Amperometric nitrogen dioxide gas sensor based on PAn/Au/Nafion® prepared by constant current and cyclic voltammetry methods

Polyaniline (PAn) was electro-deposited on Au/Nation(R) by the cyclic voltammetry (CV) and constant current (CC) methods, respectively. The electrochemical properties and surface morphologies of PAn/Au/Nafion(R) were characterized by SEM, cyclic voltammetry, and ac impedance, respectively. The maximum BET surface area was found to be 10.36 m(2) g(-1) for PAn/Au/Nation(R) prepared by CV method with cycle number of 25 in 1.0 M HClO4 aqueous solution. Using PAn/Au/Nafion(R) prepared by CV method in 1.0 M HClO4, 1.0 M HCl, and 0.5 M H2SO4 aqueous solutions as working electrodes, the sensitivities of NO2 gas sensors with a gas flow rate of 300 ml min(-1) were evaluated to be 3.04, 2.68, and 2.54 muA ppm(-1), respectively. Using PAn/Au/Nafion(R) prepared with CC method to fabricate NO2 gas sensor, the sensitivity decreased from 2.35 to 1.41 muA ppm(-1) when the current density for preparing PAn/Au/Nation(R) increased from I to 10 mA cm(-2) (C) 2004 Elsevier B.V. All rights reserved.