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

Abstract

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 Fe_0.3NiCo 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 RE-based catalysts.