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
x
clusters
with different oxygen vacancy (Ov) concentrations are synthesized
by the aid of N-rich and N-free isostructural Ce-based metal–organic
frameworks (Ce-MOFs) as templates. Ov concentration in
the derived IrO
x
clusters is effectively
regulated by the presence of heteroatoms in MOFs. The optimized IrO
x
/CeO2 catalyst with high Ov (hov-IrO
x
/CeO2) 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 HClO4, outperforming other analogues. Density functional
theory calculations also show that the rich Ov 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 CeO2 support also contribute to the high stability.
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