(Co/Fe)4O4 Cubane-Containing Nanorings Fabricated by Phosphorylating Cobalt Ferrite for Highly Efficient Oxygen Evolution Reaction

The sluggish kinetics of the oxygen evolution reaction (OER) limits the practical applications of many important energy conversion systems such as electrolysis of water, metal–air batteries, solar fuel, and so on. Here, we report a highly efficient OER electrocatalyst that features (Co/Fe)4O4 cubane motifs in an amorphous nanoring structure. The Co/Fe codopants in the cubane motifs can optimize the intermediates adsorption and significantly lower the overpotentials of the OER. In addition to finely tuning the adsorption of intermediates, the amorphous nanoring structures provide rapid ion channels and high surface area for the OER. Phosphorylation also increases the wettability of electrocatalysts. As a result, the nanorings exhibit highly catalytic activities for the OER with a low overpotential of 300 mV at 10 mA cm–2 and a small Tafel slope of 36 mV dec–1 in an alkaline solution. The long-term durability is demonstrated for at least 20 h at 10 mA cm–2. In brief, we demonstrate a tuning strategy of Co/Fe codoped cubane motifs in amorphous phosphate nanorings and thus open up an avenue of structural tunability for advanced catalyst design