Photocatalytic Production of Hypochlorous Acid over Pt/WO3 under Simulated Solar Light

The production of hypochlorous acid (HClO) over a visible-light active photocatalyst was achieved for the first time in an aqueous solution of NaCl under simulated solar light. Approximately 17.6 mu M of HClO was accumulated after 1 h of photoirradiation by employing the photocatalytic oxidation of Cl- with O-2 reduction over the Pt cocatalyst-loaded WO3. The quantum efficiency of the HClO production was 2.3% at 420 nm. Moreover, the photoelectrochemical HClO production on the WO3 photoanode was also investigated to elucidate the photocatalytic reaction mechanism. The initial faradaic efficiency of the process reached 96%, indicating high selectivity toward the production of HClO over the WO3 surface in an aqueous NaCl solution. It was found that the highly photocatalytic performance over Pt-loaded WO3 was primarily attributed to the higher oxygen reduction and lower H2O2 formation abilities in comparison to other cocatalysts.