Bias‐Free Photoelectrochemical Co‐Production of Active Chlorine and Hydrogen Peroxide From Seawater on a Pt‐WO ₃ Interface

The photoelectrochemical conversion of abundant seawater and sunlight into value‐added chemicals represents a sustainable pathway toward a zero‐emission society. Unfortunately, such a process is hindered by the inefficient utilization of photogenerated charges and the complexity of the seawater environment. Herein, we present a bias‐free photoelectrochemical system for efficient co‐production of active chlorine and H 2 O 2 from natural seawater, utilizing a Pt nanoparticle‐anchored WO 3 nanoarray (Pt‐WO 3 ) as the photoanode. The resulting metal‐support interface generates abundant oxygen vacancies and boosts strong electronic interactions, thereby improving light absorption, promoting charge separation, and facilitating interfacial charge transfer. Consequently, the photoelectrochemical system demonstrated remarkably high yields of 430.8 µmol L −1 for HClO and 1.88 mmol L −1 for H 2 O 2 derived from natural seawater, significantly exceeding those achieved with pristine WO 3 . Theoretical calculations reveal that Pt anchoring modulates the d ‐band center and induces significant charge accumulation, thereby effectively enhancing the chlorine oxidation reaction via the Volmer‐Heyrovsky pathway. This work offers a reliable interface‐engineering strategy for visible light‐driven chemical synthesis and demonstrates the practical potential of marine resource utilization in sustainable chemical transformations.