Study by EQCM on the voltammetric electrogeneration of poly(neutral red).: The effect of the pH and the nature of cations and anions on the electrochemistry of the films

Generation of poly(neutral red) films has been studied by means of the simultaneous measurements of current-potential and mass-potential curves during cyclic voltammetry (CV) experiments. It has been proved that the presence of molecular oxygen in the solution increases the amount of polymer deposited on the electrode. Otherwise, using the mass/charge ratio it is possible to obtain quantitative information about the electrodeposition by different procedures. It is observed that this ratio decreases when the amount of polymer electrogenerated increases, except when the polymer is not reduced and oxidised after its electrogeneration. The study of poly(neutral red) by CV and quartz crystal microbalance in solutions without monomer allows to discern between the role of different charged species which are present in the solution: salt cations (Cs+, Na+ and K+), salt anions (NO3-, Cl-, I- and Br-) and hydrated protons that can compensate electrical charge within the film during electrochemical processes. (C) 2003 Elsevier Ltd. All rights reserved.