FACTORS IN THE ELECTROLYTIC SORPTION OF H INTO METALS AND ITS RELATION TO CATHODIC HYDROGEN EVOLUTION KINETICS

Recent work on metal (alloy) hydrides for H storage and rechargeable anodes has stimulated renewed interest in H sorption into metals. The paper examines how H absorption should depend on the cathodic H-2 evolution mechanism, through the potential dependence of fractional coverage by adsorbed H. The states of adsorbed and absorbed H are treated in terms of site-fraction statistics in order to write chemical potentials of ad- and absorbed H. Then the relations to overpotential in the H-2 evolution reaction are derived, and the efficiency of H sorption in relation to co-evolution of H-2 (important for metal-hydride battery electrode charging) can be examined in terms of reaction mechanism.