Co−Fe‐based Heterometallo‐Supramolecular Polymer for Non‐Enzymatic Electrochemical Nitrite Detection and the Study of Electron Transfer Kinetics

A Co and Fe-based Heterometallo-supramolecular polymer is utilized as the sensing layer for the selective oxidation of nitrite. The kinetics of the irreversible electro-oxidation mechanism are also investigated through the employment of cyclic voltammetry and amperometric techniques. The studies for stability and reproducibility make polyCoFe a promising electrocatalyst with long-term stability and reproducibility.

Abstract

Here, we report the fabrication of Heterometallo-supramolecular polymer (H-SMP) for the selective oxidation of nitrite with the investigation of some kinetic parameters by the complex formation of Co(II) and Fe(II) salts with the symmetrical ligand which is composed of terpyridine moieties specially referred to as [4′,4′′′′-(1,4-Phenylene)bis(2,2′:6′,2′′-terpyridine)] to form polyCoFe. The characterization of polyCoFe was carried out using UV-Vis titration, FT-IR and SEM. The viscosity measurement of H-SMP was utilized to calculate its molecular weight using Mark-Houwink-Sakurada equation. The electrochemical performance of polyCoFe_GCE was evaluated using the CV and EIS techniques. The kinetics of the irreversible electro-oxidation mechanism were investigated by introducing variations in scan-rate and pH. The concurrence observed between the experimental and simulated CV results provided additional evidence supporting the accuracy and reliability of the determined kinetic parameters. We investigated the efficiency of polyCoFe_GCE for nitrite detection at various concentrations using CV as well as amperometry methods. The amperometric technique showed a wide linear range of 0.66 to 194.15 μM and a low detection limit of 0.11 μM. In addition, modified electrode underwent interference, stability, and reproducibility tests. Real samples were analyzed using both CV and amperometry methods, and the obtained results were compared with those obtained from standard solutions.

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