Construction Of Bi₃O₄Br-based Photocatalysts For Its Enhanced Photocatalytic Removal Of Organic Pollutants

It is well known that environmental pollution problems have arosed with the development of economy and the improvement of people's living standard.At present,the main environmental problems includeair pollution,radioactive contamination,heavy metal pollution,soil pollution,water pollution and so on,which are affecting the ecological equilibrium.It's still a challenge to economically and efficiently remove the poisonous organic pollutants in the water to ensure the final effluent quality.Generally,the traditional solutions for removing the contaminants in water contain physical adsorption,chemical treatment and biological treatment method.In recent years,semiconductor photocatalytic technology has attracted more and more attention for its friendly and efficiently solving the environmental problemswithout secondary pollutions.Phtocatalysts'structures and physico-chemical properites are the critical factors to determine the photocatalytic performance.Hence,this article focuses on the design of novel photocatalysts with visible-light response,high separation efficiency for photogenerated charge carriers and high stability,by the construction of composite photocatalytic system to efficiently remove the organic pollutants in water.Firstly,one-pot facile hydrothermal method was employed to synthesize ultrathin Bi₃O₄Br nanosheets with a dehalogenation strategy to regulate the elemental compositions.After that,series of Bi₃O₄Br-based coymposite photocatalysts have been constructed to explor their photocatalytic removal of organic pollutant existing in effluent.Finally,multiplicate characterization techniques were conducted to investigate the photocatalytic reaction mechanism.The detailed research parts are described as follows:?1?.The BN/Bi₃O₄Br composite photocatalysts have been synthesized via a simple alkalization solvothermal method.The phase structure,morphology,optical and electronic properties of the prepared materials were investigated in detail.XRD and TEM results showed that h-BN was introduced into Bi₃O₄Br sample successfully.It can also be found that a tight interfacial contact between h-BN and ultrathin Bi₃O₄Br has been built.The PL results indicated that BN/Bi₃O₄Br composite material had higher separation efficiency and lower recombination rate of photogenerated electrons and holesunder light excitation.RhB was selected as the target pollutant to evaluate the photocatalytic performance of the BN/Bi₃O₄Br composite materials.The results showed that BN/Bi₃O₄Br composites displayed higher photocatalytic activity for the degradation of RhB than Bi₃O₄Br,and the 1 wt%BN/Bi₃O₄Br possessed the best photocatalytic performance,in which the degradation efficiency can reach 99.4%.?2?.Few-layer MoS₂/Bi₃O₄Br composite photocatalysts were prepared via a simple alkalization solvothermal method successfully.A series of characterizations were employed to explore the crystalline structure,morphology,elements composition and so on of as-prepared samples.According to the TEM characterization,few-layer MoS₂ and Bi₃O₄Br materials contacted tightly with each other.The DRS results showed that the introduction of few-layer MoS₂ enhanced the light absorption properties of MoS₂/Bi₃O₄Br samples.At the same time,the visible light absorption abilitiesof MoS₂/Bi₃O₄Br composites gradually improved with the increase of introduced MoS₂ content.RhB and BPA contaminants were selected to assess the photodegradation abilities of MoS₂/Bi₃O₄Br composites.The photocatalytic degradation experiment results demonstrated that the introduction of MoS₂significantly improved the photocatalytic activities of the MoS₂/Bi₃O₄Br composite materials and the 2 wt%MoS₂/Bi₃O₄Br composite exihibited the optimal photocatalytic performance.The electron spin resonance test demonstrated that the O₂^·-was the main active species during this system.?3?.Ultrathin carbon nitride?g-C₃N₄?was selected as reaction sources to synthesize?BiO?₂CO₃/Bi₃O₄Br heterojunction via one-pot solvothermal method.In this system,g-C₃N₄ material provided the carbon for the formation of?BiO?₂CO₃/Bi₃O₄Br photocatalysts during the synthetic process.The phase composition,morphology and light absorption properties of as-prepared composites were analyzed by multiple characterizations.It can be seen from the TEM images,both?BiO?₂CO₃ and Bi₃O₄Br materials owned the ultrathin structure,and the heterojunction of?BiO?₂CO₃/Bi₃O₄Br was successfully constructed.K inds of pollutants,such as RhB,BPA,TC and CIP were selected to evaluate the photocatalytic properties of the prepared?BiO?₂CO₃/Bi₃O₄Br composites.The degradation results showed that?BiO?₂CO₃/Bi₃O₄Br-2 composite material possessed the best photocatalytic performance compared with pure?BiO?₂CO₃ and Bi₃O₄Br samples.