Ionic Liquids Self-combustion Synthesis And Performance Of Bismuth-based Photocatalysts

With continue and fast development of our country’s economy and the increasing industrialization and urbanization,the problem of environment pollution becomes more and more serious.Photocatalytic oxidation technology is a kind of green technology,and has a wide application prospect in treatment of environmental pollution because of its low cost,environmental friendly,and sustainable use.However,the most studied photocatalysts either are the UV light responded,or need complex preparation processes,which makes them to be expensive.Hence,developing visible-light-driven photocatalysts with facile synthesis process,low cost and high activity has become the focus and difficulty in the field of photocatalysis.In this work,we firstly constructed BiOCl with surface oxygen vacancies（SOVs）via ionic liquid self-combustion route.The as-prepared photocatalyst samples were characterized by XRD,SEM,TEM,DRS.The results show that the samples containing a certain surface oxygen vacancies have good absorption performance in the visible light region.The reason may be that the existence of oxygen vacancy on the surface of catalyst reduces the band gap of BiOCl.After ten minutes of visible light irradiation,the degradation rate of BiOCl for rhodamine B could reach 99%.The first order reaction kinetics rate constant was 0.196 min-1.Based on the characteristics of transferable photogenerated electron of amorphous Al₂O₃,we constructed BiOCl/Al₂O₃ with surface oxygen vacancies heterojunctions via in situ combustion synthesis.Results showed that Al₂O₃ ccould effectively transfer photogenerated electrons of BiOCl,and the photogenerated electrons could combine oxygen molecules to generate superoxide anion radicals.Solution combustion method has the advantages such as time-and energy-saving,ensuring the mixture of reactants at molecular level.In this case,the as-prepared heterojunctions have better contact areas,and promote the electric charge better transfer in the two compounds.In this experiment,we surveyed the photocatalytic performance of the BiOCl with different ratio of Al₂O₃.The results showed that there were the highest photocatalytic degration of rhodamine B when the ratio of BiOCl and Al₂O₃ was 1:1.Based on free radical scavenger experiments,we proposed the photocatalytic mechanism of the BiOCl/Al₂O₃ heterojunction materials.In this article,nanometer BiVO₄ catalyst was also successfully synthesized via solution combustion method and BiVO₄/Fe2O3 heterojunctions with core-shell structurewere prepared at room temperature through precipitation route.The photocatalytic performances of a series of samples were tested by degradation of rhodamine B and reduction of Cr6+,and the effect of heterojunction on the band position was proposed.