Space-Confined Anchoring of Fe−N_x on Concave N-Doped Carbon Cubes for Catalyzing Oxygen Reduction

Carbon-based electrocatalysts with atomically dispersed Fe−N−C display promising performance for oxygen reduction reaction (ORR) amongst non-precious electrocatalysts. Nonetheless, increasing the number and utilization of Fe−N−C active sites is challenging. Designing morphologies and adjusting the pore structure of carbon-based electrocatalysts would boost the mass transfer, enhance the utilization of the active sites, and increase the overall ORR performance. In this work, a concave N-doped carbon cubes structure adorned with highly external Fe−N_x was designed and produced by the space-confined induced strategy. The optimal electrocatalyst revealed excellent ORR activity in both alkaline and acidic electrolytes, with half-wave potentials of 0.86 and 0.75 V, respectively. The superior performance arose from its unique concave structure, possessing more accessible active sites with improved intrinsic activity, which holds promising potential for preparing advanced ORR electrocatalysts.