Co9S8 nanoparticles embedded in multiple doped and electrospun hollow carbon nanofibers as bifunctional oxygen electrocatalysts for rechargeable zinc-air battery

The development of low-cost electrocatalysts with highly efficient catalytic activity and strong durability toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for rechargeable zinc-air battery. In this work, Co9S8 nanoparticles embedded in N/S dual-doped hollow and porous carbon nanofibers (Co9S8-NSHPCNF) are prepared via the continuous coaxial electrospinning technology followed by pre-oxidation and carbonization treatment. Attributed to synergistic effects between the Co9S8 nanoparticles and NSHPCNF, higher specific surface area, hollow and porous structure, the doping of N and S and better electrical conductivity, the Co9S8-NSHPCNF bifunctional catalysts exhibit preferable performance toward ORR (E-1/2 = 0.82 V) and OER (E-j - 10 ma(-2) = 1.58 V) compared to precious metal-based catalysts. In addition, when being used as a cathode catalyst in liquid zinc-air battery, Co9S8-NSHPCNF displays excellent durability. An all solid-state zinc-air battery with Co9S8-NSHPCNF is also fabricated and presents superb charge and discharge cycling performance.