Investigation Of Modification And Photocatalytic Hydrogen Production For ZnIn₂S₄ Nanomaterials

Photocatalysis technology can convert solar energy into chemical energy,which is an important method to solve the problems of environmental pollution and energy crisis.The key issue of photocatalytic hydrogen evolution is to develop novel photocatalysts with wide visible light response,efficient carrier separation efficiency and high photoelectron migration ability.ZnIn₂S₄has become a research hot spot due to its relatively adjustable band gap,good chemical stability and simple preparation process.However,ZnIn₂S₄has some disadvantages,such as high recombination rate of photogenerated electron-hole pairs and poor carrier migration ability,which limit its application in the field of photocatalysis.In this thesis,the band structure of ZnIn₂S₄was regulated by ion doping and heterojunction,so as to improve the visible-light absorption capacity and photogenerated carrier dynamics of ZnIn₂S₄,and finally obtain high-performance ZnIn₂S₄photocatalytic material.The main research contents are as follows:（1）Preparation of Cu²⁺-doped ZnIn₂S₄for photocatalytic hydrogen production.Ni_xP-loading Cu²⁺-doped ZnIn₂S₄photocatalytic materials were successfully prepared by chemical deposition and photoreduction method.The effects of doping and Ni_xP-loading on the morphology,spectral absorption,energy band structure and hydrogen evolution performance of ZnIn₂S₄were studied in detail.The results showed that Cu²⁺doping obviously improved the photocatalytic hydrogen evolution performance of ZnIn₂S₄,and the hydrogen evolution rate of 0.5 at.%doping sample was the highest,which was 4.1 times that of pure ZnIn₂S₄.After loading Ni_xP,the photocatalytic hydrogen evolution performance of Cu_0.5ZIS-NP-t was further improved.Under visible light irradiation,the hydrogen evolution rate of Cu_0.5ZIS-NP-1/2 reached 4746.3μmol·g^-1·h^-1,which was 3.87 times that of Cu_0.5ZIS and 15.98 times that of pure ZnIn₂S₄,respectively.Further analysis showed that the improved performance was mainly due to better spectral response,faster photogenerated carrier transmission and lower recombination rate of photogenerated electron hole pair.（2）Preparation of Co²⁺-doped ZnIn₂S₄for photocatalytic hydrogen production.Co²⁺-doped ZnIn₂S₄nanomaterials were successfully prepared by hydrothermal method.The effects of Co²⁺doping on the morphology,spectral absorption,band structure and photocatalytic performance of ZnIn₂S₄were studied in detail.The results showed that Co²⁺doping significantly enhanced the visible light response of ZnIn₂S₄and improved its photocatalytic hydrogen evolution performance.The hydrogen evolution rate of the best sample reached 2171.1μmol·g^-1·h^-1,which was 2.3 times that of pure ZnIn₂S₄.Further studies showed that Co²⁺doping could significantly inhibit the recombination of photogenerated charge and improve the transmission capacity of photogenerated charge.（3）Preparation of Re S₂/ZnIn₂S₄composites for photocatalytic hydrogen production.Re S₂/ZnIn₂S₄composites were successfully prepared by hydrothermal method.The effects of Re S₂on the morphology,spectral absorption,energy band structure and photocatalytic performance of ZnIn₂S₄were studied in detail.The results showed that the morphology of Re S₂/ZnIn₂S₄photocatalytic materials became rough and irregular particles after Re S₂and ZnIn₂S₄compositing,and the visible light absorption ability was significantly improved.Compared with pure ZnIn₂S₄,RS/ZIS-x exhibited excellent photocatalytic hydrogen evolution performance,and the hydrogen evolution rate of the best sample reached 1858.6μmol·g^-1·h^-1,which was 2.8 times that of pure ZnIn₂S₄.Further analysis showed that Re S₂/ZnIn₂S₄composites could significantly inhibit the recombination of photogenerated carriers,reduce the charge transfer resistance and improve the transmission capacity of carriers.There are 40 pictures,5 tables and 115 references in this thesis.