Hexagonal CeO2 nanoplates loaded with NiFe alloy: A synergistic boost for stable oxygen evolution reaction

Nickel‑iron-based electrocatalysts have emerged as highly promising candidates for replacing precious metals in various electrochemical applications due to their abundance, high efficiency, and low cost. The deactivation of the active sites occurs, however, due to the tendency of the amorphous particles of the simple nickel‑iron alloy to agglomerate during the reaction. Therefore, maintaining long-term stable and efficient catalytic activity remains a challenge for nickel‑iron alloys. To address these challenges, here in this work, we developed a stabilized CeO 2 nanoplates as the main carrier and synthesized nickel‑iron alloy nanoparticles supported on hexagonal cerium dioxide nanoplates (NiFe/CeO 2 ) by a simple hydrothermal method. Interestingly, the introduction of NiFe can reduce the Ce O cerium‑oxygen covalency in CeO 2 , which leads to the weakening of its surface oxygen binding, the generation of a large number of oxygen vacancies, and the enhancement of the co-catalytic activity. Thereby, the NiFe/CeO 2 catalyst delivered a current of 10 mA/cm 2 at an overpotential of only 198 mV, with a Tafel slope as low as 48.6 mV/dec. Meanwhile, the unique hexagonal structure of cerium oxide nanoplates provides a stable and highly conductive support, resulting in a larger contact area between the catalyst and the electrolyte, and faster adsorption and desorption rates. This greatly solves the problem of easy agglomeration and deactivation of the catalyst and significantly improves the structural stability of NiFe. In stability tests, the NiFe/CeO 2 catalyst maintained excellent electrocatalytic stability for up to 120 h. This study provides new insights into designing high-performance OER catalysts by leveraging metal-support interactions and nanostructural engineering, highlighting the potential of hexagonal CeO 2 nanoplates as effective stabilizing carriers.