Quantitative 3D Characterization of Nanoporous Gold Nanoparticles by Transmission Electron Microscopy

Mahr, Christoph; Dworzak, Alexandra; Schowalter, Marco; Oezaslan, Mehtap; Rosenauer, A.

doi:10.1017/s1431927621000519

Cited by 5 publications

(9 citation statements)

References 51 publications

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Section: Tuning Of Structure and Composition During Dealloyingmentioning

confidence: 99%

“…A comprehensive reconstruction study of porous Au nanoparticles prepared by dealloying has been reported Figure illustrates a reconstruction of a single representative porous Au-rich particle prepared by electrochemical dealloying.…”

Section: Tuning Of Structure and Composition During Dealloyingmentioning

confidence: 99%

“…Experimentally more demanding approaches to measuring a mean ligament size involve the analysis of 3D reconstructions. ,,,,− This may provide variously defined measures for size. An example, based on “granulometry”, is the mean, L G , over all materials points in the solid phase, of the diameter of the largest in-fitting sphere containing the respective point. , A closer inspection of such approaches reveals various issues that require attention.…”

Section: Microstructure and Metrics For Its Descriptionmentioning

confidence: 99%

“…A tortuosity parameter for viscous flow in NPG has been inferred from imbibition experiments, and its value, τ = 3.2 ± 0.2, was found to be compatible with that, τ = 3.5 ± 0.3, reported for porous Vycor glass. , The agreement is in keeping with the notion that the Vycor microstructure, resulting from spinodal decomposition, is equally well compatible with the leveled-wave model as is NPG. Branch and geometric tortuosities for NPG, with values in the range 1.2 < τ < 2.0, have been estimated based on φ, or on tomographic reconstructions of nanoparticles . Apparently, these parameters remain yet to be linked to observations on transport in NPG.…”

Section: Microstructure and Metrics For Its Descriptionmentioning

confidence: 99%

“…A comprehensive reconstruction study of porous Au nanoparticles prepared by dealloying has been reported. 246 Figure 7 illustrates a reconstruction of a single representative porous Au-rich particle prepared by electrochemical dealloying. Structural information like pore size, porosity, specific surface area, and tortuosity were determined for porous Aurich nanoparticles with an initial diameter of 77 ± 22 nm, which can be used for the simulations and models of diffusion and mass transport phenomena in confined environments.…”

Section: Dealloyed Porous Nanoparticlesmentioning

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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Section: Tuning Of Structure and Composition During Dealloyingmentioning

confidence: 99%

Section: Tuning Of Structure and Composition During Dealloyingmentioning

confidence: 99%

Section: Microstructure and Metrics For Its Descriptionmentioning

confidence: 99%

Section: Microstructure and Metrics For Its Descriptionmentioning

confidence: 99%

Section: Dealloyed Porous Nanoparticlesmentioning

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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New Perspectives for Evaluating the Mass Transport in Porous Catalysts and Unfolding Macro- and Microkinetics

et al. 2022

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In this article we shed light on newly emerging perspectives to characterize and understand the interplay of diffusive mass transport and surface catalytic processes in pores of gas phase metal catalysts. As a case study, nanoporous gold, as an interesting example exhibiting a well-defined pore structure and a high activity for total and partial oxidation reactions is considered. PFG NMR (pulsed field gradient nuclear magnetic resonance) measurements allowed here for a quantitative evaluation of gas diffusivities within the material. STEM (scanning transmission electron microscopy) tomography furthermore provided additional insight into the structural details of the pore system, helping to judge which of its features are most decisive for slowing down mass transport. Based on the quantitative knowledge about the diffusion coefficients inside a porous catalyst, it becomes possible to disentangle mass transport contributions form the measured reaction kinetics and to determine the kinetic rate constant of the underlying catalytic surface reaction. In addition, predictions can be made for an improved effectiveness of the catalyst, i.e., optimized conversion rates. This approach will be discussed at the example of low-temperature CO oxidation, efficiently catalysed by npAu at 30 °C. The case study shall reveal that novel porous materials exhibiting well-defined micro- and mesoscopic features and sufficient catalytic activity, in combination with modern techniques to evaluate diffusive transport, offer interesting new opportunities for an integral understanding of catalytic processes. Graphical Abstract

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Characterization of structure and mixing in nanoparticle hetero-aggregates using convolutional neural networks: 3D-reconstruction versus 2D-projection

Mahr,

Stahl,

Gerken

et al. 2024

Ultramicroscopy

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Quantitative 3D Characterization of Nanoporous Gold Nanoparticles by Transmission Electron Microscopy

Abstract: Abstract

Cited by 5 publications

References 51 publications

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

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

New Perspectives for Evaluating the Mass Transport in Porous Catalysts and Unfolding Macro- and Microkinetics

Characterization of structure and mixing in nanoparticle hetero-aggregates using convolutional neural networks: 3D-reconstruction versus 2D-projection

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