Controlled Growth of Ceria Nanoarrays on Anatase Titania Powder: A Bottom-up Physical Picture

Kim, Hyun You; Hybertsen, Mark S.; Liu, Ping

doi:10.1021/acs.nanolett.6b04218

Cited by 30 publications

(22 citation statements)

References 51 publications

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“…Therefore, to evaluate the formation of rh-In 2 O 3 structure at low processing temperatures and phase transition from a rhombohedral to cubic structure, the growth mechanism of initial In 2 O 3 layers onto substrate was studied using DFT calculations. First, in our previous report on the epitaxial growth of CeO 2 (001) on anatase–TiO 2 (112), we found that cubic-fluoride CeO 2 (001) layers can be directly grown on the anatase–TiO 2 (112) surface without any buffer layers because of the morphological similarity in the surface structural motifs of TiO 2 (112) and CeO 2 (001) . On the other hand, because SiO 2 and In 2 O 3 differ in their crystal structures and protruding SiO x units from the SiO 2 (001) surface (see Figure a) hinder the direct growth of In 2 O 3 crystals on SiO 2 (001), initial buffer layers of In 2 O 3 were built by repeatedly depositing indium and oxygen atoms on SiO 2 (001) and the combined In 2 O 3 /SiO 2 (001) was used as a basement layer for subsequent DFT calculations of In 2 O 3 growth (Figure a–c).…”

Section: Resultsmentioning

confidence: 96%

Metastable Rhombohedral Phase Transition of Semiconducting Indium Oxide Controlled by Thermal Atomic Layer Deposition

Lee

Sheng

et al. 2020

Chem. Mater.

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Indium oxide (In 2 O 3 ) thin films were deposited via thermal atomic layer deposition (ALD) to exploit their potential as semiconductors in thin-film transistors (TFTs), using a new liquid t y p e i n d i u m c o m p l e x p r e c u r s o r ( I n -(CH 3 ) 3 [CH 3 OCH 2 CH 2 NHtBu]). In 2 O 3 films were deposited successfully at lower temperatures and exhibited a satisfactory growth rate (∼0.35 Å per cycle). In addition, we investigated the effect of deposition temperature from 100 to 250 °C on the microstructure and chemical and physical properties of In 2 O 3 films. Interestingly, the In 2 O 3 film had a clear rhombohedral structure at deposition temperatures from 100 to 150 °C. For the 200 and 250 °C deposition temperatures, the phase of In 2 O 3 transformed to a cubic structure. The crystalline structure of the In 2 O 3 film was extremely sensitive to deposition temperatures, giving rise to a wide range of tunable physical and electrical properties. Based on a comparison of comprehensive structural transmission electron microscopy analysis, density functional theory calculations, and systematic experimental measurements, we explored the possibility of TFTs with an ALD-processed In 2 O 3 layer as a semiconductor.

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Section: Resultsmentioning

confidence: 96%

Metastable Rhombohedral Phase Transition of Semiconducting Indium Oxide Controlled by Thermal Atomic Layer Deposition

Lee

Sheng

et al. 2020

Chem. Mater.

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“…56 To treat the highly localized Ce 4f orbital, DFT + U 57 with U eff = 4.5 eV was applied. 58,59 The interaction between the ionic cores and the valence electrons was described using the projector-augmented wave method. 60 Valence electron functions were extended with the planewave basis to an energy cutoff of 400 eV.…”

Section: Introductionmentioning

confidence: 99%

Catalytic CO Oxidation over Au Nanoparticles Supported on CeO₂ Nanocrystals: Effect of the Au–CeO₂ Interface

et al. 2018

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Gold nanoparticles (NPs) have attracted attention due to their superior catalytic performance in CO oxidation at low temperatures. Along with the size and shape of Au NPs, the catalytic function of Au-catalyzed CO oxidation can be further optimized by controlling the physicochemical properties of oxide-supporting materials. We applied a combinatorial approach of experimental analyses and theoretical interpretations to study the effect of a surface structure of supporting oxides and the corresponding CO oxidation activity of supported Au NPs. We synthesized Au NPs (average d ≈ 3 nm) supported on shape-controlled CeO2 nanocrystals, Au/CeO2 cubes, and Au/CeO2 octahedra for experimental analyses. The catalysts were modeled as Au/CeO2(100) and Au/CeO2(111) via density functional theory (DFT) calculations. The DFT calculations showed that the O–C–O type reaction intermediate could be spontaneously formed at the Au–CeO2(100) interface upon sequential multi-CO adsorption, accelerating CO oxidation via the Mars-van Krevelen mechanism. The additional kinetic process required for O–C–O formation at the Au–CeO2(111) interface slowed down the reaction. The experimental turnover frequency (TOF) of the Au/CeO2 cubes was 4 times greater than that of the Au/CeO2 octahedra (under 0.05 bar CO and 0.13 bar O2). The increasing TOF as a function of CO partial pressure and the positive correlation between the reducibility of CeO2 and the catalytic activity of Au/CeO2 catalysts confirmed the theoretical prediction that CO molecules occupy the surface of Au NPs and that the oxidation of Au-bound CO occurs at the Au–CeO2 interface. Through a comparative study of DFT calculations and in-depth experimental analyses, we provide insights into the catalytic function of CeO2-supported Au NPs toward CO oxidation depending on the shape of CeO2 and ratio of CO/O2.

