Synthesis Of G-C₃N₄ Based Hybrid Photocatalysts With Enhanced Photocatalytic Activity

With the development of economy and society,the problems of the environment and the energy crisis have become more and more severe.Graphitic carbon nitride?g-C₃N₄?has attracted wide attention as an excellent visible light photocatalytic.g-C₃N₄has many advantages,such as good chemical stability,narrow band gap,which make it can absorb visible light,easy processing and preparation of low cost.But at the same time,the visible light response of g-C₃N₄ is relatively poor,and the photo-electron/hole are easily compounded,and the co-catalysts is mainly precious metals,that serious limits its applications.The traditional research on the modification of g-C₃N₄ is mainly focuses on how to improve visible light response and reduce electron/hole recombination.And there are few studies on interfacial redox activity.Carbon based nanomaterials are cheap and good electrocatalysis.In this paper,in order to study the specific role of carbon based nanomaterials as co-catalysts on photocatalytic hydrogen envolution activity of g-C₃N₄,I used online photocatalytic hydrogen evolution measurement,electrochemical and photophysical analysis.The contents are as follows:1.In this part,using nitrogen and phosphorus co-doped carbon nanoparticles?NPCP?as co-catalysts to improve the photocatalytic hydrogen envolution activity of g-C₃N₄.The NPCP was synthesized by acetic acid,water,P₂O₅ and urea.The results showed that NPCP as co-catalysts not only can improve visible light absorption and reduce electron/hole recombination,but also can effectively promote the proton reduction and sacrificial agent oxidation ability.The results showed that g-C₃N₄/NPCP-0.5 had the best photocatalytic hydrogen evolution performance,about2000?mol^-1g^-1h^-1,2.47 times of pure g-C₃N₄.2.In this part,using cobalt/nitrogen doped graphitic carbon composite?Co-NG?as co-catalysts to improve the photocatalytic hydrogen envolution activity of g-C₃N₄.The Co-NG was synthesized by cobalt catalyzed carbonization and graphitization of urea under thermal treatment.Under current density of 10 mAcm^-2,Co-NG-800 has displayed the highest HER activity,the overpotential is 203mV in 0.5 M H2SO4.It wasfound that Co-NG as co-catalysts not only can improve visible light absorption and reduce electron/hole recombination,but also can effectively promote the interfacial redox reaction activity.The results showed that 0.05%Co-NG/g-C₃N₄ had the best photocatalytic hydrogen evolution performance,about 2009?mol^-1g^-1h^-1,2.48 times of pure g-C₃N₄.