Photoelectrocatalytic Degradation Mechanism of Fluorinated Pollutants Using a Bilayer WO ₃ Photoanode: Synergistic Role of Holes and Hydroxyl Radicals

Abstract Fluorinated organic pollutants pose significant environmental and health risks due to the high stability of C─F bonds, necessitating effective strategies for their degradation. Herein, we present a bilayer WO 3 photoelectrode (double‐WO 3 ) incorporating an electron transport layer (ETL) and a hexagonal‐monoclinic heterophase junction for PEC degradation of fluorinated pollutants. The double‐WO₃ catalyst achieves a high photocurrent density (4.3 mA cm −2 at 1.2 V RHE ) and nearly complete degradation (99.9%) of bisphenol AF (BPAF), 4‐fluorophenol (4‐FP), and pentafluorophenol (PFP), with 99.9% mineralization of PFP. Experimental and transient photocurrent (TPC) analyses confirm that the ETL‐heterophase junction structure enhances electron extraction and surface reaction kinetics while minimizing electron‐hole recombination. In this process, photogenerated h⁺ excites fluorinated pollutants, enhancing C─F bond susceptibility to ∙OH attack, which facilitates bond cleavage and subsequent oxidation into CO 2 , H 2 O, and F − . This study offers a promising strategy for designing advanced PEC systems and effectively remediating persistent fluorinated contaminants.