3D Porous N and S Co-doped CNT Microspheres with Highly Dispersed CoP Nanoparticles: Toward an Efficient Bifunctional Electrocatalyst for Zn-Air Batteries

The design and efficient synthesis of oxygen redox electrocatalysts possessed with high activity are of the essence for advanced rechargeable Zn-air batteries (ZABs). In particular, porous architectures composed of transition metal compound and carbonaceous material have attracted significant attention owing to their enhanced electrocatalytic activity. This study reports the fabrication of metal-free N and S co-doped porous CNT microspheres (3DNSCNT) via spray drying and subsequent post-treatment. Moreover, to hybridize with metal phosphide, CoP nanoparticles are uniformly decorated on the microspheres (3DNSCNT/CoP) by the hydrothermal method and phosphidation treatment. Due to the effect of the combination of the porous architecture inside the entangled 3DNSCNT and uniformly deposited CoP nanoparticles, 3DNSCNT/CoP exhibits superior bifunctional electrocatalytic activities for oxygen redox reaction in 0.1 M KOH electrolyte compared with noble metal-based catalysts like Pt and Ru. Furthermore, as an air cathode for ZABs, 3DNSCNT/CoP exhibits a high-power density (177 mW cm-2), low polarization overpotential, and durable cycle performance (200 h).