Water-gas shift reaction over supported Au nanoparticles

Mayank Shekhar; Wen Sheng Lee; M. Cem Akatay; Leonardo Maciel; Wenjie Tang; Jeffrey T. Miller; Eric A. Stach; Matthew Neurock; W. Nicholas Delgass; Fabio H. Ribeiro

doi:10.1016/j.jcat.2021.12.021

Water-gas shift reaction over supported Au nanoparticles

Mayank Shekhar, Wen Sheng Lee, M. Cem Akatay, Leonardo Maciel, Wenjie Tang, Jeffrey T. Miller, Eric A. Stach, Matthew Neurock, W. Nicholas Delgass, Fabio H. Ribeiro

Research output: Contribution to journal › Article › peer-review

12 Scopus citations

Abstract

The water–gas shift (WGS) reaction rates per total mole of Au at 120 °C, 7% CO, 22% H₂O, 8.5% CO₂, 37% H₂ decrease in the order Au/Anatase ∼ Au/Anatase001 (uniform anatase TiO₂ single crystals with 64 per cent of the more {0 0 1} facets) ∼ Au/P25 ∼ Au/P25-WGC (obtained from the World Gold Council) ∼ Au/Rutile > Au/ZrO₂ > Au/CeO₂ > Au/ZnO when compared at the same number average Au particle size (d) and vary as ∼ d^-3. From high resolution transmission electron microscopy images, the geometry of Au nanoparticles on these catalysts resembled truncated cubo-octahedra. A physical model of Au nanoparticles as truncated cubo-octahedra was used to calculate that the fractions of surface, perimeter and corner sites to the total Au sites vary as d^-0.7, d^-1.8 and d^-2.9, respectively. Thus, the variation in the WGS reaction rate per total mole of Au (∼d^-3) correlates well with the corner sites (d^-2.9) allowing us to determine that the dominant active sites for these catalysts are the low coordinated metallic corner Au sites. In addition, as the apparent H₂O order increases and the apparent activation energy decreases, the WGS reaction rate per total mole of Au systematically decreases for Au nanoparticles supported on anatase, anatase001, P25, rutile, ZrO₂, CeO₂, ZnO and Al₂O₃ at near 120 °C. Density functional theory calculations were carried out over Au nano-rods supported on rutile TiO₂(1 0 0) and α-Al₂O₃(0 0 0 1) surfaces to elucidate the differences in reactivity for the most reactive (Au/TiO₂) and least reactive (Au/Al₂O₃) catalysts. Water preferentially adsorbs and dissociates at the Lewis acid- Lewis base Ti⁴⁺-O_b and Al³⁺-O_b site pairs at the Au/TiO₂(1 1 0) and Au/α-Al₂O₃ interfaces with activation energies of 0.25 eV and 0.20 respectively. These barriers are significantly lower than those to activate water on the corner sites of unsupported Au nanoparticles (1.48 eV). The prediction that both the TiO₂ and Al₂O₃ readily dissociate water supports the experimental findings that the support plays an important role in activating the water in the WGS reaction. The subsequent oxidation of CO appears to proceed at the Au/support interface via the reaction of CO adsorbed on Au with the OH on the support. DFT results indicate that OH binds 0.4 eV stronger to Al³⁺ sites at the Au/Al₂O₃ interface perimeter than to Ti⁴⁺ sites at the Au/TiO₂ interface perimeter. As such, the barrier for OH to react with CO at an adjacent Au site is 0.52 eV higher for Au/Al₂O₃ (0.85 eV) than for Au/TiO₂ (0.33 eV). The theoretical results suggest that the oxidation of CO is rate-limiting on Al₂O₃ whereas both the water dissociation as well as CO oxidation limit the rate on TiO₂. This is consistent with the near first order CO dependence of the measured rates over both Au/TiO₂ and Au/Al₂O₃ as well as the changes in the water reaction orders over Au/TiO₂ (−0.2 to −0.5) and Au/Al₂O₃ (0.5 to 0.8).

Original language	English (US)
Pages (from-to)	475-488
Number of pages	14
Journal	Journal of Catalysis
Volume	405
DOIs	https://doi.org/10.1016/j.jcat.2021.12.021
State	Published - Jan 2022
Externally published	Yes

Bibliographical note

Funding Information:
We wish to dedicate this paper to our lead-author and friend, Professor W. Nicholas Delgass who passed on peacefully during the review of the manuscript. Nick played a foundational role in this work and led our efforts in both experiment and theory. Nick was an exceptional scientist, colleague and friend. He had a remarkable impact on the lives of the countless number of students and colleagues that he worked with. He was an outstanding friend to all. He will be missed but not forgotten. The authors would like to thank Professor Huagui Yang, East China University of Science and Technology, for providing the anatase001 support and the National Science Foundation and the Texas Advanced Computing Center for XSEDE computing resources. MN would like to acknowledge helpful discussions with Professor Robert J. Davis and backup calculations by Roshan Patel. We greatfully acknowledge funding from the U.S. Department of Energy, Office of Basic Energy Sciences, Catalysis Science Grant No. DE-FG02-03ER15466 and also DE-FG02-09ER16080. Use of the Advanced Photon Source is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions.

