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Christoph Langhammer - One of the best experts on this subject based on the ideXlab platform.
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heterodimers for in situ plasmonic spectroscopy cu nanoparticle Oxidation kinetics kirkendall effect and compensation in the arrhenius parameters
Journal of Physical Chemistry C, 2019Co-Authors: David Albinsson, Sara Nilsson, Tomasz J Antosiewicz, Vladimir P Zhdanov, Christoph LanghammerAbstract:The ability to study Oxidation, reduction, and other chemical transformations of nanoparticles in real time and under realistic conditions is a nontrivial task due to their small dimensions and the often challenging environment in terms of temperature and pressure. For scrutinizing Oxidation of metal nanoparticles, visible light optical spectroscopy based on the plasmonic properties of the metal has been established as a suitable method. However, directly relying on the plasmonic resonance of metal nanoparticles as a built-in probe to track Oxidation has a number of drawbacks, including the loss of optical contrast in the late Oxidation stages. To address these intrinsic limitations, we present a plasmonic heterodimer-based nanospectroscopy approach, which enables continuous self-referencing by using polarized light to eliminate parasitic signals and provides large optical contrast all the way to Complete Oxidation. Using Au-Cu heterodimers and combining experiments with finite-difference time-domain simulations, we quantitatively analyze the Oxidation kinetics of ca. 30 nm sized Cu nanoparticles up to Complete Oxidation. Taking the Kirkendall effect into account, we extract the corresponding apparent Arrhenius parameters at various extents of Oxidation and find that they exhibit a significant compensation effect, implying that changes in the Oxidation mechanism occur as Oxidation progresses and the structure of the formed oxide evolves. In a wider perspective, our work promotes the use of model-system-type in situ optical plasmonic spectroscopy experiments in combination with electrodynamics simulations to quantitatively analyze and mechanistically interpret Oxidation of metal nanoparticles and the corresponding kinetics in demanding chemical environments, such as in heterogeneous catalysis.
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Heterodimers for in Situ Plasmonic Spectroscopy: Cu Nanoparticle Oxidation Kinetics, Kirkendall Effect, and Compensation in the Arrhenius Parameters
2019Co-Authors: David Albinsson, Sara Nilsson, Tomasz J Antosiewicz, Vladimir P Zhdanov, Christoph LanghammerAbstract:The ability to study Oxidation, reduction, and other chemical transformations of nanoparticles in real time and under realistic conditions is a nontrivial task due to their small dimensions and the often challenging environment in terms of temperature and pressure. For scrutinizing Oxidation of metal nanoparticles, visible light optical spectroscopy based on the plasmonic properties of the metal has been established as a suitable method. However, directly relying on the plasmonic resonance of metal nanoparticles as a built-in probe to track Oxidation has a number of drawbacks, including the loss of optical contrast in the late Oxidation stages. To address these intrinsic limitations, we present a plasmonic heterodimer-based nanospectroscopy approach, which enables continuous self-referencing by using polarized light to eliminate parasitic signals and provides large optical contrast all the way to Complete Oxidation. Using Au–Cu heterodimers and combining experiments with finite-difference time-domain simulations, we quantitatively analyze the Oxidation kinetics of ca. 30 nm sized Cu nanoparticles up to Complete Oxidation. Taking the Kirkendall effect into account, we extract the corresponding apparent Arrhenius parameters at various extents of Oxidation and find that they exhibit a significant compensation effect, implying that changes in the Oxidation mechanism occur as Oxidation progresses and the structure of the formed oxide evolves. In a wider perspective, our work promotes the use of model-system-type in situ optical plasmonic spectroscopy experiments in combination with electrodynamics simulations to quantitatively analyze and mechanistically interpret Oxidation of metal nanoparticles and the corresponding kinetics in demanding chemical environments, such as in heterogeneous catalysis
Vladimir P Zhdanov - One of the best experts on this subject based on the ideXlab platform.
