Fl. Qiu et al., Thermal activation of electrochemical processes in a Rf-heated channel flow cell: experiment and finite element simulation, J ELEC CHEM, 492(2), 2000, pp. 150-155
A novel approach to thermoelectrochemistry is presented which involves the
direct heating of the working electrode in a channel flow cell system by ed
dy currents caused by 8 MHz radio frequency (Rf) radiation. For the model r
edox systems Fe(CN)(6)(3-/4-) and Ru(NH3)(6)(3+/2+) it is shown that it is
possible to perform electrochemical experiments with simultaneous thermal a
ctivation at temperatures close to the boiling point of the electrolyte sol
ution. Quantitative analysis of data obtained from thermoelectrochemical st
udies in the Rf-heated channel flow system is possible with the help of a c
omputer model. Numerical simulation results obtained with a finite element
program (FIDAP(TM)) for the complex heat and mass flow during voltammetric
experiments at the heated electrode are shown to be in quantitative agreeme
nt with experimental data. Both the increase in the rate of diffusion as we
ll as the change in the flow pattern in the heated low viscosity region of
the channel are shown to contribute significantly to the enhanced mass tran
sport. After confirming the quantitative agreement of the numerical model w
ith the data obtained for the oxidation of Fe(CN)(6)(4-) and the reduction
of Fe(CN)(6)(3-) in 0.1 M KCl, the activation energy for the Ru(NH3)(6)(3+/
2+) redox system diffusion in 0.1 M KCl is determined. (C) 2000 Elsevier Sc
ience B.V. All rights reserved.