Publisher Copyright:
© 2021 Elsevier Inc.

Keywords

Effect of support
Water-gas shift on Au

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10.1016/j.jcat.2021.12.021

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@article{6e91ab17c5d34672890518e5615b8f75,

title = "Water-gas shift reaction over supported Au nanoparticles",

abstract = "The water–gas shift (WGS) reaction rates per total mole of Au at 120 °C, 7% CO, 22% H2O, 8.5% CO2, 37% H2 decrease in the order Au/Anatase ∼ Au/Anatase001 (uniform anatase TiO2 single crystals with 64 per cent of the more {0 0 1} facets) ∼ Au/P25 ∼ Au/P25-WGC (obtained from the World Gold Council) ∼ Au/Rutile > Au/ZrO2 > Au/CeO2 > Au/ZnO when compared at the same number average Au particle size (d) and vary as ∼ d-3. From high resolution transmission electron microscopy images, the geometry of Au nanoparticles on these catalysts resembled truncated cubo-octahedra. A physical model of Au nanoparticles as truncated cubo-octahedra was used to calculate that the fractions of surface, perimeter and corner sites to the total Au sites vary as d-0.7, d-1.8 and d-2.9, respectively. Thus, the variation in the WGS reaction rate per total mole of Au (∼d-3) correlates well with the corner sites (d-2.9) allowing us to determine that the dominant active sites for these catalysts are the low coordinated metallic corner Au sites. In addition, as the apparent H2O order increases and the apparent activation energy decreases, the WGS reaction rate per total mole of Au systematically decreases for Au nanoparticles supported on anatase, anatase001, P25, rutile, ZrO2, CeO2, ZnO and Al2O3 at near 120 °C. Density functional theory calculations were carried out over Au nano-rods supported on rutile TiO2(1 0 0) and α-Al2O3(0 0 0 1) surfaces to elucidate the differences in reactivity for the most reactive (Au/TiO2) and least reactive (Au/Al2O3) catalysts. Water preferentially adsorbs and dissociates at the Lewis acid- Lewis base Ti4+-Ob and Al3+-Ob site pairs at the Au/TiO2(1 1 0) and Au/α-Al2O3 interfaces with activation energies of 0.25 eV and 0.20 respectively. These barriers are significantly lower than those to activate water on the corner sites of unsupported Au nanoparticles (1.48 eV). The prediction that both the TiO2 and Al2O3 readily dissociate water supports the experimental findings that the support plays an important role in activating the water in the WGS reaction. The subsequent oxidation of CO appears to proceed at the Au/support interface via the reaction of CO adsorbed on Au with the OH on the support. DFT results indicate that OH binds 0.4 eV stronger to Al3+ sites at the Au/Al2O3 interface perimeter than to Ti4+ sites at the Au/TiO2 interface perimeter. As such, the barrier for OH to react with CO at an adjacent Au site is 0.52 eV higher for Au/Al2O3 (0.85 eV) than for Au/TiO2 (0.33 eV). The theoretical results suggest that the oxidation of CO is rate-limiting on Al2O3 whereas both the water dissociation as well as CO oxidation limit the rate on TiO2. This is consistent with the near first order CO dependence of the measured rates over both Au/TiO2 and Au/Al2O3 as well as the changes in the water reaction orders over Au/TiO2 (−0.2 to −0.5) and Au/Al2O3 (0.5 to 0.8).",

keywords = "Effect of support, Water-gas shift on Au",

author = "Mayank Shekhar and Lee, {Wen Sheng} and Akatay, {M. Cem} and Leonardo Maciel and Wenjie Tang and Miller, {Jeffrey T.} and Stach, {Eric A.} and Matthew Neurock and Delgass, {W. Nicholas} and Ribeiro, {Fabio H.}",

