Stabilizing Low-Ruthenium Loaded Cobalt-Based Spinel via Cerium Incorporation for Durable Acidic Oxygen Evolution

Abstract

Developing highly active catalysts to accelerate the kinetically sluggish oxygen evolution reaction (OER) is crucial for hydrogen production via acidic water electrolysis. However, the harsh acidic OER environment severely limits practical anode catalysts to precious-metal oxides (e.g., IrO2), which offer high stability but suffer from prohibitively high cost and limited availability. Herein, we report a Ce-modulated Co3O4 spinel with low Ru loading (RuCe−Co3O4) synthesized through a metal−organic framework-templated route followed by controlled ion exchange, enabling a balance between activity, stability, and cost. Benefiting from Ce-induced electronic redistribution, the RuCe−Co3O4 catalyst with atomically dispersed Ru and Ce species delivers a low overpotential of 212 mV at 10 mA cm−2, outperforming Ru−Co3O4 and commercial RuO2, together with a high mass activity of 1611 A g−1Ru at 1.48 V vs RHE. The catalyst maintains stable operation for 200 h. Combined experimental and theoretical analyses reveal that Ce incorporation significantly suppresses Ru and Co dissolution and reinforces the local structure. Density functional theory calculations further demonstrate that Ce incorporation strengthens metal−oxygen bonding and downshifts the Ru/Co d-band centers, thereby enhancing resistance to electrochemical corrosion. This work elucidates the electronic buffering role of rare-earth modulation in spinel hosts and provides an effective strategy for designing Ir-free electrocatalysts with low Ru loading for efficient, durable acidic water electrolysis.