“Intelligent” Pt Catalysts Studied on High-Surface-Area CaTiO<sub>3</sub> Films

Lin, Chao Cheng; Foucher, Alexandre C.; Ji, Yichen; Curran, C.; Stach, Eric A.; McIntosh, Steven; Gorte, Raymond J.

doi:10.1021/acscatal.9b01278

Cited by 41 publications

(59 citation statements)

References 25 publications

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“…Similar to Ni catalysts formed by ex-solution, Ni supported on CaTiO 3 films showed extreme tolerance against coking in the presence of dry methane [7]. Finally, similar to what is observed with bulk perovskites [9], Pt, but not Pd, was found to interact strongly with CaTiO 3 [8].…”

Section: Introductionsupporting

confidence: 63%

“…In order to maintain differential conditions, rates were measured at lower temperatures on the more active catalysts. The effect of redox treatments for Pt/MAO, shown in both the Arrhenius plots and light-off profiles, has been discussed in a previous publication [8]. The sample exhibited similar activities as the conventional Pt catalysts, with results from the measurements reproduced in Figure S3.…”

Section: Co Oxidation Ratesmentioning

confidence: 61%

“…This behavior is unusual for supported metals and appears to be due to the high-temperature requirements for driving the metals into and out of the perovskite lattice. It is notable that this cycling between active and inactive states only occurs for those metal-perovskite pairs in which the metal can become part of the perovskite lattice [8]. Therefore, we employed similar CO oxidation measurements on the catalysts of this study to see whether these would also show evidence for ex-solution.…”

Section: Co Oxidation Ratesmentioning

confidence: 99%

“…In order to maintain differential conditions, rates were measured at lower temperatures on the more active catalysts. Past work with CO oxidation over perovskite-supported, ex-solution catalysts exhibited a high sensitivity to the pretreatment conditions [6][7][8]. Following high-temperature (1073 K) oxidation and relatively mild (773 K) reduction, the catalysts were inactive, but activity was restored upon hightemperature reduction.…”

Section: Co Oxidation Ratesmentioning

confidence: 99%

“…The deposited films retain a high surface area, and because the typical particle size for metal catalysts is greater than 1 nm, nucleation of particles in the bulk of the oxide can be avoided. In past published works, films of CaTiO 3 and LaFeO 3 were grown on MgAl 2 O 4 and then used as catalyst supports for Pd [6], Ni [7], and Pt [8]. The CaTiO 3 and LaFeO 3 films were found to uniformly cover the MgAl 2 O 4 support and to be stable to cycling between oxidizing and reducing conditions (redox cycling) at temperatures as high as at least 1073 K.…”

Section: Introductionmentioning

confidence: 99%

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“Intelligent” Pt Catalysts Based on Thin LaCoO3 Films Prepared by Atomic Layer Deposition

et al. 2019

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LaCoO3 films were deposited onto MgAl2O4 powders by atomic layer deposition (ALD) and then used as catalyst supports for Pt. X-ray diffraction (XRD) showed that the 0.5 nm films exhibited a perovskite structure after redox cycling at 1073 K, and scanning transmission electron microscopy and elemental mapping via energy-dispersive X-ray spectroscopy (STEM/EDS) data demonstrated that the films covered the substrate uniformly. Catalysts prepared with 3 wt % Pt showed that the Pt remained well dispersed on the perovskite film, even after repeated oxidations and reductions at 1073 K. Despite the high Pt dispersion, CO adsorption at room temperature was negligible. Compared with conventional Pt on MgAl2O4, the reduced forms of the LaCoO3-containing catalyst were highly active for the CO oxidation and water gas shift (WGS) reactions, while the oxidized catalysts showed much lower activities. Surprisingly, the reduced catalysts were much less active than the oxidized catalysts for toluene hydrogen. Catalysts prepared from thin films of Co3O4 or La2O3 exhibited properties more similar to Pt/MgAl2O4. Possible reasons for how LaCoO3 affects properties are discussed.

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Section: Introductionsupporting

confidence: 63%

Section: Co Oxidation Ratesmentioning

confidence: 61%

Section: Co Oxidation Ratesmentioning

confidence: 99%

Section: Co Oxidation Ratesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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“Intelligent” Pt Catalysts Based on Thin LaCoO3 Films Prepared by Atomic Layer Deposition

et al. 2019

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Dopant‐Driven Positive Reinforcement in Ex‐Solution Process: New Strategy to Develop Highly Capable and Durable Catalytic Materials

