Electrochemical determination of dopamine using a conductive polypyrrole/carbon-coated mesoporous silica composite electrode

Mesoporous silica (SiO2) nanoparticles were prepared using the cationic surfactant cetyltrimethylammonium bromide as a soft template in a basic medium. The particles were coated with a carbon layer through a facile hydrothermal process. The carbon-coated mesoporous SiO2 (C#SiO2) nanoparticles were used as core for the in situ chemical-oxidative polymerization of conductive polypyrrole (PPy). The structure and morphology of the PPy/C#SiO2 nanocomposites were analyzed by transmission electron microscopy, wide-angle X-ray diffraction, and Fourier transform infrared spectroscopy. A glassy carbon electrode was modified with the PPy/C#SiO2 nanocomposites. The performance of the modified electrode for the dopamine (DA) detection was examined by cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. The modified PPy/C#SiO2 glassy carbon electrode exhibit large peak currents for the DA oxidation reaction, suggesting the electrochemical performance of the nanocomposites is enhanced. The impedance evaluation of the fabricated PPy/C#SiO2 nanocomposites reveals a very small charge-transfer resistance. Additionally, the nanocomposites showed a linear response for DA detection in the concentration range of 1 × 10−6 to 2 × 10−4 M with a detection limit of 7.6 × 10−7 M (S/N = 3). Moreover, DA detection was successful in the presence of uric acid and L-ascorbic acid. Due to their outstanding electrochemical performance, the PPy/C#SiO2 nanocomposites may be considered for the DA detection devices