Atomically dispersed iridium in MnO₂ with confined vacancy-enabled dual-site synergy for stable acidic oxygen evolution

Atomically dispersed iridium (Ir) catalysts offer exceptional atom utilization efficiency for the acidic oxygen evolution reaction (OER) but are plagued by irreversible Ir dissolution and agglomeration under operational conditions. Here, we develop a one-pot synthesis strategy to anchor atomically dispersed Ir species into the γ-MnO₂ lattice, while precisely generating localized oxygen vacancies (O_Vs) adjacent to Ir sites (1.87%Ir-MnO₂). The synergy between high-valent Ir centers and adjacent O_V sites creates a unique reactive interface that enables cooperative activation of water molecules, significantly accelerating reaction kinetics through the kinetically favored dual-site adsorbate evolution mechanism (DAEM) while suppressing Ir over-oxidation and lattice oxygen degradation. The resulting catalyst exhibits outstanding performance in a proton exchange membrane water electrolyzer (PEMWE), maintaining continuous operation for over 300 h at 1000 mA cm⁻² and retaining 93.4% of its initial voltage after 7 days of solar-simulated intermittent operation (0.6–2.0 V). This work introduces a vacancy-assisted dual-site strategy that effectively overcomes the longstanding trade-off between activity and stability in acidic OER electrocatalysis.