Nucleation, Growth and Electrochemical Performances of Polyaniline Electrodeposited on ITO Substrate

In the first part of the present work, we determined for the first time the electrodeposition mechanism of a polyaniline film on the ITO (Indium tin oxide) substrate in an acidic medium (HNO 3 1 M ) using chronoamperometry. The analysis of the ascending parts and maxima of the current density-time transients and the images obtained by the SEM technique, allowed us to deduce that the polyaniline electrodeposition follows the mechanism of progressive 3D nucleation and growth. In the second part, we have studied, by cyclic voltammetry and galvanostatic charge-discharge, the effect of electropolymerization potential (0.8, 0.9, 1.0, 1.1 and 1.2 V) on the specific capacitance of the films. Cyclic voltammetry shows that the specific capacitance increases from 4.28 mF cm −2 (deposition potential 0.8 V/SCE) to 43.12 mF cm −2 (potential 1.2 V/SCE) for a scan rate of 5 mV/s. The specific capacitance decreases sharply with the scan rate for the deposition potentials 1.0, 1.1 and 1.2 V/SCE, whereas it remains almost constant for the films obtained at 0.8 and 0.9 V/SCE. A similar behaviour was obtained by galvanostatic charge-discharge: the specific capacitance increases from 4.14mF cm −2 (0.8 V/SCE) to 60.60 mF cm −2 (1.2 V/SCE) for the discharge current density 0.1 mA cm −2 .