Structure-Activity Relationship of Atomic-Scale Cobalt-Based N-C Catalysts in the Oxygen Evolution Reaction

Understanding the origin of the active site activity in the oxygen evolution reaction (OER) electrocatalysts is key for developing efficient electrocatalysts. However, crucial challenges remain due to the complexity of catalyst structure-activity relationships. Herein, various Co-N-C configurations, including single atoms, diatoms, and clusters, were designed to establish structure-activity relationships by first-principles calculations. It was revealed that the Co-N-4 exhibited the best reactivity due to the high coordination number of the metal center and moderate adsorption energies for all reaction intermediates. The diatom and cluster activities originate from the highly coordinated structures formed with reaction intermediates, which serve as coordination ligands. Furthermore, other factors influencing the OER activity based on the Co-N-4 configuration are discussed. For example, the weak metal-metal interaction can further optimize the adsorption of oxygen-containing intermediates by tuning antibonding energy levels of Co-O. Subsequently, an ultralow overpotential of 0.23 V for the OER in CoNi-type4 systems can be obtained by extrapolation of the volcano plot derived from the established structure-adsorption-activity relationships. This work uncovers the underlying OER activity mechanisms of Co-N-C catalysts, which helps to further understanding of high-performance of M-N-C base catalysts and will aid in the future design of high-efficiency OER catalysts.