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

Abstract

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.

X-ray induced reduction of Au and Pt ions on silicon substrates

“…The conventional routes utilize methods involving deposition of vaporized atoms from the gas phase, or reduction of their salts using electrochemical and/or electroless wet chemical methods. Other unconventional techniques utilizing lasers, ion-beams and Xrays have also been investigated for incorporating metal clusters on to the substrates in the desired chemical and morphological state(s) [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Use of energetic particle beams and X-rays are particularly attractive since clean lithographic techniques can also be introduced for direct-writing purposes.…”

Fabrication of Pd–Fe nanowires with a high aspect ratio by AAO template-assisted electrodeposition

“…According to the Pd-Fe and Au interaction, the current-time transient shows a sharp drop in the initial current density due to the charging of the double layer, which was followed by a nonlinear increase in the current density with electrodeposition time. Such double layer charging was also observed during the electrodeposition of various metals [29][30][31][32][33]. The elec- trodeposition kinetics of Pd-Fe on the Au electrode in the AAO template, decreasing and then beginning to increase the current density, occurred over a very short time period.…”

Fabrication of broadband omnidirectional non-reflective gold surfaces by electrodeposition

“…The observed increasing roughness of the gold deposits when the applied potential is moved to the negative direction is in agreement with the results of Martin et al about the electrodeposition of gold from acid aqueous solutions. 19 It was shown that dendritic aggregates are produced when the gold surface is negatively charged at potential less than the potential of zero charge. The authors claimed that such growth behavior results from the anisotropic corner surface diffusion caused by the varying energy barriers for the diffusion of surface atoms at step edges, as has been observed for metal deposition from vapor.…”