Preparation And Degradation Of G-C₃n₄ Based Photocatalysts

g-C₃N₄is a non-metallic polymer semiconductor material with a band gap of 2.7 eV,good chemical and photostability,and easy to regulated structure and properties with good chemical and photostability,and easy to regulated structure and properties with good photocatalytic performance.However,its photocatalytic activity is still limited by its small specific surface area,less surface active sites,high photogenerated carrier recombination rate and low quantum efficiency,so it was urgent to find more effective materials to make up for it.Therefore,g-C₃N₄-based ternary composites were prepared to improved the photocatalytic activity of g-C₃N₄materials.the photocatalytic properties of the composites were investigated using rhodamine B（RhB）and tetracycline hydrochloride（TcH）degradation as models.The specific studies are as follows:（1）:g-C₃N₄/diatomite,synthesized by impregnation on this basis,different amounts of MnO₂are added by redox,With RhB as the model pollutant,The photocatalytic activity of the composite catalyst was studied in detail.Results:Compared with g-C₃N₄and MnO₂,g-C₃N₄/diatomite/MnO₂nanocomposites exhibitd better photocatalytic performance.After50 minutes of exposure to the Xe lamp,g-C₃N₄/diatomite/MnO₂composites can degraded almost 94.1%,g-C₃N₄,diatomite and MnO₂degradation rates increased by 1.22,10.6 and36.61 times,respectively.（2）:The ultrasonic reduction method and the hydrothermal method were combined to prepare g-C₃N₄/diatomite/MnO₂composite materials with different proportions.The composite materials were prepared by SEM,XRD,BET.To characterized and analyzed the morphology and composition of the composite material,and briefly explaind the photocatalytic mechanism of the composite material through UV-vis and PL.Taking TcH as an example,compared with pure g-C₃N₄,diatomite,MnO₂,g-C₃N₄/diatomite,under simulated light conditions,g-C₃N₄/diatomite/Mn O₂composites show more excellent photocatalytic performance.At 25℃,when the addition amount of DT is 0.01 g and the addition amount MnO₂is 5%,the degradation rate of TcH（50 mg/L）by 30mg g-C₃N₄/diatomite/MnO₂composite material can reach 88%within 60 minutes.,And the degradation rate remains around 83%after three cycles.（3）:The combination of urea and ATT into g-C₃N₄/ATT binary composites by simple calcination,Based on this,the Cu₂O,was prepared by using the weak reducibility of glucose in strong alkali environment further forming g-C₃N₄/ATT/Cu₂O ternary composites.Optimum ratio and degradation rate of g-C₃N₄/ATT and g-C₃N₄/ATT/Cu₂O composite were obtained by degraded of TcH（30 mg/L）.After three cycle,the composite still has82%degradation rate,which proves that the composite has high stability.According to the experiment of radical capture,the main active species,in the whole catalytic degradation process are h⁺and·O₂^-radicals,and the contribution of·OH radicals is less.The results shown that the composite can still have excellent photocatalytic activity in high concentration waste liquid.The Zeta values can be used to further understand the surface potential of the composites.In practice,the g-C₃N₄/ATT/Cu₂O composite can be used to deal with water pollution.