Ternary nanocomposite based poly(pyrrole-co-O-toluidine), cobalt ferrite and decorated chitosan as a selective Co2+ cationic sensor

Abstract Nanostructured ternary nanocomposites (NCs) composed of a Poly(Pyrrole-co-O-Toluidine) matrix (P(Py-co-OT)), CoFe2O4 (CF) nanoparticles (NPs), and chitosan (CS) were prepared by an in situ chemical oxidation technique. The P(Py-co-OT)/CF/CS NCs were used to fabricate an electrochemical sensor for Co2+ ion detection. The CF NPs are uniformly coated with CS and P(Py-co-OT) layers. Different techniques, including FTIR, XRD, SEM, EDX, MAP, TEM, TGA, DTG, and DTA, and four point probe resistivity and sensing measurements were used to analyse the electrical, thermal, structural and electrochemical properties of the NCs. An electrode comprising the core/shell ternary NCs has a higher sensitivity compared to sensors composed of either P(Py-co-OT), binary P(Py-co-OT)/CF NCs or CF NPs. A sensor that was composed of the a core-shell P(Py-co-OT)/CF/CS NCs-modified glassy carbon electrode (GCE) was fabricated using Nafion (a 5% ethanolic suspension of Nafion) as a binder, and the sensor exhibited a limit of detection and sensitivity of 94.67 ± 4.73 pM and 16.2848 μAμM-cm−2, respectively. It was shown that the presence of P(Py-co-OT) increased the electronic interactions between the NPs and P(Py-co-OT) matrices. The excellent limit of detection, sensitivity and electronic interaction make the P(Py-co-OT)/CF/CS NCs a potential Co2+ ion sensor. The Co2+ sensor exhibited a response towards Co2+ that was linear for concentrations of 0.1 nM–0.1 mM. The proposed Co2+ ion sensor has performances that are satisfactorily reproducible and have good response times.