Modulating the electronic structure of VS 2 via Ru decoration for an efficient pH-universal electrocatalytic hydrogen evolution reaction.

High-efficiency water electrolysis over a broad pH range is desirable but challenging. Herein, Ru-decorated VS 2 on carbon cloth (Ru-VS 2 /CC) has been in situ synthesized, which features the regulated electronic structure of VS 2 by introducing Ru. It is remarkable that the optimal Ru-VS 2 /CC displays excellent electrocatalytic hydrogen evolution activity with overpotentials of 89 and 87 mV at -10 mA cm -2 in 0.5 M H 2 SO 4 and 1.0 M KOH, respectively. Theoretical calculations and electrocatalytic measurements have demonstrated that introducing Ru induces an enhanced charge density around the Fermi level, facilitating charge transfer and speeding up the electrocatalytic HER kinetics. The Gibbs free energy of the hydrogen intermediate (Δ G H* ) of Ru-VS 2 /CC (0.23 eV) is much closer to zero than that of pure VS 2 (0.51 eV) and Ru (-0.37 eV), demonstrating an easier hydrogen adsorption and desorption process for Ru-VS 2 /CC. The more favorable Δ G H* , differential charge density and the d-band center endow Ru-VS 2 with enhanced intrinsic electrocatalytic activity. This study presents a feasible strategy for enhancing electrocatalytic HER activity by the regulation of the electronic structure and the rational integration of dual active components.