Study On The Mechanism And Intrinsic Dynamics Of Photo-generated Charge Transfer In Relative P-n Junction Photocatalyst

The transfer mechanism of photo-generated charges（e-and h+）has always been a research hotspot in the field of photocatalysis.It is well known that the law of activity in photocatalytic reactions is due to the transfer mechanism of photogenerated electrons and holes.In recent years,through detailed studies on composite semiconductor photocatalysts with p-n junction structure,scientists have come to the conclusion that there is indeed an electric field in the p-n junction structure.On this basis,this paper uses different n-type photocatalysts assembled into heterojunctions as the research object,and reveals the"relative p-n junction theory"to explain the photo-generated charge transfer mechanism in heterojunction photocatalysts.The results show that the built-in internal electric field of the p-n junction formed by different photocatalysts is the internal driving force for photo-generated charge carriers to migrate in the heterojunction.The research content of this subject mainly includes the following two aspects:1.WO₃ and ZnO were prepared by calcining the corresponding precursors at high temperature,and a series of WO₃/ZnO composite photocatalysts were prepared by ball milling.Through in-depth research on the morphology,energy band structure,optical properties and catalytic activity of the photocatalyst.Through a series of characterizations,the mechanism is revealed and the photo-generated electron-hole transport is studied systematically.The Z-schem transfer mechanism proposed relative to the p-n junction is verified.A series of experimental results confirmed that the photo-excited charge on the WO₃/ZnO heterojunction photocatalyst follows the Z-scheme transfer mechanism,which has been successfully verified by the relative p-n junction theory.2.The corresponding precursors were calcined at high temperature to prepare NaNbO₃ and WO₃,and NaNbO₃/WO₃ composite photocatalysts with different weight ratios were prepared by ball milling.The activity of the photocatalyst was evaluated by degrading the dye,and the photocatalyst was evaluated by electrochemical techniques.The process of photogenerated carrier transfer has been comprehensively studied.The transfer mechanism of NaNbO₃/WO₃ heterojunction photocatalyst is proposed as Z-type transfer,and the relative p-n junction theory is verified.The relative pn junction theory we put forward explains the photocatalytic performance of common photocatalysts and the transfer mechanism of photogenerated charge in mass-junction photocatalysts.At the same time,we deeply study the transfer mechanism of light-excited carriers,which can provide excellent photocatalytic performance.The construction of the photocatalyst opened up a new path,and could also provide theoretical and practical guidance for the construction and application of a new type of heterojunction photocatalyst.