Electrosynthesis of Hydrogen Peroxide Synergistically Catalyzed by Atomic Co-Nx -C Sites and Oxygen Functional Groups in Noble-Metal-Free Electrocatalysts.

Abstract

Hydrogen peroxide (H2 O2 ) is a green oxidizer widely involved in a vast number of chemical reactions. Electrochemical reduction of oxygen to H2 O2 constitutes an environmentally friendly synthetic route. However, the oxygen reduction reaction (ORR) is kinetically sluggish and undesired water serves as the main product on most electrocatalysts. Therefore, electrocatalysts with high reactivity and selectivity are highly required for H2 O2 electrosynthesis. In this work, a synergistic strategy is proposed for the preparation of H2 O2 electrocatalysts with high ORR reactivity and high H2 O2 selectivity. A Co-Nx -C site and oxygen functional group comodified carbon-based electrocatalyst (named as Co-POC-O) is synthesized. The Co-POC-O electrocatalyst exhibits excellent catalytic performance for H2 O2 electrosynthesis in O2 -saturated 0.10 m KOH with a high selectivity over 80% as well as very high reactivity with an ORR potential at 1 mA cm-2 of 0.79 V versus the reversible hydrogen electrode (RHE). Further mechanism study identifies that the Co-Nx -C sites and oxygen functional groups contribute to the reactivity and selectivity for H2 O2 electrogeneration, respectively. This work affords not only an emerging strategy to design H2 O2 electrosynthesis catalysts with remarkable performance, but also the principles of rational combination of multiple active sites for green and sustainable synthesis of chemicals through electrochemical processes.