Growth Mode Transition Involving a Potential-Dependent Isotropic to Anisotropic Surface Atom Diffusion Change. Gold Electrodeposition on HOPG followed by STM

• Published in: Langmuir Vol. 13; no. 1; pp. 100 - 110
• Main Authors: Martín, H, Carro, P, Hernández Creus, A, González, S, Salvarezza, R. C, Arvia, A. J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 08-01-1997
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Electrodeposition, electroplating; Exact sciences and technology; Materials science; Metals. Metallurgy; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Gold; Electric potential; Surface diffusion; Experimental study; STM; Acidic solution; Crystal growth habit; Aqueous solutions; Transition elements; Growth mechanism; Adatoms; Crystal growth from solutions; Electrodeposition; Crystal nucleation; Dendrites; Kinetics; Aggregate
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la960700a

The electrodeposition of gold on highly oriented pyrolytic graphite (HOPG) from acid aqueous solutions was studied by using electrochemical techniques complemented with ex-situ scanning tunneling microscopy (STM). The kinetics of gold electrodeposition is consistent with a nucleation and three-dimensional growth process under diffusion control from the solution side. As the applied potential moves in the negative direction, the gold crystal density increases, and the crystal shape changes from a Euclidean to a dendritic fractal morphology. This transition can be assigned to the anisotropic surface diffusion of gold adatoms induced by the applied electric potential. A model including a potential-dependent energy barrier at step edges accounts for the morphology transition for gold electrodeposition on HOPG.