Nanoporous Copper-Nickel – Macroscopic bodies of a strong and deformable nanoporous base metal by dealloying

Lührs, Lukas; Weißmüller, J.

doi:10.1016/j.scriptamat.2018.06.025

Cited by 21 publications

(10 citation statements)

References 71 publications

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“…Yet, our functionalization strategy may readily be transferred to technologically more relevant materials. Nanoporous copper, [ 80,81 ] nanoporous copper‐nickel alloys, [ 82 ] or microporous titanium [ 83–85 ] have been demonstrated and may form alternatives for the skeleton structure. Thus, our study may be a first step toward the application of PPy in mm‐sized actuators.…”

Section: Resultsmentioning

confidence: 99%

Nanoporous‐Gold‐Polypyrrole Hybrid Materials for Millimeter‐Sized Free Standing Actuators

Roschning

Weißmüller

2020

Adv Materials Inter

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An important materials parameter of actuators is their strain-charge coupling coefficient, ψ = δε/δq V , where ε denotes the linear, uniaxial strain. For PPy, the magnitude and sign of ψ depend on the synthesis conditions, the species of transferred ions, the solvent and the mechanical boundary conditions. [4,5,11,21-23] Besides the magnitude of the straincharge coupling, the response time is an important characteristic of actuators. For PPy, the underlying charge transport kinetics include both, ionic transport and the formation of electronically conducting zones along the polymer chains. [24,25] If the potential interval is restricted so that the PPy is kept in its oxidized state with high electronic conductivity, the ion exchange is rate controlling. Similar to classical interdiffusion, the time constant for equilibration after a change in E increases with the square of the diffusion distance. [24-26] Acceptable response times thus require small actuator dimensions in at least one direction. Therefore, many studies investigate PPy as a thin film (typically not exceeding 10 µm) on an electrically conductive substrate. Examples for such actuators are bilayered bending cantilevers [27-29] which may exhibit roughened interfaces for enhanced adhesion, [30] multilayered axial strain actuators [31] or coated fibers spun to yarns. [10] Nanometer-thin PPy films allow for particularly fast reaction times. [15,32] For PPy films with a thickness of about 10 µm, the actuation response time increases to minutes. [33,34] Free-standing PPy actuators with a thickness of ≈100 µm and a cross-sectional gradient in microstructure have been investigated in the context of wireless actuation. [35,36] They exhibit similar response times. For even thicker geometries, the response will be prohibitively slow. PPy actuators with spatial dimensions of mm or above can be realized with PPy-coated nanoskeleton structures, such as multi-walled carbon nanotube networks [37] or electrospun microribbons. [38] In these architectures, a liquid electrolyte in the pore space provides a fast pathway for long-range ion transport. Metal-PPy-electrolyte hybrid materials obtained by the imbibition of PPy-coated nanoporous metals [39] represent a particularly interesting case, because their skeleton structure is load-bearing under compression. This enables actuation against an external compressive load by free-standing macroscopic bodies without a supporting device structure. Furthermore, the mechanical behavior of nanoporous metals has been intensively studied. [40-45] This provides the opportunity for a This work studies the actuation of hybrid materials made from nanoporous gold, polypyrrole, and aqueous electrolyte. The deposition protocol affords a conformal polypyrrole coating on the entire internal interface of millimetersized nanoporous metal specimens made by dealloying. The hybrid material emerges when the remaining pore space is filled with perchloric acid. The metal serves as load-bearing and electronically conductive substrate, the polypyrrole...

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Section: Resultsmentioning

confidence: 99%

Nanoporous‐Gold‐Polypyrrole Hybrid Materials for Millimeter‐Sized Free Standing Actuators

Roschning

Weißmüller

2020

Adv Materials Inter

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“…Although this issue has been well-known for many decades, for example, in the fields of porous semiconductors − or silica aerogels, it is hardly appreciated in the context of nanoporous metal preparation. The drying technique below, adopted from protocols for mesoporous silicon, has proved useful in the making of nanoporous metals. , …”

