Glucose sensing via green synthesis of NiO–SiO₂ composites with citrus lemon peel extract

In this study, NiO–SiO₂-based composites were synthesized through low-temperature aqueous chemical growth utilizing a facile, low-cost, and environmentally friendly approach. The composite systems were prepared using a combination of silica gel and citrus lemon peel extract. Due to the remarkable green chemicals in orange peel extract, porous nanostructures have been developed with thin sheet-like properties. The composite materials were examined in terms of their crystalline structure, morphology, optical band gap, and surface chemical composition. An advanced non-enzymatic glucose sensor developed from NiO–SiO₂ composites exhibits rich surface oxygen vacancies and abundant catalytic sites. Based on sample 2, cyclic voltammetry revealed a linear glucose concentration range between 0.1 and 20 mM, chronoamperometry exhibited glucose concentration ranges between 0.1 and 14 mM, and linear sweep voltammetry revealed glucose concentration ranges from 0.1 to 10 mM. In enzymatic glucose sensors, the minimum level of detection was estimated to be 0.08 mM. A number of sensor characterization parameters were examined, including selectivity, stability, reproducibility, and real-time applications. In addition, electrochemical impedance spectroscopy (EIS) has shown that the NiO–SiO₂ composite performs well in non-enzymatic glucose sensing due to its low charge transfer resistance and high electrochemical active surface area (ECSA). NiO–SiO₂ composites could have significant biomedical, energy conversion, and storage applications based on the results obtained.