chloride,gelation at 80℃and calcination at 900℃for 3h.The as-synthesized CuCrO₂ was combined with WO₃ and we got the CuCrO₂-WO₃ catalyst with higher photocatalytic performance.In the glycine-urea system,the molar ratio of glycine to metal ion was also set as 1.4.Several influence factors on CuCrO₂ particle size,morphologies and photocatalytic properties were investigated,such as the ratio of combustion agents,the amount of nitric acid and ammonium acetate and the calcination temperature and time.The results showed that higher dispersion of CuCrO₂ was achieved at the condition of 0.15 molar ratio of urea to glycine,0.0105 mol nitric acid,0.3 g ammonium acetate and calcination at 900 ^oC for 3h.The as-synthesized CuCrO₂-WO₃catalyst possessed high H₂ generation activity.Moreover,the photocatalytic activity of CuCrO2 was further enhanced by loading appropriate amount of Ag.