Synthesis And Mechanism Study Of Highly Active Nano-indium Oxide-based Photocatalyst

In today's society,environmental problems have become the focus of the world,and water pollution is getting more and more attention.2,4-dichloropheno is widely used as an important intermediate in the preparation of herbicides,disinfectants and pesticides.Due to the toxicity,carcinogenicity and teratogenicity of 2,4-dichloropheno,it has been listed as a key organic pollutant by the us environmental protection agency.A large amount of 2,4-dichloropheno is discharged into the water body and enters the drinking water system with the water circulation system,causing serious water pollution and seriously affecting our survival and health.Therefore,the development of effective degradation of chlorophenol technology is extremely urgent.Semiconductor photo-catalysis technology has gradually become a research hotspot,owing to its advantages of low cost and environmental friendliness.Indium oxide?In₂O₃?,as a cheap and stable photocatalytic material,has high activity in degradation of pollutants due to its suitable energy band structure?2.8 eV?and good photochemical properties.But the photocatalytic applications of isolated In_?2O?₃ have still been restricted in practice by its low photocatalytic activity,attributing to the small specific surface area and high recombination rate of photogenerated electron-hole pairs.Based on the above problems,the following work is carried out in this paper to improve the photocatalytic performance of In?₂O?₃ nanomaterials.Firstly,we used indium nitrate as indium source and citric acid?CA?as modifier to prepare In?OH?₃ precursor through hydrothermal reaction,and then obtained porous In₂O₃ with large specific surface area?125.7m²/g?through calcination.The adsorption of pollutants is greatly increased and providing more reaction sites.Then the CuO/In₂O₃nanocomposite was constructed through a simple dipping-calcining process.The complex has a large specific surface area and the reasonable structure of heterogeneous,promoted the charge separation of In₂O_3,improved oxygen activation ability effectively.The construction of CuO/In₂O₃ heterogeneous structures has been effectively improved the photocatalytic activity.Secondly,we investigated the effect of potassium on the photocatalytic performance of CuO/In₂O₃ nanocomposite.Through the regulation of the amount of potassium and the design of contrast experiment,O₂-TPD and PEC test proved that the introduction of potassium can effectively improve the photocatalytic degradation activity of the complex,and the improvement of the activity is mainly attributed to the modification of CuO by potassium,which improves the adsorption of oxygen on the surface,promotes the oxygen activation process and improves the separation of photogenic charge.In addition,radical-trapping experiments,used three kinds of captors,EDTA-2Na,BQ and IPA to capture h⁺,·O₂^-and·OH radicals,respectively.The result shows that the produced·O₂^-is dominant to induce the photocatalytic degradation of 2,4-dichloropheno.Finally,the CuO/In₂O₃ nanocomposite was modified with Ag by photodeposition.Ag modified CuO/In₂O₃ nanocomposite with the best photocatalytic degradation activity were obtained by investigating the modification amount of Ag.Through the mechanism study found that Ag can capture electron,promote photoproduction electron transfer between the heterojunction,at the same time enhances the ability of oxygen adsorption and oxygen activation of the complex,greatly improved the photocatalytic activity,the degradation rate of 2,4-DCP was 62%.