Study On Visible Light Activated Self-disinfection Effect Of Carbon Doped G-C₃N₄ Based On Energy Band Regulation

Semiconductor photoactive material,a material with the characteristics of light-excited generation of active oxygen groups and light-to-heat conversion,can effectively degrade microorganisms and organic pollutants,and produce visible light active self-cleaning effects.Therefore,it has become one of the most potential materials in solving the problems of biological environmental pollution and organic pollution.A new type of non-metallic graphite phase carbon nitride nanomaterial（g-C₃N₄）,due to its environmental and safe non-metallic properties,relatively suitable band gap,visible light excitation and diversified doping advantages,it has become the research of semiconductor photoactive materials Hot spot.However,it faces the problem of low visible light utilization.This work has optimized the specific surface area of graphite phase carbon nitride nanomaterials,and systematically studied the influence of carbon doping concentration on the energy band structure of graphite phase carbon nitride,photoactive oxygen composition,and photo-thermal effect.Two aspects of the interface effect study its visible light active self-cleaning performance and mechanism.The energy band optimization of carbon-doped carbon nitride compared to the bulk material is realized,the separation efficiency of carriers is improved,and the photoactive self-cleaning performance of the material under the synergy of photo-thermal conversion effect is effectively improved.The main content and results of this article are as follows（in this article,carbon nitride refers specifically to graphite phase carbon nitride）:（1）Optimize the specific surface area of carbon nitride materials.This work successfully increased the specific surface area of the bulk carbon nitride material from79.16 m²/g to 160.74 m²/g through the method of thermal oxygen etching,and applied it to the subsequent preparation process of carbon-doped carbon nitride;（2）Regulate the carbon doping energy band and enhance the photo-activated oxygen and photo-thermal conversion effect.In order to solve the problems of low visible light utilization of intrinsic carbon nitride and easy carrier recombination,the method of thermal copolymerization of glucose and urea was used in this work to prepare carbon-doped carbon nitride.When the doping ratio is 1.5%,the band gap of carbon nitride decreases from 2.72 e V to 2.16 e V.Studies have found that an appropriate carbon doping ratio not only introduces heterojunctions,improves the separation efficiency of electrons and holes,and increases the concentration of active oxygen generated by visible light excitation.Moreover,a carbon energy level is formed,which can not only improve the absorption of the material in the visible light band,but also serves as an electron acceptor to enhance the non-radiative relaxation of carriers,and increase the photo-thermal conversion efficiency of the material.In the study of the photoactive self-cleaning effect of E.coli as a model,the sterilization efficiency of carbon-doped carbon nitride in the solution increased from 0.2 log₁₀/h to 2.13 log₁₀/h;（3）Study on the interface effect of photoactive self-cleaning of carbon-doped carbon nitride surface.Under the irradiation of one unit of sunlight,the bulk carbon nitride film has the same temperature as the water-soluble environment,and the surface temperature of the 1.5%carbon-doped carbon nitride film is 10℃higher than that of the bulk material,which shows that during the photoactive self-cleaning process,The influence of light-to-heat conversion effect is the dominant factor.When the ambient temperature of the aqueous solution is 40℃,the sterilization rate of the thin-film carbon-doped carbon nitride film is reduced by four orders of magnitude within 40minutes,reaching 99.99%;（4）Study on the light absorption interface mechanism of carbon-doped carbon nitride films.Based on the micro-nano structure of the carbon nitride film surface,the modeling and the finite difference time domain（FDTD）were used to simulate the light field distribution during the photoactivity process,providing information on the influence of the surface morphology and optical properties of the film on self-cleaning Theoretical basis;...