Three-Dimensional Macroporous Co-Embedded N-Doped Carbon Interweaving with Carbon Nanotubes as Excellent Bifunctional...

Highly efficient noble metal-free bifunctional catalysts for expediting the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in metal-air batteries or fuel cells are still challenging and imperative. In this work, we report a facile and scalable method for syntheizing three-dimensional (3D) macroporous Co-embedded N-doped carbon interconnecting with in situ growth carbon nanotubes (CNTs). The as-synthesized material exhibits great electrocatalytic performance for ORR with an onset potential of 0.901 V vs RHE as well as a high limited current density of 4.83 mA/cm² in an alkaline electrolyte under a rotation speed of 1600 rpm at 5 mV/s. Furthermore, this 3D porous carbon also shows good electrocatalytic performance for OER in an alkaline electrolyte. This high electrocatalytic performance is mainly attributed to its large specific surface area and highly conductive CNTs and the synergistic effect between Co-active species and the carbon framework. The result of a two-electrode Zn-air battery based on this carbon material achieves a peak density of 163 mW/cm² at a voltage of 0.63 V, indicating the great potential of the catalyst for battery application.