Compounding,modification And Its Photocatalytic Degradation Of Organic Dyes By G-C₃N₄

Advanced oxidation technology has attracted much attention because its ability of oxidization organic pollutants.Among them,photo-Fenton oxidation technology is considered as a representative technology to solve the energy and environmental crisis by using solar energy.Graphite carbon nitride（g-C₃N₄）has been widely applied as photocatalyst owing to its simple synthetic preparation,high chemical stability and unique band gap structure.However,the large difference in the electronegativity of C and N in g-C₃N₄ induces agglomerate and low specific surface area.The vacancy in the 3-s-triazine ring leads to its low photocharge generation and hole separation efficiency,which weaken the photocatalytic activity and limited its efficient application.The most common methods for improving the catalytic activity of g-C₃N₄ include（1）doping or loading other elements to adjust their internal electronic structure,（2）compounding semiconductors to effectively separate charges and voids,and（3）reducing the surface of the catalyst to increase the specific surface area and increase the active site of the reaction.Based on this,this paper proposes strategies for loading Co or Cu and constructing defects to improve the catalytic performance of g-C₃N₄,and investigates the reasons and catalytic mechanism for its improved photocatalytic performance.First,the catalytic activity is enhanced by the fact that Co acts as an"electron trap"to facilitate electron transfer and that Co can react with H₂O₂ to generate a strong oxidatively active·OH.Therefore,Co particles were loaded on g-C₃N₄.The effects of the content of cobalt powder on the morphology,electrical properties and catalytic efficiency were studied.After loading Co,the composite rate of e^-and h⁺was effectively inhibited,which accelerated the electron transfer rate and improveed dredox performance.Compared with g-C₃N₄,g-C₃N₄/Co was easier to produce·O₂^-and·OH active substances to participate in the degradation of MB.After 30 minutes of visible light,the photocatalytic efficiency increased from 16.87%to 95.61%.Second,there are no the resistance of schottky barrier on the surface Cu and isolated nano-sized Cu particles will cause local surface plasmon resonance phenomenon.Thus,the excited e^-or h⁺is easy to move to Cu（or Cu₂O）,induceing a reducing recombination of e^-and h⁺.Hence,Cu metal particles were loaded on the surface of g-C₃N₄,and the electrical properties,bandgap structure and catalytic performance of catalysts synthesized by different mass ratios were characterized.And the influence of Cu on the photocatalytic performance of g-C₃N₄ was analyzed.The photocatalytic performance was 3.33 times higher than that of g-C₃N₄.Finally,suitable structural defects are constructed to adjust the electron distribution of the catalyst and optimize the energy band structure.The strong oxidative pre-oxidation treatment of H₂O₂ is used to oxidatively remove N from g-C₃N₄ and prepare N-defect g-C₃N₄,which can also disrupt the interlayer structure of g-C₃N₄,thus greatly improving the electron transfer performance and current density of g-C₃N₄,and forming ultra-thin nanosheets whose shape is more conducive to visible light absorption and full contact of the dye.The photocatalytic efficiency increased from 30.54%to 84.67%.And it has higher photocatalytic efficiency to different dyes.