Tailoring the ruthenium reactive sites on N doped molybdenum carbide nanosheets via the anti-Ostwald ripening as efficient electrocatalyst for hydrogen evolution reaction in alkaline media

The irreversible sintering of supported ruthenium (Ru) catalyst in the preparation process has seriously affected its hydrogen evolution reaction (HER) activity and stability. Herein, ultrathin nitrogen-doped molybdenum carbide nanosheets (N-Mo2C NSs) is used as a versatile support to stabilize Ru single atoms (SAs) sites via the anti-Ostwald ripening. Ru SAs are dispersed into the N-Mo2C NSs matrix via the strong bonding between the Ru atoms and Mo2C NSs regulated by N doping. The atomic isolated Ru SAs are confirmed by spherical aberration correction transmission electron microscopy (AC HAADF-STEM) and X-ray absorption fine structure (XAFS) measurements. Ru SAs/N-Mo2C NSs exhibits outstanding HER performance, with a small overpotential of 43 mV at 10 mA/cm2, and robust catalytic stability in 1.0 M KOH. Importantly, Ru SAs/N-Mo2C NSs possesses a higher mass activity of 6.44 A/mgRu than that of 20 wt% Pt/C (0.91 A/mgPt) at the overpotential of 100 mV. Theoretical calculations further reveal that the high HER activity of Ru SAs/N-Mo2C NSs is derived from the synergistically accelerated the dissociation of H2O and the optimized H adsorption strength in Mo-Ru interface. This result provides a new direction for the rational designing monatomic electrocatalysts for HER via support interaction effect.