Boosting Hydrogen Peroxide Electrosynthesis via Modulating the Interfacial Hydrogen-Bond Environment.

Abstract

Designing highly efficient and stable electrode-electrolyte interface for hydrogen peroxide (H2O2) electrosynthesis remains highly challenging. Inhibition of the side reaction of competitive 4e- oxygen reduction to H2O is essential to obtain highly selective H2O2 electrosynthesis. Instead of catalyst modification to hinder excessive hydrogenation of H2O2, we propose that the addition of a hydrogen-bond acceptor, dimethyl sulfoxide (DMSO) to the KOH electrolyte enables the improvement of the selectivity and activity of H2O2 electrosynthesis simultaneously. Spectral characterization and molecular simulation confirm that the formation of hydrogen bonds between DMSO and water molecules at the electrode-electrolyte interface can reduce the activity of water dissociation into active H* species. The suitable H* supply environment hinders excessive hydrogenation for the oxygen reduction reaction (ORR), thus improving the selectivity of 2e- ORR and achieving over 90% selectivity of H2O2. This work highlights the importance of regulating the interfacial hydrogen-bond environment by organic molecules as a means of boosting electrochemical performance in aqueous electrosynthesis and beyond.