Co single-atom catalysts for the electrochemical detection of nitrite in real samples

A dodecahedral single-atom cobalt catalysts with nitrogen-doped carbon matrices (Co-N-C) is synthesized by calcining MOFs precursors (ZIF-67), which is constructed as non-enzymatic sensor for the sensitive detection of nitrite (NO 2 − ). The characterization of the Co-N-C catalysts has been performed by X-ray powder diffraction (XRD), transmission electron microscopic (TEM) and scanning electron microscopy (SEM). The outcome shows that Co-N-C is a dodecahedron with a rough surface and a diameter of about 200–280 nm. The electrochemical measurements demonstrate that the Co-N-C/GCE sensor displays a favourable voltammetric response towards the oxidation of NO 2 − with a wide linear range from 0.1278 mM to 42.7778 mM. It also displays a low detection limit of 0.0426 mM (S/N = 3) and high sensitivity of 715.32 μA mM −1 cm −2 and 305.37 μA mM −1 cm −2 . Moreover, determinations of NO 2 − in tap water and pickle juice samples are performed respectively by the standard addition method. The results of three parallel measurements are acceptable with the relative standard deviation of 0.36–1.30 % and the recovery of 95.60–101.80 %. Therefore, Co-N-C/GCE is expected to be a new platform for NO 2 − detection.