▎ 摘　　要

In our efforts to obtain Pt-free oxygen reduction reaction (ORR) electrocatalysts with high efficiency for fuel cell and metal-air battery, design, and preparation of novel materials with desired morphology and active sites are vitally necessary. Herein, a novel MoC-based ORR catalyst with high efficiency is achieved. The proposed catalyst is comprised of ultrasmall-sized MoC nanoparticles (average size similar to 1.5 nm) entrapped into 3D porous frameworks of N-rich graphene (NGr), which is synthesized by using layered C3N4 as a sacrificial template via a facile pyrolytic approach. Possessing unique structural features (including preferential O-2 absorbing sites, good accessibility, favorable conductive and protective 3D frameworks of NGr), the MoC/NGr catalyst exhibits positive onset- and peak- potential at 0.93 and 0.80 V for ORR in alkaline media with good four-electron selectivity (n approximate to 4.0), which is promising and even competitive to commercial Pt/C, particularly in terms of cost-effectiveness, the ease of preparation, significantly improved methanol tolerance, and enhanced stability. Other prospective application of MoC/NGr could also be broadened to biomimic catalysis, energy conversion, storage devices, and so on.