Fabrication Of Bi-based Composite Photocatalyst And Its Degradation And Mechanism Of Antibiotics

At present,environmental pollution caused by refractory organic pollutants（antibiotics）becomes more serious.Solar-light-driven photocatalytic technology with sustainable,efficient and green was extensively employed to remove antibiotics in solution.Bi-based semiconductors exhibit enormous application potential owing to the properties of large specific surface area,non-poisonous,suitable energy band position.However,the rapid recombination of photogenerated charge carrier and narrow absorption range of visible light diminished their photoactivity.Constructing heterojunction to form built-in electric field is regarded as an effective strategy,which can accelerate photoexcited charge carrier separation and transfer and broaden solar light absorption range.This paper researched CuS,g-C₃N₄,WO₃with abundant oxygen vacancies photocatalyst modified Bi-based nanomaterials in organic pollutants removal.In the first section,CuS/BiVO₄（040）heterojunction photocatalysts were fabricated by growing of CuS on the surface of BiVO₄ to remove antibiotic pollutant.The photocatalytic performance of CuS/BiVO₄ was superior to pristine CuS and BiVO₄under visible irradiation.Among them,the optimal mass ratio of CuS to BiVO₄ was determined to be 7%,and 86.7%of CIP was degraded.The first-order kinetic constant of CIP degradation over 7%CuS/BiVO₄ was 0.02151 min^-1,which was 2.59 and 16.54-time higher than that of pure BiVO₄and CuS,respectively.The promoted photocatalytic activity was ascribed to the accelerated separation efficiency of photogenerated charge carrier,increased of active sites and specific surface area,and broadened of solar light absorption range.Moreover,7%CuS/BiVO₄ photocatalyst showed benign photoactivity,indicating its excellent stability.In the second section,Bi OBr/CDs/g-C₃N₄2D/2D Z-scheme heterojunction was fabricated by facile solvothermal method,and then was utilized to degrade antibiotics.The photocatalytic performance of Bi OBr/CDs/g-C₃N₄ was studied by adjust the mass ratio of Bi OBr and CDs/g-C₃N₄.The result displayed that the optimal mass ratio was30%,and 83.7%of CIP was degraded.This phenomenon can be attributed to that2D/2D Z-scheme heterojunction shortened the transfer distance of photogenerated charge carrier and increased active sites.Furthermore,the up-conversion property of CDs broadened absorption range of solar light,enhancing the photoconversion efficiency.The capture experiments and ESR spin-trapping test exhibited h⁺,?OH,?O₂^-were the main reactive oxygen species to attack and split CIP.More importantly,the composites showed excellent photostability and reusability after 10 runs for CIP degradation,indicating the enormous application potential in actual wastewater treatment.In the third section,WO₃ with abundant oxygen defect modified Bi₂WO₆（V_o-WO₃/Bi₂WO₆）atomic scale heterojunction was fabricated by a facile hydrothermal method,and then was utilized to degrade antibiotics.The presence of oxygen vacancy could promote the absorption of long wavelength solar light,thereby enhancing photoconversion efficiency.In addition,V_o-WO₃/Bi₂WO₆possessed abundant active sites owing to the existence of structure pits on the surface,which was beneficial for antibiotics adsorption.The atomic scale thickness of composite could shorten the transfer distance of photoexcited charge carrier and enhance the interface contact area,thereby facilitating the degradation efficiency.The resultant V_o-WO₃/Bi₂WO₆composite exhibited excellent photocatalytic activity under visible and near-infrared light illumination.The results revealed h⁺,?OH,?O₂^-were the main reactive oxygen species to degrade CIP.Moreover,V_o-WO₃/Bi₂WO₆ composite displayed higher photodegradation efficiency,indicating the benign stability.