Abstract
Au-group (Ag, Au) and Pt-group (Ni, Pd, Pt) metals have lower surface diffusion coefficients than Cu and are defined as LSD. The chemical composition has been designed based on the differences in diffusion coefficients, and the micro-alloying of 1 at % LSD metals with the Ti60Cu40 amorphous precursor alloy results in the formation of bi-continuous nanoporous copper (NPC) with finer nanoporous structure. LSD-stabilized NPCs have the smallest characteristic pore sizes of 7 nm and 6 nm after dealloying amorphous Ti60Cu39Pd1 and Ti60Cu39Pt1 precursor alloys, while NPC had a pore size of 39 nm after dealloying the amorphous Ti60Cu40 alloy. The refining factor increases approximately from 3.7 for Ti60Cu39Ag1 to 1780 for Ti60Cu39Pt1 precursors due to the dramatic decrease in the surface diffusivity during both preferential dissolution and rearrangement of Cu adatoms. The elaboration efficiencies of Ti60Cu40 alloy with addition of 1 at.% Pt-group elements are higher than those of Au-group elements. The homogeneous distribution of LSD elements in both the precursors and final stabilized NPCs played a key role in restriction of the long-distance diffusion of Cu adatoms. LSD-stabilized NPCs are able to have an ultrafine nanoporosity with a pore size almost one order smaller than that from LSD-free alloys.
Highlights
Nanoporous metals (NPMs), a representative type of nanostructured materials, possess intriguing properties to generate promising potentials for various important applications, including catalysis, sensors, actuators, fuel cells, micro-fluidic flow controllers, and40 New Uses of Micro and Nanomaterials so forth [1–4]
The characteristic pore sizes of Nanoporous copper (NPC) obtained from the systems mentioned above are relatively larger than those of nanoporous gold (NPG) or nanoporous platinum (NP Pt) and change from few tenth nanometers to few hundredth nanometers, for Zr-Cu system with a pore size of 500 nm [19]
While the intermetallic phases or secondary phases exist in the matrix, the final nanoporous structures inherit the characteristics of their initial microstructure of precursor alloys
Summary
Nanoporous metals (NPMs), a representative type of nanostructured materials, possess intriguing properties to generate promising potentials for various important applications, including catalysis, sensors, actuators, fuel cells, micro-fluidic flow controllers, and. Effective ways to reduce the characteristic nanopore sizes have been reported to be dealloying at low temperature [23]; chemical composition design of the precursor alloys, for example, Ag-Au-Pt [24], Al-Pt-Au [25], Ti-Cu-Au [26, 27], Ti-Cu-Ag [28], Ti-Cu-Ni [29], and Ti-Cu-Pd/Pt [30]; and modification of the solution chemistry by using organic acids [31] and by introducing the macromolecules of polyvinylpyrrolidone [32, 33]. Final nanoporous structure is affected by many factors, such as the chemical compositions and initial microstructure of the precursor alloys, the solution chemistries of dealloying solutions, and the experimental conditions (i.e., temperatures, etc.) [12, 34, 35]. The formation of highly uniform and ultrafine nanoporous structures has been realized for several amorphous alloy systems, including Mg-Cu-Y [31], Ti-Cu-Au [26, 27], Ti-Cu-Ag [28], and Ti-Cu-Ni [29] ternary alloys
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