Colloidally-synthesized cobalt molybdenum nanoparticles as active and stable electrocatalysts for the hydrogen evolution reaction under alkaline conditions

The efficient catalysis of water electrolysis using Earth-abundant materials is considered to underpin the large-scale implementation of several clean energy technologies. Here, we report the synthesis of molybdenum rich Co-Mo nanoparticles, which function as highly active and stable electrocatalysts for the hydrogen evolution reaction (HER) in alkaline aqueous solutions. The Co-Mo nanoparticles have an average diameter of approx. 3 nm, a Co:Mo ratio of approx. 1:9, and are poorly crystalline. The Co-Mo nanoparticles deposited onto Ti foil substrates at a loading of approx. 1 mg cm^-2 required an overpotential of only-75 mV to produce an operationally relevant current density of-10 mA cm^-2, placing them among the most highly active Earth-abundant HER catalysts in alkaline media.