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Catalysts
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Spectroscopy in Catalysis
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Spectroscopy in Catalysis

A special issue of Catalysts (ISSN 2073-4344).

Deadline for manuscript submissions: closed (31 May 2019) | Viewed by 27762

Special Issue Editors

Dr. Jorg Radnik

E-Mail Website
Guest Editor
Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 44-46, 12203 Berlin, Germany
Interests: X-ray photoelectron spectroscopy, nanoparticles, catalysis, X-ray Absorption Spectroscopy, thin films, surface science
Dr. Giovanni Agostini

E-Mail Website
Guest Editor
CELLS-ALBA, Carretera B.P. 1413, Cerdanyola del Vallès, 08290 Barcelona Spain
Interests: X-ray Absorption Spectroscopy, in situ and operando experiment, catalysis, metal nanoparticles, spectroscopy combination

Special Issue Information

Dear Colleagues,

The basis of knowledge-based catalyst development is a comprehensive characterization of the catalyst and the catalytic process. Only sophisticated spectroscopic methods and the combination of them led to convincing and promising results. Therefore, in the last years great progress was obtained in the development of such methods. Operando investigation combining different spectroscopies for analysis under catalytic conditions, near-ambient pressure X-ray photoelectron spectroscopy for bridging the pressure gap in surface-sensitive methods, and new mapping methods leading to spatial resolved investigation in the reactor are some striking examples to describe this development. The aim of all these efforts is to establish convincing structure–function relationships and understand the catalytic process for the development of more powerful catalysts. However, not only activity and selectivity will play an important role in our future understanding of deactivation; in general, the loss of catalytic performance will become more important.

In this Special Issue, submissions are welcome that reflect the state of research in spectroscopy in catalysis. In addition to laboratory techniques, one focus should be the powerful capability provided by modern synchrotron radiation sources both for operando and in situ experiments. Another great subject is represented by Near-Ambient Pressure X-ray photoelectron spectroscopy, which was developed at synchrotron sources, but now the step to a lab method is being taken. The contribution of modern theoretical methods, e.g., of DFT calculations for improving our understanding of the spectroscopic results, should be illustrated in this issue, too.

Dr. Jorg Radnik
Dr. Giovanni Agostini
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • operando and in situ investigation
  • catalysis
  • electronic and geometrical structure of active sites
  • reaction mechanism
  • structure-function relationships
  • combination of complementary techniques
  • spectroscopy
  • theoretical calculation

Published Papers (6 papers)

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Editorial

Jump to: Research, Review

3 pages, 166 KiB  
Editorial
Spectroscopy in Catalysis
by Giovanni Agostini and Jörg Radnik
Catalysts 2020, 10(4), 408; https://doi.org/10.3390/catal10040408 - 8 Apr 2020
Cited by 1 | Viewed by 1852
Abstract
Knowledge-based catalyst development is always an interaction between preparation, analysis and catalytic testing [...] Full article
(This article belongs to the Special Issue Spectroscopy in Catalysis)

