CO2/carbonate-mediated electrochemical water oxidation to hydrogen peroxide

Electrochemical water oxidation reaction (WOR) to hydrogen peroxide (H2O2) via a 2e(-) pathway provides a sustainable H2O2 synthetic route, but is challenged by the traditional 4e(-) counterpart of oxygen evolution. Here we report a CO2/carbonate mediation approach to steering the WOR pathway from 4e(-) to 2e(-). Using fluorine-doped tin oxide electrode in carbonate solutions, we achieved high H2O2 selectivity of up to 87%, and delivered unprecedented H2O2 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 H2O2 through the formation of carbonate radical and percarbonate intermediates. The high selectivity, industrial-relevant activity, and good durability open up practical opportunities for delocalized H2O2 production. Electrochemical H2O oxidation to H2O2 is challenged by the competitive O-2 evolution reaction. Here, the authors report a CO2/carbonate mediation approach to steering the H2O oxidation pathway from O-2 evolution to H2O2 generation.

Automated summary

In this study, a CO2/carbonate mediation approach was used to steer the pathway of electrochemical water oxidation reaction from oxygen evolution to hydrogen peroxide generation. This approach achieved high selectivity of hydrogen peroxide synthesis, along with good activity and durability.