Synergistic Role of Morphology and Vacancy Engineering in TiO2 forNon-enzymatic Glucose Sensing

Highly sensitive non-enzymatic glucose sensing is crucial for the clinical diagnosis of diabetes. In the present work, we report an electrochemical approach for the sensing of glucose using glycerol-modified TiO2 samples. Glycerol-treated (G2) and untreated (G1) TiO2 samples were prepared using a solvothermal method, with an aim to investigate the results of surface modification and vacancy engineering on glucose sensing. HRSEM images show that the morphology of TiO2 changes from spherical particles (G1) to nanorods (G2), which is responsible for the enhanced charge transport and charge transfer along and across the length of the rods, respectively. The X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) reveal a reduction in crystallite size and an increase in the surface hydroxyl groups in G2 as compared to G1. These result in more active sites in G2 caused by the synergetic role of oxygen defects and surface hydroxyl groups, which, in turn, facilitate faster interaction with the glucose molecules. Further, the electrochemical measurements, including Cyclic voltammetry, Electrochemical Impedance Spectroscopy (EIS), Nyquist plot, and Mott-Schottky measurements, show that G2 exhibited higher peak current responses, lower charge transfer resistance, and good linearity across varying scan rates and lower flat band potential. This work illustrates that the defect-engineered TiO2 can serve as an efficient, stable, and cost-effective non-enzymatic glucose sensor.