Elaboration of nanoporous copper by modifying surface diffusivity by the minor addition of gold

Dan, Zhenhua; Qin, Fengxiang; Sugawara, Yu; Muto, Izumi; Hara, Nobuyoshi

doi:10.1016/j.micromeso.2012.08.026

Cited by 30 publications

(27 citation statements)

References 39 publications

(69 reference statements)

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“…The slight increases in the pore sizes and the decreases in the length of the ligaments in nanoporous Cu allowed for the formation of ultrafine nanoporous Cu over time. When the immersion time was increased from 1.8 to 43.2 ks, the Au content of dealloyed Ti CuAu alloys increased from 3.5 to 5.2 at% for Ti 60 13) the Au content accumulated faster, which resulted from the higher concentration of HF solution. Figure 5 shows the bright-field (BFI) and high resolution TEM (HRTEM) images, and the selected area diffraction patterns (SADP) of the as-dealloyed Ti 60 Cu 38 Au 2 ribbon alloy.…”

Section: Characterization Of As-spun and As-dealloyed Ribbonmentioning

confidence: 99%

Fabrication of Ultrafine Nanoporous Copper by the Minor Addition of Gold

et al. 2012

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Ultrafine nanoporous Cu was successfully fabricated through the dealloying of amorphous Ti 60 Cu 40¹x Au x (x = 0, 1, 2 at%) ribbon alloys in 0.65 M HF solution under free immersion conditions. A bicontinuous nanoporous structure of Cu formed on Ti 60 Cu 40 , Ti 60 Cu 39 Au 1 and Ti 60 Cu 38 Au 2 ribbons with pore sizes of 134, 8.9 and 7.4 nm, respectively. The pore size of the nanoporous Cu dealloyed from Au-added alloys was more than one order smaller than that of the TiCu alloy, which resulted from the 5-order decrease in the surface diffusivity through alloying of Au into Ti 60 Cu 40 ribbons. The Au content increased rapidly during the dealloying process and eventually formed binary CuAu solid solution and Au nanoparticles. Modifying the surface diffusivity by adding Au made it possible for the formation of the ultrafine nanoporous Cu structure.

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Section: Characterization Of As-spun and As-dealloyed Ribbonmentioning

confidence: 99%

Fabrication of Ultrafine Nanoporous Copper by the Minor Addition of Gold

et al. 2012

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“…The decrease in the grain size was considered to be due to the retardation of the self-diffusion of Cu adatoms. 15,16) The diffusion distance of Cu adatoms under free diffusion patterns is prevailed in a long distance. 2,5,10,1921) However, the long-distance self-diffusion of Cu adatoms was interrupted by the LSDM adatoms during the rearrangement of adatoms and resulted in an accumulation of Cu and LSDM adatoms in a smaller scale.…”

Section: +1mentioning

confidence: 99%

“…3,14) It is believed that the absence of grain boundary, the large-scaled phase segregations, and intermetallics of amorphous precursors contributes to high uniformity in nanoporous metals. The formation of highly uniform and ultrafine nanoporous structures have been realized for several amorphous alloy systems, including PdNiP, 14) TiCuAu, 15,16) TiCuAg 17) and ). 19) The surface diffusivity of Ni in the electrolyte was one-tenth that of Cu.…”

Section: Introductionmentioning

confidence: 99%

Refinement of Nanoporous Copper: A Summary of Micro-Alloying of Au-Group and Pt-Group Elements

2014

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The micro-alloying of 1 at% metals of Au-Group (Ag, Au) and the Pt-Group (Ni, Pd, Pt) with the Ti 60 Cu 40 amorphous alloy resulted in the formation of fine nanoporous copper (NPC) in the order of 628 nm. The smallest characteristic pore size of opencell nanoporous fcc Cu was 7 and 6 nm after dealloying the amorphous Ti 60 Cu 39 Pd 1 and Ti 60 Cu 39 Pt 1 precursor alloys for 43.2 ks in 0.03 M HF solution, while NPC had a pore size of 39 nm after dealloying the amorphous Ti 60 Cu 40 precursor alloy. On the basis of TEM micrographs, the refining factor increased approximately from 4 for the Ti 60 Cu 39 Ag 1 precursor alloy to 1780 for the Ti 60 Cu 39 Pt 1 precursor alloy. The refinement was attributed to the dramatic decrease in the surface diffusivity during dealloying. The refinement efficiency of the micro-alloying of the Pt-group elements was higher than that of the Au-group elements. The homogeneous distribution of additives in both of the amorphous precursor alloys and the final stabilized NPCs played a key role in refining the NPCs. This strategy may contribute to the fabrication of cost-effective nanoporous metals with a nanoporosity comparable to that of nanoporous Au, Pd and Pt catalysts.

