Number Of Potential Cycles Research Articles

Preparation and electrochemical behaviour of conducting films of poly(naphthidine) on platinum electrodes

Poly (naphthidine) (PNAP) film was obtained from the electrooxidation of the corresponding monomer on platinum electrodes in NaClO4—acetonitrile solution. The best film was obtained by potential cycling between 0.0 and 1.14 V vs sce. Its thickness was controlled by the number of potential cycles. The film thus obtained is homogeneous, very adherent and stable in the presence of air and different solvents. Pt—PNAP has electrochemical response (E0f = 0.975 V) and can be repeatedly cycled in supporting electrolyte—solvent solution with no decomposition. It also shows electrochromic properties being yellow in the reduced state and blue in the oxidized one. The film became electroinactive when cycled in the presence of a non-nucleophilic proton acceptor such as DMSO, suggesting that a reaction of elimination/addition of protons is associated to the redox process. The voltammetric responses show large capacitive currents associated with the faradaic process. They have been interpreted according to the model recently proposed by Feldberg for this type of phenomenon.

Electrochemistry of Conductive Polymers: II . Electrochemical Studies on Growth Properties of Polyaniline

Details of the growth properties of polyaniline (PA) have been studied employing electrochemical techniques (potential cycling method) and the results are reported. The electrochemical growth may be characterized as autocatalytic, and the growth rate is first order in aniline concentration. The growth rate is also dependent on the amount of PA film on the electrode as well as the number of potential cycles. The highest oxidized PA, attacked by an aniline molecule, grows to a longer chain, and a net reduction of the PA film upon aniline addition would render the film conducting. This mechanism explains why the film continues to grow at potentials where only passivating behavior would be predicted. In addition, the growth was divided into regions of well‐defined and poorly defined (amorphous) phases; at longer oxidation times during growth, side reactions seem to play more important roles compared to the earlier phase of the growth process.

Ellipsometry of silver electrodes in base solutions under different potential controlled perturbation conditions

The ellipsometric and reflectance response at 5461 Å of silver in 0.1 M NaOH at 25°C, is studied in the Ag(0)/Ag(I) potential range when the electrode has been subjected to different complex potentiodynamic perturbations. The optical response depends remarkably on the potential sweep rate, on the accumulated anodic charge and on the number of potential cycles. The data of the complex anodic film can be interpreted in terms of a single film model in two limiting cases defined in terms of the anodic charge involved as thin and thick films, respectively: (i) for thin anodic films ( Q a < 50 mC cm −2) − n f - 1.50 –0.12 i and (ii) for thick anodic films ( Q a > 50 mC cm −2)− n f = 1.50 − 0.22 i. Time dependence of the optical parameters of both reformed silver and anodic films are shown. Optical results correlates with electrochemical data recently reported and are discussed in terms of different degree of hydrations for each type of anodic film.