Carbon-Shielded Three-Dimensional Co–Mn Nanowire Array Anchored on Ni Foam with Dual-Enzyme Mimic Performance for Selective Detection of Ascorbic Acid

Carbon-shielded 3D Co–Mn nanowire array on Ni foam (CoMn NW/NF@C) was successfully prepared by the solvothermal and thermal annealing processes. The CoMn NW/NF@C exhibits peroxidase/catalase dual-mimic activity. As a mimetic of natural enzymes, CoMn NW/NF@C has the following advantages: (1) The uniform arrangement of CoMn NW/NF@C ensures rapid transfer of electrons to the reactants or products and thus increases catalytic activity. (2) Shielding the carbon shell on the surface of CoMn NW reduces the energy barrier during electron transfer and maintains high stability in harsh chemical environments. (3) CoMn NW/NF@C is anchored on 3D NF, forming a bulk catalyst, effectively solving the problem of difficult separation of catalysts from products. Based on its high peroxidase mimetic activity, a rapid and selective colorimetric assay for ascorbic acid (AA) was established, with good linearity in the range of 0.1–1 μM and 1–30 μM and a detection limit as low as 42.8 nM. The method has been successfully applied to detect AA in brain microdialysate during the cerebral calm/ischemia process. The synthesis of CoMn NW/NF@C provides a new way to design nanozymes with excellent catalytic activity, high stability, and easy separation.