Preparation And Performance Of C₃N₄-based Composite Catalysts Based On Synergistic Photo-Fenton

In recent years,with the depletion of fossil fuel and the environmental pollution brought by the rapid development of industrialization,it is urgent to find a green technology to solve these crisis.Semiconductor photocatalysis,as a nontoxic,harmless and sustainable technology,is become one of the most potential technologies to solve the energy and environmental crisis,and has received extensive attention in recent years.However,the poor light absorption ability and high carrier recombination efficiency restrict the practical application of semiconductor photocatalyst.C₃N₄is regarded as one of the most promising semiconductor photocatalytic materials.In this paper,C₃N₄with visible light response was taken as the research object,and two different C₃N₄-based catalysts were prepared through morphology regulation and defect construction.The main research contents are as follows:（1）In this work,a carbon nitride（CNKOH_x）with three-dimensional lamellar porous structure was prepared by K⁺doping and hydroxyl modification,and the effect of Na OH dosage on CNKOH_xactivity was explored.The activity test results showed the as-prepared CNKOH_0.05had optimal photocatalytic activity at the addition of 0.05 g Na OH.Under visible light（λ≥420 nm）irradiation,the activity of hydrogen peroxide in pure water was 51.36μmol g^-1h^-1,which was 18.6 times higher than that of carbon nitride（Bulk CN）.The improved photocatalytic activity was attributed to the three-dimensional porous structure with a larger specific surface area of CNKOH_0.05,which provided more active sites for the reaction.Electrons were conducted through K⁺and defects,and holes were captured by hydroxyl groups.This dual-channel effect effectively inhibited photogenerated carrier’s recombination of CNKOH_0.05.（2）Carbon nitride（Fe-N_v/TCN）with hollow tubular structure was prepared by thermal polymerization and defect engineering regulation,and the effects of different Fe³⁺loadings on the photo-Fenton synergistic oxidation performance of the catalyst were investigated.Tetracycline was chosen as a model pollutant,2.1wt%Fe-N_v/TCN showed optimal tetracycline degradation activity.Under visible light（λ≥420 nm）irradiation for 1 h,the activity of tetracycline degradation rate of 2.1wt%Fe-N_v/TCN was 84%,which was 7 times higher than that of Bulk CN.The enhanced photocatalytic activity was attributed to the enhanced photogenerated carrier’s separation efficiency due to nitrogen defects,the abundant active sites provided by the nanotubular structure with a large specific surface area,and the increased formation of active free radicals（·OH）because of the synergistic photo-Fenton oxidation.