Highly Active Nickel–Iron Nanoparticles With and Without Ceria for the Oxygen Evolution Reaction

Anion exchange membrane water electrolysis (AEMWE) is an attractive technology for hydrogen (H2) production. This process, however, is kinetically hindered by the oxygen evolution half-cell reaction (OER). Nickel (Ni)-based materials in combination with iron (Fe) have been considered a promising option to enhance activity toward OER in alkaline media. Studies have also shown that incorporating ceria (CeO2) into electrocatalysts can help promote the OER. This study investigates the OER activity of bimetallic Ni–Fe spherical nanoparticles, with and without ceria, synthesized by chemical reduction in ethanol using sodium borohydride. First, the iron content is studied for Ni100−xFex / 50 wt% CeO2 (x = 0, 5, 10, 20, 40 at%); then, the ceria content is studied for the best two iron compositions, namely, Ni80Fe20 / y wt% CeO2 and Ni90Fe10 / y wt%CeO2 (y = 0, 5, 7, 10, 20, and 50 wt%). Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) characterization show spherical particles 4–6 nm in size, where Ni and Fe are co-distributed, and ceria is separately agglomerated. Electrochemical characterization in 1 M KOH shows that at 10 mA cm−2, the Ni80Fe20 catalyst achieved the lowest overpotential for OER of 269 mV, which is better performing than the iridium black benchmark, as well as similar NiFe materials reported in literature. Stability testing indicates that the Ni90Fe10 catalyst is the most stable material with almost no change in overpotential over 12 h at 10 mA cm−2. This study shows that the addition of CeO2 to the catalysts does not significantly improve or impede OER activity.