The Influence of Metal Impurities on NiOOH Electrocatalytic Activity in the Oxygen Evolution Reaction

The energy transition and the implementation of new electrochemical technologies will result in an increased reliance on critical raw materials for electrodes. Their large-scale application will ultimately mean working with lower grade materials. Here we study the influence of metal impurities on nickel foam electrocatalysts. We do this by electrodepositing known amounts of first-row transition metals (Cu, Cr, Mn, Fe, Co and Ni) on nickel foam and studying their performance in the oxygen evolution reaction (OER) as a model reaction. The electrodes’ performance is studied using cyclic voltammetry (CV), linear sweep voltammetry (LSV), Tafel analysis, stepwise chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Combining these results with microscopy analysis, we show that even small amounts of transition-metal impurities have profound effects on the catalytic performance of nickel electrodes. The changes affect the OER onset potential (the energy that the system requires to convert OH– to O₂) and the Tafel slope of each electrode (the electrode's initial activity in the OER onset region). Our results highlight the implications of such impurities on electrode design and future large-scale application.