Oxygen-vacancy-rich CeO2/Ru nanoparticles enable a high-performance catalyst for alkaline hydrogen oxidation

Abstract

A highly active, stable and low-cost platinum-free anode catalyst based on Ru for hydroxide exchange membrane fuel cells (HEMFCs) is hindered by the strong oxophilicity of Ru, which makes it easy to oxidize during the test. Herein, we found that Ru/CeO₂(v)/C (oxygen-vacancy-rich CeO₂/Ru nanoparticles supported on carbon) exhibit excellent catalytic activity with a mass activity of 8.06 A mg_NM⁻¹ and a specific activity of 2.85 mA cm_NM⁻², which are 19.6/20.1 and 2.3/8.4 times higher than those of Pt/C and PtRu/C, respectively. Moreover, Ru/CeO₂(v)/C also exhibits excellent stability and CO tolerance in alkaline media. Experimental and theoretical studies reveal that the improved charge transfer from Ru to CeO₂(v) significantly tunes the electronic structure of Ru sites and optimizes the hydrogen binding energy (HBE) of Ru, while CeO₂(v) provides abundant hydroxyl adsorption sites. We attribute this enhancement to the interfacial effect, which can realize the equilibrium adsorption of hydrogen and hydroxyl groups on the interface and synergistically promote the Volmer reaction, thereby enhancing the activity and stability of the catalyst.