The metal B nanoparticles 315, which are preferably formed from a metal or metal alloy having a stable metal hydride phase such as noble metal including nickel, palladium, platinum, gold, and the like, are electrodeposited, e.g., from an aqueous solution comprising 1.0???10???3 m to 10???10???3 m of the metal ion of interest using a suitable overpotential.