Study On Modified Graphite Carbon Nitride Co-doped With Transition Metal And Sulfur And Its Photocatalytic Performance

Due to the increasing depletion of traditional fossil energy,the development and utilization of new clean energy is essential to the sustainable development of mankind.Photocatalytic technology is receiving more and more attention for its ability to efficiently use clean and easily available solar energy.Graphite carbon nitride（g-C₃N₄）has inherent visible light absorption,stable structure and abundant precursor sources,so it is favored by the majority of researchers in the field of visible light catalysis.However,g-C₃N₄ itself also has some shortcomings,such as the small specific surface area,the serious recombination of photo-generated carriers,the weekness in chemical catalytic activity,and so on.Therefore,it has extensive research on its modification,mainly focusing on there aspects,namely structural design,doping,and compound modification with other materials.In this work,thiocyanuric acid was used as the sulfur-containing precursor to copolymerize with different transition metal nitrates.The co-doping of S element and one of four transition metal（Fe/Co/Ni/Mn）elements repectively into g-C₃N₄ was achieved,and the physico-chemical properties and photocatalytic performance of the modified materials was investigated further.The co-doping modification can effectively regulate the electronic structure and light absorption properties of g-C₃N₄.Meanwhile,the introduction of transition metals can improve the utilization efficiency of photogenerated carriers while providing a promoting catalytic structure.Therefore,functional nanomaterials with excellent photocatalytic performance and stability can be obtained by this metal-sulfur co-doping strategy.A series of samples were prepared by adjusting the doping ratio of the metal salt and the calcination temperature to explore the most appropriate preparation conditions for co-doping,and their microstructure,chemical environment and optical properties were characterized further.It can be concluded that metals and sulfur elements can be successfully doped into the framework structure of g-C₃N₄.When the metal doping concentration is high,the corresponding sulfide will be generated.The appropriate amount of metal doping can optimize the light absorption performance and energy band structure of the modified photocatalysts,promoting the transfer of photoinduced charge and improving the photocatalytic activity.The four optimal ratios of co-doped modified g-C₃N₄ exhibited significantly enhanced photocatalytic activity and universality in the photocatalytic epoxidation of multifarious olefin substrates.and the conversion rate is close to 100%.