Synergistic Redox Modulation via Electronic Metal–Support Interactions in Ce1−xCoxO2−δ for Enhanced Oxygen Evolution Reaction

Abstract

Designing and developing efficient electrocatalytic materials for the oxygen evolution reaction (OER) remains a challenging yet highly compelling task. Transition metal-based catalysts are widely recognized as economical, stable, and efficient materials, as the Mⁿ⁺/M⁽ⁿ⁺¹⁾⁺ redox couple facilitates the formation of a charge-transfer orbital that enables electron transfer during the OER and the formation of –OOH species through surface reconstructions. However, it is fundamentally challenging to create available charge-transfer orbitals near the Fermi energy level. Herein, we demonstrate the crucial role of efficient electronic metal-support interactions in Ce_1−xCo_xO_2−δ, facilitating an effective redox couple between Co²⁺/Co³⁺ and Ce⁴⁺/Ce³⁺ to enhance OER kinetics. The evolution of lattice oxygen during OER and the Mⁿ⁺  → M⁽ⁿ⁺¹⁾⁺ oxidation process are efficiently facilitated by reducible CeO₂ support in the Ce_1−xCo_xO_2−δ solid-solution. The aliovalent-doped, phase-pure Ce_0.93Co_0.07O_2−δ exhibited exceptional performance, achieving a current density of 10 mA cm⁻² at an overpotential of 270 mV, with stable operation over 24 h. Mechanistic studies revealed that lattice substitution of the active sites facilitated stronger electronic metal-support interaction at the atomic level to improve catalytic performance.

Graphical Abstract