Enhancement Of Carbon Nitride Film Electrode And Digradation Of Ag-cyanide Complexes

In this paper,g-C3N4 film was prepared by a liquid-based reaction onto ITO substrate during the calcination treatment.The photoelectrocatalytic activities of g-C₃N₄ were enhanced by synergistic effection,metal modifying:1.g-C₃N₄ film was used as photoanode for photoelectrocatalytic degradation of MB with H₂O₂ added.The results showed synergistic effects between g-C₃N₄ and H₂O₂ under visible-light irridiation and indicated that the degradation of MB increased efficiently with the addition of H₂O₂.It confirmed that·O₂^-as well as·OH were the main oxidized species in photoelectrocatalytic process by ESR analyses and radical masking experiments.It was proposed that photo-generated electrons could be captured by O₂ or H₂O₂ to generate·OH for the oxidative degradation of organic dye when H2O2 was added in g-C3N4-vis system.2.Ag/W-doped g-C₃N₄ films were comprehensively characterized by SEM,HRTEM,XRD,UV/vis DRS,and XPS.The photocurrent response of Ag/W-doped g-C3N4 films increased remarkably with the increasing metal content.Metal doped films exhibited a high photoelectrocatalytic activity for the degradation of methylene blue.The enhancement of photoelectrocatalysis owing to more visible light could be harvested and photogenerated electron and interfacial electron could transfer more easily after modifying metal in g-C₃N₄ film.Thus,a possible photoelectrocatalysis mechanism was proposed.The photogenerated electron was captured by O₂ or·O₂^-and then forms·OH radicals.3.g-C₃N₄ was cyclic utilized seven times with simultaneous Ag recovery.The Ag recovery on photoanode and cathode corresponds to AgO and Ag metal,respectively.The photoelectric response of the g-C₃N₄ films was obviously increased after the AgO deposition.The deposition rate and amount of AgO increased with the addition of H₂O₂.Finally,ESR and trapping experiments confirmed the existence and roles of·O₂^-and·OH in PEC oxidation.The photogenerated electrons of g-C₃N₄ could be captured by·O₂^-and H₂O₂ to perform·OH to oxidize the Ag cyanide.Meanwhile,the recovery of Ag on g-C3N4 increased electrical conductivity and the migration rate of the photogenerated electrons.AgO loading also can enhance the production of·O₂^-,which increased its photoelectrocatalytic activities towards cyanide degradation.