Electrochemical nanosensor based on Ag-doped TiO2 nanotubes for detecting ascorbic acid

Abstract

This work describes the development of an electrochemical nanosensor for the quantitative determination of ascorbic acid (AA). The transducer and receptor system of the nanosensor is based on a silver-doped titanium oxide nanotube (Ag-TiO2NTs) electrode synthesized by a one-step electrochemical anodization method followed by an annealing treatment. The synthesis was carried out at a constant potential of 30 V for 45 min in an organic electrolyte in the presence of F- ions and the dopant. The obtained structure was then subjected to morphological and compositional analysis. In addition, its analytical response to ascorbic acid was evaluated. The analytical techniques employed included scanning electron microscopy (SEM), X-ray diffraction (DRX), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results demonstrate the growth of a highly ordered nanotube array with average dimensions of 80 nm, 19 nm and 1660 nm for diameter, wall thickness and length, respectively, and suggest a major composition of silver-doped titanium oxide. The synthesized Ag-TiO2NTs successfully recorded electroanalytical activity for ascorbic acid, with a non-reversible, diffusion-controlled, and mostly capacitive electrochemical profile. It showed low resistance to change transfer and registered a sensitivity of 216.24μA/(mM∙cm2) and a detection limit of 11.1 μM in a linear range of 840–4000 μΜ. The sensor demonstrated repeatability and reproducibility with RSD values of 5.5% and 2.8%, respectively. In addition, it showed selectivity for AA in the presence of glucose at AA/GLU values (1:1, 1:10 and 1:100).