Activated adsorption of methane on Pt(1 1 1) —an<i>in situ</i>XPS study

Fuhrmann, Thomas; Kinne, M.; Tränkenschuh, B.; Papp, Christian; Zhu, Junfa; Denecke, R.; Steinrück, Hans‐Peter

doi:10.1088/1367-2630/7/1/107

Cited by 69 publications

(113 citation statements)

References 47 publications

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“…In this sense, H 2 (g) would disappear while methylidyne is formed. The only possible subsequent reaction step at low hydrogen pressure is the formation of surface carbon, which is reported to occur at temperatures above 500 K. [56] The value is in line with the high value of 120 kJ mol À1 for the calculated energy barrier. At sufficiently high coverage, carbon atoms would gather to form monolayer graphene, [46] which has been detected when heating above 890 K. [73] What happens when methane dehydrogenates on Pt nanoparticles instead of extended surfaces?…”

supporting

confidence: 65%

“…[56] The C 1s spectra were fitted with asymmetric Voigt profiles assuming that several CH x species may coexist. Specifically, the peaks associated with CH 3 and CH were fitted with two components each, which accounted for the vibrational splitting.…”

mentioning

confidence: 99%

“…These values correspond to those observed for PtA C H T U N G T R E N N U N G (111). [56] All peaks widths were kept constant for the fitted components.…”

mentioning

confidence: 99%

“…www.chemeurj.org et al, [56] who detected methyl species on PtA C H T U N G T R E N N U N G (111) single crystals at low temperature and found that, upon heating to 260 K, methyl simultaneously recombines to form methane and decomposes to form methylidyne. Once methylidyne is formed, the system is trapped in a thermodynamic sink.…”

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confidence: 99%

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Methane Activation by Platinum: Critical Role of Edge and Corner Sites of Metal Nanoparticles

Viñes

Lykhach

Staudt

et al. 2010

Chemistry A European J

133

107

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Complete dehydrogenation of methane is studied on model Pt catalysts by means of state-of-the-art DFT methods and by a combination of supersonic molecular beams with high-resolution photoelectron spectroscopy. The DFT results predict that intermediate species like CH(3) and CH(2) are specially stabilized at sites located at particles edges and corners by an amount of 50-80 kJ mol(-1). This stabilization is caused by an enhanced activity of low-coordinated sites accompanied by their special flexibility to accommodate adsorbates. The kinetics of the complete dehydrogenation of methane is substantially modified according to the reaction energy profiles when switching from Pt(111) extended surfaces to Pt nanoparticles. The CH(3) and CH(2) formation steps are endothermic on Pt(111) but markedly exothermic on Pt(79). An important decrease of the reaction barriers is observed in the latter case with values of approximately 60 kJ mol(-1) for first C-H bond scission and 40 kJ mol(-1) for methyl decomposition. DFT predictions are experimentally confirmed by methane decomposition on Pt nanoparticles supported on an ordered CeO(2) film on Cu(111). It is shown that CH(3) generated on the Pt nanoparticles undergoes spontaneous dehydrogenation at 100 K. This is in sharp contrast to previous results on Pt single-crystal surfaces in which CH(3) was stable up to much higher temperatures. This result underlines the critical role of particle edge sites in methane activation and dehydrogenation.

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supporting

confidence: 65%

mentioning

confidence: 99%

“…These values correspond to those observed for PtA C H T U N G T R E N N U N G (111). [56] All peaks widths were kept constant for the fitted components.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Methane Activation by Platinum: Critical Role of Edge and Corner Sites of Metal Nanoparticles

Viñes

Lykhach

Staudt

et al. 2010

Chemistry A European J

133

107

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“…composition and oxidation state) of the outermost 1-10 atomic layers of catalyst surfaces under ultra-high vacuum (10 À13 mbar). Over the past 15 years, time-resolved XPS [29] has helped unravel surface reaction mechanisms in precious metal catalyzed alcohol [30,31] and alkene [32,33] selective oxidation, C-C coupling, [34,35] dehalogenation, [36,37] and thermal [38][39][40] and photochemical [41] C-H activation, but has been restricted to studies of strongly-bound reactants over pristine model systems in the absence of solvents. Recent advances in surface science instrumentation, notably access to 3rd-generation synchrotron light sources and differentially-pumped, electron optics, [42] are now helping bridge the so-called 'pressure gap' in catalysis [12] and facilitate time-resolved XPS measurements at pressures up to 1 mbar, [43] sufficient to stabilize weakly bound adsorbates e.g.…”

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confidence: 99%

Active Site Elucidation in Heterogeneous Catalysis via In Situ X-Ray Spectroscopies

Lee¹

2012

Aust. J. Chem.

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Nanostructured heterogeneous catalysts will play a key role in the development of robust artificial photosynthetic systems for water photooxidation and CO 2 photoreduction. Identifying the active site responsible for driving these chemical transformations remains a significant barrier to the design of tailored catalysts, optimized for high activity, selectivity, and lifetime. This highlight reveals how select recent breakthroughs in the application of in situ surface and bulk X-ray spectroscopies are helping to identify the active catalytic sites in a range of liquid and gas phase chemistry.

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