8104
2015
2015
eng
89
doctoralthesis
1
2015-09-23
--
--
High resolution spectroscopy as a tool to unravel structure-reactivity relationships in Eu3+ doped ceria/ceria-zirconia based catalyst nanomaterials
online registration
Potsdam, Univ., Diss., 2015
Philipp-Alexander Primus
Chemie und zugeordnete Wissenschaften
Institut für Chemie
Universität Potsdam
Universität Potsdam
58658
2022
2022
eng
6316
6326
11
5
5
article
American Chemical Society
Washington
1
2022-05-05
2022-05-05
--
Low-temperature growth of reactive pyrochlore nanostructures on Zirconia-supported ceria
The use of a catalyst support for the design of nanoscale heterogeneous catalysts based on cerium oxide offers vast possibilities for future catalyst development, particularly with regard to an increased focus on the use of renewable biogas and an emerging hydrogen economy. In this study, zirconia-supported ceria catalysts were synthesized, activated by using different thermochemical treatments, and characterized by way of temperature-programmed reduction (TPR), oxygen storage capacity, Xray diffraction, electron microscopy, and luminescence spectroscopy using Eu3+ as a spectroscopic probe. Through reduction-oxidation pretreatment routines, reactive pyrochlore structures were created at temperatures as low as 600 degrees C and identified through TPR and electron microscopy experiments. A structural relationship and alignment of the crystal planes is revealed in high-resolution scanning transmission electron microscopy experiments through the digital diffraction patterns. Low-temperature pretreatment induces the formation of reactive pyrochlore domains under retention of the surface area of the catalyst system, and no further morphological changes are detected. Furthermore, the formation of pyrochlore domains achieved through severe reduction and mild reoxidation (SRMO) treatments is reversible. Over multiple alternating SRMO and severe reduction and severe reoxidation (SRSO) treatments, europium spectroscopy and TPR results indicate that pyrochlore structures are recreated over consecutive treatments, whenever the mild oxidation step at 500 degrees C is the last treatment (SRMO, SRMO-SRSO-SRMO, etc.).
ACS applied nano materials
implications for improved catalytic behavior
10.1021/acsanm.2c00416
2574-0970
outputup:dataSource:WoS:2022
WOS:000833967000037
Primus, PA (corresponding author), Univ Potsdam, UO Transfer GmbH, D-14469 Potsdam, Germany., primus@uni-potsdam.de
FEDER/MINECO [MAT2017-87579-R]; MCIN/AEI [PID2020113006RB-I00]; Federal; Ministry for Economic Affairs and Energy through the AiF (German; Federation of Industrial Research Associations) [19976 BG]
Primus, Philipp-Alexander
2023-03-31T09:36:25+00:00
sword
importub
filename=package.tar
7f1887f51148f90eefc6bce8bd3c109b
2916552-0
false
true
Maria Pilar Yeste
Juan Carlos Hernandez-Garrido
Michael Uwe Kumke
Sarah Alvarado
Miguel Angel Cauqui
Jose Juan Calvino
Philipp-Alexander Primus
eng
uncontrolled
pyrochlore
eng
uncontrolled
nanocomposite
eng
uncontrolled
ceria
eng
uncontrolled
zirconia
eng
uncontrolled
supported catalyst
eng
uncontrolled
oxygen
eng
uncontrolled
storage capacity
Chemie und zugeordnete Wissenschaften
Institut für Chemie
Referiert
Import
DOAJ gelistet
38926
2015
2015
eng
10682
10692
11
19
119
article
American Chemical Society
Washington
1
--
--
--
Fluorescence Line-Narrowing Spectroscopy as a Tool to Monitor Phase Transitions and Phase Separation in Efficient Nanocrystalline CexZr1-xO2:Eu3+ Catalyst Materials
Despite the wide range of industrial applications for ceria-zirconia mixed oxides (CexZr1-xO2), the complex correlation between their atomic structure and catalytic performance is still under debate. Catalytically interesting CexZr1-xO2 nanomaterials can form homogeneous solid solutions and, depending on the composition, show phase separation under the formation of small domains. The characterization of homogeneity and atomic structure of these materials remains a major challenge. High-resolution emission spectroscopy recorded under cryogenic conditions using Eu3+ as a structural probe in doped CeZrO2 nanoparticles offers an effective way to identify the different atomic environments of the Eu3+ dopants and, subsequently, to monitor structural parameters of the ceria-zirconia mixed oxides. It is found that, in stoichiometric CeZrO2:Eu3+, phase separation occurs at elevated temperatures beginning with the gradual formation of (pseudo)cubic crystallites in the amorphous materials at 500 degrees C and a sudden phase separation into tetragonal, zirconia-rich and cubic, ceria-rich domains over 900 degrees C. The presented technique allows us to easily monitor subtle changes even in amorphous, high surface area samples, yielding structural information not accessible by conventional techniques such as X-ray diffraction (XRD) and Raman. Moreover, in reference experiments investigating the reducibility of largely unordered Ce0.2Zr0.8O2:Eu3+, the main reduction peak in temperature-programmed reduction measurements appeared at exceptionally low temperatures below 200 degrees C, thus suggesting the outstanding potential of this oxide to activate catalytic oxidation reactions. This effect was found to be dependent on the amount of Eu3+ dopant introduced into the CeZrO2 matrix as well as to be connected to the atomic structure of the catalyst material.
