Surface activated Ni7Fe3 alloy foam as a self-supported anode for anion exchange membrane water electrolysis

Abstract

Self-supported electrodes (SSEs) offer a simplified route toward ionomer-free catalyst fabrication for anion exchange membrane water electrolyzer (AEMWE), but most reported systems rely on additional catalyst growth or deposition on porous metallic supports. Here, a commercial Ni 7 Fe 3 alloy foam is directly converted into a binder-free, self-supported oxygen evolution reaction (OER) anode through a mild surface activation, enabling the alloy to serve simultaneously as a conductive porous framework and precursor to the reconstructed OER surface. Acid activation induces preferential surface dissolution and generates a highly wettable surface that undergoes further electrochemical reconstruction under alkaline OER conditions toward a Ni-Fe oxyhydroxide rich surface. Among the investigated commercial NiFe alloy foams, activated Ni 7 Fe 3 (e-Ni 7 Fe 3 AF) exhibited the highest OER activity with a low overpotential of 256 mV at 10 mA cm −2 . In a fully non-noble metal AEMWE, the e-Ni 7 Fe 3 AF(+) || NiMo@Ni felt (−) cell delivered 1.0 A cm −2 at 2.19 V in 1.0 M KOH at 70 ° C and operated stably for 200 h at 1 .0 A cm −2 . These results demonstrate a simple route to integrated, catalyst-layer-free AEMWE electrodes using directly activated commercial Ni-Fe alloy foams.