Facile top-down fabrication of integrated amorphous NiFe-based electrocatalytic electrodes for high current and long-life oxygen evolution

Abstract

Developing an industrially relevant electrode with high catalytic activity, stability, and tunable composition/size for large-scale water electrolysis is a significant challenge. We have created an integrated electrode (NFM30-N) for the oxygen evolution reaction (OER) using a facile top-down approach that combines arc melting with dealloying-oxidation. Due to the dealloying-oxidation effect, the as-derived porous amorphous M–O, M–OH, and M–OOH (M = Ni, Fe) nanocones cover the basic NiFeMn alloy. This integrated design enables NFM30-N to exhibit outstanding OER performance at high current densities, requiring low overpotentials of only 282 and 323 mV to achieve large current densities of 100 and 500 mA cm−2, respectively. It also displays a small Tafel slope of 44.1 mV dec−1 and remarkable stability for over 100 h at 100 and 500 mA cm−2. When used as an anode, a two-electrode electrolyzer cell with NFM30-N at 500 mA cm−2 only requires a cell voltage of 1.619 V and exhibits excellent stability, with almost no performance degradation after continuous chronopotentiometry test for each 100 h at 500 and 100 mA cm−2. This exceptional OER electrocatalytic performance is attributed to the integrated structure providing high electrical conductivity and stability, the presence of numerous active sites due to dealloying and the amorphous structure, and the promotion of the OER process by M–O, M–OH, and M–OOH species. This work offers a novel idea for fabricating integrated, industrially relevant electrocatalytic electrodes through traditional metallurgy combined with dealloying-oxidation.