Hierarchically 3D bifunctional catalysts assembled with 1D MoC core/branched N-doped CNT arrays for zinc-air batteries

The development of economical and highly efficiency bifunctional oxygen catalyst is of great significance to promote the development of metal-air batteries. Herein, we report the synthesis of a hierarchical structure, assembled with Co, Zn, N-codoped carbon nanotube arrays branched out from one-dimensional (1D) molybdenum carbide (MoCoZn/NCNTA) as an effective bifunctional electrocatalyst. Owing to the synergistic effect among Co@NCNTA, 1D molybdenum carbide and the Zn dopants, the optimized MoCoZn/NCNTA has excellent bifunctional activities with a high half-wave potential of 0.914 V towards oxygen reduction reaction (ORR) and a small overpotential of 445 mV at a current density of 10 mA cm⁻² towards oxygen evolution reaction (OER). When used as an air–cathode catalyst for rechargeable zinc-air battery, the MoCoZn/NCNTA-based zinc-air battery exhibits excellent energy storage and conversion performance with a large power density, high round-trip efficiency and robust cycling stability, outperforming benchmarked Pt/C-IrO₂ mixture-based battery. This work provides a rational pathway for fabricating effective bifunctional electrocatalyst for high-performance metal-air battery.