Formation of nanoporous platinum by selective dissolution of Cu from Cu_0.75Pt_0.25

Abstract

This paper gives results demonstrating the production of nanoporous platinum through the de-alloying of Cu0.75Pt0.25alloy in 1 M H2SO4. Both field emission scanning electron microscopy and small angle neutron scattering confirm the presence of porosity with a diameter of approximately 3.4 nm. This is the smallest porosity quantitatively reported from a de-alloying process to date. The small size is attributed to the extremely small values of surface diffusivity expected for Pt at room temperature, effectively eliminating room-temperature coarsening processes. The results also show that larger length scales can be achieved through coarsening at elevated temperatures. The ease of production of porous platinum makes it attractive for possible applications, such as high surface area electrodes for biomedical devices or as catalyst materials.

Sign-inversion of charging-induced variation of electrical resistance of nanoporous platinum

“…Nanoporous Pt was prepared by technique of electrochemical dealloying [5,6,16]. The master alloy Cu 75 Pt 25 (at.%) was arc-melted from high purity Pt and Cu wires (Pt, 99.99%; Cu, 99.99+%) and subsequently homogenized at 1000 • C for 4 h. Thin foils were obtained 3 by rolling to a thickness of 120 µm.…”

“…Particularly attractive for surface charging are nanoporous metals prepared by dealloying such as nanoporous (np) Au [5] or np-Pt [6]. Compared to cluster-assembled nanocrystalline metals, effects associated with charging at surface-electrolyte interfaces emerge more pronounced in nanoporous metals prepared by dealloying owing to the reduced influence of interfaces between the crystallites, i.e., grain boundaries.…”

Deformation Behavior of Nanoporous Metals

“…The material can be very uniform, even on a macroscopic length scale, and typically exhibits a specific surface area in the order of a few m 2 /g. [12] The best-studied example is the formation of nanoporous gold (np-Au) via selective removal of Ag from a AuAg alloy, [7,8,11] but other alloys such as AuAl 2 , [13] MnCu (np-Cu), [14] and CuPt (np-Pt) [15] have also been successfully dealloyed. The process can be easily extended to twodimensional thin-film samples by using commercially available white-gold leaves with a thickness of a few hundred nanometers [7] or thin sputterdeposited alloy films.…”

Dealloying of Cu-Zr-Ti Bulk Metallic Glass in Hydrofluoric Acid Solution

“…1,2) Although dealloying has received attention in the context of corrosion, it has recently been receiving renewed attention because particular systems exhibit nanostructure or nanoporosity evolution upon dealloying. 1,2) Interesting dealloying behaviors have been observed for binary systems, including Ag-Au, [1][2][3][4][5] Cu-Zr, [6][7][8] Cu-Pt, 9) and Pt-Si. 10) Compared to the crystalline alloys, multicomponent metallic glasses are monolithic in phase with a homogeneous composition and structure down to the subnanoscale.…”