Non-aqueous electrochemical studies at a high temperature channel flow cell heated by radio frequency radiation

The effect of applied temperature was studied on various non-aqueous one- and two-electron systems of ferrocene, tris(4-bromophenyl)amine and N,N,N',N'-tetramethyl-1,4-phenylenediamine in acetonitrile solvent at both radio frequency channel cell (RFCC) and microdisk electrode apparatus. Experimentally obtained diffusion coefficients (D-c) and activation energies (E-A) for both RFCC and microelectrode experiments are in excellent agreement with each other and published data. Analysis of the data in terms of the Stokes-Einstein equation is also presented. This expands on previous work done in this area to incorporate not only solvent-based systems in addition to simple aqueous electrochemistry, but also more mechanistically complex electrode processes with coupled homogeneous kinetics such as ECE reactions. The application of the RFCC as a tool for mechanistic studies is discussed with the investigation of the well characterised ECE reaction of in-iodo-nitrobenzene in acetonitrile, giving a value of 80 +/- 5 kJ mol (- 1) for the activation energy of the rate constant for the decomposition of the m-iodo-nitrobenzene radical anion. This represents, to the authors' knowledge, the first example of a quantitative, fully modelled investigation of a mechanistically complex electrochemical process at a locally heated electrode. (C) 2001 Elsevier Science B.V. All rights reserved.