Synthesis Of G-C₃N₄/Metal Sulfide Nanocomposite And Investigation Of Its Photocatalytic Performance

At present,photocatalytic technology is widely regarded as the first choice for wastewater treatment technology,due to its advantages of green environmental protection,easy operation and low cost.Among the many photocatalyst materials,graphite phase carbon nitride(g-C3N4)is considered to be an ideal semiconductor photocatalyst with its suitable band gap(2.7 eV),stable chemical properties and high visible light utilization,which has aroused enormous research interests.However,the shortcomings of smaller specific surface area and faster recombination rate of photogenerated electron-hole pairs limit the practical application in the field of photocatalysis of g-C3N4.Therefore,in this paper,we have prepared a series of g-C3N4/metal sulfide nanocomposites by modifying g-C3N4 with other narrow band gap semiconductors,which were characterized by XRD,SEM,TEM,XPS,BET,UV-Vis,PL,FT-IR,and the results show that the composite materials have the advantages of larger specific surface area,more surface reactive sites,faster photogenerated electron-hole pairs separation efficiency,etc.The photocatalysis Performance of g-C3N4 is significantly improved.The specific research work is as follows:(1)Using SnCl4·5H2O as the tin source and melamine as the precursor of g-C3N4,a sheet-like structure of g-C3N4/SnS2 nanocomposite was synthesized by the hydrothermal method and calcination condensation method.The effects of pure phase SnS2,pure phase g-C3N4 and g-C3N4/SnS2 composite materials on the photocatalytic degradation of methylene blue(MB)were studied.The research results indicate that the g-C3N4/SnS2 composite photocatalyst has a larger specific surface area,can provide more surface reaction active sites,and has an enhanced visible light response intensity and a broadened visible light absorption range.The degradation efficiency of methylene blue was as high as 98.1%after 90 min of visible light irradiation,which further demonstrated that the introduction of SnS2 promoted the generation and separation of photo-generated carriers and improved the photocatalytic activity of the composite.(2)The g-C3N4/CuS nanocomposites with different morphologies were synthesized by hydrothermal method and high temperature heat shrinkage method.The effects of pure phase CuS,pure phase g-C3N4 and g-C3N4/CuS composites with different composite ratios on the performance of photocatalytic degradation of rhodamine B(RHB)were studied.The research results show that the prepared g-C3N4/CuS composite material has an enlarged specific surface area,a broadened spectral response range and an effective photo-generated carrier separation rate compared with the pure phase material.Among them,the composite of g-C3N4/CuS(4:1)showed the best photocatalytic activity.After visible light irradiation 60 min,the degradation rate of Rhodamine B reaches 93.8%,and the corresponding photocatalytic mechanism is proposed.(3)The porous g-C3N4/CdS nanocomposite was synthesized by the hydrothermal method and high temperature heat shrinkage method.The effects of pure phase CdS,pure phase g-C3N4 and g-C3N4/CdS composites with different composite ratios on the performance of photocatalytic degradation of rhodamine B(RHB)were studied.The research results demonstrated that CdS nanoparticles grow uniformly in the g-C3N4 pore structure,and they contact each other to form a close interface,which not only broadens the range of visible light absorption response,but also accelerates the effective separation of photogenerated electrons and holes,inhibits the photocorrosion of CdS.Among them,the g-C3N4/CdS(4:1)composite material has the best photodegradation performance.After 60 minutes of visible light irradiation,the degradation efficiency of Rhodamine B was as high as 97.8%.After four cycles of degradation experiments,it still maintains a high light catalytic activity.