Photocatalytic Hydrogen Evolution Of Defective Carbon Nitride Nanosheets Loaded With Noble Metal

Hydrogen energy is recognized as an environmentally friendly and renewable energy source,and the photocatalytic hydrogen production technology is an ideal way of hydrogen production which received widespread attention.As a metal-free semiconductor material,carbon nitride（C₃N₄）become a popular material in photocatalytic hydrogen production due to its non-toxic,visible light response,and better chemical stability.However,the photocatalytic hydrogen production efficiency of pure carbon nitride is low,because of its small specific surface area,high photogenerated electron-hole recombination rate and narrow visible light absorption region.In order to solve these problems,this paper will optimize the property of C₃N₄from two aspects:The introduction of nitrogen vacancies and the modified with noble metals.In this paper,the defective C₃N₄（C₃N_x）were used as the starting material.Through the morphological design of C₃N_x and noble metal modification of C₃N_x NS,the photocatalytic property was characterized by the decomposition of water under visible ligth irradiation.The as-prepared samples were characterized by X-ray powder diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and X-ray photon spectroscopy（XPS）,specific surface area（BET）,et al.The main research content about as-prepared samples for photocatalytic hydrogen evolution were introduced as follows:First,Carbon nitride containing nitrogen vacancies（C₃N_x）was obtained by sintering C₃N₄ in a hydrogen atmosphere,and C₃N_x NS was obtained by a simple ultrasonic stripping method.The introduction of nitrogen vacancies can inhibit the recombination of photogenerated electrons and holes,and more active sites on the surface were obtained by ultrasonic stripping.The three samples were placed under visible light for photocatalytic hydrogen production performance test.By comparing with C₃N₄ and C₃N_x photocatalytic hydrogen production performance,it is found that C₃N_x NS has excellent photocatalytic hydrogen production performance,and its visible light photocatalytic hydrogen production property can reach 0.42μmol/g/h.Second,the AgNO₃ and K₂Pt Cl₄ were useds as the silver source and the platinum source,respectively.Ag and Pt were successfully loaded on the surface of C₃N_x NS by a simple chemical deposition method.The test of visible light photocatalytic hydrogen production showed enhanced photocatalytic hydrogen production activity.The surface plasmon resonance effect of Ag broadens the response range of visible light and promotes the migration of photogenerated carriers,thereby enhancing the photocatalytic hydrogen production effect of C₃N_x NS.As a traditional photocatalytic hydrogen production promoter,the Schottky barrier formed between Pt and C₃N_x NS can capture a large number of photogenerated electrons,thereby promoting the photocatalytic hydrogen production reaction.The photocatalytic hydrogen production efficiency of Ag/C₃N_x NS and Pt/C₃N_x NS reached 35μmol/g/h and 0.74 mmol/g/h,respectively.Thirdly,the Ag-Pt bimetal is loaded on the surface of C₃N_x NS by chemical deposition method for visible light photocatalytic hydrogen production.Compared with a single noble metal modified C₃N_x NS,the cocatalyst has a greater improvement in the photocatalytic hydrogen production performance.At the same time,by comparing the photocatalytic hydrogen production performance under different ratios of Ag and Pt,it is found that the photocatalytic hydrogen production performance is best when the ratio of Ag to Pt is 1:2.This work shows that the Ag-Pt bimetallic cocatalyst can effectively utilize the surface plasmon resonance effect of Ag and the ability of Pt to trap electrons to improve the photocatalytic hydrogen production performance.Figure[30]table[6]reference[94]...