Establishing structure-sensitivity of ceria reducibility: real-time observations of surface-hydrogen interactions

Duchoň, Tomáš; Hackl, Johanna; Mueller, David N.; Kullgren, Jolla; Du, Dou; Senanayake, Sanjaya D.; Mouls, Caroline Lydie; Gottlob, Daniel M.; Khan, Muhammad Nadir; Cramm, S.; Veltruská, Kateřina; Matolín, Vladimı́r; Nemšák, Slavomír; Schneider, Claus M.

doi:10.1039/c9ta11784a

Cited by 13 publications

(10 citation statements)

References 55 publications

(42 reference statements)

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“…All the latter LEED data let assume that the reduction of the ceria NPs in our work cannot be so high, eventually well below 50 %. Indeed, XPS shows that the efficiency of the H 2 reduction is quite low: when annealing the sample at 427 °C in 1.5 × 10 −6 mbar H 2 , about 20 hours are needed to obtain a 24 % large reduction [41]. A very recent micro X-Ray absorption spectroscopy (µXAS-PEEM) study shows that the degree of reduction remains low (CeO ∼1.9 ) if a stoichiometric CeO 2 (111) film is reduced by annealing at 550 °C during a dosage of 26 000 L of H 2 [70].…”

Section: Reductionmentioning

confidence: 99%

“…To study the role of a metal support that changes its state between being metallic and oxidized, the inverse ceria/Cu(111) catalyst is an ideal model surface [21,26]. The ceria/Cu(111) system has been extensively studied in the past [27], particularly by LEED [28,29,30,31,32,33,34,35,36,37], RHEED [38,15], LEEM [39,40,41], XPS [29,30,42,26,43,44,33,34,45,35,20,46,36,47,37,15,48,41] and by STM [30,32,26,49,33,34,45,35,46,36,47,37] as well as by density functional theory (DFT) [21,…”

Section: Introductionmentioning

confidence: 99%

“…The ceria/Cu(111) system has been extensively studied in the past [27], particularly by LEED [28,29,30,31,32,33,34,35,36,37], RHEED [38,15], LEEM [39,40,41], XPS [29,30,42,26,43,44,33,34,45,35,20,46,36,47,37,15,48,41] and by STM [30,32,26,49,33,34,45,35,46,36,47,37] as well as by density functional theory (DFT) [21,26,49,50,19,…”

Section: Introductionmentioning

confidence: 99%

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High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM

Barraj¹,

Chatelain²,

Barth³

2021

J. Phys.: Condens. Matter

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The inverse catalyst 'cerium oxide (ceria) on copper' has attracted much interest in recent time because of its promising catalytic activity in the water-gas-shift reaction and the hydrogenation of CO 2 . For such reactions it is important to study the redox behaviour of this system, in particular with respect to the reduction by H 2 . Here, we investigate the high-temperature O 2 oxidation and H 2 reduction of ceria nanoparticles (NP) and a Cu(111) support by low energy electron diffraction (LEED), scanning tunnelling microscopy (STM), noncontact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). After oxidation at 550 °C, the ceria NPs and the Cu(111) support are fully oxidized, with the copper oxide exhibiting a new oxide structure as verified by LEED and STM. We show that a high H 2 dosage in the kilo Langmuir range is needed to entirely reduce the copper support at 550 °C. A work function (WF) difference of φ rCeria/Cu-Cu ≈ -0.6 eV between the ceria NPs and the metallic Cu(111) support is measured, with the Cu(111) surface showing no signatures of separated and confined surface regions composed by a CuCe alloy. After oxidation, the WF difference is close to zero ( φ Ceria/Cu-Cu ≈ -0.1 . . . 0 eV), which probably is due to a WF change of both, ceria and copper.

