Co-N-C Axially Coordination Regulated H 2 O 2  Selectivity Via Water Medicated Recombination of Solute Oh•: A New Route

Abstract

The cobalt, earth abundant transition metal, embedded in nitrogen doped carbon material as single atom site (Co-N-C) has been manifested as promising electrochemical oxygen reduction reaction (ORR) catalyst, however the unsatisfying production selectivity has hampered its widespread applications. Herein, the H2O2 selectivity of Co-N-C catalyst has been tailored with Co axial functional groups.. Thermodynamically, the selectivity is regulated due to the fine-tunning of the adsorption of the key reaction intermediates (ΔG*OOH), and five functional groups, including -O, -OH, -CN, CH3 and -SO3, endow the Co-N-C catalyst with superior H2O2 selectivity. Importantly, we unravel a new water medicated recombination of solute OH• reaction pathway for H2O2 production, which was the result of dissociation of *HOOH in explicit water environment That is two ·OH species reaction in the liquid environment which originated from the creaking of *OOH intermediates due to the weakened O-O bond by the interaction with surrounding water. This study provides foundational understanding for the ORR catalytic mechanism at the electrochemical interface and open up new avenues for rational design of targeted high efficiency electrocatalysts.

Keywords: Single atom catalyst, Surface modification, production selectivity, Reaction mechanism, dynamic simulation