Au-Co nanoparticles-embedded N-doped carbon nanotube hollow polyhedron modified electrode for electrochemical determination of quercetin.

A core-shell ZIF-8@ZIF-67 was synthesized and pyrolyzed to get a Co nanoparticles-embedded N-doped carbon nanotube hollow polyhedron (Co@NCNHP). Then Au nanoparticles were formed on the surface and core of Co@NCNHP to obtain an Au-Co bimetal decorated NCNHP (Au-Co@NCNHP). The resultant nanocomposite was characterized by various methods including transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The Au-Co@NCNHP-based electrochemical sensor displayed an obviously high electrocatalytic response to the oxidation of quercetin, which was attributed to the synergistic effects of Au-Co bimetal nanoparticles and N-doped carbon nanotube with hollow polyhedron. Under the optimal conditions, the oxidation peak currents exhibited a wide linear dynamic range for quercetin concentration from 0.050 to 35.00 μmol/L, and the detection limit was 0.023 ± 0.002 μmol/L (S/N = 3). The analytical applications of the proposed electrochemical sensor were checked by determining the content of quercetin in medical and onion samples with satisfactory results. Grapical abstract.