Multiatom activation of single-atom electrocatalysts via remote coordination for ultrahigh-rate two-electron oxygen reduction

Abstract

Electrocatalytic oxygen reduction via a two-electron pathway (2e−-ORR) is a promising and eco-friendly route for producing hydrogen peroxide (H2O2). Single-atom catalysts (SACs) typically show excellent selectivity towards 2e−-ORR due to their unique electronic structures and geometrical configurations. The very low density of single-atom active centers, however, often leads to unsatisfactory H2O2 yield rate, significantly inhibiting their practical feasibility. Addressing this, we herein introduce fluorine as a secondary doping element into conventional SACs, which does not directly coordinate with the single-atom metal centers but synergize with them in a remote manner. This strategy effectively activates the surrounding carbon atoms and converts them into highly active sites for 2e−-ORR. Consequently, a record-high H2O2 yield rate up to 27 mol g−1 h−1 has been achieved on the Mo–F–C catalyst, with high Faradaic efficiency of 90%. Density functional theory calculations further confirm the very kinetically facile 2e−-ORR over these additional active sites and the superiority of Mo as the single-atom center to others. This strategy thus not only provides a high-performance electrocatalyst for 2e−-ORR but also should shed light on new strategies to significantly increase the active centers number of SACs.