Highly Disordered Fe-Doped CeO₂ with Oxygen Vacancies Facilitates Electrocatalytic Water Oxidation

The practical application of electrocatalytic water splitting is hindered by the sluggish anodic oxygen evolution reaction (OER), where the exploration of efficient and stable electrocatalysts toward water oxidation remains a great challenge. Herein, we report an active iron-doped ceria (FeO_x/CeO₂) catalyst with a highly disordered feature decorated on three-dimensional (3D) nickel foam, which can directly serve as the superior OER electrode in alkaline media. The highly disordered Fe-doped CeO₂ catalyst displays remarkable OER performance with a low overpotential of 252 mV to achieve 10 mA cm^-2, a small Tafel slope of 45 mV dec^-1, and long-term durability for at least 48 h with a stable structure. The superior OER activity of FeO_x/CeO₂ is attributed to the lattice oxygen activation mechanism facilitated by its disordered structure as well as the high electrochemical surface area. This study provides valuable insights into the rational design of efficient OER catalysts through tailoring the catalyst structure and reaction pathway.