Construction of a sp3/sp2 Carbon Interface in 3D N‐Doped Nanocarbons for the Oxygen Reduction Reaction

The development of highly efficient metal‐free carbon electrocatalysts for the oxygen reduction reaction (ORR) is one very promising strategy for the exploitation and commercialization of renewable and clean energy, but this still remains a significant challenge. Herein, we demonstrate a facile approach to prepare three‐dimensional (3D) N‐doped carbon with a sp3/sp2 carbon interface derived from ionic liquids via a simple pyrolysis process. The tunable hybrid sp3 and sp2 carbon composition and pore structures stem from the transformation of ionic liquids to polymerized organics and introduction of a Co metal salt. Through tuning both composition and pores, the 3D N‐doped nanocarbon with a high sp3/sp2 carbon ratio on the surface exhibits a superior electrocatalytic performance for the ORR compared to that of the commercial Pt/C in Zn–air batteries. Density functional theory calculations suggest that the improved ORR performance can be ascribed to the existence of N dopants at the sp3/sp2 carbon interface, which can lower the theoretical overpotential of the ORR. Fine‐tuning: Three‐dimensional N‐doped and hierarchical carbon foam (CF) with a specific ratio of sp3‐ and sp2‐hybridized carbon atoms can be prepared from an ionic liquid by simple pyrolysis. This porous carbon material exhibited superior electrocatalytic performance for oxygen reduction reaction (ORR) in the Zn–air battery.