In situ scanning tunneling microscopy study of selective dissolution of Au3Cu and Cu3Au (001)

Progress in corrosion science at atomic and nanometric scales

“…The presence of chlorides was concluded to enhance surface diffusion, coarsening pits and islands and leading to interconnected gold islands with an average height of 2 ML and dissolution channels. For (001)-oriented Cu3Au, a Moiré pattern was imaged by EC-STM [82], which is consistent with the formation of a goldrich surface layer of lattice parameter near that of pure gold passivating the Cu3Au substrate of parameter near that of pure copper.…”

“…[INSERT Figure In acidic solutions, copper selectively dissolve from Cu-Au alloys and does not form any stable oxides which leads to surface enrichment in Au and to sequential build-up of a nanoporous gold layer at the so-called critical potential (Uc) for macroscopic dealloying,. At potentials slightly above the copper equilibrium potential, copper dissolution occurs both at the alloy substrate step edges and on terraces leading to clustering of vacancies in the first layer as observed by EC-STM on (111)-oriented Au3Cu [80] and Cu3Au [83] and on (001)oriented Au3Cu and Cu3Au [82]. This forms an interconnected network of one atom deep pits (i.e.…”

Impact of Structure and Composition on the Dealloying of AuxAg(1–x) Alloys on the Nanoscale

“…It is therefore clear that further investigation of the parameters that impact the outcome of the dealloying process such as structure, size, and shape would provide more insight into the way these parameters affect the porosity dimensions, surface area development, and structural stability of accordingly generated architectures on the nanoscale level. Experimental effort for understanding the dealloying process at the atomistic level using scanning tunneling microscopy was made for Ag 80 Au 20 (111), Cu 3 Au ( hkl ), , and Cu 3 Pt (111) . Also, a recent kinetic Monte Carlo (KMC) simulation provided more insight into the immediate mechanism of Au x Ag (1– x ) NP dealloying and stability of the resulting structure …”

Dealloying Kinetics of AgAu Nanoparticles by In Situ Liquid-Cell Scanning Transmission Electron Microscopy

“…A number of in situ characterizations of dealloying have been conducted, but none has been able to unambiguously reveal the dealloying kinetics at the sub-nanoscale. Among them, electrochemical scanning tunneling microscopy (EC-STM) revealed the morphology evolution during the initial stage of dealloying of CuAu and AgAu alloys and provided insights into the onset of dealloying. , However, EC-STM goes only as deep as the probe, which is not suitable for characterizing depth direction and morphology evolution during dealloying. In situ X-ray tomography could account for bulk dealloying with crucial insights into the topology changes during the dealloying and coarsening of AgAu, but the resolution is insufficient for revealing dealloying mechanisms of nanoparticles …”