Insight Into The Transfer Mechanisms Of Photogenerated Carriers For Heterojunction Photocatalysts

Semiconductors with suitable band gaps and simple preparation routes are considered as promising catalysts for photodegradation,photosynthesis,photoinduced hydrolysis,etc.For higher light absorption efficiency and better stability,heterojunctions are usually composed of semiconductors with matched energy levels.The mechanism of heterojunction transfer combined with photoexcited carriers and its applications in energy and environment fields have always been the focus of theoretical and practical research on photocatalysis.In recent years,semiconductor p-n junction is an effective structure to improve the efficiency of charge collection and separation,and provides theoretical guidance for the exploration of high-efficiency photocatalyst catalysts,so it has been widely studied,such as n-Ti O/p-Cu₂O,p-Mo S₂/n-Cd S and p-Ni O/n-Zn O,etc.Here,we first synthesized CN and CZS respectively,and then combined CN/CZS heterojunction composites with different weight ratios.Through the O₂Then,a series of aromatic alcohols were selectively oxidized to aromatic aldehydes to evaluate the photocatalytic activity of the composites under visible light.In addition,based on the results of photochemical tests and the number and lifetime of the reactive species,including chemical capture experiments,electron spin resonance（ESR）and time-resolved photoluminescence（TR-PL）,the transfer behavior of photoexcited carriers has been thoroughly studied.Based on the experimental results and the calculation results of density functional theory（DFT）,the mechanism of photoexcited charge transfer in CN/CZS samples is explained.The results show that the charge transfer mechanism varies with the composition of the CN/CZS heterojunction.The intrinsic reason can be clarified by using the relative p-n junction theory,and it is further proved that the relationship between the direction of the internal electric field and the direction of the transfer of photogenerated carriers has a decisive effect on the transfer mechanism of heterojunction photocatalyst.Secondly,we successfully synthesized Cd S/CZS heterojunction photocatalysts with different weight ratios by solution self-assembly method.The selectively oxidized Cd S/CZS heterostructure catalysts were characterized by XRD,DRS,FESEM,TEM,PL,BET and electrochemical analysis.Also,by XPS,ESR,PL and HR-TEM judge photocatalyst defects such as species,explain the mechanism of the process,we discussed the carrier transfer mechanism and the formation of defects of transfer mechanism,the influence of the study is expected to provide further validation of relative theory of p-n junction and innovation,will also aroused people’s widespread interest,was prepared in order to design and highly active and clear new heterojunction light catalyst transfer mechanism.