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Chen BW. Equilibrium and kinetic isotope effects in heterogeneous catalysis: A density functional theory perspective. CATAL COMMUN 2023. [DOI: 10.1016/j.catcom.2023.106654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
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2
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Kaid M, Khder AS, Ahmed SA, Ibrahim AA, Altass HM, Alsantali RI, Jassas RS, Khder MA, Al-Rooqi MM, Moussa Z, Ahmed AI. High-Efficacy Hierarchical Dy 2O 3/TiO 2 Nanoflower toward Wastewater Reclamation: A Combined Photoelectrochemical and Photocatalytic Strategy. ACS OMEGA 2022; 7:17223-17233. [PMID: 35647445 PMCID: PMC9134253 DOI: 10.1021/acsomega.2c01090] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 04/28/2022] [Indexed: 06/15/2023]
Abstract
Developing a sustainable photocatalyst is crucial to mitigate the foreseeable energy shortage and environmental pollution caused by the rapid advancement of global industry. We developed Dy2O3/TiO2 nanoflower (TNF) with a hierarchical nanoflower structure and a near-ideal anatase crystallite morphology to degrade aqueous rhodamine B solution under simulated solar light irradiation. The prepared photocatalyst was well-characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, energy-dispersive spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, diffuse reflectance UV-vis spectra, and X-ray photoelectron spectroscopy. Further analysis was performed to highlight the photoelectrochemical activity of the prepared photocatalysts such as electrochemical impedance spectroscopy, linear sweep voltammetry, photocurrent response, and a Mott-Schottky study. The crystalline Dy2O3/TNF exhibits superb photocatalytic activity attributed to the improved charge transfer, reduced recombination rate of the electron-hole pairs, and a remarkable red-shift in light absorption.
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Affiliation(s)
- Mahmoud
M. Kaid
- Department
of Chemistry, Faculty of Science, Mansoura
University, 35516 Mansoura, Egypt
| | - Abdelrahman S. Khder
- Department
of Chemistry, Faculty of Science, Mansoura
University, 35516 Mansoura, Egypt
- Chemistry
Department, Faculty of Applied Science, Umm Al-Qura University, 21955 Makkah, Saudi Arabia
| | - Saleh A. Ahmed
- Chemistry
Department, Faculty of Applied Science, Umm Al-Qura University, 21955 Makkah, Saudi Arabia
- Chemistry
Department, Faculty of Science, Assiut University, 71516 Assiut, Egypt
| | - Amr A. Ibrahim
- Department
of Chemistry, Faculty of Science, Mansoura
University, 35516 Mansoura, Egypt
| | - Hatem M. Altass
- Chemistry
Department, Faculty of Applied Science, Umm Al-Qura University, 21955 Makkah, Saudi Arabia
| | - Reem I. Alsantali
- Department
of Pharmaceutical Chemistry, College of Pharmacy, Taif University, P.O. Box 11099, 21944 Taif, Saudi Arabia
| | - Rabab S. Jassas
- Department
of Chemistry, Jamoum University College, Umm Al-Qura University, 21955 Makkah, Saudi Arabia
| | - Menna A. Khder
- Department
of Chemistry, Faculty of Science, Mansoura
University, 35516 Mansoura, Egypt
| | - Munirah M. Al-Rooqi
- Chemistry
Department, Faculty of Applied Science, Umm Al-Qura University, 21955 Makkah, Saudi Arabia
| | - Ziad Moussa
- Department
of Chemistry, College of Science, United
Arab Emirates University, P.O. Box 15551 Al Ain, Abu Dhabi, United Arab Emirates
| | - Awad I. Ahmed
- Department
of Chemistry, Faculty of Science, Mansoura
University, 35516 Mansoura, Egypt
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Park KS, Goag TY, Kwon JH, Park YM, Yu JS, Jeong HE, Choung JW, Bae JW. Effects of spatially confined nickel nanoparticles in surface-pretreated hydrophobic SBA-15 for dry reforming of CH4 with CO2. J CO2 UTIL 2021. [DOI: 10.1016/j.jcou.2021.101629] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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4
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Harris J, Silk R, Smith M, Dong Y, Chen WT, Waterhouse GIN. Hierarchical TiO 2 Nanoflower Photocatalysts with Remarkable Activity for Aqueous Methylene Blue Photo-Oxidation. ACS OMEGA 2020; 5:18919-18934. [PMID: 32775893 PMCID: PMC7408212 DOI: 10.1021/acsomega.0c02142] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/09/2020] [Indexed: 05/20/2023]
Abstract
This study systematically evaluates the performance of a series of TiO2 nanoflower (TNF) photocatalysts for aqueous methylene blue photo-oxidation under UV irradiation. TNF nanoflowers were synthesized from Ti(IV) butoxide by a hydrothermal method and then calcined at different temperatures (T = 400-800 °C) for specific periods of time (t = 1-5 h). By varying the calcination conditions, TNF-T-t photocatalysts with diverse physicochemical properties and anatase/rutile ratios were obtained. Many of the TNF-T-1 photocatalysts demonstrated remarkable activity for aqueous methylene blue photo-oxidation at pH 6 under UV excitation (365 nm), with activities following the order TNF-700-1 > TNF-600-1 > TNF-500-1 > TNF-400-1 ∼ P25 TiO2 ≫ TNF-800-1. The activity of the TNF-700-1 photocatalyst (99% anatase, 1% rutile) was 2.3 times that of P25 TiO2 at pH 6 and 14.4 times that of P25 TiO2 at pH 4. Prolonged calcination of the TNFs at 700 °C proved detrimental to dye degradation performance due to excessive rutile formation, which reduced the photocatalyst surface area and suppressed OH• generation. The outstanding activities of TNF-700-1 and TNF-600-1 are attributed to their hierarchical nanoflower morphology which benefitted UV absorption, a near-ideal anatase crystallite size for efficient charge separation, and their unusually low isoelectric point (IEP = 4.3-4.5).
