Insights into the electrochemical catalytic mechanism of atomically dispersed metal on h-BCN monolayer.

Exploiting efficient and inexpensive electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great significance for the rapid development of renewable energy technologies. The embedding of single-atom metals into two-dimensional (2D) carbon-based materials as electrocatalysts for fuel cells and metal-air batteries have become a major research focus. Herein, the catalytic properties of the ORR and OER of partial metal atoms embedded in a two-dimensional h-BCN monolayer were systematically investigated on thermodynamic and kinetic scales using density functional theory calculations. Electronic structure studies confirm that the d orbitals of metal atoms hybridize with the 2p orbitals of the O atom, modulating the adsorption free energies of oxygen-containing intermediates (OOH, O and OH). Comparison and analysis of catalytic activity results reveal that Co single-atom catalysts (Co-SACs@h-BCN) possess the lowest ORR and OER overpotentials and therefore are expected to be a kind of excellent bifunctional electrocatalyst. This study not only demonstrates that boron- and nitrogen-doped carbon-based materials embedded with partial metal atoms are superior 2D electrocatalysts, but also provides guidance for the investigation of efficient non-precious metal-based bifunctional electrocatalysts.