Ruthenium–Tungsten Composite Catalyst for the Efficient and Contamination-Resistant Electrochemical Evolution of Hydrogen

A new catalyst, prepared by a simple physical mixing of ruthenium (Ru) and tungsten (W) powders, has been discovered to interact synergistically to enhance the electrochemical hydrogen evolution reaction (HER). In an aqueous 0.5 M H2SO4 electrolyte, this catalyst, which contained a miniscule loading of 2–5 nm sized Ru nanoparticles (5.6 μg Ru per cm2 of geometric surface area of the working electrode), required an overpotential of only 85 mV to drive 10 mA/cm2 of H2 evolution. Interestingly, our catalyst also exhibited good immunity against deactivation during HER from ionic contaminants, such as Cu2+ (over 24 h). We unravel the mechanism of synergy between W and Ru for catalyzing H2 evolution using Cu underpotential deposition, photoelectron spectroscopy, and density functional theory (DFT) calculations. We found a decrease in the d-band and an increase in the electron work function of Ru in the mixed composite, which made it bind to H more weakly (more Pt-like). The H-adsorption energy on Ru deposited o...