Preparation And Photocatalytic Performance Of Defective Tungsten Oxide And Its Related Heterojunctions

Energy and the environment have always been closely related,and the use of clean energy is particularly important when facing environmental pollution issues.In recent years,photocatalytic experiments have been the main method to tackle energy and environmental issues.Among them,photocatalytic degradation of gaseous pollutants and decomposition of water for hydrogen evolution is one of the popular research fields.In the process of degrading gaseous pollutants,the oxidation reduction reaction ability of catalysts is utilized to degrade pollutants into pollution-free products.During the process of hydrogen decomposition from water,the catalyst separates electron hole pairs under light irradiation,and hydrogen ions in water combine with electrons to produce H₂.Semiconductor photocatalysts have the advantages of stable chemical properties,low cost,and high recovery rate,making them an effective solution to energy and environmental issues.However,researchers still face some challenges at present.For some photocatalysts with wide bandgaps,the concentration of photo generated carriers is low,the catalytic effect is not significant,and the rapid combination of photo generated electrons and holes in redox reactions also leads to lower efficiency of photocatalysts.1.W₁₈O₄₉rich in oxygen vacancies for photocatalytic degradation of gaseous organic pollutants.Blue tungsten oxide(W₁₈O₄₉)has excellent photocatalytic performance.Its catalyst surface is rich in a large number of oxygen vacancies,and it shows strong local Surface plasmon resonance（LSPR）effect in both visible and near-infrared regions,so it has attracted the attention of researchers.W₁₈O₄₉with large specific surface area and oxygen vacancies was prepared through hydrothermal synthesis.By characterizing and testing the performance of W₁₈O₄₉,the sample preparation was successfully achieved through XRD.SEM scanning revealed that the W₁₈O₄₉sample has a fibrous morphology.Nitrogen adsorption desorption indicates that the sample has a large specific surface area.XPS analysis revealed that the synthesized sample has abundant oxygen vacancies and defect energy levels.In the characterization of photocatalytic activity,W₁₈O₄₉has higher catalytic activity in the degradation of gaseous organic pollutants.Compared with common WO₃photocatalysts,W₁₈O₄₉has significantly improved photocatalytic performance and can be degraded into chemical raw material propylene.The reason for the high activity of W₁₈O₄₉sample is the result of a large number of oxygen vacancies,which undergo LSPR effect under light irradiation.After exciton dissociation,a large number of long-lived"hot electrons"are generated,and a large specific surface area can increase the adsorption sites between the catalyst surface and pollutants.Oxygen vacancies can change the electronic structure of materials,reduce the energy of electronic transition,promote the separation of electrons and holes,and improve the catalytic activity.2.High performance W₁₈O₄₉/ZnTiO₃photocatalyst for water decomposition and hydrogen evolution.Using ZnTiO₃powder prepared by calcination as the precursor,W₁₈O₄₉was grown on its surface by hydrothermal method to obtain W₁₈O₄₉/ZnTiO₃photocatalyst.The analysis results of XRD and SEM spectra indicate that W₁₈O₄₉/ZnTiO₃has been successfully composite.From the N₂adsorption desorption curve,it was analyzed that the composite sample had a large specific surface area,with the highest specific surface area reaching 42.9 m²g^-1.The UV visible spectrum indicates an enhanced light absorption ability of the composite sample,and XPS indicates that W₁₈O₄₉/ZnTiO₃retains a large number of oxygen vacancies in the original sample.The high concentration of long-lived holes and electrons generated by the LSPR effect of W₁₈O₄₉will be transferred to the surface of ZnTiO₃for hydrogen ion reduction reaction to produce H₂.Therefore,the W₁₈O₄₉/ZnTiO₃photocatalyst prepared in this experiment can decompose water and evolve hydrogen under light,providing a new method for preparing low-cost and highly active photocatalysts.