MOF-derived three-dimensional ordered porous carbon nanomaterial for efficient alkaline zinc-air batteries

The design and preparation of non-noble metal catalysts with high catalytic activity and robust stability are important in the research of metal-air batteries and fuel cells. Here, a three-dimensional (3D) hierarchically ordered porous carbon nanomaterial was conveniently synthesized with zeolite-imidazole framework (ZIF-8) carbonization using the silica-template method and carbon nanotube (CNT) growth. The addition of an iron source endows the porous mFeNC-CNT with Fe-based nanoparticles and abundant atomically dispersive Fe-Nx sites from its nitrogen-incorporated graphitic carbon matrix. As a result, the 3D porous structure reduces the charge transport resistance, and the iron and nitrogen codoped carbon exhibits excellent catalytic activity for oxygen reduction reaction (ORR) similar to that of commercial Pt/C. Meanwhile, the interwoven CNTs obtained under urea catalysis further shorten the ion and electron diffusion pathway. Experimental and theoretical analyses revealed that the optimized mFeNC-CNT has a high ORR activity with a half-wave potential of 0.908 V and a large open-circuit voltage (1.556 V) when applied on zinc-air batteries. This work provides a promising strategy for the rational design and facile synthesis of high-performing non-noble metal-based electrocatalysts for energy storage, conversion, and transport applications.