The journal of physical chemistry : C, Nanomaterials and interfaces
10.1021/acs.jpcc.5b01271
1932-7447
wos:2015
WOS:000354912200060
Primus, PA (reprint author), Univ Potsdam, Inst Chem, Phys Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany., primus@uni-potsdam.de; kumke@uni-potsdam.de
MINECO/FEDER [MAT2013-40823-R]
Philipp-Alexander Primus
Antonia Menski
Maria Pilar Yeste
Miguel Angel Cauqui
Michael Uwe Kumke
Institut für Chemie
Referiert
37484
2014
2014
eng
23349
23360
12
40
118
article
American Chemical Society
Washington
1
--
--
--
High-resolution spectroscopy of europium-doped ceria as a tool to correlate structure and catalytic activity
Site-selective emission spectra of Eu3+-doped CeO2 nanoparticles up to the D-5(0) - F-7(5) transition were recorded under cryogenic conditions to identify the local structure around the Eu3+ dopants in ceria. It is found that pretreatment conditions are crucial for the redistribution of dopants from a broad variety of environments to six well-defined lattice sites. The influence of the dopant and the host structure on the catalytic activity was investigated. A relationship between structure and reactivity is discussed. It is shown that oxygen transport is most efficient in particles with a pronounced amorphous character.
The journal of physical chemistry : C, Nanomaterials and interfaces
10.1021/jp505467r
1932-7447
wos:2014
WOS:000343016800061
Kumke, MU (reprint author), Univ Potsdam, Inst Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany., kumke@uni-potsdam.de
German Academic Exchange Service (DAAD); [MAT2013-40823-R];
[CSD2009-00013]
Philipp-Alexander Primus
Thomas Ritschel
Pilar Y. Sigueenza
Miguel Angel Cauqui
Juan Carlos Hernandez-Garrido
Michael Uwe Kumke
Institut für Chemie
Referiert
58210
2020
2020
eng
9
503
article
Elsevier
Amsterdam
1
2020-02-15
2020-02-15
--
Surface characterization of two Ce0.62Zr0.38O2 mixed oxides with different reducibility
This paper presents a study of the surface properties of two Ce/Zr mixed oxides with different reducibility, obtained by applying distinct thermal ageing treatments to an oxide with the composition Ce0.62Zr0.38O2. The surface composition was investigated by XPS. Chemical reactivity of the surface was studied by adsorption of the probe molecules CO2, D-2 and methanol. Nanostructural characterization was carried out by XRD, Raman and high-resolution Eu3+ spectroscopy (FLNS). The characterization showed only slight variations in surface composition and bulk Ce-Zr distribution, but hardy differences concerning the type and strength of acidic surface centres, as well as strong differences in the ability to dissociate hydrogen. Structural variations between both samples were identified by comparing the optical spectra of Eu3+ in surface doped samples.
Applied surface science : a journal devoted to applied physics and chemistry of surfaces and interfaces
10.1016/j.apsusc.2019.144255
0169-4332
1873-5584
outputup:dataSource:WoS:2020
144255
WOS:000498641500060
Yeste, MP (corresponding author), Univ Cadiz, Dept Ciencia Mat & Ingn Met & Quim Inorgan, Apdo 40, Puerto Real 11510, Cadiz, Spain., pili.yeste@uca.es
Ministry of Economy and Competitiveness of SpainSpanish Government; [MINECO/FEDER MAT2017-87579-R]; Junta de Andalucia (Spain)Junta de; AndaluciaEuropean Commission [FQM-110, FQM-334]
Yeste, Maria Pilar
2023-03-02T06:31:29+00:00
sword
importub
filename=package.tar
5cc80e459d43ef3b0ea205a2f4142957
2002520-8
52886-9
false
true
Maria Pilar Yeste
Philipp-Alexander Primus
Rodrigo Alcantara
Miguel Angel Cauqui
Juan Jose Calvino
José María Pintado
Ginesa Blanco
eng
uncontrolled
Ce/Zr
eng
uncontrolled
Surface properties
eng
uncontrolled
Reactive adsorption
eng
uncontrolled
Hydrogen activation
Physik
Chemie und zugeordnete Wissenschaften
Institut für Physik und Astronomie
Institut für Chemie
Referiert
Import
7995
2014
2015
eng
4623
4631
postprint
1
--
2015-03-17
--
White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+
Co-doping of the MOF 3∞[Zn(2-methylimidazolate-4-amide-5-imidate)] (IFP-1 = Imidazolate Framework Potsdam-1) with luminescent Eu3+ and Tb3+ ions presents an approach to utilize the porosity of the MOF for the intercalation of luminescence centers and for tuning of the chromaticity to the emission of white light of the quality of a three color emitter. Organic based fluorescence processes of the MOF backbone as well as metal based luminescence of the dopants are combined to one homogenous single source emitter while retaining the MOF's porosity. The lanthanide ions Eu3+ and Tb3+ were doped in situ into IFP-1 upon formation of the MOF by intercalation into the micropores of the growing framework without a structure directing effect. Furthermore, the color point is temperature sensitive, so that a cold white light with a higher blue content is observed at 77 K and a warmer white light at room temperature (RT) due to the reduction of the organic emission at higher temperatures. The study further illustrates the dependence of the amount of luminescent ions on porosity and sorption properties of the MOF and proves the intercalation of luminescence centers into the pore system by low-temperature site selective photoluminescence spectroscopy, SEM and EDX. It also covers an investigation of the border of homogenous uptake within the MOF pores and the formation of secondary phases of lanthanide formates on the surface of the MOF. Crossing the border from a homogenous co-doping to a two-phase composite system can be beneficially used to adjust the character and warmth of the white light. This study also describes two-color emitters of the formula Ln@IFP-1a–d (Ln: Eu, Tb) by doping with just one lanthanide Eu3+ or Tb3+.
