Enhanced Oxygen Reduction Performance on {101} CoMn₂O₄ Spinel Facets

We present a facile colloidal synthesis method to produce uniform-sized (9 nm) CoMn₂O₄ spinel nano-octahedra tailored with {101} facets. These nano-octahedra demonstrate enhanced electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline media compared to their spherical counterparts and previously reported spinel electrocatalysts. At 0.85 V, they achieve a high mass activity (MA) of 60.0 A/g, surpassing their spherical counterparts (38.6 A/g). Moreover, the CoMn₂O₄ nano-octahedra exhibit favorable stability, maintaining an MA of 47.2 A/g after 10 000 durability cycles. This work highlights a promising approach for synthesizing advanced spinel nanooxides with controlled crystal facets, which hold the potential to serve as nonprecious metal ORR electrocatalysts. The enhanced ORR performance is attributed to the exposed active catalyst surfaces in the well-defined structures of the nano-octahedra, emphasizing the significance of catalyst shape control.