Preparation And Photocatalytic Performance Of G-C₃N₄/ZnO Nanocomposites

With the development of photocatalytic technology recently,visible light catalysis using solar energy to degrade pollutants has become a research hotspot,but most of the catalysts currently used only respond to ultraviolet light,which limits the practical application.g-C₃N₄ is a new type of photocatalyst discovered in recent years.It not only responds to visible light,but also cheap and easy to obtain.However,its specific surface area is small,and the visible light absorption intensity is low,which affects the photocatalytic degradation rate.In this paper,g-C₃N₄/ZnO was recombined by simple method to prepare high-efficiency three-phase composite catalyst.The structure and photochemical absorption characteristics of the composites were characterized.The tetracycline（TC）wastewater was used as the simulation object to study its light.The performance and mechanism of catalytic degradation of TC are as follows:（1）Preparation of g-C₃N₄/ZnO/NiO three-phase composite catalyst are synthesized by thermal polycondensation,precipitation and grinding and calcination,using Z-type heterojunction and p-n structure which formed between g-C₃N₄,ZnO and NiO to effectively to improve photogeneration Separation of electron-hole pairs.The characterization results of SEM,EDX,XRD,XPS,FT-IR and UV-Vis DRS indicated that the catalyst is successfully prepared and the purity is high.The photocatalytic experimentresultsshowthatwhenthesolutionpH=7,0.15g g-C₃N₄（80%）/ZnO/NiO（9%）degraded 200mL 20mg/L to achieve the best results,but the presence of anion,cation and humic acid in the solution will inhibit the effective degradation of TC.（2）Using g-C₃N₄/ZnO modified by photochemical deposition method to obtain g-C₃N₄/ZnO/Ag,g-C₃N₄/ZnO（30%）/Ag（8%）with the surface plasmon effect of Ag.The loading of Ag inhibits the recombination of photo-generated carriers and broadened the response range of light.The wavelength of g-C₃N₄/ZnO（30%）/Ag（8%）was extended from 470nm to 510nm of g-C₃N₄,and the photolysis rate was 1.58 times than before,At the same time,experiments showed that the photocatalytic activity of g-C₃N₄ after acid modification was significantly enhanced.（3）Studies have shown that the photocatalytic degradation process of tetracycline is consistent with the second-order kinetics,and the integrated free radical trapping experiment and the energy band structure of the semiconductor.The main active substances that dominate the degradation of TC in this paper are·O₂^-.Cyclic experiments show that g-C₃N₄/ZnO/NiO and g-C₃N₄/ZnO/Ag have good stability and can be reused.Figure[43]table[7]reference[158].