Atomic manganese coordinated to nitrogen and sulfur for oxygen evolution

Lack of high-efficiency, cost-efficient, and well-stocked oxygen evolution reaction (OER) electrocatalysts is a main challenge in large-scale implementation of electrolytic water. By regulating the electronic structure of isolated single-atom metal sites, high-performance transition-metal-based catalysts can be fabricated to greatly improve the OER performance. Herein, we demonstrate single-atom manganese coordinated to nitrogen and sulfur species in two-dimensional graphene nanosheets Mn-NSG (NSG means N- and S- codoped graphene) as an active and durable OER catalyst with a low overpotential of 296 mV in alkaline media, compared to that of the benchmark IrO₂ catalyst. Theoretical calculations and experimental measurements reveal that the Mn-N₃S sites in the graphene matrix are the most active sites for the OER due to modified electronic structure of the Mn site by three nitrogen and one sulfur atoms coordination, which show lower theoretical overpotential than the Mn-N₄ sites and over which the O–O formation step is the rate-determining step.