General solutions for the I/t response for reversible processes in the presence of product in a multipotential step experiment at planar and spherical electrodes whose areas increase with any power of time

Differential pulse voltammetry and additive differential pulse voltammetry with solvent polymeric membrane ion sensors

The ion transfer across the water-solvent polymeric membrane interface is investigated by using a new device based on a modification of a commercial ion-selective electrode body that permits the accommodation of a platinum counter electrode inside the inner filling solution compartment and, therefore, use of a four-electrode potentiostat with ohmic drop compensation. This device is used here to apply two different double potential pulse techniques--differential pulse voltammetry and additive differential pulse voltammetry--which are more advantageous than other voltammetric techniques, such as normal pulse voltammetry or cyclic voltammetry, for the determination of the characteristic electrochemical parameters of the system. This is due to the concurrence of two factors in these double potential pulse techniques, the peak-shaped response together with a considerable reduction of undesirable current contributions.

Further Applications of Cyclic Voltammetry with Spherical Electrodes

In this work we show analytical and easily manageable explicit equations corresponding to the application of any multipulse potential sequence to planar, spherical and cylindrical electrodes. We apply these expressions to study reversible charge transfer electrode processes in cyclic voltammetry with spherical electrodes, by considering that both members of the redox pair are initially present in solution, and showing that a conventional symmetrical sweep can be used under these conditions. These expressions allow study in depth fundamental aspects of cyclic voltammetry with spherical electrodes. Thus, in the cyclic voltammograms obtained for simple reversible processes with conventional spherical electrodes at different sweep rates, characteristic common points of non zero current (isopoints) appear from which unknown thermodynamic parameters of these systems can be easily determined. From these equations it can be predicted and demonstrated that there are important analogies of the I/E behavior between a simple reversible charge transfer reaction and a first-order catalytic process when any single or multipulse voltammetric transient techniques are applied.