Reactions at a porous Ni electrode concurrent with hydrogen evolution

We have studied the electrochemical behavior of a commercial Raney Nickel electrode (Gaskatel Ni33 -Raney powder bonded on a Ni mesh by 7% PTFE) in KOH solution (pH=15) at 23°C. Our general purpose is to quantitatively separate the cell current signal into its main components: the gas evolution reactions (of hydrogen – HER – and oxygen – OER) and the reactions modifying the Ni catalyst: oxidation, reduction and hydriding. Previously, we have investigated these reactions (i) using cyclic voltammetry and (ii) evolving hydrogen for a variable time and successively bringing the electrode potential to higher values, recording the resulting anodic transients1. Here, we have modified the experimental setup to record accurately the volumes of gases evolved in the HER or OER stages. We further compared these volumes with those expected when water dissociation is the only reaction occurring.