Coupling Photoelectrochemical and Peroxymonosulfate Activation on a CoWO4/BiVO4 Photoanode for Synergistic Ciprofloxacin Degradation

A novel Z-scheme heterojunction photoanode, CoWO 4 /BiVO 4 , was synthesized by in situ growth of cobalt tungstate on 3D coral-like bismuth vanadate via a hydrothermal method. This photoanode was applied to degrade ciprofloxacin (CIP) in a photoelectrochemical (PEC) system coupled with peroxymonosulfate (PMS) activation. Material characterization confirmed the successful formation of the heterojunction, which broadened visible-light absorption and enhanced the separation of photogenerated charges through a built-in electric field. Under optimized conditions, the CoWO 4 /BiVO 4 photoanode degraded 82.6% of 20 ppm CIP within 30 min, exhibiting a kinetic rate constant approximately 7.1 times higher than that of pure BiVO 4 , along with good stability and broad degradation capability. Mechanistic studies revealed that holes (h + ) and superoxide radicals ( • O 2 − ) were the dominant active species, while sulfate (SO 4 •− ) and hydroxyl ( • OH) radicals contributed synergistically. This study provides a feasible strategy for designing efficient heterojunction-based PEC systems for wastewater treatment. Graphical The proposed Z‑scheme charge transfer mechanism and CIP degradation pathway over the CoWO 4 /BiVO 4 heterojunction under visible-light irradiation.