Electrochemical oxygen reduction to hydrogen peroxide at practical rates in strong acidic media

Electrochemical oxygen reduction to hydrogen peroxide (H2O2) in acidic media, especially in proton exchange membrane (PEM) electrode assembly reactors, suffers from low selectivity and the lack of low-cost catalysts. Here we present a cation-regulated interfacial engineering approach to promote the H2O2 selectivity (over 80%) under industrial-relevant generation rates (over 400 mA cm(-2)) in strong acidic media using just carbon black catalyst and a small number of alkali metal cations, representing a 25-fold improvement compared to that without cation additives. Our density functional theory simulation suggests a shielding effect of alkali metal cations which squeeze away the catalyst/electrolyte interfacial protons and thus prevent further reduction of generated H2O2 to water. A double-PEM solid electrolyte reactor was further developed to realize a continuous, selective (similar to 90%) and stable (over 500 hours) generation of H2O2 via implementing this cation effect for practical applications. Electrochemical oxygen reduction to H2O2 in acidic media suffers from low selectivity, especially at high current densities. Here, the authors report a cation-regulated shielding effect to promote the H2O2 selectivity under industrial-relevant current in strong acid.

Automated summary

In this study, a cation-regulated shielding effect is used to promote the selectivity of electrochemical oxygen reduction to H2O2 in acidic media. The method shows high efficiency, selectivity, and stability for practical applications.