Preparation And Properties Of G-C3N4 Based Photocatalysts

Because of the greenhouse effect,energy scarcity and environmental pollution caused by the excessive burning of fossil fuels by human beings,they have to find a clean renewable energy source,so scientists turned their attention to new energy sources.Photocatalysis is considered as one of the most promising technologies for the production of renewable fuels and the removal of contaminants through solar energy.Semiconductor photocatalysts have been widely used in the degradation of pollutants and hydrogen production.In the past few decades,various photocatalysts have been developed.The paper mainly studies MoS₂ and g-C₃N₄materials and optimizes their photocatalytic properties.The content is as follows:?1?Designing an efficient and stable photocatalyst to directly address environmental pollution is an ideal way to convert solar energy.Therefore,we report a simple and effective method,hydrothermal calcination that is used to synthesize highly active carbon nitrides from cheap and easily available melamine.The light-orange tubular carbon nitride exhibits excellent light responsiveness,high photogenerated charge separation efficiency and significant photodegradation activity?methyl orange?.Under visible light,M-10-200-24-600 exhibited the best photocatalytic degradation performance,which degraded more than 84%methyl orange in120 minutes.The discovery of light-orange and orange-red tubular carbon nitride can provide an opportunity for efficient photocatalysis and solar energy conversion.?2?The MoS₂/g-C₃N₄ composite catalyst with efficient charge separation was synthesized by a simple method and characterized by X-ray diffraction,FT-IR spectroscopy,SEM,TEM and XPS.By adjusting the MoS₂ to dicyandiamide molar ratio from 0.08%to 4%,the change of morphology can be easily observed for MoS₂/g-C₃N₄.It is used for Degradation of methyl orange under simulated sunlight irradiation.It was found that the performance of the MoS₂/g-C₃N₄ sample was 2-3 times higher than that of pure g-C₃N₄.The improvement of the activity is due to the low recombination rate of photogenerated charges.?3?The combination of freeze drying and calcination is a simple and feasible solution for the preparation of porous MoS₂/g-C₃N₄.Compared with the original g-C₃N₄,the bulk doping porous MoS₂/g-C₃N₄ heterojunction photocatalyst exhibits high photocatalytic hydrogen production activity under visible light.The hydrogen production rate reached 1640.3?molg^-1h^-1,which was more than 6 times the original g-C₃N₄.One of the reasons why porous MoS₂/g-C₃N₄ has excellent photocatalytic properties is its unique morphology and structure,which can provide higher specific surface area and expose more active sites.Of course the structural,optical,and electrochemical analysis indicate that another reason for high activity is to expand the absorption edge of visible light and improve the separation efficiency of photogenerated charge.