Hydrogen Spillover on CeO2/Pt: Enhanced Storage of Active Hydrogen

Dutta, Gargi; Waghmare, Umesh V.; Baidya, Tinku; Hegde, M. S.

doi:10.1021/cm071330m

Cited by 101 publications

(84 citation statements)

References 17 publications

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“…It was reported that surface cationic Pt species promote dissociation of H 2 and facilitate hydrogen spillover on Pt-doped CeO 2 powders prepared by the solution combustion method. 114 The origins of this reactivity, however, remained obscure.…”

Section: Supported Single Metal Atoms In the Absence Of Metal Particlesmentioning

confidence: 99%

“…in the absence of other active species such as Pt 4+ , Pt 0 , and oxygen vacancies. [114][115][116] Using well-defined model catalysts, atomically dispersed Pt 2+ species can be prepared and studied individually. 21,99 The corresponding approach involves the preparation of Pt-CeO 2 films with low Pt loading at low temperature followed by brief annealing to 700 K. 21 The same procedure allows the preparation of atomically dispersed Pd 2+ and Ni 2+ species on nanostructured ceria.…”

Section: Supported Single Metal Atoms In the Absence Of Metal Particlesmentioning

confidence: 99%

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Oxide-based nanomaterials for fuel cell catalysis: the interplay between supported single Pt atoms and particles

Lykhach

Bruix

Fabris

et al. 2017

Catal. Sci. Technol.

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The concept of single atom catalysis offers maximum noble metal efficiency for the development of lowcost catalytic materials. Among possible applications are catalytic materials for proton exchange membrane fuel cells. In the present review, recent efforts towards the fabrication of single atom catalysts on nanostructured ceria and their reactivity are discussed in the prospect of their employment as anode catalysts.The remarkable performance and the durability of the ceria-based anode catalysts with ultra-low Pt loading result from the interplay between two states associated with supported atomically dispersed Pt and subnanometer Pt particles. The occurrence of these two states is a consequence of strong interactions between Pt and nanostructured ceria that yield atomically dispersed species under oxidizing conditions and sub-nanometer Pt particles under reducing conditions. The square-planar arrangement of four O atoms on {100} nanoterraces has been identified as the key structural element on the surface of the nanostructured ceria where Pt is anchored in the form of Pt 2+ species. The conversion of Pt 2+ species to subnanometer Pt particles is triggered by a redox process involving Ce 3+ centers. The latter emerge due to either oxygen vacancies or adsorption of reducing agents. The unique properties of the sub-nanometer Pt particles arise from metal-support interactions involving charge transfer, structural flexibility, and spillover phenomena. The abundance of specific adsorption sites similar to those on {100} nanoterraces determines the ideal (maximum) Pt loading in Pt-CeO x films that still allows reversible switching between the atomically dispersed Pt and sub-nanometer particles yielding high activity and durability during fuel cell operation.

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Section: Supported Single Metal Atoms In the Absence Of Metal Particlesmentioning

confidence: 99%

Section: Supported Single Metal Atoms In the Absence Of Metal Particlesmentioning

confidence: 99%

Oxide-based nanomaterials for fuel cell catalysis: the interplay between supported single Pt atoms and particles

Lykhach

Bruix

Fabris

et al. 2017

Catal. Sci. Technol.

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“…However, it has been shown, for ionic Pt in CeO 2, that more than one H atom can be stabilized over a single Pt ion. 32 Therefore, step (1h) in the above equation takes place over a single site and, hence, the above set of equations can be lumped into a single equation (Eq. 1f) without affecting the kinetics of the reaction.…”

Section: Structural Studiesmentioning

confidence: 99%

Support‐dependent activity of noble metal substituted oxide catalysts for the water gas shift reaction

Deshpande

Madras

2010

AIChE Journal

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The water gas shift reaction was carried out over noble metal ion substituted nanocrystalline oxide catalysts with different supports. Spectroscopic studies of the catalysts before and after the reaction showed different surface phenomena occurring over the catalysts. Reaction mechanisms were proposed based upon the surface processes and intermediates formed. The dual site mechanism utilizing the oxide ion vacancies for water dissociation and metal ions for CO adsorption was proposed to describe the kinetics of the reaction over the reducible oxides like CeO 2 . A mechanism based on the interaction of adsorbed CO and the hydroxyl group was proposed for the reaction over ZrO 2 . A hybrid mechanism based on oxide ion vacancies and surface hydroxyl groups was proposed for the reaction over TiO 2 . The deactivation of the catalysts was also found to be support dependent. Kinetic models for both activation and deactivation were proposed.

