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-x, 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 Pb2+ and Fe3+ precursors poison the state-of-the-art platinum H-2 evolving catalyst. To address this, we demonstrate the invariably stable operation of [Co-Fe-Pb]O-x in acidic solutions through a cobalt-selective self-healing mechanism without the addition of Pb2+ and Fe3+ and investigate the kinetics of the process. Soft X-ray absorption spectroscopy reveals that low concentrations of Co2+ 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 degrees C and 10 mA cm(-2), using a flat electrode, at an overpotential of 0.56 +/- 0.01 V on a one-week timescale.

Automated summary

The study demonstrates the stable operation of [Co-Fe-Pb]O-x in acidic solutions without the addition of Pb2+ and Fe3+, showcasing promising performance in water electrooxidation. Low concentrations of Co2+ are shown to stabilize the catalytically active Co(Fe) sites, allowing for steady water electrooxidation at specific conditions.