Preparation And Photocatalytic Activities Of BN/BiOX(X=Cl、Br)modified Materials

Semiconductor-based photocatalysis has attracted massive attention due to its wide application in removing environmental pollutants and hydrogen production from splitting water using solar energy,and design of high-efficiency photocatalysts is the core issue in photocatalytic technology.BiOX（X=Cl,Br,I）materials have been proved to be promising semiconductor photocatalysts for treatment of organic contaminates and waste water with the advantage of suitable bandgap width,good stability and environmental friendliness.However,the use of bare BiOX（X=Cl,Br,I）samples are limited because of their poor visible light absorption and low utilization rate of photogenerated charges,and the introduction of BN on the surface of photocatalysts has already been proven to be an effective way to improve the photocatalytic performance of the materials,therefore,BN/BiOX materials were chose to construct composite photocatalyst,and BN/BiOX modified materials were further synthesized to obtain photocatalysts with high activity.In this paper,focusing on the improved photocatalytic performance of BN/BiOX materials,BN/OV-BiOCl and Pt/BN/BiOBr samples have been fabricated to analyze structures,morphologies,optical properties and photocatalytic properties,and their physicochemical properties and possible photocatalytic mechanism were determined,in addition,the roles of BN and Pt was investigated deeply.In this work,main contents are summarized as follows:（1）BN/OV-BiOCl composites were prepared by coupling hexagonal boron nitride with oxygen vacancy enriched bismuth oxychloride（OV-BiOCl）with mannitol as solvent assisted with PVP.The composition and morphology of materials are investigated by XRD、FTIR、XPS、SEM、TEM,indicating that OV-BiOCl was successfully combined with BN.And the photocatalytic performance experiments show that introduction of BN can greatly improve the visible-light photocatalytic activity of OV-BiOCl,which is 1.7 and 1.4 times of OV-BiOCl for degradation of Rhodamine B（RhB）and Bisphenol A（BPA）respectively when BN content is 5 wt%.The role of BN is investigated deeply and the results reveal the presence of BN has little influence in the optical property,but can improve the separating efficiency of photoinduced electrons（e^-）and holes（h⁺）of OV-BiOCl.MottSchottky plots and Valence-band X-ray photoelectron spectroscopy measurements further demonstrate the negatively charged BN on OV-BiOCl facilitate the migration of positive charged h⁺to the surface of photocatalyst due to electrostatic interactions,which can improve the separating efficiency of e^-and h⁺,therefore inducing more h⁺migrating to oxidize the pollutant directly.Meanwhile,the oxygen vacancies on OV-BiOCl are also increased with the presence of BN,which favors more·O₂^-production to oxidize pollutant,these factors result in improving photocatalytic performance of BN/OV-BiOCl composites.（2）Pt/BN/BiOBr composites were prepared by alcohol soluble hydrolysis assisted light-reduction method.The structures and morphologies were characterized,indicating that BiOBr was successfully combined with BN and Pt.The photocatalytic activity of as-prepared samples was evaluated by degradation of BPA,results showed BN and Pt could improve photocatalytic performance of BiOBr,and BN and Pt play a synergistic role in the process of degradation.By the characterization of DRS and PC,the excellent photocatalytic activity of Pt/BN/BiOBr composite photocatalyst is attributed to the broadened light-response range after Pt loading and enhanced electron-hole separation efficiency due to Pt play a vital role in acting as electron capturer and BN as a hole transfer material,which result in enhanced photocatalytic performance.