Study On Preparation And Photocatalytic Hydrogen Evolution Of Cu₂O-TiO₂ Composite Catalysts

The problems of wastewater treatment and the shortage of energy sources are affecting our regular life and work gradually. Hydrogen is one of the most ideal clean energy. The photocatalytic hydrogen generation technology is an important task in the photocatalysis field which has been widely researched. Photocatalytic degradation of organic wastewater for hydrogen evolution could combine wastewater treatment and hydrogen production result in comprehensive utilization of resources.In this paper, Cu?NO₃?₂·3H₂O, TiO₂?P25?, graphite powder were used as raw materials. Cu₂O-TiO₂ and graphene-Cu₂O/TiO₂ phtocomposites were prepared by chemical sediment method and solvothermal method. Pt was loaded on the prepared composite catalysts by in situ optical method. In order to analyze the photocatalytic performance of the composites in morphology, structure and optical properties respects, the catalysts were characterized by XRD, SEM, FT-IR and DRS.Firstly, Cu₂O-TiO₂ composite catalyst was prepared by chemical sediment method. The effect of the content of Cu₂O on the photocatalytic activity for hydrogen evolution were investigated, and the effect of the volume ratio of sacrificial agent ethanol to water on the amount of hydrogen evolution. The reaction mechanism of hydrogen production through decomposition of C₂H₅OH/H₂O mixed reaction solution was researched under ultraviolet?UV? irradiation. The experimental results show that the composite in which the Cu₂O content is 1wt% has the maximum hydrogen generation. When the volume ratio of C2H5 OH to H2 O was 35:65, the total hydrogen amount reached 1624.09?mol and 2861.90?mol under UV and sunlight irradiation reaction for 5h respectively, and the hydrogen amount of TiO₂ was 1160.16?mol and 1774.84?mol under the same conditions. The activity of hydrogen production has the obvious improvement.Secondly, graphene-Cu₂O/TiO₂ composite catalyst was prepared by chemical sediment method and solvothermal method. The sample in which the graphene content was 0.5wt% has more hydrogen evolution than Cu₂O-TiO₂ under UV, visible light and sunlight irradiation for 5h. And the amount of hydrogen production of the ternary composite catalyst was 2006.85?mol, 659.09?mol and 3428.57?mol respectively. In the process of photocatalytic hydrogen production, the graphene and the Cu₂O played a promote role which broadened the light response range, so the photocatalytic activity was enhanced, and the amount of hydrogen production was increased.Thirdly, optimal technological conditions research on the degradation of model wastewater for hydrogen production with graphene-Cu₂O/TiO₂ which has the hightest photocatalytic activity. The optimum conditions for the single factor and orthogonal experiments were as follows: reaction time 5h, the initial concentration of the solution is 1.0g/L, the amount of catalyst is 0.01 g, intial pH 10.Fourthly, study graphene-Cu₂O/TiO₂ composite catalyst photocatalytic degradation of actual wastewater for hydrogen production. The results show that the catalyst has better effect on hydrogen generation, and removal efficiency of CODcr is better.