Electrocatalytic Oxygen Evolution by Hierarchically Structured Cobalt–Iron Composites

The development of scalable routes to highly active and efficient oxygen evolution reaction (OER) electrocatalysts based on earth-abundant materials is crucial for post-fossil fuel energy schemes. Here, we demonstrate how commercial copper foam electrodes can be functionalized for water oxidation using a facile electrodeposition process. The resulting composite electrode features hierarchically structured cobalt–iron-based catalyst particles, which offer channel-like structures for the transport of electrolyte and release of oxygen gas bubbles. We report high electrocatalytic OER performance as demonstrated by high current densities at low overpotentials (293 mV at j = 50 mA cm–2) and long-term stability under technologically relevant alkaline conditions (>24 h in 1.0 M aqueous KOH).