Research

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11 pages, 2014 KiB  
Article
In Situ EPR Characterization of a Cobalt Oxide Water Oxidation Catalyst at Neutral pH
by Yury Kutin, Nicholas Cox, Wolfgang Lubitz, Alexander Schnegg and Olaf Rüdiger
Catalysts 2019, 9(11), 926; https://doi.org/10.3390/catal9110926 - 6 Nov 2019
Cited by 26 | Viewed by 6845
Abstract
Here we report an in situ electron paramagnetic resonance (EPR) study of a low-cost, high-stability cobalt oxide electrodeposited material (Co-Pi) that oxidizes water at neutral pH and low over-potential, representing a promising system for future large-scale water splitting applications. Using CW X-band EPR [...] Read more.
Here we report an in situ electron paramagnetic resonance (EPR) study of a low-cost, high-stability cobalt oxide electrodeposited material (Co-Pi) that oxidizes water at neutral pH and low over-potential, representing a promising system for future large-scale water splitting applications. Using CW X-band EPR we can follow the film formation from a Co(NO3)2 solution in phosphate buffer and quantify Co uptake into the catalytic film. As deposited, the film shows predominantly a Co(II) EPR signal, which converts into a Co(IV) signal as the electrode potential is increased. A purpose-built spectroelectrochemical cell allowed us to quantify the extent of Co(II) to Co(IV) conversion as a function of potential bias under operating conditions. Consistent with its role as an intermediate, Co(IV) is formed at potentials commensurate with electrocatalytic O2 evolution (+1.2 V, vs. SHE). The EPR resonance position of the Co(IV) species shifts to higher fields as the potential is increased above 1.2 V. Such a shift of the Co(IV) signal may be assigned to changes in the local Co structure, displaying a more distorted ligand field or more ligand radical character, suggesting it is this subset of sites that represents the catalytically ‘active’ component. The described spectroelectrochemical approach provides new information on catalyst function and reaction pathways of water oxidation. Full article
(This article belongs to the Special Issue Spectroscopy in Catalysis)
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18 pages, 2345 KiB  
Article
Chemical and Electronic Changes of the CeO2 Support during CO Oxidation on Au/CeO2 Catalysts: Time-Resolved Operando XAS at the Ce LIII Edge
by Joachim Bansmann, Ali M. Abdel-Mageed, Shilong Chen, Corinna Fauth, Thomas Häring, Gabriela Kučerová, Yuchen Wang and R. Jürgen Behm
Catalysts 2019, 9(10), 785; https://doi.org/10.3390/catal9100785 - 20 Sep 2019
Cited by 12 | Viewed by 3735
Abstract
While being highly active for the CO oxidation reaction already at low temperatures, Au/CeO2 catalysts suffer from continuous deactivation with time on stream, with the activity and deactivation depending on the initial catalyst activation procedure. In previous X-ray absorption measurements at the [...] Read more.
While being highly active for the CO oxidation reaction already at low temperatures, Au/CeO2 catalysts suffer from continuous deactivation with time on stream, with the activity and deactivation depending on the initial catalyst activation procedure. In previous X-ray absorption measurements at the Au LIII edge, which focused on changes in the electronic and geometric changes of Au, we found a modest increase of the Au particle size during reaction, with the Au nanoparticles (NPs) present in a dominantly metallic state during reaction, regardless of the pretreatment. Here we aim at expanding on these insights by examining the changes in electronic and chemical composition of the CeO2 support induced by different pretreatment procedures and during subsequent CO oxidation at 80 °C, by following changes at the Ce LIII near edge region in time-resolved operando X-ray absorption measurements. The results indicate a strong dependence of the initial concentration of Ce3+ ions on the pretreatment, while during subsequent reaction this rapidly approaches a steady-state value which depends on the oxidative/reductive character of the reaction gas mixture, but is largely independent of the pretreatment. These results are discussed and related to earlier finding on the electronic properties of Au nanoparticles under identical reaction conditions. Full article
(This article belongs to the Special Issue Spectroscopy in Catalysis)
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15 pages, 6143 KiB  
Article
Operando Dual Beam FTIR Study of Hydroxyl Groups and Zn Species over Defective HZSM-5 Zeolite Supported Zinc Catalysts
by Long Lin, Xiaotong Zhang, Ning He, Jiaxu Liu, Qin Xin and Hongchen Guo
Catalysts 2019, 9(1), 100; https://doi.org/10.3390/catal9010100 - 17 Jan 2019
Cited by 30 | Viewed by 6647
Abstract
A series of defective ZSM-5 zeolites (~300 nm, SiO2/Al2O3 ratio of 55, 100, 480 and 950) were systematically studied by XRD, SEM, 29Si MAS NMR, argon physisorption, NH3-TPD and FT-IR technologies. The nature, the amount [...] Read more.
A series of defective ZSM-5 zeolites (~300 nm, SiO2/Al2O3 ratio of 55, 100, 480 and 950) were systematically studied by XRD, SEM, 29Si MAS NMR, argon physisorption, NH3-TPD and FT-IR technologies. The nature, the amount and the accessibility of the acid sites of defective ZSM-5 zeolites are greatly different from reported ZSM-5 zeolites with a perfect crystal structure. The Brønsted acid sites (Si(OH)Al) with strong acid strength and the Brønsted acid sites (hydroxyl nests) with weak acid strength co-existed over defective ZSM-5 zeolites, which leads to a unique catalytic function. Zn(C2H5)2 was grafted onto defective ZSM-5 zeolites through the chemical liquid deposition (CLD) method. Interestingly, FT-IR spectroscopic studies found that Zn(C2H5)2 was preferentially grafted on the hydroxyl nests with weak acid strength rather than the Si(OH)Al groups with strong acid strength over different defective ZSM-5 zeolites. In particular, home-built operando dual beam FTIR-MS was applied to study the catalytic performance of Zn species located in different sites of defective ZSM-5 zeolites under real n-hexane transformation conditions. Results show that Zn species grafted over hydroxyl nests obtain better dehydrogenative aromatization performance than Zn species over Si(OH)Al groups. This study provides guidance for the rational design of highly efficient alkane dehydrogenative aromatization catalysts. Full article
(This article belongs to the Special Issue Spectroscopy in Catalysis)
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13 pages, 4568 KiB  
Article
Toward an Accurate Spectrophotometric Evaluation of the Efficiencies of Photocatalysts in Processes Involving Their Separation Using Nylon Membranes
by Halema Al-Kandari, Peter Kasak, Ahmed M. Mohamed, Shekhah Al-Kandari, Dusan Chorvat Jr. and Aboubakr M. Abdullah
Catalysts 2018, 8(12), 576; https://doi.org/10.3390/catal8120576 - 22 Nov 2018
Cited by 2 | Viewed by 3322
Abstract
Many works include the use of nylon membranes to separate the solid particles of photocatalysts from the photocatalytic reactors, before using spectrophotometers to evaluate the catalysts’ performance in the photocatalytic degradation of many pollutants. This might lead to significant errors due to the [...] Read more.
Many works include the use of nylon membranes to separate the solid particles of photocatalysts from the photocatalytic reactors, before using spectrophotometers to evaluate the catalysts’ performance in the photocatalytic degradation of many pollutants. This might lead to significant errors due to the adsorption of some pollutants within the structure of the membranes during the filtration process used to separate the solid particles of the photocatalysts to get a clear filtrate. This, consequently, leads to incorrect calculations, which in turn are translated into false high photocatalytic efficiencies of the used catalysts. In this work, the authors study the interaction between nylon membrane filters and five different model compounds—phenol red, methylene blue, rhodamine B, rhodamine 6G, and phenol. The study reveals a significant interaction between the nylon membranes and both rhodamine B and phenol red. Full article
(This article belongs to the Special Issue Spectroscopy in Catalysis)
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Review

