Silver residues as a possible key to a remarkable oxidative catalytic activity of nanoporous gold

Moskaleva, Lyudmila V.; Röhe, Sarah; Wittstock, Arne; Zielasek, Volkmar; Klüner, Thorsten; Neyman, Konstantin M.; Bäumer, Marcus

doi:10.1039/c0cp02372h

Cited by 127 publications

(199 citation statements)

References 62 publications

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“…The catalyst with a mass ratio of Ag : SiO 2 : show catalytic performance for oxygen transfer reaction superior to that of their monometallic counterparts. The degree of enhancement is strongly correlated with the surface silver content [48][49][50][51][52][53][54][55][56]. In addition, the synthetic approach of monodispersed Ag-containing alloy nanoparticles with controlled particle size and composition is still of key issue in the study of catalytic mechanisms and the kinetics of reaction.…”

Section: Page 6 Of 58mentioning

confidence: 99%

Recent advances in silver-based heterogeneous catalysts for green chemistry processes

Wen

Yin

Dai

2014

Applied Catalysis B: Environmental

159

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Section: Page 6 Of 58mentioning

confidence: 99%

Recent advances in silver-based heterogeneous catalysts for green chemistry processes

Wen

Yin

Dai

2014

Applied Catalysis B: Environmental

159

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“…Trace amounts of silver can complicate the chemistry taking place at the interface, which can either be construed as a good thing or a bad thing depending on the outcome. In the catalytic oxidation of CO, the presence of small amounts of silver has been shown to play an important role [95,96,112]. In contrast, for methanol oxidation, increases in Ag do not improve activity [113].…”

Section: Specific Features Of Nanoporous Goldmentioning

confidence: 99%

Nanoporous Gold Electrodes and Their Applications in Analytical Chemistry

Collinson

2013

ISRN Analytical Chemistry

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Nanoporous gold prepared by dealloying Au:Ag alloys has recently become an attractive material in the field of analytical chemistry. This conductive material has an open, 3D porous framework consisting of nanosized pores and ligaments with surface areas that are 10s to 100s of times larger than planar gold of an equivalent geometric area. The high surface area coupled with an open pore network makes nanoporous gold an ideal support for the development of chemical sensors. Important attributes include conductivity, high surface area, ease of preparation and modification, tunable pore size, and a bicontinuous open pore network. In this paper, the fabrication, characterization, and applications of nanoporous gold in chemical sensing are reviewed specifically as they relate to the development of immunosensors, enzyme-based biosensors, DNA sensors, Raman sensors, and small molecule sensors.

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“…A least-squares fit through the data from HClO 4 corrosion provides a slope of −0.83 which enables a scarce estimation of x Ag from the charge ratio Q/Q F within a range of x Ag = 0-20 at.% for route A. An accurate predictability is desirable since the Ag content is discussed to crucially affect the catalytic activity 23,46 and the mechanical properties of NPG. 47 This experimental approach to x Ag has no analog in route B.…”

Section: Electrochemicalmentioning

confidence: 99%

“…for CO oxidation) is under discussion. [22][23][24][25] As another instance, reports on the mechanical strength and stiffness of nominally comparable structures disagree by up to one order of magnitude. 26,27 Therefore it is significant to note that a number of different dealloying protocols are applied within these studies.…”

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confidence: 99%

Nanoporous Gold by Alloy Corrosion: Method-Structure-Property Relationships

Graf

Roschning

Weißmüller

2017

J. Electrochem. Soc.

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Nanoporous gold (NPG) made by selective corrosion, or dealloying, serves as a model system for the investigation of electrochemical and mechanical properties of nanomaterials. While various dealloying protocols are in use, it is typically assumed that the structural characteristics are identical and independent of the preparation technique. Yet, reported properties such as strength, Young's modulus, or catalytic behavior can vary widely. Here, we compare the microstructure and the mechanical behavior of NPG structures prepared by three different synthesis protocols reported in the literature. We find that corrosion rates, the content of residual sacrificial metal, the average ligament size and the densification by shrinkage strongly depend on the synthesis protocol and show the consequences on the mechanical properties. NPG exhibits an open-cell nanoscale network structure with a well-defined characteristic size of the metal phase, the so-called ligaments. These can be scaled ranging from as small as 5 nm up to 1 μm 17-21 so that NPG established as a model system for the investigation of nanoscale materials behavior.Studies of the catalytic or mechanical behavior of NPG by different authors do not report consistent observations in all instances. The role of the residual sacrificial metal content as an origin for the remarkable catalytic activity (e.g. for CO oxidation) is under discussion. 22-25As another instance, reports on the mechanical strength and stiffness of nominally comparable structures disagree by up to one order of magnitude. 26,27 Therefore it is significant to note that a number of different dealloying protocols are applied within these studies. Conceivably, diverging observations on the material's behavior may be related to the impact of these protocols on the microstructure. Here, we explore this issue by comparing the microstructures of NPG made by three common preparation routes.The elementary steps of dealloying are the removal of atoms of the less noble element from the parent phase and the redistribution of the nobler element atoms on the crystal lattice by surface diffusion. 21This creates a network structure, typically with sizes between 5 and 20 nm. 28,29 When assuming complete removal of the less noble element from a parent alloy (e.g. Ag x Au 1-x which is composed of similarly sized atoms), the solid volume fraction, ϕ, of the porous structure will ideally agree with the atom fraction of the more noble element in the master alloy. Yet, the shrinkage during dealloying may reduce the external sample dimensions, thereby increasing ϕ.29 Structural coarsening begins during dealloying 28 and its rate is affected e.g. by the composition of the electrolyte, 30 additional alloy elements 31,32 or the temperature. 33 These observations emphasize that details of the dealloying process may have a substantial effect on the microstructure of the nanoporous material. Table I lists several synthesis protocols for NPG; these are often implicitly expected to result in similar structures. As the object of...

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Silver residues as a possible key to a remarkable oxidative catalytic activity of nanoporous gold

Cited by 127 publications

References 62 publications

Recent advances in silver-based heterogeneous catalysts for green chemistry processes

Recent advances in silver-based heterogeneous catalysts for green chemistry processes

Nanoporous Gold Electrodes and Their Applications in Analytical Chemistry

Nanoporous Gold by Alloy Corrosion: Method-Structure-Property Relationships

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