Fabrication Of ZnS-based Photocatalysts For Photocatalytic Hydrogen Production From Water

The development of clean and renewable energy has great theoretical and strategic significance.Hydrogen energy is clean and efficient,and it is the most ideal green energy.Water splitting for H₂ using solar energy is recognized as the most promising alternative energy technology in the future due to its simple operation and environmental friendliness,and its core is photocatalyst with high activity and long life.ZnS is a direct band gap semiconductor material with good chemical and thermal stability,non-toxic and environmentally friendly,and has been widely studied in the field of photocatalysis.In order to improve the utilization of ZnS for sunlight,reduce the recombination of photogenerated carriers,and enhance the photocatalytic activity,a series of ZnS-based composite photocatalysts were prepared in this paper.The crystal structure,morphology,composition and optical properties of photocatalysts were analyzed by means of XRD,SEM,TEM,XPS,UV-Vis,PL,photocurrent and AC impedance.The H₂ evolution performance of photocatalysts under visible light irradiation was investigated,and the corresponding hydrogen production mechanism was proposed.（1）Cu₃P/ZnS composite photocatalysts were prepared by a mechanical grinding for the first time.The visible light photocatalytic hydrogen production activity of Cu₃P/ZnS were tested and the effect of the mass ratio of Cu₃P to ZnS on the catalytic performance was discussed.The water splitting hydrogen evolution results showed that when the mass ratio of Cu₃P to ZnS is 1%,the performance of the pthotocatalyst is optimal,and the rate of hydrogen production is 6 times higher than that of pure ZnS sample.Cu₃P coupled with ZnS forms p-n heterojunction,which accelerates photogenerated charge carrier separation for enhanced photocatalytic H₂ evolution activity.（2）For the first time,Cu₇S₄/ZnS composite photocatalysts were constructed by combining ZnS and Cu₇S₄.The co-catalyst Cu₇S₄can significantly enhance the charge transfer at the interface between ZnS and Cu₇S₄,and reduce the recombination rate of photogenerated electron-hole pairs under light irradiation.The experimental results show that when the mass ratio of Cu₇S₄ to ZnS is 1%,the hydrogen production rate reaches the maximum value,which is 6 times higher than that of pure ZnS.（3）Cu S/ZnS composite photocatalysts were successfully prepared through cation-exchange reaction,and the effect of Cu S content on the hydrogen production performance of the composite catalysts was investigated.The water splitting hydrogen evolution results showed that when the mass ratio of Cu S to ZnS is 1%,the hydrogen production rate of Cu S/ZnS reaches the maximum value,which is 14 times higher than that of ZnS.Visible light induces the direct interfacial charge transfer from the VB of ZnS to Cu S,which decrease electron-hole recombination and thus enhance photocatalytic hydrogen production activity.