Heteroatom-Mediated Interactions between Ruthenium Single Atoms and an MXene Support for Efficient Hydrogen Evolution.

A titanium carbide (Ti C T ) MXene is employed as an efficient solid support to host a nitrogen (N) and sulfur (S) coordinated ruthenium single atom (Ru ) catalyst, which displays superior activity toward the hydrogen evolution reaction (HER). X-ray absorption fine structure spectroscopy and aberration corrected scanning transmission electron microscopy reveal the atomic dispersion of Ru on the Ti C T MXene support and the successful coordination of Ru with the N and S species on the Ti C T MXene. The resultant Ru -N-S-Ti C T catalyst exhibits a low overpotential of 76 mV to achieve the current density of 10 mA cm . Furthermore, it is shown that integrating the Ru -N-S-Ti C T catalyst on n np -Si photocathode enables photoelectrochemical hydrogen production with exceptionally high photocurrent density of 37.6 mA cm that is higher than the reported precious Pt and other noble metals catalysts coupled to Si photocathodes. Density functional theory calculations suggest that Ru coordinated with N and S sites on the Ti C T MXene support is the origin of this enhanced HER activity. This work would extend the possibility of using the MXene family as a solid support for the rational design of various single atom catalysts.