STM studies of cyclohexene hydrogenation/dehydrogenation and its poisoning by carbon monoxide on Pt(111)

Montano, Max; Salmerón, Miquel; Somorjai, Gábor A.

doi:10.1016/j.susc.2006.02.026

Cited by 48 publications

(54 citation statements)

References 28 publications

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“…The high pressure scanning tunneling microscopy allows us to look at surface mobility (figure 10a) [24][25][26][27][28] , while sum frequency generation vibrational spectroscopy allows us to measure the vibrational spectra of adsorbed molecules [29][30][31] (figure 10b). Figure 11a shows that during cyclohexene hydrogenation/dehydrogenation the three species on the catalytically active surfaces are 1,3 cyclohexadiene π-allyl and 1,4 cyclohexadiene [32] .…”

Section: Catalyst Characterization Under Reaction Conditionsmentioning

confidence: 99%

“…The mobility of the adsorbate must be greater than 100 Ǻ per millisecond to make it impossible to exhibit ordered structure (figure 11b). However, when the reaction is poisoned by the introduction of carbon monoxide ordered structure forms and the catalytic turnover stops (figure 11c) [26] . Thus the mobility is an important feature of the catalytically reactive surface as the adsorbate has to be mobile in order to turn over.…”

Section: Catalyst Characterization Under Reaction Conditionsmentioning

confidence: 99%

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Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and Their Influence on Activity and Selectivity

2008

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Recent breakthroughs in synthesis in nanosciences have achieved control of size and shapes of nanoparticles that are relevant for catalyst design. In this article, we review the advance of synthesis of nanoparticles, fabrication of two and three dimensional model catalyst system, characterization, and studies of activity and selectivity. The ability to synthesize monodispersed platinum and rhodium nanoparticles in the 1-10 nm range permitted us to study the influence of composition, structure, and dynamic properties of monodispersed metal nanoparticle on chemical reactivity and selectivity. We review the importance of size and shape of nanoparticles to determine the reaction selectivity in multi-path reactions. The influence of metal-support interaction has been studied by probing the hot electron flows through the metal-oxide interface in catalytic nanodiodes. Novel designs of nanoparticle catalytic systems are discussed.2

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Section: Catalyst Characterization Under Reaction Conditionsmentioning

confidence: 99%

Section: Catalyst Characterization Under Reaction Conditionsmentioning

confidence: 99%

Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and Their Influence on Activity and Selectivity

2008

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“…High pressure scanning tunneling microscopy (HPSTM) provides atomically resolved images of surfaces under high gas pressures and during catalytic reactions [35][36][37] ( Figure 6c). While most spectroscopic techniques yield time-averaged information of structure and bonding, STM detects surface dynamics when motion of adsorbates and metal atoms occurs at speeds comparable to or less than the scan rate of approximately 10 µm/s.…”

Section: Iiia Development Of Instruments For High Pressure Studiesmentioning

confidence: 99%

Molecular surface chemistry by metal single crystals and nanoparticles from vacuum to high pressure

2008

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Model systems for studying molecular surface chemistry have evolved from single crystal surfaces at low pressure to colloidal nanoparticles at high pressure. Low pressure surface structure studies of platinum single crystals using molecular beam surface scattering and low energy electron diffraction techniques probe the unique activity of defects, steps and kinks at the surface for dissociation reactions (H-H, C-H, C-C, O=O bonds). High-pressure investigations of platinum single crystals using sum frequency generation vibrational spectroscopy have revealed the presence and the nature of reaction intermediates. High pressure scanning tunneling microscopy of platinum single crystal surfaces showed adsorbate mobility during a catalytic reaction. Nanoparticle systems are used to determine the role of metal-oxide interfaces, site blocking and the role of surface structures in reactive surface chemistry. The size, shape and composition of nanoparticles play important roles in determining reaction activity and selectivity.

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“…This method permits the surface-specific XPS signal to be examined and the surface composition of the bimetallic nanoparticles to be determined. The adsorbate mobility during catalytic turnover has been observed by high pressure scanning tunneling microscopy 41,[46][47][48] (Figure 13a). No distinctive feature of the surface can be observed when scanning the surface at the rate of 100 Å per millisecond during the hydrogenation/dehydrogenation of cyclohexene or hydrogenation of ethylene.…”

Section: Surface Composition and Oxidation States Under Reaction Condmentioning

confidence: 99%

Advancing the Frontiers in Nanocatalysis, Biointerfaces, and Renewable Energy Conversion by Innovations of Surface Techniques

2009

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The challenge of chemistry in the 21 st century is to achieve 100% selectivity of the desired product molecule in multi-path reactions (green chemistry) and develop renewable energy based processes. Surface chemistry and catalysis play key roles in this enterprise. Development of in-situ surface techniques such as high pressure scanning tunneling microscopy (STM), sum frequency generation (SFG) vibrational spectroscopy, time-resolved Fourier Transform Infrared (FT-IR) methods and ambient pressure X-ray photoelectron spectroscopy (AP-XPS) enabled the rapid advancing of three fields; nanocatalysts, biointerfaces, and renewable energy conversion chemistry. In materials nanoscience, synthetic methods have been developed to produce monodisperse metal and oxide nanoparticles (NP) in the 0.8 -10 nm range with controlled shape, oxidation states, and composition, which can be used as selective catalysts since chemical selectivity appears to be dependent on all of these experimental parameters. New spectroscopic and microscopic techniques have been developed that operate under reaction conditions and reveal the dynamic change of molecular structure of catalysts and adsorbed molecules as the reactions proceed with changes in reaction intermediates, catalyst composition, and oxidation states. SFG vibrational spectroscopy detects amino acids, peptides and proteins adsorbed at hydrophobic and hydrophilic interfaces and monitors the change of surface structure and interactions with coadsorbed water. Exothermic reactions and photons generate hot electrons in metal nanoparticles that may be utilized in chemical energy conversion. The photo-splitting of water and carbon dioxide that are important research directions in renewable energy conversion is discussed.2

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STM studies of cyclohexene hydrogenation/dehydrogenation and its poisoning by carbon monoxide on Pt(111)

Cited by 48 publications

References 28 publications

Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and Their Influence on Activity and Selectivity

Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and Their Influence on Activity and Selectivity

Molecular surface chemistry by metal single crystals and nanoparticles from vacuum to high pressure

Advancing the Frontiers in Nanocatalysis, Biointerfaces, and Renewable Energy Conversion by Innovations of Surface Techniques

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