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“…In an effort to achieve a more uniform np-Cu with smaller nanopores, metal elements with a low surface diffusivity, such as Ag, Au, Ni, Pd, Pt, have been added to the precursor alloys. [23][24][25][26][27] A significant reduction in the mean pore size of the np-Cu achieved by the addition of elements with a low surface diffusivity has been demonstrated, in some cases exceeding two orders of magnitude. However, the addition of noble metals such as Au, Pd, Pt, increases the cost of producing np-Cu considerably.…”

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confidence: 94%

Refinement of Nanoporous Copper by Dealloying MgCuY Amorphous Alloys in Sulfuric Acids Containing Polyvinylpyrrolidone

Dan

Qin

Yamaura

et al. 2014

J. Electrochem. Soc.

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Nanoporous Cu was fabricated by dealloying Mg 65 Cu 25 Y 10 amorphous alloy in a mixed solution of poly-vinylpyrrolidone (PVP) and sulfuric acid. A significant change was observed in the pore and ligament size when dealloying in the mixed solution rather than in a 0.1 M H 2 SO 4 solution free of PVP: in the mixed solution containing 10 g/L PVP the mean sizes of pores and ligaments were 10 nm and 14 nm, whereas they were 66 nm and 84 nm in the PVP-free solution. With increasing concentration of PVP in the dealloying solutions, the size of nanopores and ligaments decreased in the following manner: the decrease was small in the PVP concentration range of 0 to 0.1 g/L (Type I), and large in the 0.1 to 10 g/L range (Type II). A decrease in the surface diffusivity of more than three orders of magnitude was noted with the addition of 10 g/L PVP. This can be explained by the restrictions on free diffusion of Cu adatoms due to the adsorption of PVP macromolecules which force Cu adatoms to diffuse in a relatively narrower range, and thus smaller Cu ligaments and nanopores formed. The introduction of organic macromolecule into dealloying solution helps refine nanoporous structures.The excellent physical and chemical properties of nanoporous metals (NPMs) has made them the focus of much attention over the last few decades. 1-5 Many unique physicochemical properties of NPMs have been reported, such as enhanced surface Raman scattering, 6 a supercapacitive property, 7,8 superior catalytic performance, 9-11 higher mechanical strength than bulk metals, 12 and a biosensing ability. 13 The np-Cu materials in particular have a great potential for practical applications since they are cost effective compared to np-Au, electrochemically stable, and their mechanical performance is reliable. The np-Cu materials have been typically fabricated by dealloying crystalline 14-17 or amorphous precursors. 18,19 The uniform microstructure of np-Cu is of importance for its catalytic performance. As has been reported, the np-Cu fabricated from amorphous precursors has a relatively uniform distribution of nanopores and Cu ligaments because of its homogenous chemical composition and the microstructure of the amorphous precursors. 18,19 As has been reported before, 18,20-22 initial microstructure and homogeneity of chemical composition of precursor alloys affect the uniformity of the final np-Cu, and an absence of heterogeneous intermetallic phases and grain boundary in amorphous precursor alloys is considered to be helpful for the uniform evolution of nanoporosity. The extent of nanoporosity is determined by the size of nanopores and ligaments, and influences the mechanical properties and catalytic performances. The nanopores in np-Cu structures prepared from crystalline Al-Cu, 15-17 Mn-Cu 14 or other alloys in acid or alkaline solutions range between 30∼500 nm in size. In order to have superior catalytic performance, the np-Cu nanopores need to be refined. In an effort to achieve a more uniform np-Cu with smaller nanopores, metal elements with a l...

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Elaboration of nanoporous copper by modifying surface diffusivity by the minor addition of gold

Cited by 30 publications

References 39 publications

Fabrication of Ultrafine Nanoporous Copper by the Minor Addition of Gold

Fabrication of Ultrafine Nanoporous Copper by the Minor Addition of Gold

Refinement of Nanoporous Copper: A Summary of Micro-Alloying of Au-Group and Pt-Group Elements

Refinement of Nanoporous Copper by Dealloying MgCuY Amorphous Alloys in Sulfuric Acids Containing Polyvinylpyrrolidone

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