Boosting Hydrogen Oxidation Activity of Ni in Alkaline Media through Oxygen-Vacancy-Rich CeO₂ /Ni Heterostructures

The search for highly efficient platinum group metal (PGM)-free electrocatalysts for the hydrogen oxidation reaction (HOR) in alkaline electrolytes remains a great challenge in the development of alkaline exchange membrane fuel cells (AEMFCs). Here we report the synthesis of an oxygen-vacancy-rich CeO₂ /Ni heterostructure and its remarkable HOR performance in alkaline media. Experimental results and density functional theory (DFT) calculations indicate the electron transfer between CeO₂ and Ni could lead to thermoneutral adsorption free energies of H* (ΔG_H* ). This, together with the promoted OH* adsorption strength derived from the abundance of oxygen vacancies in the CeO₂ species, contributes to the excellent HOR performance with the exchange current density and mass activity of 0.038 mA cm_Ni ^-2 and 12.28 mA mg_Ni ^-1 , respectively. This presents a new benchmark for PGM-free alkaline HOR and opens a new avenue toward the rational design of high-performance PGM-free electrocatalysts for alkaline HOR.