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Harmsen, Jma Jan; Jansen, Wpa Wim; Hoebink, Jhbj Jozef; Schouten, JC Jaap; Brongersma, H.H.

doi:10.1023/a:1016633114136

Cited by 21 publications

(5 citation statements)

References 14 publications

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“…One particular technique of interest is ion scattering, which uses ionized gas molecules as depth sensitive probes, like low energy ion scattering [112][113][114]. When reactive gas molecules are employed as probing ion sources, like atom probe microscopy (APM), an atomically resolved layer by layer construction of catalysts can be achieved [115][116][117][118][119].…”

Section: Summary and Future Challengesmentioning

confidence: 99%

Nanocatalysis II: In Situ Surface Probes of Nano-Catalysts and Correlative Structure–Reactivity Studies

Alayoǧlu

Somorjai

2014

Catal Lett

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Model nano-catalysts with monodisperse particle sizes and architectures are essential for a fundamental understanding of surface property dynamics during catalytic reactions. Surface tools and techniques, when conducted under catalytically relevant temperature and pressure conditions, render possible measurements of dynamic surface properties such as oxidation state, composition, coordination, and bonding. Near edge X-ray absorption fine structure (NEXAFS) spectroscopy with purposely built in situ reaction cells and ambient pressure X-ray photoelectron spectroscopy (APXPS) provide (near) surface sensitive and chemical specific information on the oxidation states of metal and oxide (co-)catalysts as well as adsorbent functional elements such C, O and N under reactive gas atmospheres and even liquid environments. Likewise, sum frequency generation (SFG) vibrational spectroscopy with in situ reaction cells helps uncover the bonding geometry and configuration of the topmost surface again under conditions pertinent to catalysis. Furthermore, the local dynamics in the nanoscale and on the single particle level are revealed by environmental transmission electron microscopy (ETEM) and the spectro-microscopy techniques equipped within. A correlative approach, where an array of these in situ tools and techniques were conducted in parallel with catalytic measurements, was employed to gain molecular insight into some of the modern scientific challenges in heterogeneous catalysis.Several case examples of this correlative approach are presented here. The CO oxidation reaction over hybrid nano-catalysts of Pt nanoparticles (NPs) with various mesoporous metal oxides such as Co 3 O 4 , MnO 2 and CeO 2 was explored in relation to bifunctional catalysis and interfacial charge transfer chemistry by using in situ NEXAFS spectroscopy. Likewise, bimetallic CoPt and PtSn nanoparticle catalysts supported on silica were investigated by using a combination of in situ NEXAFS spectroscopy and APXPS. Next, CO 2 hydrogenation was carried out over bimetallic CoPt/SiO 2 and Co/TiO 2 hybrid nano-catalysts. In this case, in situ NEXAFS spectroscopy, APXPS, and ETEM indicated severe, yet reversible, surface restructuring that involved hydrogen atom spillover. Finally, *2 nm Pt NPs were investigated using in situ SFG to study hydrogenation and hydrogenative isomerization reactions. Specifically, SFG indicated that the hydrogenation of furfural and crotonaldehyde proceed by interfacial hydrogen atom spillover from TiO 2 , while the hydrogenative isomerization of methylcyclopentane (MCP) proceeds by spillover and surface diffusion of cyclohexene over mesoporous zeolites. These studies unequivocally indicated the presence of a particular reaction channel that involved one way flow of charged (i.e. electrons or protons) or neutral species (i.e. reactants) at a broadly defined interface between metals and oxides. In addition to these case studies, experimental approaches employing capillary flow micro-reactors are discussed in relation toward t...

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Section: Summary and Future Challengesmentioning

confidence: 99%

Nanocatalysis II: In Situ Surface Probes of Nano-Catalysts and Correlative Structure–Reactivity Studies

Alayoǧlu

Somorjai

2014

Catal Lett

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“…It was found that the Ce remained immobile up to temperatures of at least 900 K. Low energy ion scattering (LEIS) measurements on fresh and used commercial three way catalysts (Pt/Rh/CeO 2 /gamma-Al 2 O 3 ) has demonstrated the poisoning effects of coke on the surface of the catalyst. 372 Under cold-start conditions, the Pt surface concentration was decreased by approximately 50%, but it was found that it could be regenerated completely. The authors stated that LEIS was superior for this task because conventional surface analysis techniques, such as XPS, SIMS or Auger spectroscopy, would have yielded ambiguous results because of their lack of specificity for the outermost atomic layer.…”

Section: Catalystsmentioning

confidence: 99%

Atomic spectrometry update. Industrial analysis: metals, chemicals and advanced materials

Fisher

Hinds

Nelms³

et al. 2002

J. Anal. At. Spectrom.

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“…A very common application is the analysis of coke and coke formation [11]. These carbon-rich phases are deposited during operation of the catalyst and often limit the lifetime of the material.…”

Section: Applicationsmentioning

confidence: 99%

Surface Microanalysis by Low-Energy Ion Scattering

Grehl¹,

Niehuis²,

Brongersma³

2011

Micros. Today

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Low-energy ion scattering (LEIS) has gained new capabilities and now provides high-end instrumentation for real-world surface analytical applications. Although the technique has been available for some decades, recent developments in instrumentation make the unique capabilities of LEIS accessible for everyday applications. Special ion energy analyzer designs allow LEIS to be used for non-destructive quantitative analysis of the elemental composition of the outermost atomic layer with high sensitivity and high mass resolution. At the same time, the composition of the first 10 nm of sub-surface material is also assessed. Applications are very broad, ranging from catalysts to various thin films to polymers.

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Cited by 21 publications

References 14 publications

Nanocatalysis II: In Situ Surface Probes of Nano-Catalysts and Correlative Structure–Reactivity Studies

Nanocatalysis II: In Situ Surface Probes of Nano-Catalysts and Correlative Structure–Reactivity Studies

Atomic spectrometry update. Industrial analysis: metals, chemicals and advanced materials

Surface Microanalysis by Low-Energy Ion Scattering

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