Highly Defective Ultrafine Carbon Nanoreactors Enriched with Edge-Type Zn-NP Moiety Boosting Oxygen Electrocatalysis.

High-active nonplatinum group metal oxygen reduction reaction (ORR) catalysts have great potential to improve fuel cell and metal-air battery performance due to their efficiency and cost-effectiveness. However, a fundamental understanding of their size-dependent structure-performance relationships remain elusive. Here a mesoporous-dominant carbon nanoreactor with dimensions in the range of 15-43 nm with edge-rich defective atomic Zn sites is designed. The crystal size and pore diameter of this carbon nanoreactors can be precisely adjusted to enable tunable mass diffusion pathways and porosities. Importantly, the hydrophobic nature of 25 nm nanoreactors maximizes the nonkinetic advantages of active site exposure and rapid O mass transfer at the triple-phase interface. The developed Zn-N-P/NPC catalysts delivers outstanding alkaline and acidic ORR performance with half-wave potentials of 0.92 and 0.80 V, respectively, as well as excellent zinc-air battery performance with charge/discharge over 400 h under 20 mA cm. X-ray absorption spectroscopy and theoretical calculations indicate that the enhanced ORR catalytic activity of Zn-N-P/NPC stems from the introduction of P atoms and edge carbon defects effectively exciting the localized electronic asymmetric distribution of Zn species. The findings provide new perspectives on the size effect of porous carbon supports for the development of efficient cathodes catalysts with multifunctionality.