The Desgn And Synthesis Of Semiconductor Based Heterjunction Photocatalyst And Study On Properties

Over the last few decades,photocatalysts production of H2 from water using solar light energy has attracted increasing interest due to energy crisis are affecting human survival and development.Owing to the photocatalytic process include the generation of photoelectrons and holes,a slower recombination process of the photoinduced electrons and a broad spectrum absorbing should be had for a perfect photocatalyst.Therefore,seek effective solutions to improve migration process of the photoinduced charge and enlarge the spectrum responsive range is indispensabl.The present study aimed at design and synthesis a series of high-performance heterojunction for photocatalytic H2 production and removal of methyl orange,studying the internal relations between heterojunction and photocatalytic activity.It will provide the theoretical support for design and synthesis photocatalysts with high-performace.This study mainly includes the following three parts:1)In this contribution,photocatalytic H2 production and organic pollutant removal using g-C₃N₄/Cu S composite was demonstrated.Well dispersed Cu S nanoparticles?NPs?with a size of about 10 nm were successfully grown on the surface of g-C₃N₄ nanosheet via a facile hydrothermal method.The as-prepared g-C₃N₄/Cu S nanocomposite at an optimized loading exhibited a much higher visible light photoactivity,giving up to 2.7 times and 1.5 times enhancements in comparison to pure g-C₃N₄ for photocatalytic H2 production and methylene orange?MO?degradation,respectively.2)Here,excellent photocatalytic performance using Cu5 Fe S4 as a co-catalyst was displayed.The C₃N₄/0.75 wt%Cu₅FeS₄ nanocomposite exhibited highest photocatalytic H2 generation?27.92 ?mol h-1 g-1?and removal efficiencies of methyl orange?Kapp=0.01982 min-1,about 68.2% after 60 min?under identical conditions.This research offers important insights for rational design of low cost and high efficiency photocatalysts.3)We developed a facile wet-chemical approach to in situ synthesize Ag doped ZnIn₂S₄ rectangle nanoplates,in a single step,on RGO nanosheets?denoted as Ag:ZnIn₂S₄/RGO?.The effects of Ag+ doping and intimate RGO coupling on the properties of the ZnIn₂S₄ nanoplates through face-to-face contact were systematically investigated and high efficiency of the visible-light-driven photocatalytic H2 production was achieved.Density functional theory?DFT?calculations show the effect of Ag+ doping,at the low doping level,on the energy band structure of ZnIn₂S₄,that is,through the substitutional doping and interstitial doping,Ag+ could create acceptor and donor states,respectively,which shift the Fermi energy within the bandgap of ZnIn₂S₄.As both types are shallow states,they do not act as charge recombination centers.Instead they help with light absorption and/or increase the lifetime of charge carriers and thus contribute to the better performances of the Ag-doped ZnIn₂S₄ as compared to the pristine crystal for the application of interest here.Furthermore,the strong interfacial interaction between the RGO supports and Ag:ZnIn₂S₄ rectangle nanoplates also plays a vital role in enhancing the overall photocatalytic activity by efficiently separating charge carriers.