Photoelectrocatalytic Degradation Mechanism of Fluorinated Pollutants Using a Bilayer WO3 Photoanode: Synergistic Role of Holes and Hydroxyl Radicals

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 WO3 photoelectrode (double‐WO3) 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 VRHE) 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 CO2, H2O, and F‐. This study offers a promising strategy for designing advanced PEC systems and effectively remediating persistent fluorinated contaminants.