A facile controlled synthesis of 3D cobalt nanoparticle-embedded nitrogen-doped carbon materials towards efficient bifunctional electrocatalysts for rechargeable Zn-air batteries

Abstract Rational morphology engineering of bifunctional catalysts for air electrode is desperately urgent for Zn-air batteries (ZABs). This work reports a type of three-dimensional (3D) carbon materials, comprising cobalt nanoparticle-embedded nitrogen-doped carbon nanotubes grown on carbon nanosheets (termed as Co@NC-0.1 ),. The resulting Co@NC-0.1 can synchronously accelerate the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), representing a preponderant universal catalytic activity and outstanding stability in alkaline electrolyte. Such a remarkable performance is mainly credited to considerable specific surface area, high pore volume, well-dispersed copious active sites (especially efficient Co-Nx moieties) and the synergy of a close contact between cobalt nanoparticles and carbon frameworks. Accordingly, a Co@NC-0.1 driven liquid rechargeable ZAB can achieve well-qualified assembly, including a confined discharge–charge voltage gap of 0.85 V at 20 mA cm−2 and well-maintained cycling stability beyond 200 h. More attractively, Co@NC-0.1 is also utilized as a cathode catalyst for button-type and flexible rechargeable ZABs, which performs respectable performances. Undoubtedly, this finding provides a simple tactic for allowing one to construct advanced 3D bifunctional catalyst toward affordable catalysis and future energy conversion technologies.