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heterodimers for in situ plasmonic spectroscopy cu nanoparticle Oxidation kinetics kirkendall effect and compensation in the arrhenius parameters
Journal of Physical Chemistry C, 2019Co-Authors: David Albinsson, Sara Nilsson, Tomasz J Antosiewicz, Vladimir P Zhdanov, Christoph LanghammerAbstract:The ability to study Oxidation, reduction, and other chemical transformations of nanoparticles in real time and under realistic conditions is a nontrivial task due to their small dimensions and the often challenging environment in terms of temperature and pressure. For scrutinizing Oxidation of metal nanoparticles, visible light optical spectroscopy based on the plasmonic properties of the metal has been established as a suitable method. However, directly relying on the plasmonic resonance of metal nanoparticles as a built-in probe to track Oxidation has a number of drawbacks, including the loss of optical contrast in the late Oxidation stages. To address these intrinsic limitations, we present a plasmonic heterodimer-based nanospectroscopy approach, which enables continuous self-referencing by using polarized light to eliminate parasitic signals and provides large optical contrast all the way to Complete Oxidation. Using Au-Cu heterodimers and combining experiments with finite-difference time-domain simulations, we quantitatively analyze the Oxidation kinetics of ca. 30 nm sized Cu nanoparticles up to Complete Oxidation. Taking the Kirkendall effect into account, we extract the corresponding apparent Arrhenius parameters at various extents of Oxidation and find that they exhibit a significant compensation effect, implying that changes in the Oxidation mechanism occur as Oxidation progresses and the structure of the formed oxide evolves. In a wider perspective, our work promotes the use of model-system-type in situ optical plasmonic spectroscopy experiments in combination with electrodynamics simulations to quantitatively analyze and mechanistically interpret Oxidation of metal nanoparticles and the corresponding kinetics in demanding chemical environments, such as in heterogeneous catalysis.
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Heterodimers for in Situ Plasmonic Spectroscopy: Cu Nanoparticle Oxidation Kinetics, Kirkendall Effect, and Compensation in the Arrhenius Parameters
2019Co-Authors: David Albinsson, Sara Nilsson, Tomasz J Antosiewicz, Vladimir P Zhdanov, Christoph LanghammerAbstract:The ability to study Oxidation, reduction, and other chemical transformations of nanoparticles in real time and under realistic conditions is a nontrivial task due to their small dimensions and the often challenging environment in terms of temperature and pressure. For scrutinizing Oxidation of metal nanoparticles, visible light optical spectroscopy based on the plasmonic properties of the metal has been established as a suitable method. However, directly relying on the plasmonic resonance of metal nanoparticles as a built-in probe to track Oxidation has a number of drawbacks, including the loss of optical contrast in the late Oxidation stages. To address these intrinsic limitations, we present a plasmonic heterodimer-based nanospectroscopy approach, which enables continuous self-referencing by using polarized light to eliminate parasitic signals and provides large optical contrast all the way to Complete Oxidation. Using Au–Cu heterodimers and combining experiments with finite-difference time-domain simulations, we quantitatively analyze the Oxidation kinetics of ca. 30 nm sized Cu nanoparticles up to Complete Oxidation. Taking the Kirkendall effect into account, we extract the corresponding apparent Arrhenius parameters at various extents of Oxidation and find that they exhibit a significant compensation effect, implying that changes in the Oxidation mechanism occur as Oxidation progresses and the structure of the formed oxide evolves. In a wider perspective, our work promotes the use of model-system-type in situ optical plasmonic spectroscopy experiments in combination with electrodynamics simulations to quantitatively analyze and mechanistically interpret Oxidation of metal nanoparticles and the corresponding kinetics in demanding chemical environments, such as in heterogeneous catalysis
David Albinsson - One of the best experts on this subject based on the ideXlab platform.
