Atomic Imaging of Carbon-Supported Pt, Pt/Co, and Ir@Pt Nanocatalysts by Atom-Probe Tomography

Li, Tong; Bagot, P.A.J.; Christian, Elvis; Theobald, Brian; Sharman, Jonathan; Özkaya, Doğan; Moody, Michael P.; Tsang, Shik Chi Edman; Smith, George Davey

doi:10.1021/cs401117e

Cited by 52 publications

(47 citation statements)

References 36 publications

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“…Unlike for crystallized materials, the investigation of the location and distribution of Al atoms is impossible in ASAs by routine characterization methods, such as X-ray diffraction (XRD) and highresolution transmission electron microscopy (HRTEM), due to their amorphous structure. Atom probe tomography (APT) can provide quantitative three-dimensional (3D) information on elemental distributions in catalyst nanoparticles at the atomic scale 37,38 . It has recently been employed with sub-nanometerscale resolution on zeolite-based catalysts to establish their structure-composition-property relationships [39][40][41][42][43] .…”

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confidence: 99%

Acidity enhancement through synergy of penta- and tetra-coordinated aluminum species in amorphous silica networks

Wang

Jiang

et al. 2020

Nat Commun

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Amorphous silica-aluminas (ASAs) are widely used in acid-catalyzed C-H activation reactions and biomass conversions in large scale, which can be promoted by increasing the strength of surface Brønsted acid sites (BAS). Here, we demonstrate the first observation on a synergistic effect caused by two neighboring Al centers interacting with the same silanol group in flame-made ASAs with high Al content. The two close Al centers decrease the electron density on the silanol oxygen and thereby enhance its acidity, which is comparable to that of dealuminated zeolites, while ASAs with small or moderate Al contents provide mainly moderate acidity, much lower than that of zeolites. The ASAs with enhanced acidity exhibit outstanding performances in C-H bond activation of benzene and glucose dehydration to 5-hydroxymethylfurfural, simultaneously with an excellent calcination stability and resistance to leaching, and they offer an interesting potential for a wide range of acid and multifunctional catalysis.

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confidence: 99%

Acidity enhancement through synergy of penta- and tetra-coordinated aluminum species in amorphous silica networks

Wang

Jiang

et al. 2020

Nat Commun

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“…Even though such studies have investigated the nature of coke formed during ethanol conversion reactions at a bulk average level or at a macroscopic level, nanoscale imaging of the carbonaceous molecules present in spent catalyst materials using depth profiling is lacking in the literature. Recently, a relatively new characterization capability called atom probe tomography (APT) has been increasingly used to perform 3D quantitative analysis of element distribution in catalyst materials with sub-nanometer–scale spatial resolution and high mass sensitivity up to the few parts per million level of concentration of elements in materials2627282930313233. It has also been demonstrated that APT can be used to quantitatively image the Al distribution in zeolite materials, and evidence for changes in Al distribution can be obtained by comparing results before and after severe steam treatment of HZSM-5 at 700 °C34.…”

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confidence: 99%

Discerning the Location and Nature of Coke Deposition from Surface to Bulk of Spent Zeolite Catalysts

Devaraj

Vijayakumar

Bao

et al. 2016

Sci Rep

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The formation of carbonaceous deposits (coke) in zeolite pores during catalysis leads to temporary deactivation of catalyst, necessitating regeneration steps, affecting throughput, and resulting in partial permanent loss of catalytic efficiency. Yet, even to date, the coke molecule distribution is quite challenging to study with high spatial resolution from surface to bulk of the catalyst particles at a single particle level. To address this challenge we investigated the coke molecules in HZSM-5 catalyst after ethanol conversion treatment by a combination of C K-edge X-ray absorption spectroscopy (XAS), 13C Cross polarization-magic angle spinning nuclear magnetic resonance (CP-MAS NMR) spectroscopy, and atom probe tomography (APT). XAS and NMR highlighted the aromatic character of coke molecules. APT permitted the imaging of the spatial distribution of hydrocarbon molecules located within the pores of spent HZSM-5 catalyst from surface to bulk at a single particle level. 27Al NMR results and APT results indicated association of coke molecules with Al enriched regions within the spent HZSM-5 catalyst particles. The experimental results were additionally validated by a level-set–based APT field evaporation model. These results provide a new approach to investigate catalytic deactivation due to hydrocarbon coking or poisoning of zeolites at an unprecedented spatial resolution.

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“…Another type of support commonly used for catalytic and electrocatalytic applications is based on high surface area porous carbon, and different C-supported commercial catalysts were analyzed by APT [121]: C-supported Pt, Pt/Co, and Ir@Pt nanoparticles. The samples were first dissolved in a methanol/water solution prior to sample preparation by electrophoresis.…”

Section: Carbon-supported Nanoparticlesmentioning

confidence: 99%

“…showing the presence of methanol and water fragment, as well as the expected Pt 1+ species and the non-expected Na 1+ from the synthesis. Reprinted with permission from [121]. Copyright (2014) American Chemical Society.…”

Section: Carbon-supported Nanoparticlesmentioning

confidence: 99%

Atom Probe Tomography for Catalysis Applications: A Review

2019

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Atom probe tomography is a well-established analytical instrument for imaging the 3D structure and composition of materials with high mass resolution, sub-nanometer spatial resolution and ppm elemental sensitivity. Thanks to recent hardware developments in Atom Probe Tomography (APT), combined with progress on site-specific focused ion beam (FIB)-based sample preparation methods and improved data treatment software, complex materials can now be routinely investigated. From model samples to complex, usable porous structures, there is currently a growing interest in the analysis of catalytic materials. APT is able to probe the end state of atomic-scale processes, providing information needed to improve the synthesis of catalysts and to unravel structure/composition/reactivity relationships. This review focuses on the study of catalytic materials with increasing complexity (tip-sample, unsupported and supported nanoparticles, powders, self-supported catalysts and zeolites), as well as sample preparation methods developed to obtain suitable specimens for APT experiments.

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Atomic Imaging of Carbon-Supported Pt, Pt/Co, and Ir@Pt Nanocatalysts by Atom-Probe Tomography

Abstract: SI 1. A series of TEM images c.a. 3 nm Pt/Ru nanoparticles deposited on Pt-Rh APT tips for 2 seconds, 3seconds and 6 seconds at 1.5V. It reveals that the amount of Pt/Ru nanoparticles increases with the deposition time.

Cited by 52 publications

References 36 publications

Acidity enhancement through synergy of penta- and tetra-coordinated aluminum species in amorphous silica networks

Acidity enhancement through synergy of penta- and tetra-coordinated aluminum species in amorphous silica networks

Discerning the Location and Nature of Coke Deposition from Surface to Bulk of Spent Zeolite Catalysts

Atom Probe Tomography for Catalysis Applications: A Review

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