Preparation Of Carbon Nitride-based Single-atom Catalysts And Study Of Their Photocatalytic Properties

With the rapid development of economy,the problem of air pollution becomes more and more serious,among which the pollution of volatile organic compounds(VOCs)in indoor air attracts more and more public attention.Carbon nitride(g-C₃N₄)is one of the commonly used indoor VOCs purification technologies in photocatalysis.The technology can degrade organic matter effectively and has the advantages of low energy consumption,environmental friendliness and high degradation rate.As a new type of semiconductor material,carbon nitride(g-C₃N₄)is favored by researchers.It has good chemical stability and good visible light response ability.However,due to its short photocarrier life and narrow visible light response range,VOCs photocatalytic efficiency is not high,which restricts its large-scale promotion and application.For this reason,this paper made the following improvements in view of its shortcomings:(1)Facile synthesis of[Pt]-CNHS monatomic catalyst with enhanced visible light photoactivity toward toluene degradationThe[Pt]-CNHS composite photocatalytic material was successfully prepared by photochemical reduction using the ultra-thin porous carbon nitride nanosheet(CNHS)as the carrier,potassium chloroplatinate as the platinum source,xenon lamp as the visible light source and melamine as the precursor.[Pt]_0.1-CNHS were characterized by high-resolution transmission electron microscope and element distribution map,and the results showed that the single-atom catalyst was successfully prepared.[Pt]_0.1-CNHS had the highest photocatalytic activity.The degradation rate of toluene in gas phase was 68.5%,which was better than that of pure substance.The improvement of photocatalytic activity of the[Pt]_0.1-CNHS composite material was attributed to the high dispersion of Pt under the monatomic form,which could be used as the active center to inhibit the photogenic electron hole pair recombination.(2)Controlled preparation of[Pt]-CNHS/HCNTs catalyst with enhanced visible light photoactivity toward toluene degradationUsing single-atom catalyst[Pt]_0.1-CNHS as the carrier and helical carbon nanotubes(HCNTs)as the carbon material,the photocatalytic composite material[Pt]_0.1-CNHS/HCNTs was successfully prepared by-self-assembly.The prepared materials were characterized by XRD,SEM,TEM,FT-IR and PL.[Pt]_0.1-CNHS/HCNTs-0.5 had the best photocatalytic activity and the degradation rate of toluene in gas phase reached 98.5%.After HCNTs were loaded,multistage pore structures were constructed,which enhanced adsorption on the one hand and inhibited electron and hole recombination on the other.(3)Controlled preparation of[Pt]-CNHS/BCFs catalyst with enhanced visible light photoactivity toward toluene degradationBiomass cellulose was extracted from sisal as precursor.Biomass carbon fiber(BCFs)was obtained by carbonization at high temperature under nitrogen atmosphere.Similarly,[Pt]_0.1-CNHS was selected as the support and[Pt]_0.1-CNHS/BCFs was also prepared by the method of-self-assembly.The prepared materials were characterized by XRD,SEM,TEM,FT-IR and PL.The photocatalytic activity of[Pt]_0.1-CNHS/BCFs-1 material was the best,and the degradation rate of toluene to gas phase reached 100%.After BCFs intercalation with three-dimensional network structure,the specific surface area of the material is increased,the migration of photogenerated electrons is accelerated,and the electron and hole recombination is effectively inhibited,which leads to the improvement of the activity of photodegradation toluene.