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heterodimers for in situ plasmonic spectroscopy cu nanoparticle Oxidation kinetics kirkendall effect and compensation in the arrhenius parameters
Journal of Physical Chemistry C, 2019Co-Authors: David Albinsson, Sara Nilsson, Tomasz J Antosiewicz, Vladimir P Zhdanov, Christoph LanghammerAbstract:The ability to study Oxidation, reduction, and other chemical transformations of nanoparticles in real time and under realistic conditions is a nontrivial task due to their small dimensions and the often challenging environment in terms of temperature and pressure. For scrutinizing Oxidation of metal nanoparticles, visible light optical spectroscopy based on the plasmonic properties of the metal has been established as a suitable method. However, directly relying on the plasmonic resonance of metal nanoparticles as a built-in probe to track Oxidation has a number of drawbacks, including the loss of optical contrast in the late Oxidation stages. To address these intrinsic limitations, we present a plasmonic heterodimer-based nanospectroscopy approach, which enables continuous self-referencing by using polarized light to eliminate parasitic signals and provides large optical contrast all the way to Complete Oxidation. Using Au-Cu heterodimers and combining experiments with finite-difference time-domain simulations, we quantitatively analyze the Oxidation kinetics of ca. 30 nm sized Cu nanoparticles up to Complete Oxidation. Taking the Kirkendall effect into account, we extract the corresponding apparent Arrhenius parameters at various extents of Oxidation and find that they exhibit a significant compensation effect, implying that changes in the Oxidation mechanism occur as Oxidation progresses and the structure of the formed oxide evolves. In a wider perspective, our work promotes the use of model-system-type in situ optical plasmonic spectroscopy experiments in combination with electrodynamics simulations to quantitatively analyze and mechanistically interpret Oxidation of metal nanoparticles and the corresponding kinetics in demanding chemical environments, such as in heterogeneous catalysis.
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Heterodimers for in Situ Plasmonic Spectroscopy: Cu Nanoparticle Oxidation Kinetics, Kirkendall Effect, and Compensation in the Arrhenius Parameters
2019Co-Authors: David Albinsson, Sara Nilsson, Tomasz J Antosiewicz, Vladimir P Zhdanov, Christoph LanghammerAbstract:The ability to study Oxidation, reduction, and other chemical transformations of nanoparticles in real time and under realistic conditions is a nontrivial task due to their small dimensions and the often challenging environment in terms of temperature and pressure. For scrutinizing Oxidation of metal nanoparticles, visible light optical spectroscopy based on the plasmonic properties of the metal has been established as a suitable method. However, directly relying on the plasmonic resonance of metal nanoparticles as a built-in probe to track Oxidation has a number of drawbacks, including the loss of optical contrast in the late Oxidation stages. To address these intrinsic limitations, we present a plasmonic heterodimer-based nanospectroscopy approach, which enables continuous self-referencing by using polarized light to eliminate parasitic signals and provides large optical contrast all the way to Complete Oxidation. Using Au–Cu heterodimers and combining experiments with finite-difference time-domain simulations, we quantitatively analyze the Oxidation kinetics of ca. 30 nm sized Cu nanoparticles up to Complete Oxidation. Taking the Kirkendall effect into account, we extract the corresponding apparent Arrhenius parameters at various extents of Oxidation and find that they exhibit a significant compensation effect, implying that changes in the Oxidation mechanism occur as Oxidation progresses and the structure of the formed oxide evolves. In a wider perspective, our work promotes the use of model-system-type in situ optical plasmonic spectroscopy experiments in combination with electrodynamics simulations to quantitatively analyze and mechanistically interpret Oxidation of metal nanoparticles and the corresponding kinetics in demanding chemical environments, such as in heterogeneous catalysis
Xingfu Tang - One of the best experts on this subject based on the ideXlab platform.
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tunnel structure effect of manganese oxides in Complete Oxidation of formaldehyde
Microporous and Mesoporous Materials, 2009Co-Authors: Tan Chen, Xingfu Tang, Xiaoling Li, Junhua LiAbstract:Abstract Three manganese oxides with different square tunnel sizes, pyrolusite, cryptomelane and todorokite, were prepared, and characterized by X-ray powder diffraction, specific surface area measurement, temperature programmed reduction by H 2 , high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The results of catalytic tests in Complete Oxidation of formaldehyde revealed that cryptomelane had much higher activity than pyrolusite or todorokite. The characterization results suggested that the catalytic activity was primarily predominated by the tunnel structures of manganese oxides rather than specific surface area, degree of crystallinity, reducibility and average Oxidation state of manganese. The effective tunnel diameter of cryptomelane similar to the dynamic diameter of formaldehyde molecule was proposed to be a major factor to give rise to the high catalytic activity.
