Research Of The Controllable Preparation And Catalytic Performance Of Bi-and ZnIn₂S₄-based Composite Photocatalytic Materials

In recent years,photocatalytic technology is one of the important measures to effectively solve serious problems such as increasing energy demand and environmental pollution,and it is also a research hotspot in recent years.At present,many semiconductor photocatalysts have been studied and applied to photocatalytic energy conversion and photocatalytic degradation of organic pollutants.However,their low visible light response and low separation efficiency of photogenerated carriers limit their practical applications.It is still an important challenge to improve the photocatalytic performance by increasing the light absorption response range of the semiconductor photocatalyst as much as possible to make full use of solar energy and achieve high-efficiency solar energy conversion.Therefore,it is of great significance to explore new catalytic materials with high solar energy utilization and high photogenerated electron-hole pair separation efficiency to solve the environmental and energy crisis.In the paper,bismuth oxyiodide（BiOI）and sulphur-zinc-indium compounds（ZnIn₂S₄）are used as the research objects,and then regulates the microscopic morphology and energy band structure of BiOI through two-dimensional layered Mo S₂ and nano-particle Cd S.In addition,two-dimensional layered transition metal carbide（MXene（Ti₃C₂））and ZnIn₂S₄ are combined to construct an efficient hierarchical heterostructure catalyst.The main research contents of the paper are as follows:（1）The nano-flower-like BiOI/Mo S₂ microspheres with uniform size and controllable structure were successfully synthesized by a simple two-step solvothermal method.And its microscopic morphology,composition,optical properties,electrochemical properties and photocatalytic properties have been studied.The results show that 3D BiOI/Mo S₂ microspheres can effectively limit the recombination of photogenerated electron-hole pairs,and exhibit excellent photocatalytic activity for the degradation of organic pollutants methyl orange（MO）and tetracycline（TC）.This can be attributed to the large number of defects in the（001）plane of the BiOI lattice structure and the abundant catalytical active sites of Mo S₂,which can quickly separate photogenerated electron-hole pairs.Among them,the degradation rates of 3D BiOI/Mo S₂-0.01 microspheres to MO and TC are as high as 95.6%and 91.5%,respectively.The synergistic effect of Mo S₂ and BiOI can effectively enhance the charge-carrier separation and expand the visible light absorption range.Therefore,BiOI/Mo S₂ microspheres have high photocatalytic effects under visible light and have a wide range of application prospects.（2）The hierarchical BiOI/Mo S₂/Cd S-0.03 heterostructure microspheres were successfully synthesized by a simple three-step solvothermal method.The microscopic morphology,composition,optical properties,electrochemical properties and photocatalytic properties of BiOI/Mo S₂/Cd S-0.03 heterostructure microspheres have been studied.The results showed that the layered BiOI/Mo S₂/Cd S-0.03 heterostructure microspheres exhibit excellent photocatalytic activity for the reduction of CO₂ to CH₄and CO under visible light,and the reduction rates of CH₄ and CO are 46.22μmolg^-1h^-1 and 36.98μmolg^-1h^-1,respectively.At the same time,the layered BiOI/Mo S₂/Cd S-0.03 heterostructure microspheres also showed the best photocatalytic effect on the degradation of TC.This can be attributed the introduction of Mo S₂ and Cd S on BiOI can effectively increase the specific surface area,expose more catalytic sites and form a tightly connected interface,providing more paths for carrier transport,thereby increasing the utilization of visible light and significantly inhibit the recombination of electron-hole pairs.The composite material can realize the reduction of CO₂ into usable energy under visible light,which provides a design idea for the structure of layered heterostructure materials.（3）The hierarchical MXene/ZnIn₂S₄ heterostructure catalyst was successfully synthesized by a simple water bath method.The microscopic morphology,composition,optical properties,electrochemical properties and photocatalytic properties of hierarchical MXene/ZnIn₂S₄ heterostructure catalyst have been studied.The results showed that the 5%MXene/ZnIn₂S₄ heterostructure catalyst can achieve the reduction of potassium dichromate（Cr（VI））and the degradation of MO under visible light.This can be attributed the layered MXene/ZnIn₂S₄ heterostructure catalyst can expose more catalytically active sites,the interface formed between MXene and ZnIn₂S₄ can create a convenient channel for charge transfer and MXene with excellent conductivity can quickly transfer charge,effectively inhibit the recombination of electron-hole pairs and improve the utilization rate of visible light.The composite material can achieve degradation of organic matter and reduction of Cr（VI）under visible light,which provides a design idea for the structure of layered heterostructure materials.