Reconstructing bridging carbon atoms (from sp3-C to sp2-C) of pyrolytic N-doped carbon to enhance oxygen reduction reaction

The development of new regulation strategy for constructing functional carbon skeletons is a standing challenge for oxygen reduction reaction (ORR). Herein, the locally ordered graphene microcrystals with suitable N-sites derived from glucose are synthesized under the assistance of low melting point zinc molten salt. Utilizing the structural features of graphene microcrystals ("house of cards" model), the work function of carbon skeleton is reduced after inducing the conversion of bridging sp3-C to bridging sp2-C (ratio of sp2-C to sp3-C increases from 3.75 to 7.41). The lower work function of locally ordered microarchitectures decreases the long-range electron transfer barrier in outer-Helmholtz plane. And the synergy between pyridinic N and graphitic N is beneficial for enhancing short-range electron transfer process in inner-Helmholtz plane. After rearrangement of carbon skel-etons, the half-wave potential can increase from 0.846 V to 0.874 V, and the HO2- by-product yield decreases from 31.5 % to 6.9 %. Furthermore, the discharge voltage of locally ordered microarchitecture (1.31 V) at 10 mA cm -2 can surpass the commercial Pt/C (1.25 V) in Zn-air battery devices. In brief, it provides a new direction of structure design for carbonaceous catalysts.