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“…We performed spin-polarized DFT calculations with the Vienna ab initio simulation package (VASP) and the PW91 functional. To treat the highly localized Ce 4f orbital, DFT+U with U eff = 4.5 eV , was applied. The interaction between the ionic cores and the valence electrons was described by the projector-augmented wave method .…”

Section: Computational Detailsmentioning

confidence: 99%

Catalytic CO Oxidation by CO-Saturated Au Nanoparticles Supported on CeO₂: Effect of CO Coverage

Yoo

et al. 2017

J. Phys. Chem. C

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Understanding the reaction mechanism and the nature of the reactive species of heterogeneous catalysts under reaction conditions is the first step in the design of more consistent, reliable, and practical catalysts. We used density functional theory (DFT) calculations to study the mechanism of CO oxidation catalyzed by CeO2-supported Au nanoparticles (NPs) under reaction conditions by considering the sequential CO adsorption onto and CO saturation of Au NPs. We found that the Au9 NPs supported by CeO2(100) and CeO2(111) bind as many as eight or four CO molecules, respectively. The last-bound CO molecule opens the fast CO oxidation pathway. The CO oxidation pathways constructed on both systems show that the reaction occurs at the Au–CeO2 interface via the Mars–van Krevelen mechanism. We found that the most important O–C–O-type intermediate was spontaneously formed at the Au–CeO2(100) interface upon the sequential binding of CO molecules onto the Au NPs. The reaction pathway therefore becomes relatively simpler than the CO oxidation pathways constructed with a first-bound single CO molecule. Although the O–C–O formation at the Au–CeO2(111) interface requires overcoming an activation energy barrier, the rate of CO oxidation shows that the Au/CeO2(111) was also highly reactive even at room temperature. Our findings show that the surface of Au NPs supported by CeO2 will be saturated with CO under CO oxidation conditions and that subsequent CO oxidation occurs at the Au–CeO2 interface. Our results suggest that the interaction between the catalysts and the reacting molecules should be more intensively studied to understand the catalytic performance of supported NP catalysts under reaction conditions.

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Controlled Growth of Ceria Nanoarrays on Anatase Titania Powder: A Bottom-up Physical Picture

Cited by 30 publications

References 51 publications

Metastable Rhombohedral Phase Transition of Semiconducting Indium Oxide Controlled by Thermal Atomic Layer Deposition

Metastable Rhombohedral Phase Transition of Semiconducting Indium Oxide Controlled by Thermal Atomic Layer Deposition

Catalytic CO Oxidation over Au Nanoparticles Supported on CeO₂ Nanocrystals: Effect of the Au–CeO₂ Interface

Catalytic CO Oxidation by CO-Saturated Au Nanoparticles Supported on CeO₂: Effect of CO Coverage

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Controlled Growth of Ceria Nanoarrays on Anatase Titania Powder: A Bottom-up Physical Picture

Cited by 30 publications

References 51 publications

Metastable Rhombohedral Phase Transition of Semiconducting Indium Oxide Controlled by Thermal Atomic Layer Deposition

Metastable Rhombohedral Phase Transition of Semiconducting Indium Oxide Controlled by Thermal Atomic Layer Deposition

Catalytic CO Oxidation over Au Nanoparticles Supported on CeO2 Nanocrystals: Effect of the Au–CeO2 Interface

Catalytic CO Oxidation by CO-Saturated Au Nanoparticles Supported on CeO2: Effect of CO Coverage

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Catalytic CO Oxidation over Au Nanoparticles Supported on CeO₂ Nanocrystals: Effect of the Au–CeO₂ Interface

Catalytic CO Oxidation by CO-Saturated Au Nanoparticles Supported on CeO₂: Effect of CO Coverage