Rational design of a RuO2/0.5CeO2 heterostructure as an efficient and stable electrocatalyst for acidic water splitting

Abstract

The large-scale commercialization of low-cost Ru-based catalysts in proton exchange membrane water electrolyzers (PEMWEs) is fundamentally hindered by structural degradation through lattice oxygen oxidation (LOM) pathways during the acidic oxygen evolution reaction (OER). To address this challenge, we present an interfacial engineering strategy for the construction of a ruthenium-cerium oxide heterostructure (RuO₂/xCeO₂) via a facile impregnation-pyrolysis method. Morphological and electronic structure characterizations confirm the formation of heterojunction interfaces between RuO₂ and CeO₂. The developed RuO₂/0.5CeO₂ catalyst achieves an overpotential of 214 mV and maintains negligible activity loss over 550 h at 10 mA cm⁻². Furthermore, the membrane electrode assembly (MEA) employing RuO₂/0.5CeO₂ as the anode delivers 1.59 V at 1 A cm⁻² with over 300 h durability at 500 mA cm⁻², showcasing its practicality for PEMWE. Electronic structure analysis confirms that interfacial charge transfer lowers the oxidation state of Ru species and diminishes the lattice oxygen content. Catalytic mechanism investigations and density functional theory (DFT) calculations reveal that the formation of a heterointerface induces a transition in RuO₂ from a hybrid mechanism to an adsorbate evolution mechanism (AEM)-dominated OER pathway, lowering the energy barrier of the rate-determining step while suppressing lattice oxygen participation, synergistically enhancing activity and durability. This work proposes an effective strategy for designing highly active and durable ruthenium-based catalysts.