Engineering Oxygen Vacancies in IrO<sub><i>x</i></sub> Clusters Supported on Metal–Organic Framework Derived Porous CeO<sub>2</sub> for Enhanced Oxygen Evolution in Acidic Media
Wenrui Li, Jianning Lv, Di Liu, Wenjun Cai, Xianchun Chen, Qirui Huang, Lu Wang, Bo Wang
Abstract
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 CeO 2 -supported IrO x clusters 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 v concentration in the derived IrO x clusters is effectively regulated by the presence of heteroatoms in MOFs. The optimized IrO x /CeO 2 catalyst with high O v (ho v -IrO x /CeO 2 ) exhibits a low overpotential of 251 mV at 10 mA cm –2, a higher turnover frequency (TOF) of 5400 h –1 and outstanding durability for at least 98 h of catalysis in 0.1 M HClO 4, outperforming other analogues. Density functional theory calculations also show that the rich O v in IrO x can 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 CeO 2 support also contribute to the high stability.