Pearl Necklace Fibrous Carbon Sharing Fe-N/Fe-P Dual Active Sites as Efficient Oxygen Reduction Catalyst in Broad Media and for Liquid/Solid-State Rechargeable Zn-Air Battery

Optimized catalysts are attractive from the standpoint of energy storage and conversion. Herein, a pearl necklace fibrous carbon catalyst with Fe-N/Fe-P dual active sites (Fe-P/NHCF) is fabricated via carbonization-phosphidation of metal-organic framework (MOF)/polyacrylonitrile nanofibers. Benefiting from Fe-N/Fe-P doping-induced active sites, accompanied by particular hierarchical porous merit and a 1D necklace network to facilitate the oxygen reduction reaction (ORR), it exhibits a half-wave potential of 0.82 V in alkaline medium and outperforms commercial Pt/C in terms of stability in acid medium. Furthermore, a low voltage gap (1.04 V) is acquired in a liquid Zn-air battery with Fe-P/NHCF as the cathode. Meanwhile, the portable solid-state Zn-air battery displays an open circuit voltage of 1.32 V and a power density of 42 mW cm(-2). This strategy puts forward a protocol to develop tailored geometry with dual active sites for ORR in alkaline/acid media, which is expected to promote devices of practical significance.