CO(2)/carbonate-mediated electrochemical water oxidation to hydrogen peroxide

Electrochemical water oxidation reaction (WOR) to hydrogen peroxide (H(2)O(2)) via a 2e(−) pathway provides a sustainable H(2)O(2) synthetic route, but is challenged by the traditional 4e(−) counterpart of oxygen evolution. Here we report a CO(2)/carbonate mediation approach to steering the WOR pathway from 4e(−) to 2e(−). Using fluorine-doped tin oxide electrode in carbonate solutions, we achieved high H(2)O(2) selectivity of up to 87%, and delivered unprecedented H(2)O(2) partial currents of up to 1.3 A cm(−2), which represents orders of magnitude improvement compared to literature. Molecular dynamics simulations, coupled with electron paramagnetic resonance and isotope labeling experiments, suggested that carbonate mediates the WOR pathway to H(2)O(2) through the formation of carbonate radical and percarbonate intermediates. The high selectivity, industrial-relevant activity, and good durability open up practical opportunities for delocalized H(2)O(2) production.