Jang

Kim

et al. 2020

Advanced Materials

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Supported catalysts, in which metal nanoparticles (NPs) are distributed on oxide supports, are widely used in a variety of industrial processes, including in catalysis, [1] sensing, [2] and renewable energy. [3] To improve the reactivity, costeffectiveness, and durability of catalysts, decreasing their particle size to ensure uniform dispersion on the support and to suppress their aggregation during operation, particularly at high temperatures (>500 °C) is of utmost importance. Thus far, not only conventional impregnation and coprecipitation approaches but also numerous new synthesis and dispersion techniques have been actively studied. [4] Recently, the spontaneous growth of metal NPs on the surface of a host oxide, called "ex-solution," has attracted much attention as a new route to obtain supported catalysts. [5] It is based on the phenomenon that certain cations in a complex oxide lattice selectively precipitate on the surface when the oxide is partially reduced at high temperatures. [6] In particular, when catalytically active and highly reducible transition metals are used as dopants, metal NPs can be uniformly dispersed on the oxide surface with only a single heat treatment. [7] Furthermore, the metal NPs produced by ex-solution are strongly bound to the host oxide and thus have excellent thermal and chemical stability. [8,9] Accordingly, thanks to these advantages, the ex-solution process is now being applied in high-temperature chemical and electrochemical applications, such as solid oxide fuel cells, [10] electrolyzers, [11] and oxidation catalysts. [12] However, the high-temperature heat treatment required to obtain ex-solved particles is a substantial barrier that significantly limits the use of this process in a wider range of applications. To achieve high catalytic reactivity, not only the metal particles but also the oxide support should have a large specific surface area, whereas at high temperatures, sintering between the oxide supports often occurs, deactivating the catalysts. Therefore, it is necessary to develop a strategy for activating the ex-solution process at a temperature low enough that the nanoscale oxide supports do not aggregate. In this regard, Irvine et al. proposed facilitating the extrusion of B-site cations The ex-solution phenomenon, a central platform for growing metal nanoparticles on the surface of host oxides in real time with high durability and a fine distribution, has recently been applied to various scientific and industrial fields, such as catalysis, sensing, and renewable energy. However, the high-temperature processing required for ex-solutions (>700 °C) limits the applicable material compositions and has hindered advances in this technique. Here, an unprecedented approach is reported for lowtemperature particle ex-solution on important nanoscale binary oxides. WO 3 with a nanosheet structure is selected as the parent oxide, and Ir serves as the active metal species that produces the ex-solved metallic particles. Importantly, Ir doping facilitates a phase transition ...

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Emergence and Future of Exsolved Materials

Kousi

Tang

Metcalfe

et al. 2021

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game-changing across multiple fields including but not limited to energy conversion and storage and catalysis, as evidenced by more than 300 papers having been published since the first reports of the method a decade ago. However, to the best of our knowledge only four reviews covering different application-related aspects of exsolution have been published so far. [17][18][19][20] Here, we review the trends that define the development of the exsolution concept in terms of design, tunability, functionality, and applicability. We analyze a set of 300 papers published so far on exsolution, to extract statistical information in terms of design elements (types of crystal structures, exsolvable and host lattice elements), synthesis routes, functionalities, and fields of application, including electrochemistry, catalysis photocatalysis, and other (discussed separately for noble and non-noble metal systems). The selected papers are listed and analyzed in the Supporting Information and the results are summarized in the infographic shown in Figure 3 and in Table 1 and based on these, we highlight exciting future directions of research in this fast-growing field. Figure 3. Exsolution infographic. Statistical analysis on a pool of 300 papers published on the field of exsolution since 2010.

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“Intelligent” Pt Catalysts Studied on High-Surface-Area CaTiO₃ Films

Cited by 41 publications

References 25 publications

“Intelligent” Pt Catalysts Based on Thin LaCoO3 Films Prepared by Atomic Layer Deposition

“Intelligent” Pt Catalysts Based on Thin LaCoO3 Films Prepared by Atomic Layer Deposition

Dopant‐Driven Positive Reinforcement in Ex‐Solution Process: New Strategy to Develop Highly Capable and Durable Catalytic Materials

Emergence and Future of Exsolved Materials

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“Intelligent” Pt Catalysts Studied on High-Surface-Area CaTiO3 Films

Cited by 41 publications

References 25 publications

“Intelligent” Pt Catalysts Based on Thin LaCoO3 Films Prepared by Atomic Layer Deposition

“Intelligent” Pt Catalysts Based on Thin LaCoO3 Films Prepared by Atomic Layer Deposition

Dopant‐Driven Positive Reinforcement in Ex‐Solution Process: New Strategy to Develop Highly Capable and Durable Catalytic Materials

Emergence and Future of Exsolved Materials

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“Intelligent” Pt Catalysts Studied on High-Surface-Area CaTiO₃ Films