Strategies And Mechanisms To Improve The Visible Light Photocatalytic Activity Of Nano-Fe₂O₃

Nano-sized iron oxide(Fe₂O₃)has been one of the hot photocatalytic materials due to its wide solar spectral response range,strong photogenerated hole oxidation capacity,cheap,stable and environmentally friendly advantages.However,there are still some problems,such as short carrier diffusion distance,low conduction band bottom position(insufficient photoelectric reduction ability)and few surface catalytic sites,which seriously restrict the improvement of its photocatalytic performance.In view of the above problems,this paper focuses on Fe₂O₃nanostructure regulation,complex construction,complex interface regulation and related mechanisms to carry out the following specific research work:(1)The molecular photocatalyst CuPc and ultra-thin?-Fe₂O₃(UTFO)were innovatively proposed to construct the S-type heterojunction photocatalytic material.The material showed excellent CO₂reduction performance under wide visible light response,and the activity of the optimal sample was 15 times that of the ordinary?-Fe₂O₃nanoparticles.The significant increase in its activity is mainly attributed to the following points:1)By controlling the amount of Al³⁺in the hydrothermal reaction system,the morphology of?-Fe₂O₃can be effectively controlled.Finally,the pure?-Fe₂O₃sample with ultra-thin nano-sheet structure is prepared,and the ultra-thin structure is conducive to the separation of photogenerated carriers in?-Fe₂O₃,thus improving its photocatalytic performance.2)On this basis,the effective recombination between CuPc and UTFO is achieved through the strong interaction of hydrogen bonds,and the S-type photogenerated charge separation mechanism is proved by focusing on the use of the atmosphere controllable(single-wavelength assisted)surface photovoltage spectrum and single-wavelength photocurrent interaction spectrum.In addition,the important catalytic effect of Cu²⁺in Cu PC in the process of CO₂reduction was confirmed by in-situ diffuse reflectance infrared spectroscopy.(2)Au nanoparticles were used to further regulate the composite interface between CuPc and UTFO,and the mechanism of its improvement on the photocatalytic performance of heterojunction materials was revealed.The results show that the proper amount of gold nanoparticles on the surface of UTFO can effectively promote the separation of UTFO photogenerated carriers,and thus improve the photocatalytic performance of UTFO.In particular,as the interface regulator of CUPC and UTFO,Au nanoparticles are beneficial to improve the effective loading capacity of CUPC on UTFO surface.On the other hand,it greatly promotes the photoelectric charge transfer between CuPc and UTFO,improves the charge separation efficiency of the S-type heterojunction,and further improves its photocatalytic performance.