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Section: Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM

Barraj¹,

Chatelain²,

Barth³

2021

J. Phys.: Condens. Matter

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“…The study of the interaction between H 2 and ceria is crucial to understanding the mechanism of ceria catalyzed selective hydrogenation reactions [25][26][27][28][29]. Many studies have found that the homolytic dissociation of H 2 to form two hydroxyl (OH) groups is thermodynamically favored on the stoichiometric surface of ceria [6,30].…”

Section: Introductionmentioning

confidence: 99%

Hydride Generation on the Cu-Doped CeO2(111) Surface and Its Role in CO2 Hydrogenation Reactions

Wang

Liu

et al. 2022

Catalysts

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Ceria-based catalysts exhibit great activity in catalyzing selective hydrogenation of CO2 to methanol. However, the underlying mechanism of this reaction, especially the generation of active H species, remains unclear. In this work, we performed extensive density functional theory calculations corrected by on-site Coulomb interaction (DFT + U) to investigate the H2 dissociation and the reaction between the active H species and CO2 on the pristine and Cu-doped CeO2(111) (denoted as Cu/CeO2(111)) surfaces. Our calculations evidenced that the heterolytic H2 dissociation for hydride generation can more readily occur on the Cu/CeO2(111) surface than on the pristine CeO2(111) surface. We also found that the Cu dopant can facilitate the formation of surface oxygen vacancies, further promoting the generation of hydride species. Moreover, the adsorption of CO2 and the hydrogenation of CO2 to HCOO* can be greatly promoted on the Cu/CeO2(111) surface with hydride species, which can lead to the high activity and selectivity toward CO2 hydrogenation to methanol.

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“…The processes that alter the surface structure and chemistry during operation are spatially heterogeneous in nature and thus require spatially nonaveraging techniques, 16 such as spectromicroscopy, to be captured in their entirety. However, while separate spectroscopic and microscopic studies are abundant, as discussed, a proper spectromicroscopical study is missing.…”

Section: ■ Introductionmentioning

confidence: 99%

Nanoscopic Surface Decomposition of Pr_0.5Ba_0.5CoO_3−δ Perovskites Turns Performance Descriptors Ambiguous

et al. 2021

Self Cite

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The surface electronic structure of a material is frequently used to identify simple descriptors for its catalytic efficacy and other properties. To harness the predictive ability of such descriptors, structural and chemical evolutions of the material when exposed to operating conditions, such as oxidizing environments and high temperatures, need to be considered. These evolutions occur at length scales not easily observable, leading to averaging over short-range variations and thus misinterpretation of the property in question. Here, we investigate perovskite Pr0.5Ba0.5CoO3−δ as a prototypical mixed ionic–electronic conductor that exhibits promising catalytic properties toward the oxygen evolution reaction in electrochemical cells, which have been characterized by such descriptors. We employ spatially resolved X-ray absorption spectroscopy and find a Cahn–Hilliard-type decomposition process at sub-micrometer length scales after mere hours at operating or processing conditions. The observation is in contrast to the thermodynamic stability of the Pr0.5Ba0.5CoO3−δ bulk, suggesting the decomposition to be confined to the surface. Our results showcase a considerable lateral inhomogeneity of the surface electronic structure, emphasizing that descriptors derived through spatially averaging techniques have to be heavily scrutinized.

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Establishing structure-sensitivity of ceria reducibility: real-time observations of surface-hydrogen interactions

Abstract: Unraveling the thermodynamic origin of the structure–reducibility of cerium oxide (100) and (111) surface planes.

Cited by 13 publications

References 55 publications

High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM

High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM

Hydride Generation on the Cu-Doped CeO2(111) Surface and Its Role in CO2 Hydrogenation Reactions

Nanoscopic Surface Decomposition of Pr_0.5Ba_0.5CoO_3−δ Perovskites Turns Performance Descriptors Ambiguous

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Establishing structure-sensitivity of ceria reducibility: real-time observations of surface-hydrogen interactions

Abstract: Unraveling the thermodynamic origin of the structure–reducibility of cerium oxide (100) and (111) surface planes.

Cited by 13 publications

References 55 publications

High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM

High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM

Hydride Generation on the Cu-Doped CeO2(111) Surface and Its Role in CO2 Hydrogenation Reactions

Nanoscopic Surface Decomposition of Pr0.5Ba0.5CoO3−δ Perovskites Turns Performance Descriptors Ambiguous

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Nanoscopic Surface Decomposition of Pr_0.5Ba_0.5CoO_3−δ Perovskites Turns Performance Descriptors Ambiguous