Preparation Of Two-dimensional Thin-layer Materials And Their Combined Composite Photocatalyst Hydrogen Evolution Research

Using photocatalytic technology with the assistance of photocatalyst to convert solar energy into chemical energy is a valid method to dissolve present environment and energy crisis and has been paid wide attention.To achieve this goal,finding efficient,stable,cheap semiconductor photocatalyst is significant.However,with the drawbacks of high combination rate of electron-hole pairs and low mobility of electron,single semiconductor photocatalyst is not able to improve photocatalytic reaction.When semiconductor combined with cocatalyst,electron will quickly move to the surface of cocatalyst and speed up hydrogen production reaction,so it is meaningful to assist the semiconductor with cocatalyst.Besides,the structural relation between semiconductor and cocatalyst is also of significance to improve photocatalytic reaction.Inorganic two-dimensional materials have atomic-level thickness and well connection with other two-dimensional layers when compared with their bulk counterpart.Special layer-layer contact structures endow their interface special properties.Thin layer and high specific area expose a large amount of unsaturated atoms which can act as catalytic reactive sites during photocatalytic process.Based on the above,we fabricate thin-layer MXene,g-C₃N₄ and their combination.Related research process and experimental conclusions are showed here:?1?By using LiF/HCl acid-etching method,nano MXene flakes with well structure was fabricated with size of around 1?m and thickness of 2³ nm.It is proved that the MXene has strong light absorption between 200¹300 nm wavelength,good dispersity and stability if kept properly.?2?By exploiting high-temperature calcination method,g-C₃N₄ nanosheet was prepared.The S-g-C₃N₄ has the size of 1?m and thickness of 2 nm with high porosity and specific area and can expose more reactive sites.When compared with its bulk counterpart,its band gap increases 0.3 eV,PL intensity decreased and transient PL lifetime extend from?₁,?₂,?₃ of 0.99,3.84,19.71 ns to 2.46,9.51,49.30 which strongly prove better electron-hole splitting rate and electron mobility.?3?To combined two two-dimensional MXene and S-g-C₃N₄,MXene/S-g-C₃N₄ composite catalyst was fabricated.The morphology and composition has been characterized by various analytic instruments.It shows that MXene/S-g-C₃N₄ has better hydrogen production performance to S-g-C₃N₄ with the help of cocatalyst MXene.Under the condition of 30 mg catalyst and 10%TEOA as sacrificial reagent,hydrogen evolution performance reach 108.95?mol h^-1g^-11 which increases 7 times when compared to pure S-g-C₃N₄.Consequently,possible MXene/S-g-C₃N₄ composite catalyst hydrogen evolution mechanism is deduced.