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Redokop E, Poelman H, Filez M, Ramachandran RK, Dendooven J, Detavernier C, Marin GB, Olsbye U, Galvita V. Aligning time-resolved kinetics (TAP) and surface spectroscopy (AP-XPS) for a more comprehensive understanding of ALD-derived 2D and 3D model catalysts. Faraday Discuss 2022; 236:485-509. [DOI: 10.1039/d1fd00120e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spectro-kinetic characterization of complex catalytic materials, i.e. relating the observed reaction kinetics to spectroscopic descriptors of the catalyst state, presents a fundamental challenge with a potentially significant impact on various...
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Shavorskiy A, D’Acunto G, Boix de la Cruz V, Scardamaglia M, Zhu S, Temperton RH, Schnadt J, Knudsen J. Gas Pulse-X-Ray Probe Ambient Pressure Photoelectron Spectroscopy with Submillisecond Time Resolution. ACS Appl Mater Interfaces 2021; 13:47629-47641. [PMID: 34590812 PMCID: PMC8517956 DOI: 10.1021/acsami.1c13590] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
A setup capable of conducting gas pulse-X-ray probe ambient pressure photoelectron spectroscopy with high time resolution is presented. The setup makes use of a fast valve that creates gas pulses with an internal pressure in the mbar range and a rising edge of few hundreds of microseconds. A gated detector based on a fast camera is synchronized with the valve operation to measure X-ray photoemission spectra with up to 20 μs time resolution. The setup is characterized in several experiments in which the N2 gas is pulsed either into vacuum or a constant flow of another gas. The observed width of the pulse rising edge is 80 μs, and the maximum internal pulse pressure is ∼1 mbar. The CO oxidation reaction over Pt (111) was used to demonstrate the capability of the setup to correlate the gas phase composition with that of the surface during transient supply of CO gas into an O2 stream. Thus, formation of both chemisorbed and oxide oxygen species was observed prior to CO gas perturbation. Also, the data indicated that both the Langmuir-Hinshelwood and Mars-van-Krevelen mechanisms play an important role in the oxidation of carbon monoxide under ambient conditions.
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Affiliation(s)
| | - Giulio D’Acunto
- Division
of Synchrotron Radiation, Department of Physics, Lund University, Lund 221 00, Sweden
| | | | | | - Suyun Zhu
- MAX
IV Laboratory, Lund University, Lund 221 00, Sweden
| | | | - Joachim Schnadt
- MAX
IV Laboratory, Lund University, Lund 221 00, Sweden
- Division
of Synchrotron Radiation, Department of Physics, Lund University, Lund 221 00, Sweden
| | - Jan Knudsen
- MAX
IV Laboratory, Lund University, Lund 221 00, Sweden
- Division
of Synchrotron Radiation, Department of Physics, Lund University, Lund 221 00, Sweden
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Artiglia L, Orlando F, Roy K, Kopelent R, Safonova O, Nachtegaal M, Huthwelker T, van Bokhoven JA. Introducing Time Resolution to Detect Ce 3+ Catalytically Active Sites at the Pt/CeO 2 Interface through Ambient Pressure X-ray Photoelectron Spectroscopy. J Phys Chem Lett 2017; 8:102-108. [PMID: 27936758 DOI: 10.1021/acs.jpclett.6b02314] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
X-ray photoelectron spectroscopy has been employed for the qualitative and quantitative characterization of both model and real catalytic surfaces. Recent progress in the detection of photoelectrons has enabled the acquisition of spectra at pressures up to a few tens of millibars. Although reducing the pressure gap represents a remarkable advantage for catalysis, active sites may be short-lived or hidden in the majority of spectator species. Time-resolved experiments, conducted under transient conditions, are a suitable strategy for discriminating between active sites and spectators. In the present work, we characterized the surface of a Pt/CeO2 powder catalyst at 1.0 mbar of a reacting mixture of carbon monoxide and oxygen and, by means of time resolution, identified short-lived active species. We replaced oxygen with nitrogen in the reaction mixture while fast-detecting the core level peaks of cerium. The results indicate that active Ce3+ sites form transiently at the surface when the oxygen is switched off. Analysis of the depth profile shows that Ce3+ ions are located at the ceria surface. The same experiment, performed on platinum-free ceria, reveals negligible reduction, indicating that platinum boosts the formation of Ce3+ active sites at the interface.
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Affiliation(s)
- Luca Artiglia
- Paul Scherrer Institute , CH-5232 Villigen, Switzerland
| | | | - Kanak Roy
- Institute for Chemical and Bioengineering, ETH Zurich , CH-8093 Zurich, Switzerland
| | - René Kopelent
- Paul Scherrer Institute , CH-5232 Villigen, Switzerland
| | - Olga Safonova
- Paul Scherrer Institute , CH-5232 Villigen, Switzerland
| | | | | | - Jeroen A van Bokhoven
- Paul Scherrer Institute , CH-5232 Villigen, Switzerland
- Institute for Chemical and Bioengineering, ETH Zurich , CH-8093 Zurich, Switzerland
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Shavorskiy A, Neppl S, Slaughter DS, Cryan JP, Siefermann KR, Weise F, Lin MF, Bacellar C, Ziemkiewicz MP, Zegkinoglou I, Fraund MW, Khurmi C, Hertlein MP, Wright TW, Huse N, Schoenlein RW, Tyliszczak T, Coslovich G, Robinson J, Kaindl RA, Rude BS, Ölsner A, Mähl S, Bluhm H, Gessner O. Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources. Rev Sci Instrum 2014; 85:093102. [PMID: 25273702 DOI: 10.1063/1.4894208] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ~0.1 mm spatial resolution and ~150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E(p) = 150 eV and an electron kinetic energy range KE = 503-508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ~9 ns at a pass energy of 50 eV and ~1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular spread with the retarding ratio can be well approximated by applying Liouville's theorem of constant emittance to the electron trajectories inside the lens system. The performance of the setup is demonstrated by characterizing the laser fluence-dependent transient surface photovoltage response of a laser-excited Si(100) sample.
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Affiliation(s)
- Andrey Shavorskiy
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Stefan Neppl
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Daniel S Slaughter
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - James P Cryan
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Katrin R Siefermann
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Fabian Weise
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Ming-Fu Lin
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Camila Bacellar
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Michael P Ziemkiewicz
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Ioannis Zegkinoglou
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Matthew W Fraund
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Champak Khurmi
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Marcus P Hertlein
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Travis W Wright
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Nils Huse
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Robert W Schoenlein
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Tolek Tyliszczak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Giacomo Coslovich
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Joseph Robinson
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Robert A Kaindl
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Bruce S Rude
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | | | - Sven Mähl
- SPECS Surface Nano Analysis GmbH, 13355 Berlin, Germany
| | - Hendrik Bluhm
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Oliver Gessner
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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