Urchin-like Medium-Entropy Oxyhydroxide FeCoNiOOH Nanoparticles Supported on Nickel Foam for Seawater Oxidation

Developing electrocatalysts with exceptional efficiency and remarkable corrosion resistance for seawater electrolysis presents a significant challenge. Here, an urchin-like medium-entropy Fe–Co–Ni oxyhydroxide on nickel foam (NF) exhibits high surface area, rich active sites, and a short charge diffusion path to enhance oxygen evolution reaction (OER) activity. In 1 M KOH, 1 M KOH + 0.5 M NaCl, 1 M KOH + 1 M NaCl, and 1 M KOH + seawater electrolyte, FeCoNiOOH/NF exhibits exceptional OER performance, featuring impressively low overpotentials (η10) of 182, 195, 205, and 216 mV, respectively. Furthermore, FeCoNiOOH/NF displays remarkable stability in alkaline freshwater and seawater at 100 mA cm–2 for over 25 h. In situ Raman measurements demonstrate that NiOOH is the key active component in the OER process. This study provides an avenue to design medium-entropy oxyhydroxide catalysts for seawater splitting.