Construction Of ZnS-based Heterojunction And Its Hydrogen Evolution Performance

Zinc sulfide（ZnS）semiconductor has suitable energy band structure,good chemical and thermal stability and low cost,especially suitable redox potential,which has been widely used in the photocatalytic decomposition of water to produce hydrogen.Despite the many advantages of ZnS,the efficiency of photocatalytic hydrogen production is still limited by the rapid recombination of photoexcited electron-hole pairs.In order to overcome the above challenges,many design and improvement methods have been proposed,among which,heterogeneous structures are constructed by combining with other semiconductors to effectively achieve solar photodissociation of water to produce hydrogen.In order to obtain highly active photocatalysts,ZnS/Cu₃P,ZnS/Ag₆Si₂O₇,ZnS/Ni@Trimellitic heterojunction composites with high photocatalytic activity were prepared to accelerate the separation and transfer of photogenerated electron hole pairs.The major research contents of this paper are as follows:（1）A novel non-noble metal type I ZnS/Cu₃P heterojunction was prepared by hydrothermal calcination method,and its structure and morphology were characterized.The results show that the photocatalytic performance of pure ZnS nanoparticles is very weak.However,the addition of Cu₃P significantly improves the photocatalytic performance.The yield of the best sample（2%ZnS/Cu₃P）was 729μmolg^-1h^-1,about 17times that of ZnS.The improvement of photocatalytic performance of ZnS/Cu₃P is mainly due to the addition of Cu₃P nanoparticles,which not only expands the specific surface area of ZnS/Cu₃P,but also provides rich reaction sites.Photocurrent,photoluminescence and electrochemical impedance spectroscopy confirm that the formation of heterojunction enhances the efficiency of charge separation.（2）A novel 0D/0D ZnS/Ag₆Si₂O₇ heterojunction photocatalyst was successfully prepared by hydrothermal calcination method.The experimental results show that the maximum hydrogen production of ZnS/Ag₆Si₂O₇ composite is 524μmolg^-1h^-1,about 5times of the original ZnS.Using various characterization techniques to study the enhancement mechanism of high activity and high stability of samples,it is revealed that the construction of 0D/0D heterojunction and the close interface contact between ZnS and Ag₆Si₂O₇ can accelerate the transfer and separation of photoexcited e^--h⁺pairs.In addition,the reasonable mechanism of improving photocatalytic activity is discussed,which also provides new insights for the design and application of 0D/0D heterojunction photocatalyst in the field of photocatalysis.（3）ZnS NPs/Ni@Trimellitic（Ni-TA）heterojunction photocatalyst was prepared by in-situ surface growth method.The structure,optical properties and elemental composition of ZnS/Ni-TA heterojunction were systematically analyzed.The experimental results show that the hydrogen production efficiency of the best sample（3%ZnS/Ni-TA）reaches 1098μmolg^-1h^-1,about 12 times that of pure ZnS.The Ni-TA can not only be used as the main body of metal nanoparticles,but also can prevent the agglomeration of nanoparticles with porous channels on the surface.The improvement of hydrogen production efficiency is mainly attributed to the tight interfacial contact and well-matched band position,which facilitates effective carrier separation and thus facilitates electron transfer to the exposed edge of Ni-TA for hydrogen reduction.The combination of inorganic semiconductor and new organic semiconductor provides an idea for photocatalytic hydrogen production.Figure[36]table[9]reference[157]...