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16 pages, 4148 KiB  
Review
Recent In Situ/Operando Spectroscopy Studies of Heterogeneous Catalysis with Reducible Metal Oxides as Supports
by Fei Wang, Jianzhun Jiang and Bin Wang
Catalysts 2019, 9(5), 477; https://doi.org/10.3390/catal9050477 - 23 May 2019
Cited by 11 | Viewed by 4657
Abstract
For heterogeneous catalysis, the metal catalysts supported on reducible metal oxides, especially CeO2 and TiO2, have long been a research focus because of their excellent catalytic performance in a variety of catalytic reactions. Detailed understanding of the promotion effect of [...] Read more.
For heterogeneous catalysis, the metal catalysts supported on reducible metal oxides, especially CeO2 and TiO2, have long been a research focus because of their excellent catalytic performance in a variety of catalytic reactions. Detailed understanding of the promotion effect of reducible metal oxides on catalytic reactions is beneficial to the rational design of new catalysts. The important catalytic roles of reducible metal oxides are attributed to their intimate interactions with the supported metals (e.g., strong metal-support interaction, electronic metal-support interaction) and unique support structures (e.g., oxygen vacancy, reversible valence change, surface hydroxyl). However, the structures of the catalysts and reaction mechanisms are strongly affected by environmental conditions. For this reason, in situ/operando spectroscopy studies under working conditions are necessary to obtain accurate information about the structure-activity relationship. In this review, the recent applications of the in situ/operando spectroscopy methodology on metal catalysts with reducible metal oxides as supports are summarized. Full article
(This article belongs to the Special Issue Spectroscopy in Catalysis)
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