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impact of synthesis method on catalytic performance of mnox sno2 for controlling formaldehyde emission
Catalysis Communications, 2009Co-Authors: Yiran Wen, Xin Tang, Jiming Hao, Lisi Wei, Xingfu TangAbstract:Abstract The impact of synthesis method on catalytic performances of MnO x –SnO 2 was studied for controlling formaldehyde emission during cold start and warm-up periods of methanol-gasoline/diesel fuel vehicles. MnO x –SnO 2 synthesized by a redox co-precipitation method exhibited much higher activity towards Complete Oxidation of formaldehyde than that by a conventional co-precipitation one. The results of XPS, XRD and H 2 -TPR characterizations revealed that higher Oxidation state of manganese, the formation of solid solution between MnO x and SnO 2 , and more facile redox capability were responsible for higher activity.
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pt mnox ceo2 catalysts for the Complete Oxidation of formaldehyde at ambient temperature
Applied Catalysis B-environmental, 2008Co-Authors: Xingfu Tang, Xiumin Huang, Yide Xu, Junli Chen, Wenjie ShenAbstract:Abstract MnO x –CeO 2 mixed oxides with a Mn/(Mn + Ce) molar ratios of 0–1 were prepared by a modified coprecipitation method and investigated for the Complete Oxidation of formaldehyde. The MnO x –CeO 2 with Mn/(Mn + Ce) molar ratio of 0.5 exhibited the highest catalytic activity among the MnO x –CeO 2 mixed oxides. Structure analysis by X-ray powder diffraction and temperature-programmed reduction of hydrogen revealed that the formation of MnO x –CeO 2 solid solution greatly improved the low-temperature reducibility, resulting in a higher catalytic activity for the Oxidation of formaldehyde. Promoting effect of Pt on the MnO x –CeO 2 mixed oxide indicated that both the Pt precursors and the reduction temperature greatly affected the catalytic performance. Pt/MnO x –CeO 2 catalyst prepared from chlorine-free precursor showed extremely high activity and stability after pretreatment with hydrogen at 473 K. 100% conversion of formaldehyde was achieved at ambient temperature and no deactivation was observed for 120 h time-on-stream. The promoting effect of Pt was ascribed to enhance the effective activation of oxygen molecule on the MnO x –CeO 2 support.
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mnox ceo2 mixed oxide catalysts for Complete Oxidation of formaldehyde effect of preparation method and calcination temperature
Applied Catalysis B-environmental, 2006Co-Authors: Xingfu Tang, Yonggang Li, Xiumin Huang, Yide Xu, Jianguo Wang, Wenjie ShenAbstract:Abstract MnO x –CeO 2 mixed oxides prepared by sol–gel method, coprecipitation method and modified coprecipitation method were investigated for the Complete Oxidation of formaldehyde. Structure analysis by H 2 -TPR and XPS revealed that there were more Mn 4+ species and richer lattice oxygen on the surface of the catalyst prepared by the modified coprecipitation method than those of the catalysts prepared by sol–gel and coprecipitation methods, resulting in much higher catalytic activity toward Complete Oxidation of formaldehyde. The effect of calcination temperature on the structural features and catalytic behavior of the MnO x –CeO 2 mixed oxides prepared by the modified coprecipitation was further examined, and the catalyst calcined at 773 K showed 100% formaldehyde conversion at a temperature as low as 373 K. For the samples calcined below 773 K, no any diffraction peak corresponding to manganese oxides could be detected by XRD measurement due to the formation of MnO x –CeO 2 solid solution. While the diffraction peaks corresponding to MnO 2 phase in the samples calcined above 773 K were clearly observed, indicating the occurrence of phase segregation between MnO 2 and CeO 2 . Accordingly, it was supposed that the strong interaction between MnO x and CeO 2 , which depends on the preparation route and the calcination temperature, played a crucial role in determining the catalytic activity toward the Complete Oxidation of formaldehyde.
Renaud Metz - One of the best experts on this subject based on the ideXlab platform.
