<i>IN-SITU</i> CORE-LEVEL PHOTOELECTRON SPECTROSCOPY OF ADSORBATES ON SURFACES INVOLVING A MOLECULAR BEAM — GENERAL SETUP AND FIRST EXPERIMENTS

Denecke, R.; Kinne, M.; Whelan, Caroline M.; Steinrück, Hans‐Peter

doi:10.1142/s0218625x0200297x

Cited by 95 publications

(69 citation statements)

References 8 publications

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“…16 The preparation chamber provides typical surface-science instruments such as low energy electron diffraction (LEED), electron beam evaporators for metal deposition (Focus EFM 3), and a sputter gun (Specs IQE 11/35). The measurement chamber is equipped with an electron energy analyzer (Omicron EA 125 HR U7) and is directly connected to a supersonic molecular beam and an evaporator unit for LOHC deposition, which allows us to dose substances while taking XP spectra.…”

Section: Methodsmentioning

confidence: 99%

Alkyl chain length-dependent surface reaction of dodecahydro-N-alkylcarbazoles on Pt model catalysts

Gleichweit

Amende

Bauer

et al. 2014

The Journal of Chemical Physics

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Articles you may be interested inPerformance and characteristics of a high pressure, high temperature capillary cell with facile construction for operando x-ray absorption spectroscopy Rev. Sci. Instrum. 85, 084105 (2014) The concept of liquid organic hydrogen carriers (LOHC) holds the potential for large scale chemical storage of hydrogen at ambient conditions. Herein, we compare the dehydrogenation and decomposition of three alkylated carbazole-based LOHCs, dodecahydro-N-ethylcarbazole (H 12 -NEC), dodecahydro-N-propylcarbazole (H 12 -NPC), and dodecahydro-N-butylcarbazole (H 12 -NBC), on Pt(111) and on Al 2 O 3 -supported Pt nanoparticles. We follow the thermal evolution of these systems quantitatively by in situ high-resolution X-ray photoelectron spectroscopy. We show that on Pt(111) the relevant reaction steps are not affected by the different alkyl substituents: for all LOHCs, stepwise dehydrogenation to NEC, NPC, and NBC is followed by cleavage of the C-N bond of the alkyl chain starting at 380-390 K. On Pt/Al 2 O 3 , we discern dealkylation on defect sites already at 350 K, and on ordered, (111)-like facets at 390 K. The dealkylation process at the defects is most pronounced for NEC and least pronounced for NBC. © 2014 AIP Publishing LLC.

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Section: Methodsmentioning

confidence: 99%

Alkyl chain length-dependent surface reaction of dodecahydro-N-alkylcarbazoles on Pt model catalysts

Gleichweit

Amende

Bauer

et al. 2014

The Journal of Chemical Physics

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“…The XPS measurements were performed at the synchrotron facility BESSY II in Berlin at beamline U49/2 PGM1 with a transportable setup 30 equipped with an electron energy analyzer (Omicron EA 125 U7 HR), a low energy electron diffraction optics, a capillary array doser system, a quadrupole mass spectrometer for residual gas analysis, and a three-stage supersonic molecular beam.…”

Section: Methodsmentioning

confidence: 99%

Kinetics of the sulfur oxidation on palladium: A combined in situ x-ray photoelectron spectroscopy and density-functional study

Gotterbarm

Luckas

Höfert

et al. 2012

The Journal of Chemical Physics

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We studied the reaction kinetics of sulfur oxidation on the Pd(100) surface by in situ high resolution x-ray photoelectron spectroscopy and ab initio density functional calculations. Isothermal oxidation experiments were performed between 400 and 500 K for small amounts (∼0.02 ML) of preadsorbed sulfur, with oxygen in large excess. The main stable reaction intermediate found on the surface is SO 4 , with SO 2 and SO 3 being only present in minor amounts. Density-functional calculations depict a reaction energy profile, which explains the sequential formation of SO 2 , SO 3 , and eventually SO 4 , also highlighting that the in-plane formation of SO from S and O adatoms is the rate limiting step. From the experiments we determined the activation energy of the rate limiting step to be 85 ± 6 kJ mol −1 by Arrhenius analysis, matching the calculated endothermicity of the SO formation.

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“…A beam flag mounted on a pneumatic feed-through in the second pumping stage allowed for fast switching (< 0.1 s) of the beam. [55] . In the current experiments, methane (99.995 %, Linde) with a KE of 0.83 eV was used.…”

Section: Methodsmentioning

confidence: 99%

“…For more details on the experimental procedure, refer to the literature. [55] CH 4 and He gases were additionally cleaned by using cooling traps. Still, CO contamination generated in the nozzle could not be avoided due to the large gas exposure.…”

Section: Methodsmentioning

confidence: 99%

Microscopic Insights into Methane Activation and Related Processes on Pt/Ceria Model Catalysts

et al. 2010

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Ceria-based supported noble-metal catalysts release oxygen, which may help to reduce the formation of carbonaceous residues, for example during hydrocarbon reforming. To gain insight into the microscopic origins of these effects, a model study is performed under ultrahigh-vacuum conditions using single-crystal-based supported model catalysts. The model systems are based on ordered CeO(2)(111) films on Cu(111), on which Pt nanoparticles are grown by physical vapor deposition. The growth and structure of the surfaces are characterized by means of scanning tunneling microscopy, and the electronic structure and reactivity are probed by X-ray photoelectron spectroscopy. Specifically, it is shown that the fully oxidized CeO(2) thin films undergo slight reduction upon Pt deposition (CeO(1.99)). This effect is enhanced upon annealing (CeO(1.96)), thus indicating facile oxygen release and reverse spillover. The model system is structurally stable up to temperatures exceeding 700 K. The activation of methane is investigated using high-kinetic-energy CH(4) (0.83 eV), generated by a supersonic molecular beam. It is shown that dehydrogenation occurs under rapid formation of CH or C species without detectable amounts of CH(3) being formed, even at low temperatures (100 K). The released hydrogen spills over to the CeO(2) support, which leads to the formation of OH groups. At 200 K and above, the OH groups start to decompose leaving additional Ce(3+) centers behind (CeO(1.97-1.94)). At up to 700 K, carbon deposits are quantitatively removed by reaction with oxygen, which is supplied by reverse spillover from the CeO(2) film, thus leading to substantial reduction of the support (approximately CeO(1.90-1.85)).

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IN-SITU CORE-LEVEL PHOTOELECTRON SPECTROSCOPY OF ADSORBATES ON SURFACES INVOLVING A MOLECULAR BEAM — GENERAL SETUP AND FIRST EXPERIMENTS

Cited by 95 publications

References 8 publications

Alkyl chain length-dependent surface reaction of dodecahydro-N-alkylcarbazoles on Pt model catalysts

Alkyl chain length-dependent surface reaction of dodecahydro-N-alkylcarbazoles on Pt model catalysts

Kinetics of the sulfur oxidation on palladium: A combined in situ x-ray photoelectron spectroscopy and density-functional study

Microscopic Insights into Methane Activation and Related Processes on Pt/Ceria Model Catalysts

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