Ketjen black/Co3O4 nanocomposite prepared using polydopamine pre-coating layer as a reaction agent: Effective catalyst for air electrodes of Li/air batteries

•A Ketjen black/Co3O4 nanocomposite was fabricated for use in an enhanced air electrode.•Polydopamine layer was used as a coating on Ketjen black to act as a reaction agent.•It was effective for ensuring homogeneous reaction and distribution of the catalyst.•The composite electrode exhibited a low over-potential and excellent capacity. A Ketjen black/Co3O4 catalyst nanocomposite was fabricated for use in an enhanced air electrode for Li/air batteries. Polydopamine was used as a coating on Ketjen black to act as a reaction agent, for ensuring homogeneous reaction and adequate distribution of the catalyst nanoparticles on the surface. The results of various characterization analyses indicated successful immobilization of Co3O4 via the polydopamine layer. An electrode prepared using the polydopamine-assisted Ketjen black/Co3O4 nanocomposite exhibited a low overpotential and excellent capacity and cyclic performance, demonstrating the suitability of this novel nanocomposite for use in the air electrode of a Li/air cell.