Study On Modification Of Photocatalytic Materials Based On G-C₃N₄

Graphite-like carbon nitride（g-C₃N₄）is widely used in the field of photocatalytic degradation of liquid-phase pollutants due to its unique energy band structure,high chemical stability,low cost,and environmental friendliness.However,g-C₃N₄ has some disadvantages,such as a small specific surface area,low visible light response and low photogenerated charge separation rate,so its practical application is still limited.To solve the above problems,in this thesis,the morphology of the g-C₃N₄ monomer was first modified by different methods to obtain an ultrathin porous nanosheet structure and improve the specific surface area.On this basis,doping modification and preparation of heterojunction material modification were carried out to expand the visible light response and promote photoinduced carrier separation and transfer,thus improving the performance of photocatalytic degradation of liquid phase pollutants.The research content can be summarized as the following three points:1.The morphology of g-C₃N₄ was controlled by the Z204 nickel catalyst and thermal oxidation to obtain ultrathin,porous,and coiled nanosheet structures.The structure can significantly improve the specific surface area,promote charge transfer,and effectively improve the photocatalytic degradation of liquid phase pollutants.Under irradiation with simulated visible light,the degradation performance of rhodamine B by morphology-modified g-C₃N₄ was improved,which was approximately 8 times that of monolithic bulk g-C₃N₄.The test analysis shows that the change in the morphology leads to an increase in the specific surface area,which is the key factor for the improvement of the photocatalytic performance.2.Based on the morphology control process,Cl-doped g-C₃N₄ was prepared by a one-pot pyrolysis method using melamine and ammonium chloride as raw materials.The interlayer of g-C₃N₄ is intercalated with Cl ions to form C-Cl bonds with C,which has a strong influence on the band edge of g-C₃N₄,thus changing the redox capacity of the g-C₃N₄photocatalyst and forming a doping energy level-adjusted band structure to expand the visible light response.Under visible light irradiation,the degradation performance of rhodamine B is greatly improved,which is approximately 29 times that of the monolithic bulk g-C₃N₄.3.Follwing the morphology control process,a p-n-type Cr₂O₃/g-C₃N₄ heterojunction photocatalyst was obtained by one-pot pyrolysis.Under visible light irradiation,the degradation rate of rhodamine B was approximately 24 times that of monolithic bulk g-C₃N₄.The close interfacial effect and the matched energy band structure in Cr₂O₃/g-C₃N₄can effectively promote photoinduced carrier separation and transfer,which is the key factor for the improvement of photocatalytic activity.