Enhancing catalytic activity in Mo2C nanodots via nitrogen doping and graphene integration for efficient hydrogen evolution under alkaline conditions.

Abstract

Due to its exceptional electronic properties and catalytic activity, Mo₂C has garnered significant attention for its application in electrocatalysis, particularly for the hydrogen evolution reaction (HER). However, several critical challenges continue to impede its widespread use, especially under strongly alkaline conditions. A primary obstacle is the enhancement of its intrinsic activity through further modification strategies, which remains a key limitation for its broader utilization. Additionally, issues related to poor stability and durability during prolonged electrochemical tests raise concerns about the practical viability of Mo₂C -based electrocatalysts. In this work, we present a novel strategy to enhance the electrocatalytic performance of Mo₂C nanodots for HER through the synergistic modification involving nitrogen doping and graphene incorporation. The incorporation of nitrogen into the Mo₂C structure significantly alters its electronic properties, leading to an increased density of active sites and improved conductivity. When further combined with graphene, the resulting N-Mo₂C-NDs@graphene composite catalyst exhibits remarkable electrochemical HER performances in 1 M KOH electrolyte, achieving a low overpotential of 84 mV at 10 mA cm^-2 and a reduced Tafel slope of 74 mV dec^-2, along with excellent long-term stability test. Computational analyses reveal that that incorporating nitrogen and graphene significantly reduces the free energy of intermediate states (*H₂O), thereby enhancing the electrocatalytic HER activities. These findings highlight the potential of designing advanced transition metal carbides-based composite electrocatalysts via synergistic approaches for energy conversion applications.