Deactivation mechanism of nickel cathodes in alkaline media

Time-dependent hydrogen evolution reaction (HER) on Ni electrodes shows a large increase in electrode over potential with time. This is ascribed to hydride formation at active Ni cathode surfaces. Hydride formation was detected by X-ray diffraction. By taking into account the nickel electronic density of states variation following hydrogen sorption, we are able to satisfactorily explain the increase in nickel over potential after a few hours of HER.