Electrochemical generation of hydrogen peroxide from a zinc gallium oxide anode with dual active sites.

Electrochemical water oxidation enables the conversion of H 2 O to H 2 O 2 . It holds distinct advantages to the O 2 reduction reaction, which is restricted by the inefficient mass transfer and limited solubility of O 2 in aqueous media. Nonetheless, most reported anodes suffer from high overpotentials (usually >1000 mV) and low selectivity. Electrolysis at high overpotentials often causes serious decomposition of peroxides and leads to declined selectivity. Herein, we report a ZnGa 2 O 4 anode with dual active sites to improve the selectivity and resist the decomposition of peroxides. Its faradaic efficiency reaches 82% at 2.3 V versus RHE for H 2 O 2 generation through both direct (via OH - ) and indirect (via HCO 3 - ) pathways. The percarbonate is the critical species generated through the conversion of bicarbonate at Ga-Ga dual sites. The peroxy bond is stable on the surface of the ZnGa 2 O 4 anode, significantly improving faradaic efficiency.