•First demonstration of lattice oxygen redox in Ir single-site catalyst (Ir–MnO2)•Ir–MnO2 exhibited an over 42 times mass activity than that commercial IrO2•Ir–MnO2 show only 15 mV increasement overpotential after 650 h durability test Proton exchange membrane water electrolyzers (PEMWEs) represent a promising technology to efficiently convert renewable energy into high-quality hydrogen. Howeve...