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“…The low-temperature desorption peaks (centred at 60 8C) are ascribed to the hydrogen adsorbed on the surface of Pt, and the high temperature desorption peaks nearly 400 8C are assigned to spillover hydrogen. [14] The intensity of the lowtemperature peak of 2Al-Pt-in-ANTsi sl ess than that of Pt-inANTs. The H 2 uptake ( Table 2) relatedt ot he low temperature of 2Al-Pt-in-ANTs (1.81 mmol g À1 -Pt) is approximately 47 % smaller than that of Pt-in-ANTs( 3.44 mmol g À1 -Pt), indicating that 2Al-Pt-in-ANTs has al ower exposed fractiono fP ta tom than that of Pt-in-ANTs.…”

mentioning

confidence: 96%

Ultrathin Coating of Confined Pt Nanocatalysts by Atomic Layer Deposition for Enhanced Catalytic Performance in Hydrogenation Reactions

Wang

Gao

Zhang

et al. 2016

Chemistry A European J

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What is the most significant result of this study? In this work, atomic layer deposition (ALD) was applied to deposit ultrathin Al 2 O 3 coats on Pt nanoparticles that are confined in Al 2 O 3 nanotubes. This catalyst was elaborately designed to maximize the metal oxide interfaces and exhibited the maximized catalytic activity compared with the conventional confined catalysts and/or supported catalysts. We believe that applying ALD ultrathin coats on confined catalysts is ap romising way to achieve enhanced performance for other catalysts. What prompted you to investigate this topic/problem? Metal-support interfaces play ap rominent role in heterogeneous catalysis. However,t ailoring the metal-support interfaces to realize full utilization remains am ajor challenge. Our previous work has demonstrated that metal nanoparticles not only confined in the nanotubes but also embedded in the internal wall have increased interfacial sites compared with the same metal nanoparticles supported on the outside of the nanotubes. This result prompted us to further modify the confined catalysts for the increased interfaces. Therefore, we attempt to coat the confined catalysts with an ultrathin coating to maximize the metal-support interfaces. What was the biggest surprise? In the course of the study,w es urprisingly found that the ALD cycle number of ultrathin coats has ah uge effect on the hydroge-nation activity.T he catalyst with two cycles Al 2 O 3 coatings showed significantly higher activity (about five times) than that of the un-coated catalyst. However,a fter further depositing only three cycles of Al 2 O 3 coatings ,t he activity of the catalyst sharply decreased to 1:10 of the uncoated catalyst. This result indicates that the metal-support interfaces have as trong effect on the performance of the catalyst and that ap recise and optimal cycle numbers for ALD Al 2 O 3 is necessary for the maximized interfaces. What future opportunities do you see (in the light of the results presented in this paper)? The method of coating the confined catalysts can be extended to other catalytic systems in which the metal-support interfaces have astrong effect on the catalytic performance. Invited for the cover of this issue is the group of Yong Qin at the Chinese Academy of Sciences. The image depicts the main features of the designed catalyst, whicha re the Al 2 O 3 nanotubes, confined Pt nanoparticles, and ultrathin Al 2 O 3 coats. Read the full textoft he article at

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Hydrogen Spillover on CeO₂/Pt: Enhanced Storage of Active Hydrogen

Cited by 101 publications

References 17 publications

Oxide-based nanomaterials for fuel cell catalysis: the interplay between supported single Pt atoms and particles

Oxide-based nanomaterials for fuel cell catalysis: the interplay between supported single Pt atoms and particles

Support‐dependent activity of noble metal substituted oxide catalysts for the water gas shift reaction

Ultrathin Coating of Confined Pt Nanocatalysts by Atomic Layer Deposition for Enhanced Catalytic Performance in Hydrogenation Reactions

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