Boosting the Oxygen Evolution Reaction Performance of Ni-Fe-Electrodes by Tailored Conditioning

Abstract

To meet the rising demand for green hydrogen, efficient alkaline water electrolysis demands highly active and low-cost electrocatalysts for the oxygen evolution reaction (OER). We address this issue by focusing our work on optimizing the conditioning of promising Ni-(Fe)-based electrodes to improve their electrocatalytic performances. Systematic parameter variation for cyclic voltammetry conditioning revealed that a large potential window, low scan rate, and a high number of cycles result in improved activation. If the conditioning time is fixed, a high scan rate was found beneficial. A remarkable 47±6 mV potential drop at 10 mA cm⁻² was achieved for Ni₇₀Fe₃₀ when conditioning between −0.35–1.6 V at 100 mV s⁻¹ for just 30 min. We could demonstrate that this activation persisted over 100 h at 100 mA cm⁻², underscoring its enduring efficacy. We suggest that this activation effect results from the growth of a hydrous hydroxide layer, which is supported by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Fe incorporation or dissolution played only a minor role in the differences in electrode activation, as demonstrated by variation of the Fe content in the electrolyte. Our work stresses the importance of conditioning in enhancing OER performance and explores how to improve the catalysts′ effectiveness by tailoring oxides.