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NAP-XPS Laboratory-Based Near-Ambient Pressure(NAP) X-ray Photoelectron Spectrometer (XPS)

English title NAP-XPS Laboratory-Based Near-Ambient Pressure(NAP) X-ray Photoelectron Spectrometer (XPS)
Applicant Züttel Andreas
Number 170736
Funding scheme R'EQUIP
Research institution Laboratoire des matériaux pour les énergies renouvelables EPFL - SB - ISIC - LMER
Institution of higher education EPF Lausanne - EPFL
Main discipline Physical Chemistry
Start/End 01.01.2017 - 30.06.2019
Approved amount 550'000.00
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All Disciplines (2)

Discipline
Physical Chemistry
Chemical Engineering

Keywords (5)

Adsorption; Catalysis; Chemical state; Reaction mechanism; Photoelectron Spectroscopy

Lay Summary (German)

Lead
Photoelektronen Spektroskopie bei kleinem Druck (<20 mbar) stellt eine einzigartige Methode zur Untersuchung der chemischen Zusammensetzung von Oberflächen dar. Materialien, welche mit der Gas phase in Kontakt stehen verändern sich durch die Wechselwirkung mit den Gasmolekülen. Die Mechanismen der Adsorption von Gasmolekülen, sind für das Verständnis der Aktivität und Selektivität von katalytischen Oberflächen von entscheidender Bedeutung. Zudem führt die Wechselwirkung von Oberflächen mit der Gasphase of zu Veränderungen der Oberfläche, welche mit dem NAP-XPS in-situ verfolgt werden können.
Lay summary

Die Analyse von Oberflächen durch Photoelektronen Spektroskopie (XPS) war lange Zeit auf Oberflächen im Ultrahochvakuum (UHV) beschränkt und erlaubte die chemische Zusammensetzung sowie de chemischen Bindungen an der Oberfläche von im UHV stabilen Materialien zu untersuchen. Mit der Entwicklung der Photoelektronen Spektroskopie unter Druck (<20 mbar) eröffnet sich die Möglichkeit Veränderungen an der Oberflächen während der Wechselwirkung mit der Gas phase zu verfolgen und damit Adsorptionen und Reaktionen von Gasmolekülen in-situ zu analysieren. Damit wird es möglich, z.B. die Veränderungen an heterogenen Katalysatoren währen der Reaktion zu verfolgen und sowohl den Reaktionsmechanismus als auch den Zusammenhang zwischen der Oberfläche und der Aktivität und Selektivität zu verstehen. Dies ist von fundamentaler Bedeutung für die Aktivitäten derForschungsgruppen im Energypolis der EPFL in Sion, welche insbesondere die Wechselwirkung von Wasserstoff und CO2 mit Oberflächen untersuchen.

 

Direct link to Lay Summary Last update: 05.01.2017

Responsible applicant and co-applicants

Associated projects

Number Title Start Funding scheme
163010 Investigation and modeling of new CO2 Adsorption materials and their interaction with hydrogen 01.10.2015 Project funding (Div. I-III)

Abstract

The analysis of surfaces by X-ray photoelectron spectroscopy in ultra-high vacuum (UHV) reveals the chemical state and the elemental composition of the top surface layers (typically, < 5 nm, depending on the electron kinetic energy). The top surface layers form the interface between the solid and the gas phase, and therefore are the atoms, which interact with the adsorbents. Recently, commercialy available spectrometers were developed, to perform XPS not only in UHV but also in a gas atmosphere up to about 20 mbar gas pressure, i.e. at near ambient pressure conditions (NAP). This allows not only to ana- lyse the surface in-situ, i.e. during the interaction of the surface and the gas phase takes place, namely the substrate and the substrate with adsorbents as well as the adsorbents itself can be analysed in view of the composition and the chemical state. The analysis of the interaction of gases with surfaces is a crucial part of the research activities of the research groups located at Energypolis, EPFL Valais/Wallis focussing on the fundamental aspects of the extraction of CO2 from the atmosphere, production and storage of hydrogen and the reduction of CO2 with hydrogen in order to store renewable energy. There- fore, the near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) is essential for the platform analytical equipment.NAP-XPS has become an immerging tool over a wide range of research fields such as heterogeneous catalysis, environmental science, and electrochemistry. The number of the installation is rapidly increas- ing worldwide: Total = 27 (as of 2012), laboratory-based = 14, synchrotron-based = 13. In Switzerland, the first synchrotron-based NAP-XPS was installed at the Swiss Light Source (Paul Scherrer Institute) in 2012. For the new campus EPFL Valais/Wallis, we plan to install the first laboratory-based NAP-XPS in Switzerland and provide an unique experimental platform for the investigation of gas solid interactions to all interested researcher.NAP-XPS provides information about electronic structure of matter (gas, liquid, solid) under defined conditions and bridges the pressure gap between an ultra-high vacuum-based surface-science experi- ment and an experiment simulating realistic conditions at mbar pressures, thus providing valuable in- formation about interfacial reactions, gas-solid, gas-liquid, and liquid-solid reactions. For example, in heterogeneous catalysis, restructuring of a surface during reactions and the dependence of surface properties on gas atmosphere can be analysed in situ with respect to elemental composition, oxidation state, and chemical specificity of surfaces and adsorbates on the molecular scale at pressures of up to 20 mbar or even higher. A correlation between surface chemistry and surface properties is determined by the in situ surface analysis.For investigations of interfacial reactions, for examples, in heterogonous catalysis, hydrogen storage, CO2 capture and CO2 reduction, the laboratory-based NAP-XPS allows immediate investigations, as com- pared to the synchrotron-based NAP-XPS at SLS, and the sample environment can be perfectly con- trolled, i.e. no transport, no exposure to air and local synthesis of samples becomes possible. Further, the NAP-XPS system is to be combined with a multifunctional UHV system comprised of, for example, atomic force microscope (AFM), Kevin probe force microscope (KPFM). The preparation of the nano- scale catalysts (metallic clusters) as well as thin film deposition in the UHV system avoids the exposure to air and uncontrolled reactions during transport of the samples. The instrument will be connected with a transfer system to an Ar-glove box, which enables also the transfer of samples from outside into the NAP-XPS without exposure to the atmosphere. Therefore, we will be able to work with in-situ prepared samples as well as samples from anywhere else under fully controlled conditions. Moreover, the labora- tory-based NAP-XPS system could be operated more frequently, compared to a synchrotron-based NAP- XPS which requires beam time at a synchrotron.The instrument is essential for the internal collaboration between the groups in EPFL but also offers a powerful tool for collaboration with leading groups in a wide range of research fields in Switzerland and worldwide.
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