Two reduction processes for hydrogen adsorption and absorption at MmNi(5)-type alloy electrodes

The electrochemical hydrating/dehydrating behavior of MmNi(5)-type alloy el ectrodes in an alkaline solution was investigated with cyclic voltammetry, scanning electron microscopy and X-ray photoelectron spectroscopy analysis. At an Mm(Ni3.8Co0.5Al0.4Mn0.3)(5) powder microelectrode, a hydrogen absorp tion peak was observed at more negative potential than that of the water el ectroreduction and hydrogen adsorption peak in its cyclic voltammograms. In addition, the electrochemical mechanism of the hydrogen absorption and des orption at the hydride electrodes in the alkaline solution is discussed. (C ) 1999 Elsevier Science Ltd. All rights reserved.