The effect of polyaniline morphology on hydroquinone/quinone redox reaction

• Published in: Electrochimica acta Vol. 46; no. 18; pp. 2795 - 2803
• Main Authors: DUIC, Lj, GRIGIC, S
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 31.05.2001; Elsevier
• Subjects: Chemistry; Counter-ion influence; Electrocatalysis; Electrochemistry; Exact sciences and technology; General and physical chemistry; Kinetics and mechanism of reactions; Morphology; Polyaniline; Quinone/hydroquinone; Electrocatalysis; Quinone/hydroquinone; Polyaniline; Counter-ion influence; Morphology; Scanning electron microscopy; Oxidation reduction; Electrolyte solution; Quinone; Transition metal; Experimental study; Acidic solution; Surface structure; Sulfuric acid; Hydrochloric acid; Hydroquinone; Conducting polymers; Redox couple; Medium effect; Platinum; Noble metal; Electrochemical reaction; Aniline polymer; Disk electrode; Modified material
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/S0013-4686(01)00491-1

The catalytic effect of polyaniline (PANI) on the hydroquinone/quinone (H 2Q/Q) redox reaction, has been investigated with respect to different morphologies which are known to depend on the counter-ions during the synthesis. It has been established that PANI lowers the H 2Q/Q reaction potential, as well as the potential difference, ΔE p, obtained by cyclic voltammetry. It is shown that the decrease in ΔE p does not depend on the increase in the thickness of the PANI layer, and there is no difference in the case of PANISO 4 and PANICl electrode. The increase in the I p values in the cyclic voltammograms of PANI, as well as in I lim in rotating disc electrodes (RDE) measurements, compared to Pt-electrodes, is explained by the increase in the real surface area of PANI electrodes, and the difference in PANISO 4 and PANICl by the different morphologies. In general, the redox reaction on PANI electrodes is explained by the specific adsorption of H 2Q molecules onto EM 2+ centres. The inclined current plateau obtained by RDE measurements is explained by the slow process in the recombination of the reduced PANI (LE) to the oxidised form (EM 2+) which in the presence of high concentrations of H 2Q becomes the rate-determining step in the overall reaction.