Layer-by-layer self-assembly of copper oxide/graphene nanocomposites immobilized modified electrode for L-vanillin determination

Abstract

In this study, a straightforward layer-by-layer self-assembled method was utilized to fabricate well-aligned copper oxide sandwiched graphene nanocomposite (CuOSG-NC) stacks through electrostatic attraction. The successful formation of densely packed CuOSG-NC structure was confirmed by field emission scanning electron microscopy and X-ray diffraction analysis. A simple, sensitive electrochemical approach was developed for the detection of L-vanillin, a widely used food preservative and potent antimicrobial agent, employing a CuOSG-NC modified graphite electrode. Cyclic voltammetry revealed that the CuOSG-NC modified electrode demonstrated outstanding electrocatalytic activity for the L-vanillin oxidation in 0.1 M NaOH electrolyte. Under optimal conditions, the oxidation peak current showed linearity with the vanillin concentration ranging from 3.3 × 10⁻⁶ to 1.7 × 10⁻³ M, achieving a limit of detection 1.1 × 10⁻⁶ M (S/N = 3). The modified electrode for L-vanillin detection provided benefits including simple preparation, high sensitivity, and strong stability. Its practical use as an amperometric sensor for L-vanillin in flow systems was assessed through chronoamperometric analysis. Additionally, the modified electrode was effectively applied to determine vanillin in commercial roasted coffee bean samples, highlighting its potential for real-world applications in food products. Future research could explore the adaptation of this CuOSG-NC based electrochemical sensor for detecting other phenolic compounds or emerging contaminants, broadening its applications in food safety and environmental monitoring.