Oxygen Electrocatalytic Activity Investigation for a Single Co Atom with Diverse Coordination Environments on the h-BCN Monolayer

Developing efficient and inexpensive bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is essential to promote the application of metal–air battery and fuel cell technologies. In this study, the ORR and OER catalytic activities of a Co single atom embedded in different positions of the hexagonal graphene-like boron–carbon–nitrogen (h-BCN) material to form various types of Co single-atom active sites have been comprehensively and systematically investigated by using density functional theory (DFT) calculations. The adsorption properties of different active sites on the h-BCN surface for oxygen-containing intermediates during electrochemical reaction processes are calculated, obtaining h-BCN with Co single atom (Co@h-BCN SACs)-embedded materials exhibiting superior ORR and OER catalytic activities. Theoretical calculations and analyses of the structure, electronic properties, and reactivity characteristics of Co@h-BCN SACs show that Co@h-BCN SAC-2 possesses excellent bifunctional catalytic activity, with ORR and OER overpotentials of 0.51 and 0.46 V, respectively. In addition, Co@h-BCN SAC-7 and Co@h-BCN SAC-8 also exhibit good ORR electrocatalytic performance with ORR overpotentials of 0.49 and 0.43 V, respectively. This study reveals that embedding a single Co atom into the h-BCN lattice results in the formation of multiple catalytically active sites, and only the appropriate positions have efficient ORR and OER catalytic activities. These findings facilitate the rational design of Co-embedded h-BCN materials for highly efficient OER and ORR electrocatalysis.