Stable Acidic Water Oxidation with a Cobalt-Iron-Lead Oxide Catalyst Operating via a Cobalt-Selective Self-Healing Mechanism.

The instability and expense of anodes for water electrolyzers with acidic electrolytes can be overcome through the implementation of a cobalt-iron-lead oxide electrocatalyst, [Co-Fe-Pb]O , that is self-healing in the presence of dissolved metal precursors. However, the latter requirement is pernicious for the membrane and especially the cathode half-reaction since Pb and Fe precursors poison the state-of-the-art platinum H evolving catalyst. To address this, we demonstrate the invariably stable operation of [Co-Fe-Pb]O in acidic solutions through a cobalt-selective self-healing mechanism without the addition of Pb and Fe and investigate the kinetics of the process. Soft X-ray absorption spectroscopy reveals that low concentrations of Co in the solution stabilize the catalytically active Co(Fe) sites. The highly promising performance of this system is showcased by steady water electrooxidation at 80±1 °C and 10 mA cm , using a flat electrode, at an overpotential of 0.56±0.01 V on a one-week timescale.