Sulfur doped ruthenium nanoparticles as a highly efficient electrocatalyst for hydrogen evolution reaction in alkaline media

Efficient catalysts for the hydrogen evolution reaction (HER) play a crucial role in electrochemical water splitting, which is one of the most promising approaches for alleviating the problem of the energy crisis and environmental pollution. However, it is still challenging to develop highly efficient, stable and platinum-free HER electrocatalysts. Herein, a sulfur-doped ruthenium (Ru–S) catalyst via a one-step solvothermal synthesis procedure is presented. Remarkably, the as-prepared Ru–S-2 catalyst exhibits an ultralow overpotential of only 10 mV to achieve a current density of 10 mA cm−2, which is better than that of Pt (25 mV), and much more superior than those of the commercially available Ru (105 mV) and commercially available 20% Pt/C catalyst (43 mV) in 1.0 M KOH aqueous solution. In addition, the Ru–S-2/C catalyst with a low ruthenium content only requires 40 mV to achieve a current density of 10 mA cm−2 in 1.0 M KOH. Furthermore, the Ru–S-2 catalyst shows a smaller Tafel slope, a larger exchange current density and a better durability than the reference materials. The density functional theory (DFT) calculations demonstrate that the appropriate adsorption and dissociation energies of the water molecules on the Ru–S surface could be responsible for the excellent electrocatalytic performances observed.