Fundamental and Second Harmonic Alternating Current Cyclic Voltammetric Theory and Experimental Results for Simple Electrode Reactions Involving Solution-Soluble Redox Couples

A quantitative theoretical and experimental study of fundamental and second harmonic ac cyclic voltammetry is presented for a simple electrode reaction Involving solution-soluble redox forms, and rate control by diffusion and/or heterogeneous charge transfer. Rate laws are presented for the ac cyclic responses at stationary planar and spherical electrodes, and their predictions surveyed. Experimental data for several redox couples with widely varying ks values are found to confirm detailed predictions of the theory. Particular attention is paid the situation where the dc process is non-Nernstian, under which conditions variation of the kinetic status of the dc process leads to some Interesting and useful effects in the ac observables. Some novel bases for characterizing the heterogeneous charge transfer rate parameters are revealed for the cyclic ac experiment. It is concluded that fundamental and second harmonic ac cyclic voltammograms both complement and, in many cases, provide more sensitive and convenient insights about the electrode reaction than widely-used conventional (dc) cyclic voltammetry.