| With the rapid development of human society and economy and the increasing global population,the social problems caused by environmental pollution and energy shortage are becoming more and more serious.As a renewable green energy,solar energy reaching the earth’s surface hourly exceeds the annual global energy consumption,so more and more people focus on how to use the abundant solar energy on the earth to fill the energy demand gap.Hydrogen is a potential energy carrier with high energy density and no carbon emissions,and the only product is water.Semiconductor photocatalysts are used to split water to produce hydrogen,and the energy given by solar radiation is stored in the chemical bonds of diatomic hydrogen.Therefore,the sustainable production of hydrogen through water splitting using photocatalysts is considered as the Holy Grail of modern science,and artificial photosynthesis is one of the most important challenges in the coming decades.As a semiconductor material,metal sulfides,on the one hand,because of their suitable band gap,such as Cd S,can expand the spectral response range of wide-band gap semiconductors to the visible light region;on the other hand,combined with their excellent optoelectronic properties,as a co-catalyst,can enable the rapid separation of photogenerated electron-hole pairs.In this paper,several photocatalytic hydrogen production systems based on metal sulfide composite were explored and developed by means of structural design,preparation process and reaction activity.The main research contents and results include:（1）The mpg-C3N4/CNT/Ni S composites were synthesized via sol-gel method and precipitation process.The photocatalytic activity of C3N4-based materials for hydrogen evolution under visible light irradiation can be improved by manufacturing mesoporous enlarged specific surface area and co-existence of CNTs and Ni S.It is also proved that Ni S-based cocatalysts can effectively inhibit the combination of photogenerated electrons and holes and accelerate the rate of photocatalytic hydrogen evolution.The hydrogen evolution rate of mpg-C3N4/CNT/1%Ni S nanocomposites under visible light（λ≥420 nm）is about521μmol g-1 h-1.The photocatalytic activity of mpg-C3N4/CNT nanocomposites is almost148 times higher than that of pure mpg-C3N4/CNT samples.（2）A novel Cd S/Zn O/r GO membrane photocatalyst was prepared by simple liquid-phase chemical method and heat treatment.It has a three-dimensional layer structure composed of Cd S-modified Zn O nanocage arrays connected to multilayer r GO nanosheets,which ensures the close combination of Zn O with Cd S and r GO,as well as three-dimensional porous network structure and high specific surface area.In the experiment of photocatalytic hydrogen evolution,Cd S/Zn O/r GO photomembranes have an average rate of hydrogen evolution of about 46.08μmol·cm-2·h-1 under visible light(lambda（λ≥420 nm）,while the maximum apparent quantum efficiency can reach 2.54%（500 nm）.The ABPE efficiency can achieve 4.51%and the maximum IPCE efficiency reaches up to 45%（420 nm）.（3）A novel 1D/1D rod-like Cd S branched Ti O2 film was successfully prepared on conductive FTO substrates.By changing the ratio of water to ethanol in solution and adjusting the solubility of glutathione（GSH）,the surface volume ratio and load of Cd S nanorod branchs could be easily adjusted.Under appropriate density of Cd S nanobranches,the best photocatalytic performance can be obtained in the system of photoelectrocatalysis（ABPE,η=1.5%;IPCE=34%,450 nm）or photocatalytic hydrogen evolution(11.9μmol·cm-2·h-1).（4）Through simple liquid-phase chemical method and high temperature treatment,the Zn O/Cd S nanorods with pore structure were successfully grafted on the surface of three-dimensional porous nickel foam.By using the efficiency light capture ability of Zn O/Cd S heterojunction and the conductivity of nickel foam,a fast transmission path of photo generated electrons between the photocatalyst and substrate materials can be constructed.Under irradiation,the average rate of hydrogen evolution is 16.31μmol·cm-2·h-1,and the applied bias photo to current conversion efficiency（ABPE）can achieve 2.0%,while the highest IPCE reaches up to 35%. |
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