Dealloying of Cu₃Pd Single Crystal Surfaces

Abstract

Nanoporous metallic structures formed from dealloying have recently attracted considerable interest due to a wide range of potential applications in areas such as catalysis, actuators, biomedical sensors and fuel cell electrodes. The Cu-Pd system is interesting as a model system for corrosion as well as a potential catalyst material. We report a combined in-situ X-ray diffraction (XRD) and ex-situ atomic force microscopy (AFM) study of the initial structural evolution during the selective dissolution of Cu from Cu3Pd (111) and Cu3Pd (100). The experiments were performed under potential control in 0.1 M H2SO4 solution. Below the critical potential, no distinct diffraction signal is evidenced by in-situ XRD but AFM reveals the existence of islands on the surfaces. At the critical potential, on both single crystal surfaces the formation of an epitaxial Pd layer exhibiting substrate orientation is evidenced by XRD. Ex-situ AFM imaging clearly showed at comparable stages the formation of larger nanoscale islands. We further compare and contrast the behavior of the dealloyed Cu-Pd surfaces with that of Cu-Au alloys.

Localized dealloying corrosion mediated by self-assembled monolayers used as an inhibitor system

“…The surface morphology clearly resembles the island formation on bare Cu 3 Au surfaces at much lower potentials and can be clearly distinguished from other alloys such as Cu-Pd. 36 The in situ AFM imaging was stopped at 905 mV and SEM images, such as shown in Fig. 8a, were taken.…”

In Situ and Operando X-ray Scattering Methods in Electrochemistry and Electrocatalysis

“…On Cu 3 Au­(100), a layer of islands with (111) facets was observed . Dealloying of (111) and (100) oriented Cu 3 Pd led to the formation of epitaxial passivation layers of Pd on both surfaces. , …”

“…548 Dealloying of ( 111) and (100) oriented Cu 3 Pd led to the formation of epitaxial passivation layers of Pd on both surfaces. 548,552 More recently, dealloying has become of interest for the formation of nanoporous metals, especially nanoporous gold. A prototypical system here is the dealloying of AuAg in nitric acid solution under open circuit conditions.…”

“…Here, the less noble component dissolves selectively, leaving behind the matrix of the more noble metal. Pioneering work in this area was performed by Renner et al, who studied this process by in situ SXRD and anomalous GIXRD on alloy single crystals. − Studies of (111)-oriented Cu 3 Au, an important model system for dealloying, in sulfuric acid solution revealed in the first stage of this process the formation of a 2–3 ML thick passivation layer with depleted Cu content (less than 40%). , Interestingly, the stacking sequence of the atomic planes in this passivation layer was inverted relative to the fcc stacking sequence in the underlying Cu 3 Au substrate (Figure . In the later stages of the dealloying process, the passivation layer transformed into a thicker layer consisting of Au-rich islands.…”

Review—Electrolytic Metal Atoms Enabled Manufacturing of Nanostructured Sensor Electrodes

“…In the literature, a range of nanostructured metals have also been successfully fabricated through chemical or electrochemical alloying of different alloy precursors based on selective dissolution of active components from the precursors. [138][139][140][141][142][143][144][145][146][147][148][149][150][151][152] Special attention has been paid to the evolution of nanostructures during the dealloying. [140][141][142][143][144] Several dealloying mechanisms have been proposed.…”