Interfacial Regulation And Photocatalytic Properties Of G-C₃N₄/Molybdenum Compound Composite Heterostructures

Semiconductor-based photocatalysis has received extensive attention due to its ability to directly utilize solar energy to produce solar fuels such as hydrogen and hydrocarbon fuels and to degrade various pollutants.However,the efficiency of photocatalytic reactions is still low due to fast electron-hole recombination and low utilization of sunlight.The most effective way to solve these problems is to construct heterojunction photocatalysts.In this regard,heterojunctions based on g-C₃N₄ are particularly favored due to their suitable band gap,flexible structure,easy availability,and green environmental protection.Nevertheless,g-C₃N₄-based heterojunction photocatalysts also expose many problems while improving the photocatalytic activity.These problems are either related to the process level of the heterojunction preparation,or are related to the structure and energy level matching relationship between the two component materials that make up the heterojunction.On the one hand,it is difficult for composite structures synthesized by simple physical mixing or hydrothermal schemes to form dense interfacial contacts,which greatly hinders charge transfer and separation;on the other hand,high-efficiency heterogeneous photocatalysts have strict requirements on the composition,structure,and performance of semiconductor materials.In particular,the charge transfer efficiency varies greatly under different energy level matching relationships.There are many types of heterostructures and complex mechanisms,which often require in-depth and meticulous research to give full play to their advantages.Ultimately,it is necessary to clarify the transfer mechanism of photogenerated carriers.Based on this,the main research object of this paper is the composite heterostructure composed of g-C₃N₄ and molybdenum compounds（Mo S₂,Mo O₃）.The g-C₃N₄/Mo S₂ heterojunction is based on the solution of insufficient interfacial contact and the design of the g-C₃N₄/Mo O₃ heterojunction is dedicated to the construction of efficient Z-type heterojunction catalysts.The main contents and conclusions of the study are as follows:1)Tightly coupled heterojunction g-C₃N₄/1T@2H-Mo S₂ with strong electronic interfacial interactions was prepared by hydrothermal synthesis by generating N vacancies on g-C₃N₄ flakes and inducing S atoms into nitrogen vacancies to form Mo-S-C bonds.The Mo S₂ loaded on the g-C₃N₄ nanosheets is a mixed phase of 1T metal and 2H semiconductor.g-C₃N₄/2H-Mo S₂ is used as a good photosensitizer and catalyst,while 1T-Mo S₂ acts as an electron acceptor.Due to the close contact and the synergistic effect of the Mo S₂ mixed phase,the currently designed unique heterostructure photocatalyst has greatly improved catalytic performance under visible light,which may open up new prospects for the hierarchical structure of photocatalytic materials.2)Z-type Mo O₃/g-C₃N₄ heterostructures were synthesized by simple thermal polymerization.Not only the composition,structure and morphology of the materials were analyzed by conventional characterization methods,but also the photocatalytic mechanism of the composites was analyzed by electrochemical testing methods,which closely combined the performance improvement of the materials with the mechanism.Composite heterostructures show high performance for a variety of simulated dye pollutants and expand the diversity,which is mainly due to the strong redox ability of heterostructures.In addition,through in-depth analysis of the energy level structure and free radicals of the material,it is clear that the formation of Z-type heterostructure of Mo O₃/g-C₃N₄ complex is the main reason for the strong redox ability of the catalyst.Figure[27]Table[5]Reference[141]...