Engineering Oxygen Vacancies in IrO_xClusters Supported on Metal-Organic Framework Derived Porous CeO₂for Enhanced Oxygen Evolution in Acidic Media

Developing highly active and stable electrocatalysts for the oxygen evolution reaction (OER) in acidic media for proton exchange membrane water electrolysis is urgent but still challenging. Herein, porous CeO₂-supported IrO_xclusters with different oxygen vacancy (O_v) concentrations are synthesized by the aid of N-rich and N-free isostructural Ce-based metal-organic frameworks (Ce-MOFs) as templates. O_vconcentration in the derived IrO_xclusters is effectively regulated by the presence of heteroatoms in MOFs. The optimized IrO_x/CeO₂catalyst with high O_v(ho_v-IrO_x/CeO₂) exhibits a low overpotential of 251 mV at 10 mA cm^-2, a higher turnover frequency (TOF) of 5400 h^-1and outstanding durability for at least 98 h of catalysis in 0.1 M HClO₄, outperforming other analogues. Density functional theory calculations also show that the rich O_vin IrO_xcan weaken the binding energy between Ir and *O intermediates, which decreases the energy barriers for forming *OOH from *O in the rate-determining step. Additionally, the suppressed over-oxidation of Ir species as well as the corrosion resistance of the CeO₂support also contribute to the high stability.