Monometallic Co@N-doped carbon nanotubes derived from zeolitic imidazolate framework as oxygen reduction reaction catalyst for metal-air battery

The transition metal nitrogen-doped carbon-based materials (M-N-C) catalysts are promising alternatives to noble metal-based oxygen reduction catalysts in metal-air batteries due to their high catalytic activity and low-cost. However, the M-N-C catalyst derived from a single zeolitic imidazolate precursor often suffers from poor electrical conductivity, insufficient mesoporosity and low nitrogen content. In this study, we develop high-performance monometallic Co@N-doped carbon nanotubes as oxygen reduction reaction (ORR) catalyst by pyrolyzing ZIF-8@ZIF-67 and melamine. The Co@NC-1 catalyst is characterized by unique architecture, abundant porosity, excellent electrical conductivity and high cobalt content (20.335 %). The optimized Co@NC-1 catalyst exhibits exceptional ORR performance with a positive half-wave potential of 0.85 V and superior kinetic current density comparing to the commercial Pt/C catalyst. The primary zinc-air battery equipped with Co@NC-1 deliver outstanding energy and power densities of 928 Wh kg −1 (Zn-based) and 202 mW cm −2 , respectively. The electrochemical performance of zinc-air and magnesium-air batteries gives strong evidence of the feasibility of monometallic Co@N-doped carbon nanotubes in metal-air batteries.