Engineering Synergistic Edge‐N Dipole in Metal‐Free Carbon Nanoflakes toward Intensified Oxygen Reduction Electrocatalysis
Linjie Zhang, Tengteng Gu, K. T. Lu, Liujiang Zhou, Dong‐Sheng Li, Ruihu Wang
Abstract
Abstract Nitrogen doping represents an effective way to induce charge/spin polarization in nanocarbons for promoting oxygen reduction reaction (ORR) activity. However, it remains elusive to define the dominant active sites with respect to two critical N‐configurations of pyridinic‐N and graphitic‐N. Herein, a tandem catalytic graphitization and nitrogen modification strategy for the synthesis of metal‐free nitrogen‐doped carbon nanoflakes (NCF) featuring the edge‐suffused and graphite‐analogous structure is presented. NCF exhibits superb Pt‐like ORR activity (0.85 V for half‐wave potential and 5.9 mA cm −2 for diffusion‐limited current density) but much stronger robustness in the alkaline medium. The experimental and theoretical studies suggest the key role of graphitic‐N in ORR. Furthermore, it unveils that the high activity of NCF should be traced to a synergistic polarization of the edge‐type pyridinic‐N/graphitic‐N dipole spaced by one edge peak carbon atom on the armchair edges. This study sheds light on the understanding of ORR active sites in the nitrogen‐doped nanocarbons for ORR.