urn:nbn:de:kobv:517-opus4-79953
online registration
J. Mater. Chem. C, 2015, 3, 4623-4631 - DOI: 10.1039/C4TC02919D
<a href="http://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/7994">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
Suvendu Sekhar Mondal
Karsten Behrens
Philipp R. Matthes
Fabian Schönfeld
Jörn Nitsch
Andreas Steffen
Philipp-Alexander Primus
Michael Uwe Kumke
Klaus Müller-Buschbaum
Hans-Jürgen Holdt
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
190
Chemie und zugeordnete Wissenschaften
open_access
Institut für Chemie
Referiert
Open Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/7995/pmnr190.pdf
7994
2015
eng
4623
4631
3
18
article
Royal Society of Chemistry
Cambridge
1
--
2015-03-17
--
White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+
Co-doping of the MOF 3∞[Zn(2-methylimidazolate-4-amide-5-imidate)] (IFP-1 = Imidazolate Framework Potsdam-1) with luminescent Eu3+ and Tb3+ ions presents an approach to utilize the porosity of the MOF for the intercalation of luminescence centers and for tuning of the chromaticity to the emission of white light of the quality of a three color emitter. Organic based fluorescence processes of the MOF backbone as well as metal based luminescence of the dopants are combined to one homogenous single source emitter while retaining the MOF's porosity. The lanthanide ions Eu3+ and Tb3+ were doped in situ into IFP-1 upon formation of the MOF by intercalation into the micropores of the growing framework without a structure directing effect. Furthermore, the color point is temperature sensitive, so that a cold white light with a higher blue content is observed at 77 K and a warmer white light at room temperature (RT) due to the reduction of the organic emission at higher temperatures. The study further illustrates the dependence of the amount of luminescent ions on porosity and sorption properties of the MOF and proves the intercalation of luminescence centers into the pore system by low-temperature site selective photoluminescence spectroscopy, SEM and EDX. It also covers an investigation of the border of homogenous uptake within the MOF pores and the formation of secondary phases of lanthanide formates on the surface of the MOF. Crossing the border from a homogenous co-doping to a two-phase composite system can be beneficially used to adjust the character and warmth of the white light. This study also describes two-color emitters of the formula Ln@IFP-1a–d (Ln: Eu, Tb) by doping with just one lanthanide Eu3+ or Tb3+.
Journal of materials chemistry : C, Materials for optical and electronic devices
10.1039/C4TC02919D
2050-7534
2050-7526
online registration
<a href="http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-79953">Zweitveröffentlichung in der Schriftenreihe Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe ; 190</a>
Au-018912
Suvendu Sekhar Mondal
Karsten Behrens
Philipp R. Matthes
Fabian Schönfeld
Jörn Nitsch
Andreas Steffen
Philipp-Alexander Primus
Michael Uwe Kumke
Klaus Müller-Buschbaum
Hans-Jürgen Holdt
Chemie und zugeordnete Wissenschaften
Institut für Chemie
Referiert
Open Access
RSC
Universität Potsdam
39355
2015
2015
eng
4623
4631
9
18
3
article
Royal Society of Chemistry
Cambridge
1
--
--
--
White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+
Journal of materials chemistry : C, Materials for optical and electronic devices
10.1039/c4tc02919d
2050-7526
2050-7534
wos:2015
WOS:000353768100004
Holdt, HJ (reprint author), Univ Potsdam, Inst Chem, Anorgan Chem, Karl Liebknecht Str 26, D-14476 Golm, Germany., k.mueller-buschbaum@uni-wuerzburg.de; holdt@uni-potsdam.de
Priority Program of the German Research Foundation on "Metal-Organic Frameworks' [1362]; Dr Klaus-Romer foundation
Suvendu Sekhar Mondal
Karsten Behrens
Philipp R. Matthes
Fabian Schönfeld
Jörn Nitsch
Andreas Steffen
Philipp-Alexander Primus
Michael Uwe Kumke
Klaus Müller-Buschbaum
Hans-Jürgen Holdt
Institut für Chemie
Referiert