note = "Funding Information: We wish to dedicate this paper to our lead-author and friend, Professor W. Nicholas Delgass who passed on peacefully during the review of the manuscript. Nick played a foundational role in this work and led our efforts in both experiment and theory. Nick was an exceptional scientist, colleague and friend. He had a remarkable impact on the lives of the countless number of students and colleagues that he worked with. He was an outstanding friend to all. He will be missed but not forgotten. The authors would like to thank Professor Huagui Yang, East China University of Science and Technology, for providing the anatase001 support and the National Science Foundation and the Texas Advanced Computing Center for XSEDE computing resources. MN would like to acknowledge helpful discussions with Professor Robert J. Davis and backup calculations by Roshan Patel. We greatfully acknowledge funding from the U.S. Department of Energy, Office of Basic Energy Sciences, Catalysis Science Grant No. DE-FG02-03ER15466 and also DE-FG02-09ER16080. Use of the Advanced Photon Source is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. Publisher Copyright: {\textcopyright} 2021 Elsevier Inc.",

year = "2022",

month = jan,

doi = "10.1016/j.jcat.2021.12.021",

language = "English (US)",

volume = "405",

pages = "475--488",

journal = "Journal of Catalysis",

issn = "0021-9517",

publisher = "Academic Press Inc.",

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TY - JOUR

T1 - Water-gas shift reaction over supported Au nanoparticles

AU - Shekhar, Mayank

AU - Lee, Wen Sheng

AU - Akatay, M. Cem

AU - Maciel, Leonardo

AU - Tang, Wenjie

AU - Miller, Jeffrey T.

AU - Stach, Eric A.

AU - Neurock, Matthew

AU - Delgass, W. Nicholas

AU - Ribeiro, Fabio H.

N1 - Funding Information: We wish to dedicate this paper to our lead-author and friend, Professor W. Nicholas Delgass who passed on peacefully during the review of the manuscript. Nick played a foundational role in this work and led our efforts in both experiment and theory. Nick was an exceptional scientist, colleague and friend. He had a remarkable impact on the lives of the countless number of students and colleagues that he worked with. He was an outstanding friend to all. He will be missed but not forgotten. The authors would like to thank Professor Huagui Yang, East China University of Science and Technology, for providing the anatase001 support and the National Science Foundation and the Texas Advanced Computing Center for XSEDE computing resources. MN would like to acknowledge helpful discussions with Professor Robert J. Davis and backup calculations by Roshan Patel. We greatfully acknowledge funding from the U.S. Department of Energy, Office of Basic Energy Sciences, Catalysis Science Grant No. DE-FG02-03ER15466 and also DE-FG02-09ER16080. Use of the Advanced Photon Source is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. Publisher Copyright: © 2021 Elsevier Inc.

PY - 2022/1

Y1 - 2022/1

N2 - The water–gas shift (WGS) reaction rates per total mole of Au at 120 °C, 7% CO, 22% H2O, 8.5% CO2, 37% H2 decrease in the order Au/Anatase ∼ Au/Anatase001 (uniform anatase TiO2 single crystals with 64 per cent of the more {0 0 1} facets) ∼ Au/P25 ∼ Au/P25-WGC (obtained from the World Gold Council) ∼ Au/Rutile > Au/ZrO2 > Au/CeO2 > Au/ZnO when compared at the same number average Au particle size (d) and vary as ∼ d-3. From high resolution transmission electron microscopy images, the geometry of Au nanoparticles on these catalysts resembled truncated cubo-octahedra. A physical model of Au nanoparticles as truncated cubo-octahedra was used to calculate that the fractions of surface, perimeter and corner sites to the total Au sites vary as d-0.7, d-1.8 and d-2.9, respectively. Thus, the variation in the WGS reaction rate per total mole of Au (∼d-3) correlates well with the corner sites (d-2.9) allowing us to determine that the dominant active sites for these catalysts are the low coordinated metallic corner Au sites. In addition, as the apparent H2O order increases and the apparent activation energy decreases, the WGS reaction rate per total mole of Au systematically decreases for Au nanoparticles supported on anatase, anatase001, P25, rutile, ZrO2, CeO2, ZnO and Al2O3 at near 120 °C. Density functional theory calculations were carried out over Au nano-rods supported on rutile TiO2(1 0 0) and α-Al2O3(0 0 0 1) surfaces to elucidate the differences in reactivity for the most reactive (Au/TiO2) and least reactive (Au/Al2O3) catalysts. Water preferentially adsorbs and dissociates at the Lewis acid- Lewis base Ti4+-Ob and Al3+-Ob site pairs at the Au/TiO2(1 1 0) and Au/α-Al2O3 interfaces with activation energies of 0.25 eV and 0.20 respectively. These barriers are significantly lower than those to activate water on the corner sites of unsupported Au nanoparticles (1.48 eV). The prediction that both the TiO2 and Al2O3 readily dissociate water supports the experimental findings that the support plays an important role in activating the water in the WGS reaction. The subsequent oxidation of CO appears to proceed at the Au/support interface via the reaction of CO adsorbed on Au with the OH on the support. DFT results indicate that OH binds 0.4 eV stronger to Al3+ sites at the Au/Al2O3 interface perimeter than to Ti4+ sites at the Au/TiO2 interface perimeter. As such, the barrier for OH to react with CO at an adjacent Au site is 0.52 eV higher for Au/Al2O3 (0.85 eV) than for Au/TiO2 (0.33 eV). The theoretical results suggest that the oxidation of CO is rate-limiting on Al2O3 whereas both the water dissociation as well as CO oxidation limit the rate on TiO2. This is consistent with the near first order CO dependence of the measured rates over both Au/TiO2 and Au/Al2O3 as well as the changes in the water reaction orders over Au/TiO2 (−0.2 to −0.5) and Au/Al2O3 (0.5 to 0.8).

