An amperometric nitrate sensor based on well-aligned cone-shaped polypyrrole-nanorods

Abstract

An amperometric nitrate sensor is developed based on a well-aligned cone-shaped polypyrrole (PPy)-nanorod modified glassy carbon (GC) electrode, in which the three-dimensional interconnected porous PPy-nanorod matrix is electrochemically polymerized onto the GC substrate. The electrochemical reduction peak of PPy is employed to quantify nitrate, since the electrochemical redox process of PPy is accompanied by the doping/de-doping of nitrate. The influences of several experimental parameters on the electrochemical response to nitrate detection, including the pH value of the electropolymerization electrolyte, the potential and time of polymerization, the accumulation potential and duration, are thoroughly investigated. The optimal experimental parameters are then verified. Under the optimized conditions, a linear range from 1.0 × 10⁻⁴ to 5.0 × 10⁻³ mol L⁻¹ and a detection limit of 5.0 × 10⁻⁵ mol L⁻¹ (signal to noise ratio = S/N = 3) are estimated. The corresponding nitrate sensor shows good stability and satisfactory resistance to the interferences of some cations and anions.