Porous coralloid Polyaniline/SnO2-based enzyme-free sensor for sensitive and selective detection of nitrite

A porous coralloid nanocomposite termed as Polyaniline/tin dioxide (PANI/SnO2) is designed based on the p-n junction and prepared by a method of an in-situ chemical polymerization, which is constructed as an enzyme-free sensor for nitrite (NO2-) in aqueous solution. The structure and morphology of the proposed nanocomposite has been characterized by Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), field emission scanning electron microscopic (FE-SEM) and transmission electron microscopy (TEM) respectively, showing it interconnects with coralloid morphology with the size of about 31-46 nm in diameter and 111-200 nm in length. A series of electrochemical studies reveal that the porous coralloid PANI/SnO2 exhibits an excellent electrochemical performance towards the oxidation of NO2- and has acceptable linear response concentration range from 0.12 mu M to 7.8 mM to NO2- oxidation, with lower detection limit of 0.04 mu M (signal-to-noise ratio is 3, S/ N = 3) and higher sensitivity of 121.2 mu A mM(-1)cm(-2). These results imply that PANI/SnO2 may be a potential candidate for developing electrochemical sensors to detect NO2- in aqueous solution.