Implanted-Electron-hydrogen boosted breaking of W[sbnd]O bonds to generate crater/oxygen vacancy filled WO3 nanoflakes for efficient oxidation of emerging pollutant

Abstract

Creating craters and oxygen vacancies in WO3 nanoflakes with a simple in-situ strategy was carried out by taking WO3/W mesh as cathode and conducting electrochemical reduction at − 3 V in acid solution. Because of the special chessboard-like arrangement of WO6 octahedra, both H+ and electrons driven by the electric field migrate into WO3, and H+ ions turn into H2 there. The implanted H2 microbubbles release from WO3 lattice by breaking the WO bonds, the anisotropy of the elastic forces when H2 microbubbles diffuse outward boosts the exfoliation of WO3. Consequently, many craters accompanied with oxygen vacancies (OVs) are manufactured in WO3 nanoflakes, which work as active centers for attracting O2 from air and help to increase the conductivity of WO3. As OVs enable WO3 to become sensitive to lights, abundant reactive oxygen species (ROS) including •O2-, •OH, 1O2 are generated, rendering an oxidation-governing degradation of florfenicol (FLO) molecules. When treating water contaminated with 4 mg/L FLO, a perfect degradation efficiency, 93.7%, was achieved under irradiation at 1.2 V with significantly minimizing the ecotoxicity of the chemicals from FLO degradation. This work provides a comprehensive elucidation on creating OVs in WO3 by electrochemical approach with shedding light on the oxidation mechanism in FLO detoxification.