Facile Synthesis of Bimetallic Fluoride Heterojunctions on Defect-Enriched Porous Carbon Nanofibers for Efficient ORR Catalysts.

The development of efficient and stable catalysts for the oxygen reduction reaction (ORR) at low cost is crucial for realizing the large-scale application of metal-air batteries. Herein, we report an efficient ORR catalyst of bimetallic copper and cobalt fluoride heterojunctions, which are uniformly dispersed in nitrogen-fluorine-oxygen triply doped porous carbon nanofibers (PCNFs) that contain hierarchical macro-meso-micro pores. The composite catalyst materials are fabricated with a facile and green method of electrospinning with water as the solvent. By using poly(tetrafluoroethylene) as the pore inducer to anchor electropositive copper and cobalt salts in the electrospun hybrid nanofibers, bimetallic fluoride heterojunctions can be directly formed in PCNFs after calcination. The hierachical porous structures provide an effective way to transport matter, while the bimetallic fluorides expose abundant electroactive sites, both of which result in stable ORR activities with a high half-wave potential of 0.84 V. The study proposes a feasible strategy for the fabrication of nonprecious catalysts.