In situ decorated 2D vanadium disulphide on optimized reduced graphene oxide-based interface for highly sensitive nonenzymatic glutamate detection

Abstract

2D layered transition metal dichalcogenides (TMDs) possess eccentric nanostructures, large surface areas, and unique semiconducting properties, making them exceptional for non-enzymatic applications compared to metal oxides. However, TMDs like vanadium disulfide (VS2), with peroxidase-like nanozymatic characteristics, suffer from limited electronic conductivity, restricting their use as electrochemical (EC) sensors. To address this, reduced graphene oxide (rGO) is introduced to enhance electronic conductivity and leverage the enzyme-like property of VS2. This study introduces a novel enzyme-free EC sensor, rGO/VS2 nanocomposite-based, for accurate and efficient glutamate (Glut) detection. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated that rGO/VS2 electrodes with varying rGO to VS2 composition ratios exhibit superior EC properties compared to pure VS2 electrodes. The EC response of the rGO/VS2 modified electrode towards Glut was investigated using CV and differential pulse voltammetry (DPV). The fabricated electrode displayed a linear relationship with Glut concentration (4–300 μM) (normal levels 30–80 μM), boasting a low limit of detection (LOD) (0.056 μM) and higher sensitivity (0.797 μA/(mM·cm2)) compared to existing non-enzymatic Glut sensors. Structural and morphological characterizations employed Raman spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and energy-dispersive X-ray spectroscopy (EDX). Furthermore, the proposed electrode's electroanalytical activity was assessed in spiked real samples, establishing its reliability and precision in Glut detection. The developed rGO/VS2-based EC sensor holds practical utility in biomedical research, clinical diagnostics, and environmental monitoring, where Glut detection is essential.