Preparation Of Novel Hollow Composites And The Photocatalytic Hydrogen Evolution Performance

The use of a large number of fossil fuels and the positive growth of population index have led to the exhaustion of natural resources and serious environmental pollution.Photocatalytic decomposition of water to produce hydrogen is one of the most promising technologies to solve these problems.In this paper,a series of new hollow composite photocatalysts were obtained by compounding hollow materials with nanoparticles.The morphology and structure were characterized,the photocatalytic performance for hydrogen production from water was tested,and the potential mechanism of their improved photocatalytic performance was explored.The specific research contents are as follows:（1）ZnTiO₃ nanospheres were synthesized by in-situ deposition method using carbon spheres as templates,which were then calcined to form a hollow structure.Zn S were then loaded onto the surface of ZnTiO₃.Finally,the outermost layer was modified with Zn_0.98Cu_0.02Se nanocrystals with different concentrations.Within 6 h,the photocatalytic hydrogen evolution amount of Zn_0.98Cu_0.02Se/Zn S/ZnTiO₃ can reach6110.37μmol g^-1 h^-1.The construction of ternary photocatalyst can effectively improve the utilization rate of light absorption,realize the rapid separation and transfer of electrons,and significantly inhibit the recombination of carrier,which was beneficial to improve the performance of photocatalytic hydrogen evolution.（2）Hollow Cd_0.9In_0.1Se/Cu₂Mo S₄ nanocube photocatalyst was successfully designed and synthesized via hydrothermal method,and its photocatalytic performance and reaction mechanism for hydrogen production from water were studied.The results revealed that the visible light absorption of hollow Cd_0.9In_0.1Se/Cu₂Mo S₄ nanocube was enhanced,the charge transfer and separation were accelerated and the active sites were increased.Based on the ultraviolet photoelectron spectroscopy and electron spin resonance analysis,the photocatalytic electron transfer path of S-scheme heterojunction between Cd_0.9In_0.1Se and Cu₂Mo S₄ was proposed.After optimization,the hydrogen production rate of Cd_0.9In_0.1Se/Cu₂Mo S₄-2 can reach 6358.42μmol g^-1 h^-1,and it has good stability.（3）CuCo₂O₄ hollow double-shell nanospheres were obtained by calcining CuCo-glyceric acid precursor in air,and then deposited and compounded with Mn_0.2Cd_0.8S according to different mass ratios to obtain CuCo₂O₄-Mn_0.2Cd_0.8S hollow double-shell nanospheres,and their photocatalytic hydrogen production performance was studied.Without noble metal cocatalyst,when the mass ratio of CuCo₂O₄ to Mn_0.2Cd_0.8S was1:10,the hydrogen production rate reached 25.17 mmol g^-1 h^-1,and it showd good cycle stability.The high photocatalytic performance of 10%CCO-MCS benefited from the hollow structure of CuCo₂O₄ and the heterojunction formed by CuCo₂O₄ and Mn_0.2Cd_0.8S,which improved the utilization rate of visible light and accelerated the charge transfer.At the same time,CuCo₂O₄ nanospheres provided support for Mn_0.2Cd_0.8S,reducing the agglomeration phenomenon.