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Kinetic studies by cyclic voltammetry at low temperatures using microelectrodes

1989; Elsevier BV; Volume: 262; Issue: 1-2 Linguagem: Inglês

10.1016/0022-0728(89)80012-9

2590-2954

Walter J. Bowyer, E.Eric Engelman, Dennis H. Evans,

Analytical Chemistry and Sensors

Conditions and procedures needed for accurate kinetic measurements at low temperatures are developed and illustrated. Resistivities of tetra-n-butylammonium hexafluorophosphate and perchlorate electrolytes in acetonitrile, n-butyronitrile and N, N-dimethylformamide are reported for temperatures from 25 to as low as −80 ° C, as are diffusion coefficients of three representative solutes: cobaltocenium ion, 9,10-anthraquinone and 4-nitrotoluene. Establishment of a practical range of scan rates within which errors due to solution resistance will be small for a given electrode size is illustrated for cyclic voltammetry with microdisk electrodes under low temperature conditions. A procedure for correcting experimental voltammograms for solution IR drop and for the effect of the faradaic current on the charging current is utilized along with evaluation of the data by digital simulation employing the actual scan rate as input to the simulation program. This procedure was illustrated and evaluated using data for reduction of 9,10-anthraquinone at room temperature and nitromesitylene at −50° C. Finally, cyclic voltammetry with microelectrodes at low temperature was used to determine rate constants for structural changes associated with the electrochemical reduction of 1,1'-dimethylbianthrone and dixanthylene.