Electronic metal–support interaction via Ni defect-induced Ru-modified Ni–CeO2 for enhanced hydrogen oxidation activity

Abstract

The creation of refined surface vacancies, a crucial bridge between theoretical structural studies and catalyst design, has attracted significant attention. Herein, we utilize a MOF pyrolytic derivatization strategy to create monodispersed Ru nanoparticles anchored on Ni–CeO₂ mesoporous microspheres with abundant Ni vacancies (Ru/Ni–CeO₂). Introducing nickel vacancies in Ru/Ni–CeO₂ is conducive to enhancing electrical conductivity and accelerating mass-charge transfer efficiency. As anticipated, the Ru/Ni–CeO₂ displays admirable hydrogen oxidation reaction (HOR) electrocatalytic activity with exchange current density (j₀) and mass activity reaching 3.27 mA cm⁻² and 1.93 mA g_Ru⁻¹, respectively, surpassing the values for cutting-edge Pt/C and most recorded Ru-based HOR electrocatalysts. Surprisingly, Ru/Ni–CeO₂ demonstrates robust tolerance to 1000 ppm CO, outperforming Pt/C. Integrated analysis suggests that Ni defect-induced directional electron transfer at the Ru/Ni–CeO₂ heterointerface arises from a strong electron–metal support interaction (EMSI) effect between Ru and Ni–CeO₂. This interaction optimizes the adsorption of H and OH, thereby enhancing HOR behavior.