AB - The water–gas shift (WGS) reaction rates per total mole of Au at 120 °C, 7% CO, 22% H2O, 8.5% CO2, 37% H2 decrease in the order Au/Anatase ∼ Au/Anatase001 (uniform anatase TiO2 single crystals with 64 per cent of the more {0 0 1} facets) ∼ Au/P25 ∼ Au/P25-WGC (obtained from the World Gold Council) ∼ Au/Rutile > Au/ZrO2 > Au/CeO2 > Au/ZnO when compared at the same number average Au particle size (d) and vary as ∼ d-3. From high resolution transmission electron microscopy images, the geometry of Au nanoparticles on these catalysts resembled truncated cubo-octahedra. A physical model of Au nanoparticles as truncated cubo-octahedra was used to calculate that the fractions of surface, perimeter and corner sites to the total Au sites vary as d-0.7, d-1.8 and d-2.9, respectively. Thus, the variation in the WGS reaction rate per total mole of Au (∼d-3) correlates well with the corner sites (d-2.9) allowing us to determine that the dominant active sites for these catalysts are the low coordinated metallic corner Au sites. In addition, as the apparent H2O order increases and the apparent activation energy decreases, the WGS reaction rate per total mole of Au systematically decreases for Au nanoparticles supported on anatase, anatase001, P25, rutile, ZrO2, CeO2, ZnO and Al2O3 at near 120 °C. Density functional theory calculations were carried out over Au nano-rods supported on rutile TiO2(1 0 0) and α-Al2O3(0 0 0 1) surfaces to elucidate the differences in reactivity for the most reactive (Au/TiO2) and least reactive (Au/Al2O3) catalysts. Water preferentially adsorbs and dissociates at the Lewis acid- Lewis base Ti4+-Ob and Al3+-Ob site pairs at the Au/TiO2(1 1 0) and Au/α-Al2O3 interfaces with activation energies of 0.25 eV and 0.20 respectively. These barriers are significantly lower than those to activate water on the corner sites of unsupported Au nanoparticles (1.48 eV). The prediction that both the TiO2 and Al2O3 readily dissociate water supports the experimental findings that the support plays an important role in activating the water in the WGS reaction. The subsequent oxidation of CO appears to proceed at the Au/support interface via the reaction of CO adsorbed on Au with the OH on the support. DFT results indicate that OH binds 0.4 eV stronger to Al3+ sites at the Au/Al2O3 interface perimeter than to Ti4+ sites at the Au/TiO2 interface perimeter. As such, the barrier for OH to react with CO at an adjacent Au site is 0.52 eV higher for Au/Al2O3 (0.85 eV) than for Au/TiO2 (0.33 eV). The theoretical results suggest that the oxidation of CO is rate-limiting on Al2O3 whereas both the water dissociation as well as CO oxidation limit the rate on TiO2. This is consistent with the near first order CO dependence of the measured rates over both Au/TiO2 and Au/Al2O3 as well as the changes in the water reaction orders over Au/TiO2 (−0.2 to −0.5) and Au/Al2O3 (0.5 to 0.8).

KW - Effect of support

KW - Water-gas shift on Au

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UR - http://www.scopus.com/inward/citedby.url?scp=85123077912&partnerID=8YFLogxK

U2 - 10.1016/j.jcat.2021.12.021

DO - 10.1016/j.jcat.2021.12.021

M3 - Article

AN - SCOPUS:85123077912

SN - 0021-9517

VL - 405

SP - 475

EP - 488

JO - Journal of Catalysis

JF - Journal of Catalysis

ER -

Water-gas shift reaction over supported Au nanoparticles

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