Construction Of GC₃N₄-based Composite Materials And Study Of Their Photocatalytic Propertie

In recent years,scientific and technological progress has brought us a lot of conveniences.For example,energy-consuming cars have brought us a convenient way of life.The rapid development of the chemical industry has greatly improved the human production level.However,the rapid loss of non-renewable energy,water pollution,and air pollution caused by waste discharged from industrial production have posed a serious threat to the ecological environment and people’s health.To solve these problems,researchers focus on the development of clean energy and the degradation of organic pollution in water.With the development of research,it is found that the strong oxidation and reduction ability of semiconductor photocatalyst can be used to change H⁺in water into hydrogen under light irradiation;Organic pollutants can also be completely decomposed into CO₂ and water,and their loss.This has important application prospects in energy and the environment.First of all,g-C₃N₄,as a common semiconductor material,has the advantages of low cost,simple production process,and high stability,making it a focus of attention in the fields of photohydrolysis of water to produce hydrogen and organic degradation.However,any single component semiconductor will have many shortcomings,such as low solar energy conversion efficiency,low charge separation/transfer capacity,the photocatalytic reaction rate is not ideal,and so on.In this paper,g-C₃N₄ was chosen as the matrix,and other semiconductors were used to improve the rate of hydrogen production and degradation of organic matter.Therefore,it is a potential strategy to further improve the photocatalytic efficiency of heterostructures by preparing heterostructures systematically,adjusting the transport and separation of interfacial and internal carriers,and maximizing the charge utilization.The main research contents are as follows:（1）g-C₃N₄/ZnIn₂S₄ composites were prepared by a simple hydrothermal method and characterized utilizing X-ray diffraction（XRD）,transmission electron microscopy（TEM）,Fourier transforms infrared spectroscopy（FT-IR）,UV-Vis diffuse reflectance spectroscopy（UV-Vis DRS）and fluorescence spectroscopy（PL）.The results show that g-C₃N₄/20 wt%Zn In₂S₄ composite shows the best photocatalytic hydrogen production performance when the loading capacity of Zn In₂S₄ was up to 20 wt%,and the photocatalytic hydrogen production rate was up to 637.1μmol?g^-1?h^-1.It is 4 times pure Zn In₂S₄ and 37 times pure g-C₃N₄.The reason lies in the close heterojunction structure between Zn In₂S₄ and g-C₃N₄.The effective combination of Zn In₂S₄ and g-C₃N₄ improves the band matching and interfacial charge transfer of components,thus greatly enhancing the separation and migration of carriers,and thus improving the photocatalytic performance.（2）W₁₈O₄₉ nanowires were synthesized on the ultrathin nanosheets of the g-C₃N₄matrix as a composite catalyst for degradation.By simple two-step,hydrothermal synthesis method,g-C₃N₄,W₁₈O_49,and RGO were combined to form an efficient ternary composite heterojunction photocatalyst.The degradation of methyl orange under the direct irradiation of ultraviolet light（UV）,visible light（Vis）and near-infrared light（NIR）was studied systematically.Combined with a series of characteristics,the methyl orange removal effect of g-C₃N₄/W₁₈O₄₉/RGO composite under UV light is about 90%,which is62.3 times that of pure g-C₃N₄;The removal effect of methyl orange under visible light was about 82%,4.65 times that of pure g-C₃N₄;The removal effect of methyl orange under NIR light is about 65%,6 times that of pure g-C₃N₄.This study provides an important idea on how to design low-cost catalysts reasonably to solve the problem of organic pollution.