Enhanced HClO production from chloride by dual cocatalyst loaded WO3 under visible light

Abstract

Hypochlorous acid (HClO) as a high value-added oxidation reagent is produced conventionally by a chlor-alkali electrolysis process, which causes a heavy economic burden and leads to considerable CO₂ emissions. Herein, we reported the photocatalytic production of HClO by oxidation of chloride (Cl⁻) in a dilute saline solution close to that of seawater over various dual cocatalyst-loaded WO₃ powder photocatalysts using visible light as the energy source. The activities were improved more than twice by co-loading of Mn compared to the standard Pt/WO₃. A maximum HClO formation rate of 37 μmol h⁻¹ (about 2.6 ppm) was achieved when using Pt–Mn dual catalyst loaded WO₃, which is effective for inactivation of various bacteria and fungi in drinking water. The photochemical and electrochemical studies revealed that the synergistic effect between Pt and Mn could not only promote the decomposition of H₂O₂ derived from the oxygen reduction reaction, but also increase the selectivity for oxidation of Cl⁻ into HClO. This Pt–Mn dual cocatalyst modification strategy opens up prospects for efficient and economical production of HClO based on visible light energy.