Kinetics of Two-Dimensional Phase Transitions of Sulfide and Halide Ions on Ag(111)

Abstract

The kinetics of two-dimensional phase transitions of sulfide, iodide, bromide, and chloride ions on Ag(111) was investigated at anionic concentrations ranging from 1 × 10 -4 to 1 × 10 -3 M by measuring the time dependence of the charge following steps from a potential negative enough to exclude anionic adsorption to a potential in the range of stability of either the first or the second, more compressed, ordered overlayer of the anions. The kinetic behavior is interpreted by a model that accounts for diffusion-controlled random adsorption of the anions, followed by progressive polynucleation and growth. When stepping to the potential range of stability of the second overlayer, the kinetic behavior is accounted for by assuming that the passage from total desorption to the second overlayer occurs via the intermediate formation of the first one.

Cadmium selenide electrodeposited by ECALE: electrochemical characterization and preliminary results by EXAFS

“…The formation of two-dimensional films can be shown indirectly from voltammetric, as well as chronocoulometric measurements. A chronocoulometric study on the first S layer on Ag(1 1 1) [21] confirmed the presence of a two-dimensional phase transition between two overlayers of different structures. Such studies cannot be performed on Se layers, since the formation of Se upd layers takes place through the dissolution of bulk deposited Se, thus preventing any possible kinetic investigation.…”

In situ X-ray analysis under controlled potential conditions: An innovative setup and its application to the investigation of ultrathin films electrodeposited on Ag(111)

“…With ECALE, ultrathin films of CdS are obtained by alternating the underpotential deposition of Cd with the underpotential deposition of S in a cycle that can be repeated as many times as necessary to produce films of the desired thickness [22]. Both the first S layer deposited at underpotential and the CdS deposits had been investigated with electrochemical, scanning tunneling microscopy (STM), atomic force microscopy (AFM) and X-ray photoelectron diffraction (XPD) measurements [23][24][25][26][27].…”

Formation of a 2D phase in the electrochemical reduction of 4,4′-bipyridine on mercury in the presence of iodide ions via a desorption-nucleation, reorientation-nucleation mechanisms

“…Chronoamperometry has proved the most suitable technique for characterizing electrochemical 2D nucleation processes; also, special mathematical models have been developed that account accurately for the behaviour of a wide variety of real systems [2,[4][5][6][7]. In recent work [8], we reported a new mathematical model based on a desorption-nucleation, reorientation-nucleation mechanisms that was successfully applied to the 2D nucleation of heptyl viologen in the presence of adsorbed anions on a mercury electrode.…”