Preparation And Photocatalytic Properties Of Copper And Iron Doped Carbon Nitride Materials

Graphitic carbon nitride(g-C₃N₄)as a non-metallic semiconductor photocatalyst has received extensive attention in the photocatalytic CO₂ reduction due to its low cost,facile preparation,excellent physicochemical stability and suitable band gap for visible light response.However,the bulk g-C₃N₄ suffers from the low surface area,limited light harvesting and rapid recombination of photogenerated electron-hole,which restrict its further application.In this work,transition metal modified g-C₃N₄ was prepared by chemical vapor co-deposition and applied to photocatalytic CO₂ reduction with high photocatalytic efficiency.The detail work was summarized as the follows:The homogeneous mixture of urea and chlorophyllin sodium copper salt is prepared as the precursor,and cellulose-based carbon paper is used as the substrate.The precursor is pyrolyzed in a nitrogen atmosphere to obtain Cu modified g-C₃N₄.The ingenuity of this method is that the introduction of Cu successfully induces the growth of g-C₃N₄ into bundle-like structure composed of nanorods.It is confirmed that the copper content affects the morphology and structure of the bundles,and the formation mechanism of the bundles is discussed.The introduction of copper effectively promotes the transfer of photogenerated electrons,suppresses carrier recombination,and expands the absorption range of visible light.The Cu modified g-C₃N₄ is applied to photocatalytic CO₂reduction.A large amount of CO and a small amount of CH₄ are detected in the product.The CH₄yield is 0.935?mol g^-1 h^-1,and the CO yield of 9.9?mol g^-1 h^-1 is about 5 times that of the bulk g-C₃N₄.Moreover,it shows excellent stability in 5 cycle experiments.The Fe modified g-C₃N₄ nanorod bundles are prepared by chemical vapor co-deposition using the mixture of urea and chlorophyllin sodium copper salt as precursor.The method of chemical vapor co-deposition is adopted to introduce Fe into g-C₃N₄,which effectively solves the problems of poor utilization and insufficient active sites due to metal aggregation,increases the adsorption ability of visible light,and promotes the separation and transfer of charge.The prepared Fe modified g-C₃N₄ exhibits excellent photocatalytic activity for CO₂ reduction CO₂ reduction.It is applied to photocatalytic CO₂reduction,and the CO is the main product with a yield of 18.5?mol g^-1,about 1.9times that of bulk g-C₃N₄.This work provides a strategy to prepare carbon nitride-based photocatalysts for efficient CO₂ reduction.