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full transition from metal to ceramic by direct Oxidation of metallic cobalt powder
Ceramics International, 2010Co-Authors: Renaud Metz, Jonathan Morel, Solaiappan Ananthakumar, Henri Delalu, Mehrdad HassanzadehAbstract:The study deals with the direct Oxidation kinetics of micronic cobalt metal particles and its simulation for the Complete transition from metal to ceramic. The simulation was also experimentally verified. All the three possible interfaces, Co/CoO, CoO/Co3O4 and Co3O4/O2 (air), have been taken into consideration for the simulation. The Complete Oxidation kinetics has been investigated from the thermogravimetric studies under isothermal conditions in the temperatures 973–1173 K. A quantitative interpretation based on the diffusion of Co or oxygen ions through the grown oxide layer has been proposed. The activation energy for the Oxidation kinetics calculated from the Arrhenius law was 161 ± 20 kJ mol−1.
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direct Oxidation route from metal to ceramic study on cobalt oxide
Materials Research Bulletin, 2009Co-Authors: Renaud Metz, Jonathan Morel, Solaiappan Ananthakumar, Henri Delalu, Mehrdad HassanzadehAbstract:Abstract The study deals with the direct-Oxidation kinetics of micronic-cobalt metal particles and its simulation for the Complete transition from metal to ceramic. The simulation was also experimentally verified. All the three possible interfaces, Co/CoO, CoO/Co 3 O 4 and Co 3 O 4 /O 2 (air), have been taken into consideration for the simulation. The Complete Oxidation kinetics has been investigated from the thermogravimetric studies under isothermal conditions in the temperatures 973–1173 K. A quantitative interpretation based on the diffusion of Co or oxygen ions through the grown oxide layer has been proposed. The activation energy for the Oxidation kinetics calculated from the Arrhenius law was 161 ± 20 kJ mol −1 .
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direct Oxidation of an alloy precursor Complete Oxidation of bismuth and zinc powder
Journal of Electroceramics, 2004Co-Authors: Renaud Metz, Celine Machado, Mehrdad Hassanzadeh, Ramon PuyanēAbstract:This work reports on a process (DOPA: Direct Oxidation of a Precursory Alloy) of preparation of ceramics used as varistors for the electric protection against power surges. This new route has been applied for the production of ZnO varistors doped with Bi2O3, Sb2O3 and other oxides. One important stage of this process is the total conversion of an alloy into the corresponding mixed oxide. We have reported here the studies of the full conversions metal-ceramic powders of the main components of these varistors: zinc and bismuth.
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validation of a kinetic model of diffusion for Complete Oxidation of bismuth powder influence of granulometry and temperature
Solid State Ionics, 2002Co-Authors: Celine Machado, Henri Delalu, S Aidel, M Elkhatib, Renaud MetzAbstract:The kinetics of Complete Oxidation of bismuth powder by air has been investigated by thermogravimetric studies under isothermal conditions in the range 729–968 K. Particles size was chosen in the 35–375-Am range. We have been able to carry out the full Oxidation of the powder far above the bismuth metal melting point (544.3 K) without coalescence of the particles. A quantitative interpretation based on the diffusion of reactants through the oxide layer has been proposed. The activation energy calculated from the Arrhenius law is close to 139 kJ mol � 1 . D 2002 Elsevier Science B.V. All rights reserved.
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kinetics and modeling of diffusion phenomena occurring during the Complete Oxidation of zinc powder influence of granulometry temperature and relative humidity of the oxidizing fluid
Solid State Sciences, 2000Co-Authors: Henri Delalu, M Elkhatib, J R Vignalou, Renaud MetzAbstract:Abstract The kinetics of the Complete Oxidation of zinc powder by oxygen or air has been investigated from thermogravimetric studies under isothermal conditions in the range 772–1107 K. Particles size and hygrometry were chosen in the 65–375 μm and 0–50% ranges, respectively. We have been able to carry out the powder Oxidation above the zinc metal melting point without coalescence of the particles. A quantitative interpretation based on the diffusion of reactants through the oxide layer has been proposed. The activation energy calculated from the Arrhenius law is close to 130 kJ mol −1 .