KINETICS OF THE HYDROGEN EVOLUTION REACTION AT VARIOUS ZR-BASED LAVES-PHASE HYDROGEN-STORAGE ALLOY ELECTRODES

The kinetics of the hydrogen evolution reaction at various Zr-based la ves-phase hydrogen-storage alloy electrodes was investigated by measur ing an overpotential-decay curve immediately after the interruption of an applied constant current. The measured overpotential was divided i nto two partial overpotentials corresponding to the elementary reactio ns, i.e., the Volmer (discharge) and Tafel (combination) reactions. Th e ratio of exchange current density for the Volmer (discharge) reactio n to that for the Tafel (combination) reaction increased with increasi ng unit-cell volume of the hydrogen-storage allays used, suggesting th at the Tafel (combination) reaction is effectively suppressed.