Graphitic carbon-encapsulated cobalt nanoparticles embedded 1D porous hollow carbon nanofibers as advanced multifunctional electrocatalysts for overall water splitting and Zn-air batteries

Physical mixing of monofunctional noble metal catalysts, such as Pt/C or Ru/IrO2, increases the commercial cost and stability risk of electrodes. Therefore, it is desirable to develop a multifunctional electrocatalyst for zinc-air batteries and integrated electrolytic devices. To develop an effective way to fabricate high-performance multifunctional electrocatalysts by modifying advanced nanostructures, a coaxial electrospinning approach with in-situ synthesis and subsequent carbonization was used to construct a highly integrated threefunction catalyst composed of graphitic carbon-encapsulated cobalt nanoparticles embedded into one-dimensional (1D) porous hollow carbon nanofibers (CoNC-HCNFs). Under the synergistic effect of the active material and the advanced nanostructure, the asprepared CoNC-HCNFs demonstrated an operating overpotential of 186 mV (10 mA cm-2) for the hydrogen evolution reaction (HER), a half-wave potential of 0.83 V (vs. RHE at 10 mA cm-2) for the oxygen reduction reaction (ORR), and a potential of 1.58 V (10 mA cm-2) for the oxygen evolution reaction (OER). With their exceptional multifunctional activities, two CoNC-HCNF-based aqueous zinc-air batteries (ZABs) in series could drive an alkaline water electrolyzer for splitting water. Furthermore, due to the superior mechanical flexibility and rechargeability of the solid-state ZAB, it has great application prospects in powering portable and wearable electronics. This research is expected to offer inspiration for the development of other excellent MOF-based hollow carbon nanofibers and to enable them to be adopted more widely in electrochemical energy conversion and energy storage. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.