A novel synthesis of inorganic–organic nanohybrid based on SiW11Co@Cu–BTC/MWCNTs-COOH for electrocatalytic oxidation of dopamine

Abstract

Polyoxometalate (POM)-based inorganic–organic hybrid compounds exhibit a remarkable range of properties. These compounds are distinguished by their strong acidity, oxygen-rich surfaces, and excellent redox capabilities. Importantly, they do not share the typical limitations of POMs, such as low specific surface area and instability in aqueous solutions. In this paper, we present the design of a novel modified glassy carbon electrode (GCE) using a tri-component nanocomposite consisting of SiW₁₁O₃₉Co(H₂O) (SiW₁₁Co), Cu–BTC (BTC is benzene-1,3,5-tricarboxylate), and carboxyl functionalized multi-walled carbon nanotubes (MWCNTs-COOH) fabricated through a drop-casting method followed by electrodeposition reduction. The resulting hybrid nanocomposite (SiW₁₁Co@Cu–BTC/MWCNTs-COOH) was characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Additionally, elemental composition was analyzed via inductively coupled plasma-optical emission spectrometry (ICP-OES), while surface area and pore volume distribution were measured using Brunauer–Emmett–Teller (BET) analysis. The morphology, electrochemical properties, and electrocatalytic activity of the SiW₁₁Co@Cu–BTC/MWCNTs-COOH/GCE were evaluated through field emission scanning electron microscopy/energy-dispersive X-ray analysis (FE-SEM/EDX), voltammetry, and amperometry techniques. Under optimized conditions, the sensor exhibited outstanding electrocatalytic activity toward dopamine (DA), achieving two linear detection ranges of 5–80 μM and 80–600 μM, with a limit of detection (LOD) of 2.35 μM (S/N = 3) using square wave voltammetry (SWV). Furthermore, the sensor exhibited high repeatability and reproducibility, ensuring consistent performance across multiple measurements. It also showed robust stability and outstanding selectivity. The sensor's analytical performance was further validated by its successful application to real samples.