Nitrogen plasma engineered MoS₂ for catalyzing hydrogen evolution reaction

Monolayer molybdenum disulfide (MoS₂) possesses exceptional electrical characteristics and a substantial specific surface area, rendering it an optimal material for electrocatalysis. However, its inert basal planes account for a relatively large proportion, and the limited exposure of active edge sites restricts its further utilization and development. Here, we report a remote nitrogen (N)-plasma treatment that incorporates substituted N into monolayer MoS₂ (ML-MoS₂) and activates its basal plane for the hydrogen evolution reaction (HER). The optimized N-doped ML-MoS₂ delivers an overpotential of 348 mV at 10 mA cm^-2 and a Tafel slope of 94 mV·dec^-1. Experimental and theoretical results show that nitrogen incorporation induces lattice defects and charge redistribution and increases active-site density, thereby enhancing HER activity. This plasma-based, controllable surface activation strategy provides a scalable route to tune the catalytic performance of two-dimensional transition-metal dichalcogenides.