On‐Site Production of Dilute H₂O₂ with Zinc–Air Battery

Abstract Hydrogen peroxide (H₂O₂) is extensively applied in environmental remediation, disinfection, bleaching, and so on. Two‐electron oxygen reduction reaction for synthesizing H₂O₂ is the most promising alternative to the traditional energy‐intensive anthraquinone process. Existing strategies for electrocatalytic synthesis of H₂O₂ generally proceed well in alkaline electrolytes. But environmental application demands the reaction to take place in a broad pH range, especially in acidic medium. Here a zinc‐air battery technology is developed for on‐site production of H₂O₂ in alkaline, neutral, and acidic conditions. A key component of the battery is the tubular cathode fabricated by partially oxidized carbon nanotubes self‐assembled on the substrate of nickel foam. The battery exhibits an unusual 2e⁻ discharge property and achieves an appreciable H₂O₂ accumulation (215.1 µmol, 497 ppm, 162.5 mg L⁻¹ h⁻¹) in acidic solution within 3 h, which is among the highest value ever been reported through electrosynthesis. Excitingly, the battery coupled with UV light demonstrates a promising application in water purification, which enables rapid degradation of model pollutants and actual pollutants ranging from municipal sewage to dye and pesticide wastewaters. Furthermore, this water treatment technology can be self‐powered, as the battery in the system generates the power that is available to drive UV lights.