A flexible, dictyophora-like sponge of porous N-doped carbon microtubes demonstrates excellent electrocatalytic activities for both the oxygen reduction reaction and oxygen evolution reaction.

Highly efficient noble-metal-free electrocatalysts for oxygen reduction reaction (ORR) are essential to reduce the costs of fuel cells and metal–air batteries. Herein, a single-atom Ce–N–C catalyst, constructed of atomically dispersed Ce anchored on N-doped porous carbon nanowires, is proposed to boost the ORR. This catalyst has a high Ce content of 8.55 wt % and a high activity with ORR half-wave potentials of 0.88 V in alkaline media and 0.75 V in acidic electrolytes, which are comparable to widely studied Fe–N–C catalysts. A Zn–air battery based on this material shows excellent performance and durability. Density functional theory calculations reveal that atomically dispersed Ce with adsorbed hydroxyl species (OH) can significantly reduce the energy barrier of the rate-determining step resulting in an improved ORR activity.

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