Abstract
A titanium carbide (Ti3C2Tx) MXene is employed as an efficient solid support to host a nitrogen (N) and sulfur (S) coordinated ruthenium single atom (Ru-SA) 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 Ti3C2Tx MXene support and the successful coordination of Ru-SA with the N and S species on the Ti3C2Tx MXene. The resultant Ru-SA-N-S-Ti3C2Tx catalyst exhibits a low overpotential of 76 mV to achieve the current density of 10 mA cm(-2). Furthermore, it is shown that integrating the Ru-SA-N-S-Ti3C2Tx catalyst on n(+)np(+)-Si photocathode enables photoelectrochemical hydrogen production with exceptionally high photocurrent density of 37.6 mA cm(-2) that is higher than the reported precious Pt and other noble metals catalysts coupled to Si photocathodes. Density functional theory calculations suggest that Ru-SA coordinated with N and S sites on the Ti3C2Tx 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.