Defect–Engineered Photonic Coupling in Nanostructured WO ₃ Inverse Opals for Enhanced Photoelectrocatalytic Removal of Pharmaceuticals

High Resolution Image Download MS PowerPoint Slide The increasing presence of pharmaceutical residues in aquatic environments poses a major challenge for sustainable water treatment and prompts the development of advanced photoactive nanomaterials for solar-driven remediation. Photoelectrocatalysis (PEC) offers a promising solar-driven strategy by coupling photocatalysis with bias-assisted charge separation. Herein, we report defect-engineered tungsten trioxide inverse opal (WO 3– x IO) photoanodes designed for enhanced PEC removal of pharmaceuticals through the synergistic combination of oxygen vacancy engineering and photonic light management. Ordered WO 3– x IOs were prepared via acid-induced metal reduction followed by mild N 2 annealing, enabling stabilization of oxygen vacancies while preserving the periodic architecture. The optimized WO 3– x photoanodes exhibited a volcano-type PEC response with increasing vacancy concentration, achieving a 3-fold photocurrent enhancement compared with pristine WO 3 IOs and significantly improved degradation rates for tetracycline, ciprofloxacin, and ibuprofen pharmaceuticals at an intermediate oxygen deficiency (∼2%). Mechanistic analysis revealed substrate-dependent reactive oxygen species pathways associated with vacancy-mediated O 2 activation and hole accumulation. These findings demonstrate that defect–photonic engineering is an effective strategy for developing photonic oxide photoanodes for solar-driven PEC water treatment and pharmaceutical contaminant removal.