On-Site Production of Dilute H2O2 with Zinc-Air Battery

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 mu mol, 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.