Reconstructing the Hydrogen-Bonded Network on an IrNi Sponge for the Alkaline Oxygen Evolution Reaction

Abstract

Precise regulation of the interfacial hydrogen-bonded network is critical for enhancing both electrocatalytic activity and long-term stability in the oxygen evolution reaction (OER). Herein, we successfully construct a flexible, metallic fibrous IrNi sponge that effectively reshapes the hydrogen-bonded network, thereby improving alkaline OER performance. The resulting IrNi sponge achieves a low overpotential of 270 mV at 200 mA cm–2 and maintains this current density for over 100 h in 1.0 M KOH, significantly outperforming the Ni sponge and IrO2/Ni sponge. When integrated as the anode in an anion exchange membrane water electrolyzer, the system achieves 0.5 A cm–2 at 1.65 V and exhibits remarkably stable operation for 500 h. Mechanistic investigations reveal that the in situ-generated Lewis acid sites (Irδ+) within the IrNi sponge reinforce the interfacial hydrogen-bonded network. This strengthened network facilitates OH– diffusion and lowers the energy barrier of the rate-determining step (*O → *OOH), thereby markedly enhancing the OER activity. This work underscores the importance of Lewis acid sites in regulating the hydrogen-bonded network and offers a viable design strategy for achieving high-current-density, durable catalysts for water electrolysis.