Climbing the hydrogen evolution volcano with a NiTi shape memory alloy

Alkaline water electrolysis is a sustainable way to produce green hydrogen using renewable electricity. Even though the rates of the cathodic Hydrogen Evolution Reaction (HER) are two to three orders of magnitude less in alkaline compared to acidic conditions, the possibility of using non-precious catalysts makes alkaline HER appealing. We identify a novel and facile route for substantially improving HER performance via the use of commercially available NiTi shape memory alloys, which upon heating undergo a phase transformation from the monoclinic martensite to cubic austenite structure. While room temperature performance is modest, austenitic NiTi outperforms in terms of current density Pt (which is the state-of-the-art HER electrocatalyst) by up to 50 % at 80 °C. Surface ensembles presented by the austenite phase are computed with density functional theory to bind hydrogen more weakly than either metallic Ni or Ti and to have binding energies ideally suited for HER.