Ni–Mo Nanopowders for Efficient Electrochemical Hydrogen Evolution

Earth-abundant metals are attractive alternatives to
the noble
metal composite catalysts that are used in water electrolyzers based
on proton-exchange membrane technology. Ni–Mo alloys have been
previously developed for the hydrogen evolution reaction (HER), but
synthesis methods to date have been limited to formation of catalyst
coatings directly on a substrate. We report a method for generating
unsupported nanopowders of Ni–Mo, which can be suspended in
common solvents and cast onto arbitrary substrates. The mass-specific
catalytic activity under alkaline conditions approaches that of the
most active reported non-noble HER catalysts, and the coatings display
good stability under alkaline conditions. We have also estimated turnover
frequencies per surface atom at various overpotentials and conclude
that the activity enhancement for Ni–Mo relative to pure Ni
is due to a combination of increased surface area and increased fundamental
catalytic activity.