Utilizing oxygen vacancies in cerium oxide to narrow the gap between d and f band centers for efficient alkaline water oxidation

Rare earth oxides (REOs) hold a pivotal position in enhancing electrocatalytic performance, yet the comprehension of their underlying mechanisms poses significant challenges. In this study, REOs loaded with a ternary alloy, abundant in oxygen vacancies, were synthesized through a one-pot reduction method and exhibited remarkable oxygen evolution reaction (OER) activity. The interaction at the interface between Fe0.3NiCo and CeO2 induced substantial lattice distortion and modulated the oxygen vacancy concentration within the REOs. A unique electron transport channel, incorporating transition metal (3d) -oxygen vacancy (Vo) -rare earth (4 f) elements, was constructed at the interface, significantly boosting the OER activity of NiCo-CeO2. Notably, a current density of 10 mA cm-2 was achieved at a low overpotential of 151 mV. Comprehensive characterizations revealed that the interplay between the alloy and REOs regulated the oxygen vacancy concentration of the latter. In-situ attenuated total reflection infrared spectroscopy (ATR-IR) further confirmed that REOs facilitated the adsorption of O2/-OH, thereby enhancing OER activity. Theoretical calculations also indicated that oxygen vacancies effectively shifted the d and f band centers near the Fermi level, promoting d-f electron exchange and ensuring efficient electron transfer. This study offers a novel perspective for the development of efficient REbased catalysts.