Synthesis Of ZnIn₂S₄-based Photocatalysts For Photocatalytic Water Splitting

The major problems facing the world today are energy shortages and environmental pollution.For this reason,clean energy has become a hot spot of global concern.Photocatalysis technology can use sunlight to drive a series of important chemical reactions,such as photolysis of water to produce hydrogen,carbon dioxide reduction,and degradation of pollutants.Photocatalytic technology is one of the ideal ways for clean energy production and environmental pollution control in the future,and has important application prospects in solving energy and environmental problems.The factors that limit the photocatalytic efficiency are narrow light absorption range,low charge separation efficiency and slow surface reaction kinetics.Therefore,this paper takes ZnIn₂S₄ as the research object and systematically studies the light absorption characteristics,charge separation efficiency and surface charge dynamics characteristics of ZnIn₂S₄ based catalysts through defect engineering,heterojunction engineering and co-catalyst loading strategies.Through these measures,the photocatalytic performance of ZnIn₂S₄-based catalyst for water splitting can be optimized.The research content can be shown below:?1?The dispersive In₂S₃,ZnIn₂S₄ and CdIn₂S₄ nanosheets were successfully constructed by low temperature reflow process.A series of two-dimensional S_v-In₂S₃,S_v-ZnIn₂S₄ and S_v-CdIn₂S₄ nanosheets with the defects were prepared through the low-temperature lithiation chemical process.Based on defect engineering,the effect of defects on the light absorption characteristics of the nanosheets was investigated,and it was found that S_v-ZnIn₂S₄nanosheets had the best efficiency of hydrogen production by water splitting.Based on defect engineering and heterojunction engineering,V_s-ZnIn₂S₄/WO₃ heterojunction was controllably synthesized through low-temperature reflow and lithiation chemical processes.It was found that the photocatalytic performance of V_s-ZnIn₂S₄/WO₃ heterojunction nanosheets changed with the change of WO₃ content.When the mass fraction of WO₃ loading is 10%,the optimal performance of photocatalytic hydrogen production can be achieved.Raman spectroscopy proves that W-S chemical bond was constructed between the interfaces of V_s-ZnIn₂S₄/WO₃heterojunction.The presence of the chemical bonds between the interfaces creates a high-speed channel for the transfer of charges between the interfaces,thereby optimizing the charge separation efficiency of the composite system.Through band structure and electron spin resonance spectrum analysis,it was found that V_s-ZnIn₂S₄/WO₃ heterojunction nanosheets have a Z-type charge transport mechanism,thus ensuring the excellent photocatalytic performance.In order to optimize surface charge dynamic characteristics,V_s-ZnIn₂S₄/WO₃ heterojunction loaded with NiS quantum dots?NiS/V_s-ZnIn₂S₄/WO₃?were synthesized by a low-temperature reflow process.The mass fraction of WO₃ and NiS loading is optimized.When the mass fraction of WO₃ loading is 10%and NiS loading is 1%,the best photocatalytic hydrogen production rate of NiS/V_s-ZnIn₂S₄/WO₃ can be obtained.?2?ZnIn₂S₄/NiO two-dimensional heterojunction nanosheets were synthesized by a low temperature reflow process.It was found that the photocatalytic performance of the two-dimensional ZnIn₂S₄/NiO heterojunction nanosheets changes with the content of NiO.When the mass fraction of NiO loading is 30%,the optimal performance of photocatalytic hydrogen production can be reached.Compared to ZnIn₂S₄/WO₃,a high photocatalytic hydrogen production efficiency can be achieved by ZnIn₂S₄/NiO heterojunction owe to the excellent charge separation efficiency.