Graphite phase carbon nitride(g?C₃N₄), as an environmentally benign semiconductor material, has good application prospects in photocatalysis. However, the disadvantages of pure g?C₃N₄ such as small specific surface area and difficult separation of photogenerated carriers will limit its photocatalytic performance, which will restrict its large?scale application.From the synthetic methods and modification strategies, the research progress of g?C₃N₄ photocatalysts by researchers in recent years is reviewed, and the development of g?C₃N₄ photocatalysts in the fields of degradation of pollutants in water treatment, H₂ and H₂O₂ production is summarised, and it can be found that the performance of the modified g?C₃N₄ photocatalysts has been greatly improved.Finally,the development direction of g?C₃N₄ photocatalyst is prospected.

As a classic non?metallic semiconductor photocatalyst, graphite phase carbon nitride material （g?C₃N₄） has attracted widespread attention in recent years due to its stable physical and chemical properties, reasonable band structure, low cost, easy availability, safety, and pollution?free advantages. It has good application and development prospects in the fields of environmental protection, purification and energy catalysis. However, the utilization of g?C₃N₄ in studies is significantly hampered by its tiny specific surface area, limited absorption of visible light, and high rate of recombination of photogenerated electrons and holes. The basic structure, characteristics and main modifications of g?C₃N₄ are reviewed, covering modification means such as elemental doping, morphological modulation, noble metal deposition and the practical applications of g?C₃N₄ in recent years at home and abroad.

A nitrogen?doped carbon catalyst was prepared by the calcination of the CN _y precursor synthesized by the polymerization of paraformaldehyde,1,3,5?trimethylbenzene and p?phenylenediamine.This paper also investigated the effect of catalyst calcination temperature on the performance of acetylene hydrochlorination.The results indicate that CN _y ?700?1 catalyst has the best reaction activity.It has an acetylene conversion of up to 89.8% under the optimized conditions of acetylene?to?hydrogen chloride volume ratio of 1.0∶1.1,reaction temperature of 280 ℃ and GHSV(C₂H₂) of 90 h^-1.The catalyst characterization manifests that the activity of the catalyst is related to the specific surface area,pore volume,and pyrrole nitrogen content.The active site of the catalyst is the carbon atom bonding with the pyrrole nitrogen atom.Increasing the calcination temperature results in a larger specific surface area within a certain temperature range,and the pyridine nitrogen can also be converted to pyrrole nitrogen to a certain extent.The main cause of catalyst deactivation is carbon deposit.

Supported SnCl₂ is a mercury?ree catalyst for acetylene hydrochlorination.5.0%Sn(acac)₂Cl₂/AC catalyst was prepared by introducing acetylacetone ligand to enhance the catalytic performance of SnCl₂ in acetylene hydrochlorination.The results show that the acetylene conversion of 5.0%Sn(acac)₂Cl₂/AC catalyst is up to 96% under the conditions of acetylene?to?hydrogen chloride molar ratio of 1∶1.1,170 ℃ and GHSV(C₂H₂) of 90 h^-1, which is higher than that of the 5.0%SnCl₂/AC catalyst. The physical and chemical properties of the catalysts before and after the reaction also proved that the introduction of acetylacetone ligand can enhance the acetylene adsorption capacity of the SnCl₂ catalyst and inhibit Sn loss during the reaction.Therefore,the activity and stability of the SnCl₂ catalyst were effectively improved.

The photocatalysis technology becomes more and more mature. As a non?metallic visible light responsive catalyst, carbon nitride (g?C₃N₄) has attracted wide attention in the field of solar energy conversion and environmental protection due to its adjustable band gap structure, high physicochemical stability and environmental friendliness. It has become a new research hotspot. However, g?C₃N₄ also has some defects, such as small specific surface area, recombination of photogenerated electron and holes, and low utilization rate of light energy,which limit the application of g?C₃N₄ in practice.Therefore,the review focus on the development and research results of g?C₃N₄,and summarizes g?C₃N₄ from the aspects of development process,synthesis method, performance application,modification and optimization,and predicts how to further improve the performance of g?C₃N₄ to cope with the future development of the world.