Fabrication And Photocatalytic Properties Of G-C₃N₄-based Nanocomposites

Semiconductor photocatalysis is widely regarded as a promising strategy for solving energy and environmental problems because of its unique advantages in economy and environmental protection.Preparationoflargespecificsurfaceareananostructures,constructionof semiconductor-semiconductor heterostructures,and construction of noble metal-semiconductor structures are three major ways to improve photocatalytic properties of photocatalytic materials.In this paper,graphitic carbon nitride（g-C₃N₄）is the main research object,and g-C₃N₄ nanosheets,Ag/g-C₃N₄ nanosheets composite,Bi₄O₇/g-C₃N₄ nanosheets composite,Ag/Bi₄O₇/g-C₃N₄nanosheets photocatalyst were prepared by thermal etching,chemical impregnation,photochemical deposition.In addition,some tests were performed to understand the performance parameters of these materials.details as follows:（1）The g-C₃N₄ nanosheets were prepared by hot exfoliation method.The experimental data show that the specific surface area of g-C₃N₄ nanosheets is as high as 162 m²g^-1,which is much higher than that of bulk g-C₃N₄(11 m²g^-1).The higher specific surface area can provide more reactive sites for the catalytic reaction.（2）Photochemical deposition method was used to synthesize Ag/g-C₃N₄ nanosheets.The silver nanoparticles（Ag NPs）with a size of about 10¹5 nm are uniformly distributed on the surface of the g-C₃N₄ nanosheets.The presence of Ag NPs not only promotes the separation of photoelectron-hole pairs of catalyst,but also expands the light response range of the composite.（3）The synthesis of Bi₄O₇/g-C₃N₄ heterojunction mainly adopts hydrothermal and chemical impregnation method.The experimental data show that the construction of Bi₄O₇/g-C₃N₄heterojunction effectively promotes the separation of photoelectron-hole pairs.In addition,the deposition of PbO₂ and Ag NPs on Bi₄O₇/g-C₃N₄ can show the photocarrier transfer path,and then infer the type of Bi₄O₇/g-C₃N₄ heterojunction.（4）Ag/Bi₄O₇/g-C₃N₄ composite photocatalyst were synthesized by chemical impregnation method and photochemical deposition method.Ternary composite photocatalysts can combine multiple catalytic enhancements to achieve catalytic synergistic effects.The experimental data show that Ag/Bi₄O₇/g-C₃N₄ composite achieve high level in specific surface area,photoelectron-hole pairs separation,and photoresponse range.