Kinetics of radical dimerization. Simple evaluation of rate constant from convolution voltammetry and faradaic phase angle data

0511919 - ÚFCH JH 2020 RIV GB eng J - Článek v odborném periodiku
Pospíšil, Lubomír - Hromadová, Magdaléna - Sokolová, Romana - Lanza, C.
Kinetics of radical dimerization. Simple evaluation of rate constant from convolution voltammetry and faradaic phase angle data.
Electrochimica acta. Roč. 300, MAR 2019 (2019), s. 284-289. ISSN 0013-4686. E-ISSN 1873-3859
Grant CEP: GA ČR(CZ) GA18-04682S
Institucionální podpora: RVO:61388955
Klíčová slova: irreversible dimerization * ac polarography * pyridinium * reduction * Eis * Convolution voltammetry * Rate constants * Dimerization * Fitting
Obor OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)
Impakt faktor: 6.215, rok: 2019
Způsob publikování: Omezený přístup

Search for possible ways of the binary information storage evoked an interest in the mechanism of the electrochemical monomer/dimer switching. Thus, determination of the rate of radical-to-dimer conversion became an issue. Mathematical formulation describing the electrochemical generation of a radical followed by a bimolecular chemical reaction contains a quadratic term, in which case the inverse Laplace transformation does not exist. Until now, kinetic data were obtained by using finite difference simulations. We report an alternative and simpler evaluation method, which uses the frequency dependence of the faradaic impedance. Determination of the required surface concentration uses convoluted voltammogram recorded at the same bulk concentration as the impedance data. Functional dependence of the faradaic phase angle on frequency (cot phi vs. omega(1/2)) shows a maximum at lower frequencies containing information on the dimerization kinetics and a linear asymptote at the highest frequency range yields the electron transfer rate. This new procedure was applied to four different known redox systems, all involving radical dimerization process. (C) 2019 Elsevier Ltd. All rights reserved.
Trvalý link: http://hdl.handle.net/11104/0302153