Preparation And Photocatalytic Properties Of Graphitic Carbon Nitride Based Photocatalysts

Large-scale industrialized production has brought many conveniences to our life,but it also inevitably pollutes our air,water and soil in the environment.How to effectively solve the worsening environmental crisis and create a comfortable and safe living environment is the pursuit of people.The study found that semiconductor photocatalyst is a green and non-polluting technology,which can effectively convert light energy into chemical energy,and realize the degradation of harmful substances in air or the removal of organic pollutants in water and the reduction of harmful heavy metals.As a non-metallic semiconductor material,graphite phase carbonitride(g-C3N4)has received lots of attentions by researchers because of the advantages of visible light response(Eg=2.7 eV),non-toxic and harmless,good chemical stability,abundant raw material source,simple preparation method,etc.However,the traditional powder g-C3N4 is very easy to agglomerate in water treatment applications,and it is difficult to recover,and the visible light absorption range is narrow,and the photogenerated electrons-holes are also easily recombined,which greatly reduces the utilization of sunlight.Therefore,how to improve the photocatalytic activity of the catalyst and the high efficiency of loading technology has become the focus of research at this stage.From the above two perspectives,a polyester fiber reinforced porous cellulose aerogel carrier(CA/B-PET)was prepared,and g-C3N4 was successfully loaded to form g-C3N4@CA/B-PET composite catalyst.We used FESEM,FTIR,DRS,XRD and TG characterization to confirm the successful loading of g-C3N4 in polyester fiber reinforced cellulose aerogel.The three-dimensional porous structure of aerogel not only creates more active sites,but also facilitates the contact of the reaction substrate with catalyst and mass transfer.Driven by sunlight,g-C3N4@CA/B-PET composite material can effectively treat complex polluted,and degrade water organic pollutants and reduce heavy metal hexavalent chromium ions simultaneously.What’s more,through the cycle experiments,g-C3N4@CA/B-PET has excellent reusability and stability,and the activity is hardly affected in the complex water background.The free radical trapping experiment and EPR spin capture technique indicated that the reactive species in the catalytic process was ·O2-,and the catalytic degradation mechanism was proposed.In addition,the degradation products and degradation history of the antibiotic sulfaquinoxaline were analyzed by ultra performance liquid chromatography-high resolution mass spectrometry.The loading of the cellulose aerogel effectively solves the problem that the powder catalyst is easy to agglomerate and difficult to recover,which greatly improve the photocatalytic activity of the powder catalyst.On the other hand,in order to broaden the visible light absorption of g-C3N4,and improve the electron transport efficiency of the catalyst.We prepared four binary composite catalysts of g-C3N4/FePc、g-C3N4/FePcCl16 g-C3N4/Fe2O3、g-C3N4/GR,respectively.After a series of characterization and photocatalytic performance tests,it was found that the combination of FePc,FePcCl16,Fe2O3 and GR significantly broadened the visible light absorption of the catalyst,enhanced the photogenerated electron-hole separation efficiency and unchanged the chemical structure of g-C3N4,and did not destroy the lattice structure of g-C3N4.The g-C3N4-based catalysts not only can degrade nicotine and sulfachlorpyridazine efficiently under sunlight,but also have good photocatalytic performance under low energy density LED lamp.Similarly,radical trapping experiments and EPR spin trapping techniques have proved that·O2-is the main active free radical in g-C3N4-based catalytic reaction process.The degradation products and degradation process of nicotine were analyzed by Ultra High Performance Liquid Chromatography-High Resolution Mass Spectrometry(UHPLC-HRMS).It was found that the degradation pathway of nicotine was ring-opening degradation with pyrrole ring as the active site.In addition,we found that g-C3N4 modified by FePc,FePcCl16,Fe2O3 and GR not only broadened the visible light range of the catalyst and increased its catalytic activity,but also made the pale yellow g-C3N4 present colorful colors,like pigments.Therefore,we applied these colored catalysts for fiber coloring and painting to prepare catalytic functional textiles and artistic paintings.