Modification Of ZnIn₂S₄ Semiconductor For Enhancing Photocatalytic Hydrogen Production

The photocatalytic hydrogen production has attracted much attention owing to energy and environmental issues.ZnIn2S4 is a layered visible light responsive photocatalyst with excellent band structure.However,the easily recombination of photogenerated charges of ZnIn₂S₄ greatly limits its photocatalytic hydrogen production performance.In order to solve this problem,heterojunction,doping element and cocatalyst were introduced to ZnIn₂S₄ in this work.This work can be divided into the following three parts:?1?Heterojunction construction has been proved to be an effective method to improve charge separation.In this work,a homogeneous TiO₂/ZnIn₂S₄ was prepared and researched by XRD,SEM,XPS,Mott-schottky plots and UV-vis absorption spectrum.As a result,TiO₂/ZnIn₂S₄ is 1.3 times of ZnIn₂S₄ in photocatalytic hydrogen production performance under visible light.?2?Low dimensional materials with large specific surface and short carrier transmission path are beneficial to charge separation.In this work,surfactant?CTAB?was added to prepare ZnIn₂S₄ nanosheets.When the dosage of CTAB was 1 mmol,ZnIn₂S₄ is 2.2 times of original ZnIn₂S₄ in hydrogen production rate(4.49mmol·h^-1g^-1),which is the highest one.Under this CTAB dosage,Mn was doped into ZnIn₂S₄ to further improve charge separation efficiency by introducing carrier trap.The highest hydrogen production rate is 2.9 times as high as original ZnIn₂S₄.?3?The cocatalyst can effectively capture the photogenerated electrons of the photocatalyst,thereby facilitating carrier separation.In this work,the nickel nanoparticles was photo-reduced as a catalyst on the surface of ZnIn₂S₄.The effect of nickel amounts on hydrogen production performance was investigated.As a result,2.0 wt%Ni/ZnIn₂S₄ has the highest photocatalytic hydrogen production performance in all samples.This 2.0 wt%Ni/ZnIn₂S₄(22.2 mmol·h^-1g^-1)is about 10.6 times of pure ZnIn₂S₄(2.1 mmol·h^-1g^-1)in hydrogen production rate.In this experiment,the photocatalytic hydrogen production rate of Ni/ZnIn2S4 is higher than that of other reported cocatalysts/ZnIn₂S₄.