Abstract: Zeolitic imidazolate framework (ZIF-67) derived metal-nitrogen carbon composites have emerged as promising bifunctional catalysts for oxygen reduction (ORR) and oxygen evolution reaction (OER), due to their high specific surface area and well-defined porous structure. However, the oversized ZIF-67 precursor severely restricts the catalytic activity of the cobalt-nitrogen carbon materials, making the synthesis of cobalt-nitrogen carbon nanocrystals a significant challenge. In this study, a Triton X-100-mediated strategy was developed to synthesize ZIF-67 nanocrystals, followed by the preparation of cobalt-nitrogen carbon nanocrystals (Co-NC-800) with a diameter of ~30 nm after pyrolysis processes. Co-NC-800 nanocrystals exhibited a high specific surface area of 447.4 m²/g, featuring hierarchical porosity and an abundance of catalytically active sites, which promoted the efficient mass transfer/diffusion pathways for oxygen and ion transmission. Owing to these structural advantages, the Co-NC-800 nanocrystals exhibited remarkable bifunctional performance, with a competitive ORR half-wave potential of 0.83 V and a low OER potential of 1.63 V at 10 mA/cm², comparable to those of commercial Pt/C and RuO₂, respectively. The rechargeable Zn-air battery assembled using Co-NC-800 nanocrystals achieved a peak power density of 116.5 mW/cm² and maintained excellent stability for over 100 h at a current density of 10 mA/cm². This work not only proposes a novel synthetic method for ZIF-67 nanocrystals but also provides new insights into the design of high-performance non-precious metal-based bifunctional electrocatalysts.