Section: Tuning Of Structure and Composition During Dealloyingmentioning

confidence: 99%

“…The drying technique below, adopted from protocols for mesoporous silicon, 194 has proved useful in the making of nanoporous metals. 198,199 An efficient way to minimize capillary-induced stresses is to transfer the nanoporous metals from the preparation medium first into water, then into ethanol and finally into n-pentane, whereupon the samples are deposited on glass and allowed to dry. This procedure profits from the considerably lower surface tension of n-pentane, which is γ LV = 14 mJ/m 2 as opposed to the 72 mJ/m 2 of water.…”

Section: Dealloying Potential and Postdealloyingmentioning

confidence: 99%

“…The dealloying of Au-based metallic glasses exemplifies this situation. 319,320 Nanocrystalline nanoporous metals have also been obtained by dealloying crystalline precursors, for instance, from Al- 321 and Mn-based 198 master alloys. The absence of simple epitaxial relations between master alloy and the product structure may favor such nanocrystalline nanoporous products.…”

Section: Grain Sizementioning

confidence: 99%

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Nanoporous Gold: From Structure Evolution to Functional Properties in Catalysis and Electrochemistry

et al. 2023

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Nanoporous gold (NPG) is characterized by a bicontinuous network of nanometer-sized metallic struts and interconnected pores formed spontaneously by oxidative dissolution of the less noble element from gold alloys. The resulting material exhibits decent catalytic activity for low-temperature, aerobic total as well as partial oxidation reactions, the oxidative coupling of methanol to methyl formate being the prototypical example. This review not only provides a critical discussion of ways to tune the morphology and composition of this material and its implication for catalysis and electrocatalysis, but will also exemplarily review the current mechanistic understanding of the partial oxidation of methanol using information from quantum chemical studies, model studies on single-crystal surfaces, gas phase catalysis, aerobic liquid phase oxidation, and electrocatalysis. In this respect, a particular focus will be on mechanistic aspects not well understood, yet. Apart from the mechanistic aspects of catalysis, best practice examples with respect to material preparation and characterization will be discussed. These can improve the reproducibility of the materials property such as the catalytic activity and selectivity as well as the scope of reactions being identified as the main challenges for a broader application of NPG in target-oriented organic synthesis.

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“…The dealloying process was considered to be complete when the current corresponding to each applied potential dropped to <10 μA. [ 19 ] The potential stimuli were provided by a potentiostat (CHI760E, Chenhua).…”

Section: Methodsmentioning

confidence: 99%

Microstructural/Compositional Regulations and Actuation Properties of Nanoporous Ternary CuMnNi Alloys Fabricated by Electrochemical Dealloying

Tan

Yan

Yang

et al. 2022

Physica Status Solidi (a)

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Metallic actuators have received a wide range of attention in the past two decades because of their larger strains than piezoelectric ceramics and higher strength relative to conducting polymers. However, the metallic actuators composed of noble metals are limited to the high material cost for further development and practical applications. Here, nanoporous CuMnNi (np‐CMN) alloys are fabricated from a ternary Mn70Cu20Ni10 precursor through an electrochemical dealloying method, and their microstructures/compositions are further regulated through different electrochemical processes (multi‐step and two‐step). The np‐CMN alloys show good electrochemical actuation properties in 1 m NaOH solution, and the sample obtained from two‐step dealloying exhibits much better actuation performance than that from multi‐step dealloying. The maximum strain amplitude of np‐CMN could reach up to 0.46%, which is comparable to or even better than that of noble metal‐based actuators. Our work indicates that the low‐cost np‐CMN alloy could be a competitive material among electrochemical metallic actuators.

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Nanoporous Copper-Nickel – Macroscopic bodies of a strong and deformable nanoporous base metal by dealloying

Cited by 21 publications

References 71 publications

Nanoporous‐Gold‐Polypyrrole Hybrid Materials for Millimeter‐Sized Free Standing Actuators

Nanoporous‐Gold‐Polypyrrole Hybrid Materials for Millimeter‐Sized Free Standing Actuators

Nanoporous Gold: From Structure Evolution to Functional Properties in Catalysis and Electrochemistry

Microstructural/Compositional Regulations and Actuation Properties of Nanoporous Ternary CuMnNi Alloys Fabricated by Electrochemical Dealloying

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