Synthesis And High Activity Mechanism Of Carbon Fiber Supported Carbon Nitride-based Photocatalyst

2,4-DCP is urgent to be removed from polluted water bodies by effective techniques because of its high stability and carcinogenicity.Semiconductor photocatalysis,as a‘green'chemistry technology using sunlight,has been attracting much attention.The key to this technology is the development of efficient photocatalysts.In recent years,the polymeric graphitic carbon nitride?g-C₃N₄?is widely used because it can absorb visible light,has good stability,and is easy to be obtained.However,some factors will affect its widespread use.For exsample,it is difficult to be separated due to its the nanopowder type.Its photo-generated electrons-holes are easily recombined,resulting in insufficient photocatalytic activity.In order to solve the above key problems,this paper has carried out the following works:First of all,we used an in-situ thermal polycondensation method to realize the construction of g-C₃N₄/carbon fiber?ACF?supported nanophotocatalyst,which solved the inseparability of nanopowdered g-C₃N₄ and realized the recycling of photocatalyst.The results based on some measurements,such as the hydroxyl radical test,show that ACF can receive photogenerated electrons,promote photo-generated charge separation,and thereby improve its photocatalytic activity.Secondly,in order to improve the interface contacts between ACF and g-C₃N₄,a nickel-regulating carbon layer was successfully introduced between them.Based on Raman,hydroxyl radical and electrochemical oxygen reduction tests,it is confirmed that the nickel regulation is beneficial to the improvement of graphitization degree of carbon layer and the reception of photogenerated electrons,and it has an activation effect on the adsorption of oxygen,which promote the separation of photo-generated charges and improve thereby the photocatalytic performance.Furthermore,the photocatalytic activity was improved by further surface phosphoric acid modification.The O₂-TPD results show that the improvement of activity is attributed to the increase of oxygen adsorption,which promoted the separation of photogenerated charges.It is demonstrated through the radical-trapping experiments that·O₂^-is the dominant active species in photocatalytic degradation of 2,4-dichlorophenol.Finally,in order to solve the problem that the large pore structure exists in ACF and affects the loading amount of g-C₃N₄,activated carbon was successfully used to fill in the ACF substrate and g-C₃N₄/ACF nanophotocatalyst was further modified by cellulose.Based on hydroxyl radical and solid fluorescence results,cellulose modification promotes photo-generated charge separation and enhances its photocatalytic degradation activities of 2,4-dichlorophenol and bisphenol A.This paper will provide a novel route to design and prepare g-C₃N₄-based supported photocatalysts with high photocatalytic activities and recyclability.