Structure And Photocatalytic Performance Of Copper Nitride And Its Composite Films Prepared By Magnetron Sputtering

With the development of two-dimensional materials in various fields,they show superior photoelectric properties.Cu₃N composite film has a good application in the field of photocatalysis.In order to improve its photocatalytic performance,we modified the coyer fimposition and structure of Cu₃N composite film.Cu₃N thin films and their composite and multilalms were prepared by RF magnetron sputtering under different parameters.The microstructure and photocatalytic properties of Cu₃N thin films were effectively controlled by reasonable sputtering parameters.Through the characterization of the microstructure and photocatalytic properties of the films,the internal relationship between the structure and properties of the composite films was emphatically explored,and the process method of preparing Cu₃N composite films with excellent properties was thoroughly studied.The main results are as follows:1.The effects of gas flow ratio r(r=[N₂]/[Ar+N₂])on the structure,morphology and photocatalytic degradation performance of Cu₃N films were investigated.The results show that the microstructure of Cu₃N films is uniform and compact.With the increase of r value,the number of large particles on the surface of Cu₃N films increases obviously,and the preferred crystal planes of Cu₃N films change from(100)and(200)to(110).The optical band gap of Cu₃N thin films is between 1.96 e V and 2.09 e V.When r=1/3,there are more defects and copper atoms in the film,which is beneficial to the effective separation of photoelectron-hole pairs.The film has the best photocatalytic performance,and the degradation rate of methyl orange is 99.5%within 30 min.2.The structure and photocatalytic performance of TiO₂/Cu₃N composite films prepared under different r conditions were investigated.The results show that the optical band gap of the composite films is lower than that of the TiO₂films prepared under the same conditions.Two phases of TiO₂coexist in the composite film,which is mainly presented as anatase phase.At r=1/4,the prepared Cu₃N nanoparticles promote the formation of effective TiO₂electron traps on the surface of the composite films.This is because the nano-Cu₃N grains inserted into TiO₂are conducive to the conversion of Ti⁴⁺to Ti³⁺,which significantly improves the photocatalytic activity of the composite film.3.The effect of MoS₂deposition power on the structure and photocatalytic performance of Cu₃N/MoS₂composite films was studied.The results show that with the increase of MoS₂deposition power,the content of MoS₂in the composite film increases,the crystallinity of the film increases,and the photocatalytic performance increases first and then decreases.This is due to the fact that the growth of MoS₂crystals in the film is preferred to that of Cu₃N crystals in the film,which affects the growth of Cu₃N crystals and leads to the change of optical band gap in the composite film.When the power of MoS₂is 4 W,the surface grain of the composite film is uniform and there is no obvious crack,which shows the best photocatalytic degradation performance.4.The structural characteristics of Cu₃N/MoS₂heterojunction are studied.It is shown that the optical band gap of Cu₃N/MoS₂heterojunction is 1.98 e V.The valence band offset(VBO)and conduction band offset(CBO)of Cu₃N/MoS₂heterojunction are 1.42 e V and 0.82e V,respectively.It was found that Cu₃N films and MoS₂films formed type II heterostructures.Because the Fermi levels of the two materials are not consistent,the interface electrons flow from MoS₂to Cu₃N after the two materials contact to form a heterojunction,so that there are more electrons in Cu₃N layer,there are more holes in MoS layer,so that the optical band gap changes.