cobalt nanoparticles embedded in nitrogen-doped carbon nanotubes for efficient catalysis of oxygen reduction reaction

The oxygen reduction reaction (orr) is a key process to limit the property of the metal-air batteries. in this paper, cobalt nanoparticles embedded in nitrogen-doped carbon nanotubes (co-ncnts) were designed and prepared by pyrolysis of co-based metal–organic frameworks and cyanoguanidine under an ar–h2 atmosphere. the relationship between the morphology and electrocatalytic activity toward orr was discussed using a variety of physical characterization and electrochemical methods. the obtained co-ncnt with 3.39 at% nitrogen has a diameter of 30–50 nm. electrochemical activities of these co-ncnts toward orr in koh solution were characterized by cyclic voltammetry and rotating disk electrode (rde) methods. the co-ncnts catalysts were also estimated for their stability and methanol-tolerant performance by chronoamperometry in the presence of oxygen. experimental results display that the onset potential, half-wave potential, tafel slope and the transferred electron number are 0.95 v (vs. rhe), 0.747 v (vs. rhe), 110.6 mv decade−1 and close to 3, respectively. moreover, the optimized co-ncnt has an outstanding durability compared with the commercial pt/c. this work affords a simple approach for exploring low-cost electrocatalysts with practical performance for metal-air batteries.