Synthesis of nano-Fe3O4-loaded tubular carbon nanofibers and their application as negative electrodes for Fe/air batteries

► Nano-Fe3O4-loaded tubular carbon nanofibers (TCNFs) were synthesized by a high-temperature solution-phase reaction. ► The nano-Fe3O4/TCNFs were applied as the active material of negative electrodes for Fe/air batteries. ► With K2S as an electrolyte additive, a high specific capacity of 786 mAh g−1 and good cycling efficiency were obtained. ► The downsizing of the conductive Fe3O4 nanoparticles was considered to have contributed to the good electrochemical properties of the material.