Cu₂O/MXene/rGO Ternary Nanocomposites as Sensing Electrodes for Nonenzymatic Glucose Sensors

Fine-tuning of the morphology from two-dimensional (2D) to three-dimensional (3D) nanostructures by structural engineering leads to improved biosensing. Herein, a 3D assembly of MXene and rGO nanosheets was synthesized by a hydrothermal process, and then, a naturally abundant and promising biosensing catalyst of Cu₂O was added by a coprecipitation method to prepare a 3D ternary composite (MXene graphene aerogel–Cu₂O composite). The prepared ternary nanocomposite was characterized by X-ray diffraction, field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and Brunauer–Emmett–Teller (BET). It exhibited a low crystallite size, spherical-shaped Cu₂O, and a large surface area with a porous structure. Further, a sensing electrode was fabricated by the drop-casting method, and then, a chronoamperometric (CA) study was performed to understand the sensing performance of the 3D ternary composite. The fabricated electrode showed sensitivities of 264.52 and 137.95 μA cm^–2 mM^–1 compared to 2D composites (126.6 μA cm^–2 mM^–1) with two wide linear ranges of 0.1–14 and 15–40 mM, respectively. The electrode also gave a low detection limit and good stability, selectivity, and reproducibility, thus making it suitable for the determination of glucose levels in human serum samples. These findings reveal that the 3D network of MXene and rGO nanosheets assists in effective charge transfer and promotes the sensing activity of nonenzymatic glucose sensors.