HETEROGENEOUS ECE PROCESSES AT CHANNEL ELECTRODES - VOLTAMMETRIC WAVESHAPE THEORY - APPLICATION TO THE REDUCTION OF NITROMETHANE AT PLATINUM-ELECTRODES

Theory is developed for heterogeneous ECE reactions occurring at chann el electrode that predicts the voltammetric waveshape, as characterize d by the half-wave potential and the Tafel slope as a function of the rate of mass transport and the cell geometry. Working surfaces are rep orted that allow the ready mechanistic interpretation of experimental data and the deduction of corresponding rate constants. Experiments ar e reported on the reduction of nitromethane in aqueous buffered soluti on (7 < pH < 9) at platinum electrodes that is thought to proceed via a heterogeneous ECEEE mechanism. Analysis of both waveshape and limiti ng current data confirm this mechanistic assignment, allowing the foll owing appropriate kinetic parameters to be reported: heterogeneous rat e constant, 0.26 +/- 0.07 cm s(-1); and standard electrochemical rate constant, 0.13 +/- 0.01 cm s(-1).