Surfactant-Assisted Synthesis of Metallic-Ag/Nickel Oxide on Graphitic Carbon Nitride Composite: An Electrochemical Investigation of Synthetic Vanillin

In this study, we developed a sensor based on surfactant-assisted synthesis of metallic silver-enriched nickel oxide confined on graphitic carbon nitride (Ag/NiO/g-CN)-modified electrode to construct a sensitive and selective voltammetric sensor for detecting vanillin in confectionaries samples. The X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy analyses confirmed the crystal structure and respective functional groups of the synthesized Ag/NiO/g-CN composite. The valence states of silver, nickel, oxygen, carbon, and nitrogen were analyzed using X-ray photoelectron spectroscopy (XPS), while energy-dispersive X-ray analysis (EDX) and morphological investigations revealed the elemental distribution and nano-structured particles, respectively. The electrocatalyst-modified electrode properties and electrochemical sensing performances were evaluated using different voltammetric and spectroscopic techniques. The Ag/NiO/g-CN composite, exhibiting a large active surface area, excellent conductivity, and synergistic interaction, proved to be a suitable electrode material for electrochemical sensor applications. The sensor demonstrated a detection limit of 0.9 nM and a broad linear range of 0.004–366.8 μM. Electrochemical investigations further highlighted the sensor’s excellent reproducibility, repeatability, fast response, and functional stability. The constructed sensor also exhibited outstanding selectivity against potential interferents and demonstrated its practical applicability by successfully detecting vanillin in spiked food samples.