Kinetics and Mechanism of Gold Dendrite Electroformation on C(0001) : Activation Energy for Gold Adatom Surface Diffusion

• Autores: Martín, H.; Carro, P.; Hernández Creus, A.; González, S.; Salvarezza and A. J. Arvi
• Año de publicación: 1999
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas; Química; Electrodeposition; Gold; Kinetics
• Institución: Universidad Nacional de La Plata

Au electrodeposition on C(0001) from aqueous solutions with different concentrations of AuCl₃·HCl, at a constant ionic mass transport rate (j_L), in the temperature range 275 ≤ T ≤ 313 K, results in the initial formation of nanometer-sized Au islands consisting of a central core and symmetrically distributed branches with the island fractal dimension D_f = 1.6. For all values of T, the time dependence of the Au island radius fulfills a r ∝ t_n relationship with n = 0.25 ± 0.05. At constant T, the density of Au islands (N_s) increases according to N_s ∝ j_L^X with X = 0.69 ± 0.03. At constant j_L, the value of N_s decreases as T is increased, following an Arrhenius-type relationship. Kinetic data are consistent with a growth mechanism involving surface diffusion of Au adatoms from the island core towards branch tips. From the dependence of N_s on T at constant j_L, the activation energy for Au adatom surface diffusion results in E_a^* ≈ 11 Kcal/mol. This figure is slightly smaller than E_a^* ≈ 14 Kcal/mol that has been reported for Au atom surface diffusion in Cl^--ion free acid solutions.
Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas