Role of electronic, geometric, and surface properties on the mechanism of the electrochemical hydriding/dehydriding reactions

Since 1990 there has been an ongoing collaboration among the authors to investigate the role of individual elements on the thermodynamics and kinetics of hydriding/dehydriding reactions. This review article presents the electrochemical and physicochemical characteristics of hydriding/dehydriding reactions from the point of view of their dependence on electronic, geometric and surface properties of the hydride materials. X-ray absorption spectroscopy (XAS), x-ray diffraction spectroscopy (XRD) and scanning vibrating electrode technique (SVET) studies were carried on AB5 type alloys, partially substituted by other elements. Expansion of the unit cell volume and a larger Ni d band vacancy are beneficial for increasing the amount of the hydrogen storage. XAS and SVET showed that the Ce substitution for La in an AB5 alloy enhances the lifetime of hydride electrode.