Synthesis of three-dimensional Co/CoO/N-doped carbon nanotube composite for zinc air battery

Development of bifunctional electrocatalysts for oxygen electrocatalytic reactions is significant in improving the performance of Zn-air batteries. Among all candidates, transition metal compounds and carbon nanotube composites have attracted considerable attention owing to their great catalytic activities. Herein, three-dimensional (3D) macroporous carbon nanotube (CNT) microspheres interconnected with thorn-like N-doped CNT surrounding Co/CoO (m-C@Co/CoO-bC) are synthesized via spray pyrolysis, followed by N-doped CNT growth and oxidation. Hierarchical nanohybrids with porous N-doped CNT-network and Co/CoO catalysts are rationally designed and applied as an efficient oxygen electrocatalyst. The porous carbon backbone exhibits high electrical conductivity with robust corrosion resistance. In addition, interconnected N-doped CNTs wrapping Co/CoO nanocatalysts exhibit enhanced catalytic properties as compared to commercial Pt/C and RuO₂ in alkaline media. m-C@Co/CoO-bC exhibits a robust cycle stability, higher power density, and lower polarization potential difference when applied as the oxygen electrode in a rechargeable Zn-air battery, in comparison to commercial Pt/C-RuO₂ mixed powders.