Core–shell Co3O4@FeOx catalysts for efficient oxygen evolution reaction

Rational fabrication of oxygen evolution reaction (OER) electrocatalysts based on earth-abundant elements is crucial for sustainable energy applications. Although Fe–Co-based (oxy)hydroxides show excellent catalytic activity for OER, a comprehensive understanding of the role of Fe and Co is still lacking. Here, we prepared a core–shell Co3O4@FeOx catalyst with an ultrathin FeOx (<1 nm) coating onto ultrafine Co3O4 nanoparticles (~3.1 nm), which exhibit higher OER activity than Fe/Co-based mixed oxides. The enhanced OER electrocatalytic performance is attributed to the introduction of ultrathin FeOx, which can (1) combine water molecules to promote the reaction, (2) enhance the charge transfer ability of Co3O4, and (3) speed up the diffusion of the reactant water close to the active sites and the produced oxygen away from the active sites.