Cu-based active sites supported on nitrogen-rich polymer derived porous carbon fibers as an oxygen reduction electrocatalyst for zinc-air batteries

The rational design of electrocatalysts with highly exposed active sites and maximized active sites utilization is challenging and urgent problem. Herein, a facile strategy is employed to fabricate Cu-based active sites anchored in nitrogen doped porous carbon nanofiber as an effective and enduring oxygen reduction reaction (ORR) electrocatalyst, which is achieved by the coordination-pyrolysis way of the pre-designed covalent organic polymer (COP) precursors with unique molecular structure. Meanwhile, COP-derived N-doped carbon nanofiber could provide porous structure and facilitate the rapid mass/electron transport, which can insure the strong fastness and high reaction activity of Cu-based active sites. The as-obtained catalyst (Cu0.4/NPC) displays excellent activity (E1/2=0.845 V) and stability for ORR performance. Remarkably, the Cu0.4/NPC as cathode catalyst assembled Zn-air battery achieves the peak power density of 142 mA cm-2 and a large specific capacity of 829 mA h g-1 at large current. Additionally, the Cu0.4/NPC catalyst assembled in the solid Zn-air battery achieves the peak power density of 157 mA cm-2. This work offers great opportunity to design advanced ORR catalysts with high density and maximum utilization of active sites.