Electrochemically grown vertically aligned titanium dioxide nanotubes for photoelectrochemical self-powered glucose sensing applications

One-dimensional (1D) TiO₂ nanostructures such as nanorods, nanowires, and nanotubes (NTs) are attractive for applications in solar cells, photocatalytic solar energy conversion, photoelectrochemical cells, gas sensors, and biomedical sensors due to their high surface-to-volume ratio, fast charge carrier transport, high catalytic activity, and superior chemical stability. In this study, highly ordered, vertically aligned TiO₂ NTs were fabricated by two-electrode electrochemical anodization of titanium foils. The surface morphology, crystal structure, and chemical bonding of the NTs were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy measurements. Non-enzymatic glucose sensing properties of NTs have been investigated using cyclic voltammetry (CV), amperometric measurements, and electrochemical impedance spectroscopy. TiO₂ NTs demonstrated sensitivity of 81.56 µA mM⁻¹ cm⁻² in the linear detection range 0.005–3.325 mM with a detection limit of 71.5 nM. The sensor exhibited excellent selectivity towards glucose in the presence of common interfering substances such as ascorbic acid, uric acid, urea, dopamine, and K⁺, Na⁺, Mg²⁺, and Cl⁻ ions. Furthermore, self-powered glucose-sensing performance of the NTs was evaluated under light and dark conditions without any external bias. The sensor achieved a self-powered glucose sensitivity of 7.749 µA mM⁻¹ cm⁻². The fabricated sensor also successfully demonstrated non-enzymatic detection of salivary glucose, achieving a sensitivity of 0.0963 µA cm⁻² μM⁻¹.