DIRECT DETERMINATION OF THE TRANSFER-COEFFICIENT FROM CYCLIC VOLTAMMETRY - ISOPOINTS AS DIAGNOSTICS

Isopoints are observed when cyclic voltammograms recorded at several s can rates are all plotted on the same potential axis, The isopoint is the point where all curves intersect. Here, isopoints are used as a di agnostic under reversible and quasireversible electron transfer condit ions, A method is presented for determining the transfer coefficient, alpha, using only the isopoint potential, switching potential, and pea k potentials, all readily identifiable points on the voltammograms, It is not necessary to know the diffusion coefficients, standard rate co nstant, standard potential, electrode area, or solution concentration to apply this method, The isopoint method is applicable for difference s in peak potentials of 0.073-0.145 V. The method is verified experime ntally by comparing the values of a determined by the isopoint and con volution methods, A linearization of the dimensionless kinetic paramet er, psi, developed by Nicholson, with the difference in peak potential s is presented, It is also shown that the average of the peak potentia ls yields the half-wave potential within 1 mV for differences in the p eak potential of less than approximately 0.145 V. Ah models were devel oped by computer simulation (Digisim).