The Synthesis And Photocatalytic Properties Study Of C₂N/carbon Nitride Nanocomposites

As a material with graphitic structure,graphitic carbon nitride(g-C₃N₄)has became one of the most widely studied visible light response catalytic material because of its characteristics of visible light response and excellent physical and chemical stability.Carbon dinitrogen(C₂N)is also a graphitic two-dimensional material with uniformly distributed holes and nitrogen atoms,matching the structure of g-C₃N₄.In this dissertation,different methods have been designed to control the synthesis of C₂N and g-C₃N₄ nanocomposites.The photocatalytic performance and mechanism of C₂N and g-C₃N₄ nanocomposites were investigated.The main contributions of this dissertation are described as follows:(1)Preparation and structure characterization of C₂N nanosheets.In this paper,C₂N nanosheets were prepared via a simple wet chemical method using 100 nm SiO₂ spheres as hard template.A series of characterization methods including FT-IR,XRD,SEM,BET were used to prove that C₂N nanosheets have been successfully prepared.The thickness of C₂N nanosheets is around 40 nm.Besides,the as-prepared C₂N nanosheets have a large specific surface area.(2)Preparation and photocatalytic performance of C₂N/protonated carbon nitride(C₂N/PCN)nanocomposites.A straightforward strategy was designed for fabrication of C₂N/PCN nanocomposites with differing C₂N contents via a simply electrostatic self-assembly approach.The photocatalytic activity for hydrogen production and degradation of Rh B were systematically studied.The as-prepared catalyst showed excellent photocatalytic performance.The C₂N/PCN-3%nanocomposites possessed the highest photocatalytic activity with a hydrogen generation rate of 938.8?mol h^-1 g^-1.The apparent quantum yield at 420 nm was 5.64%.It also showed excellent photocatalytic activity towards Rh B degradation.Under visible light irradiation,the degradation rate of Rh B reached93.4%after 90 min.The excellent photocatalytic performance of PCN/C₂N nanocomposites could be ascribed to efficient charge carrier separation and enhanced photo-absorption efficiency.(3)Preparation and photocatalytic performance of C₂N/acid modified carbon nitride(C₂N/CN-H)nanocomposites.Here,we reported a facile strategy to fabricate C₂N/CN-H nanocomposites.First,different quantity of C₂N was complexed with nitric acid modified dicyandiamine.Then,C₂N/CN-H nanocomposites were gained by calcining with the complex.Moreover,the as-prepared C₂N/CN-H nanocomposites were characterized by XRD,FT-IR,XPS,SEM and TEM.The results indicated that C₂N/CN-H nanocomposites possess small lamellar structure and large specific surface area.The as-prepared catalyst showed excellent photocatalytic performance.The C₂N/CN-H-3 nanocomposites possessed the highest photocatalytic activity with a hydrogen generation rate of 1630.8?mol h^-1 g^-1.The apparent quantum yield at 420 nm reached 6.79%.It also showed excellent photocatalytic activity towards Rh B degradation.Under visible light irradiation,the degradation rate of Rh B reached 88.9%after 105 min.The excellent photocatalytic performance of PCN/C₂N nanocomposites could be ascribed to large specific surface area,efficient charge carrier separation and enhanced photo-absorption efficiency.