Fe3C/Nitrogen-Doped Carbon Nanofibers as Highly Efficient Biocatalyst with Oxidase-Mimicking Activity for Colorimetric Sensing

The synthesis of functional nanomaterials with unique structures and morphologies as efficient biocatalysts for sensing application has attracted tremendous interest. Herein, Fe3C nanoparticles encapsulated within nitrogen-doped carbon (Fe3C/N–C) nanofibers have been prepared through a facile electrospinning strategy and a carbonization process. The resulting Fe3C/N–C hybrid nanofibers display a superior oxidase-like performance toward the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and other substrates, which is dependent on the formation of Fe3C nanoparticles and their crystallinity. The obtained Fe3C/N–C hybrid nanofibers-based oxidase-like catalyst shows a good long-term stability and reusability. Thanks to the unique catalytic activity for oxidase mimicking, an efficient sensing platform to sensitively determine sulfite and l-cysteine with low detection limits of 24.9 and 23.0 nM (S/N = 3), respectively, as well as excellent selectivity and anti-interference ability has been developed. This work demonstrates a versatile approach to fabricate Fe3C/N–C hybrid nanofibers as enzyme mimics with perfect catalytic efficiency, affording a facile and sensitive colorimetric approach for potential applications in biosensing and other biotechnologies.