A new approach to the estimation of electrocrystallization parameters

To overcome the drawbacks in estimating electrocrystallization parameters using traditional methods, we propose a genetic algorithm using a novel crossover operator based on the non-convex linear combination of multiple parents to estimate the electrocrystallization parameters A (the nucleation rate constant), N-0 (the nucleation density) and D (the diffusion coefficient of Zn2+ ions) simultaneously in the general current-time expression of Scharifker and Mostany for nucleation and growth by fitting the whole current transients for zinc electrodeposition onto glassy carbon electrode immersed in the acetate solutions. By running the algorithm, we obtained for different step potentials, D values close to 2.10 x 10(-6)cm(2) s(-1), which are comparable to reported values. The values of A obtained for all step potentials are identical, 1.41 x 10(9) s(-1), which indicates that zinc deposition onto glassy carbon electrode follows three-dimensional instantaneous nucleation and growth. In addition, from the values of N-0 obtained, one can observe that an increase in step potential leads to a higher N-0. These results show that our algorithm works stably and effectively in solving the problem of estimating the electrocrystallization parameters, and more importantly, it can be extended easily to a general algorithm to estimate multiple parameters in an arbitrary chemical model. (C) 1999 Elsevier Science S.A. All rights reserved.