Analytical theory of the catalytic mechanism in square wave voltammetry at disc electrodes

A simple analytical expression is presented for the study of the first-order catalytic mechanism using Square Wave Voltammetry (SWV) at disc electrodes. These electrodes are extensively used in electrochemical studies but modelling the electrochemical response at this geometry is complex and usually requires the use of sophisticated numerical methods. By contrast, the analytical solution presented in this work is easy to compute and it is applicable to any size of the disc and for arbitrary kinetics of the catalytic reaction. The effects of the electrode size, the homogeneous rate constants, the frequency and the square wave amplitude on the SWV response are analyzed. Criteria are given for the detection of the steady-state response as well as procedures for the extraction of the catalytic rate constant from the value of the peak current. The theory is applied to obtain the kinetics of the reduction of the anion nitrite by an electrogenerated heteropolyanion [P(W(3)O(10))(4)](4-) at gold microdiscs.