Single-atom Ru anchored in nitrogen-doped MXene (Ti3C2Tx) as an efficient catalyst for the hydrogen evolution reaction at all pH values

Abstract

Precise control of isolated single-atom ruthenium (Ru_SA) sites supported on nitrogen (N)-doped Ti₃C₂T_x MXene (N-Ti₃C₂T_x) through a coordination-assisted strategy is reported. The catalyst displays superior activity toward the hydrogen evolution reaction (HER). The atomic dispersion of Ru_SA on N-Ti₃C₂T_x is verified by spherical aberration-corrected electron microscopy and X-ray absorption fine structure measurements. The resultant Ru_SA–N-Ti₃C₂T_x catalyst exhibits outstanding catalytic performance with low overpotentials of 23, 27, and 81 mV to achieve a current density of 10 mA cm⁻² in 0.5 M H₂SO₄, 1 M KOH, and 1 M PBS solutions, respectively. In addition, Ru_SA–N-Ti₃C₂T_x shows long-term stability with negligible degradation in basic, acidic, and neutral media, which is much better than that of the commercial Pt/C catalyst. Density functional theory calculations suggest that the strong covalent interactions between Ru_SA and N sites on the Ti₃C₂T_x MXene support contribute to the exceptional catalytic performance and stability. This work provides a coordination-engineered strategy to effectively modulate the catalytic properties of the MXene family by an atomic-level engineering strategy.