Hydrohalic-acid anion interaction with gold surfaces: Au(100) – chloride
In this chapter the experimental results on adsorption of chloride ion on Au(100) surface is described.
In 0.1 M H2SO4 + 1 mM HCl, Cl displaces SO4. At +0.12 V (SCE), the adsorption of a disordered Cl layer begins and lifts the Au(100) reconstruction. At +0.71 V (SCE), a phase transitions into an ordered c(√2 × p)R45° (22 ≥ p ≥ 2.3) structure, a uniaxially incommensurate, quasi-hexagonal structure. Dissolution of Au starts from steps via the formation of AuCl, AuCl2, AuCl3, and AuCl4 complexes.
The detachment of an Au atom from a step edge proceeds with an activation energy of 0.7 eV.
In agreement with the displacement of SO4 by Cl, gold islands on the surface decay fast in the presence of Cl ions in sulfuric acid solution, a process also known as “electrochemical annealing” [1, 2, 3, 4, 5, 6, 7, 8] (see also Sect. 179.13[ https://doi.org/10.1007/978-3-662-53908-8_179]).
saturated calomel electrode
- 4.Mesgar, M.: Ph.D. Thesis, University of Ulm (1996)Google Scholar