RuN Monolayer: A Highly Efficient Electrocatalyst for Oxygen Reduction Reaction.

The transition metal-based nitride (TMN) holds great promise as catalysts with high efficiency for energy-related technologies. Herein, on the basis of global structure search and density functional theory calculations, a novel two-dimensional (2D) TMN was identified: RuN monolayer with tetracoordinated Ru atoms and isolated N═N dimers, which is revealed to possess high thermal, dynamic, and chemical stabilities as well as metallic nature, thus providing great feasibility for its practical application in electrochemical reactions. Remarkably, we found that the predicted RuN monolayer exhibits superior catalytic performance for the oxygen reduction reaction (ORR) with a rather high limiting potential (0.99 V) and an overwhelming four-electron reduction pathway selectivity. Thus, our results suggested the robust applicability of RuN monolayer as a novel non-Pt catalyst due to its excellent catalytic efficiency and outstanding selectivity for ORR, which not only proposes a new member to the hypercoordinate 2D TMN with novel properties, but also provides a feasible strategy to further develop novel TMN-based nanomaterials for electrocatalytic energy conversion.