Theoretical study of a catalytic mechanism using cyclic and derivative chronopotentiometric techniques with spherical electrodes

A general analytical solution for a pseudo-first order catalytic process in chronopotentiometric techniques (reversal chronopotentiometry, cyclic chronopotentiometry and reciprocal derivative chronopotentiometry) when using spherical electrodes of any size is presented. The evolution from transient to stationary potential–time responses, characterized by the disappearance of the periodical signal in the neighbourhood of the steady state, is analyzed in cyclic and reversal chronopotentiometry. From reversal potential–time responses, the reciprocal derivative dt1/2/dE–E curves – which are more sensitive than traditional dt/dE–E curves – have been obtained. The characteristic peaks presented by the dt1/2/dE–E curves are quantitatively related to the rate constants of the chemical reaction and show a very different behaviour in catalytic and EC processes, allowing the easy discrimination between both mechanisms. Several types of working curves have been proposed to obtain the rate constants of the chemical reaction in a catalytic process.