Preparation Of Non-metal Doped Bismuth-based Composite Photocatalyst And Its Photocatalytic Mechanism

The power industries of China are dominated by thermal power,and the situation will not be shaken in the next 10 years,and the coal-fired process of thermal power plants will inevitably bring environmental pollution.Among the many pollutants brought by coal-fired power plants,the toxicity and persistence of heavy metal mercury have attracted the attention of the international community and have been identified as global pollutants.While paying attention to mercury pollution,China has promulgated the"Emission Standards for Air Pollutants in Thermal Power Plants",among which the mercury emission standards for coal-fired power stations have been proposed for the first time.Photocatalytic oxidation technology has attracted much attention in many mercury removal technologies due to its strong oxidizing ability,no secondary pollution and low price.A simple hydrothermal method was used to prepare pure phase BiOI photocatalyst and single phase BiOIO₃ photocatalyst,and the carbon-doped BiOI photocatalyst was further prepared by calcination method,and characterized by XRD,SEM,TEM,PL and UV-vis.Simultaneously the photocatalytic performance evaluation system was used to analyze the photocatalytic removal of fumed gas elemental mercury.It was found that doping carbon can not only reduce the band gap width of BiOI,broaden the visible light response range of BiOI,but also act as a photosensitizer.That makes the separation ability of photogenerated electrons and holes strengthened,and the recombination of photogenerated electrons and holes suppressed as well.Since the oxidation-reduction potential of BiOI is lower than that of BiOIO₃,and the redox potential of BiOIO₃ is more suitable for photocatalytic demercuration,BiOIO₃ exhibits better photocatalytic activity despite carbon modification of BiOI.Thispaperdidnon-metaldopingofBiOIO₃withbetter oxidation-reduction potential.In this paper,carbon-doped BiOI/BiOIO₃heterostructures containing oxygen vacancies are prepared by simple hydrothermal and calcination methods,and XRD,Raman,XPS,FTIR,SEM,TEM,PL,UV-vis are performed.Characterization test analysis,while using photocatalytic performance evaluation system to analyze its photocatalytic removal of fumed gaseous elemental mercury,we found that the prepared structure can effectively promote charge separation and inhibit electron-hole pair recombination.When the gas phase elemental mercury?Hg⁰?is removed using a ternary photocatalyst under visible light irradiation,excellent photocatalytic performance is exhibited.The carbon-doped BiOIO₃ can introduce an additional carbon doping level above the VB of BiOIO₃ while forming an in-situ grown BiOI/BiOIO₃ heterojunction.In situ reduction of BiOIO₃ contributes to the in situ growth of BiOI on BiOIO₃ and facilitates the increase of active sites.Due to the calcination method,a certain amount of oxygen vacancies appeared on the surface of the prepared sample.Surface oxygen vacancies have a significant impact on the separation of electron-hole pairs because oxygen vacancies can act as capture centers,preferentially capturing light from the conduction band to excite electrons.Non-metallic doping as a promising method for improving photocatalytic performance is beneficial for designing high-efficiency photocatalysts and environmental optimization applications.