Electrochemical sensor based on conductive polyaniline coated hollow tin oxide nanoparticles and nitrogen doped graphene quantum dots for sensitively detecting dopamine

The hollow tin(IV) oxide (SnO₂) nanoparticles prepared using a simple hydrothermal synthesis were served as a core for the fabrication of SnO₂/polyaniline (PANI) nanocomposites using in situ chemical oxidative polymerization. The chemical and structure of the nanocomposites were characterized using Fourier transform infrared, X-ray diffraction, and transmission electron microscopy. The nanocomposites were then coated with nitrogen doped graphene quantum dots (N-GQDs) obtained by hydrothermal synthesis through electrostatic interaction. The catalytic behavior of nanocomposites modified glass carbon electrode towards dopamine (DA) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry and differential pulse voltammetry. The EIS test for prepared SnO₂/PANI/N-GQD nanocomposites shows the very low charge-transfer resistance. The electrochemical performance of SnO₂/PANI/N-GQD nanocomposites present the large peak currents, indicating the nanocomposites reveal better electrochemical activity of the presence of N-GQD. The SnO₂/PANI/N-GQD nanocomposites contained linear response of detecting DA in the concentration range of 5 × 10⁻⁷–2 × 10⁻⁴ M with detection limit 2.2 × 10⁻⁷ M (S/N = 3). The fabricated nanocomposites also show excellent determination of DA at the presence of a mixture of l-ascorbic acid and uric acid. Because of the excellent electrochemical performance obtained in this report, we believe that the SnO₂/PANI/N-GQD nanocomposites will be a promising biosensor material for the detection of dopamine.