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Affiliation(s)
- Jonathan Harris
- School
of Chemical Sciences, The University of
Auckland, Auckland 1010, New Zealand
| | - Ryan Silk
- School
of Chemical Sciences, The University of
Auckland, Auckland 1010, New Zealand
| | - Mark Smith
- School
of Chemical Sciences, The University of
Auckland, Auckland 1010, New Zealand
| | - Yusong Dong
- School
of Chemical Sciences, The University of
Auckland, Auckland 1010, New Zealand
- The
MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
- The
Dodd Walls Centre for Photonic and Quantum Technologies, Dunedin 9056, New Zealand
| | - Wan-Ting Chen
- School
of Chemical Sciences, The University of
Auckland, Auckland 1010, New Zealand
- The
MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
- The
Dodd Walls Centre for Photonic and Quantum Technologies, Dunedin 9056, New Zealand
| | - Geoffrey I. N. Waterhouse
- School
of Chemical Sciences, The University of
Auckland, Auckland 1010, New Zealand
- The
MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
- The
Dodd Walls Centre for Photonic and Quantum Technologies, Dunedin 9056, New Zealand
- . Telephone: 64-9-923 7212. Fax: 64-9-373 7422
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Kung MC, Ye J, Kung HH. 110th Anniversary: A Perspective on Catalytic Oxidative Processes for Sustainable Water Remediation. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b04581] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Mayfair C. Kung
- Chemical and Biological Engineering Department, Northwestern University, Evanston, Illinois 60208, United States
| | - Junqing Ye
- Chemical and Biological Engineering Department, Northwestern University, Evanston, Illinois 60208, United States
- College of Science, China University of Petroleum, Beijing, China
| | - Harold H. Kung
- Chemical and Biological Engineering Department, Northwestern University, Evanston, Illinois 60208, United States
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Theoretical Studies on the Direct Propylene Epoxidation Using Gold-Based Catalysts: A Mini-Review. Catalysts 2018. [DOI: 10.3390/catal8100421] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Direct propylene epoxidation using Au-based catalysts is an important gas-phase reaction and is clearly a promising route for the future industrial production of propylene oxide (PO). For instance, gold nanoparticles or clusters that consist of a small number of atoms demonstrate unique and even unexpected properties, since the high ratio of surface to bulk atoms can provide new reaction pathways with lower activation barriers. Support materials can have a remarkable effect on Au nanoparticles or clusters due to charge transfer. Moreover, Au (or Au-based alloy, such as Au–Pd) can be loaded on supports to form active interfacial sites (or multiple interfaces). Model studies are needed to help probe the underlying mechanistic aspects and identify key factors controlling the activity and selectivity. The current theoretical/computational progress on this system is reviewed with respect to the molecular- and catalyst-level aspects (e.g., first-principles calculations and kinetic modeling) of propylene epoxidation over Au-based catalysts. This includes an analysis of H2 and O2 adsorption, H2O2 (OOH) species formation, epoxidation of propylene into PO, as well as possible byproduct formation. These studies have provided a better understanding of the nature of the active centers and the dominant reaction mechanisms, and thus, could potentially be used to design novel catalysts with improved efficiency.
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Au Atom Diffusions on Reduced and Cl-Adsorbed Rutile TiO<sub>2</sub>(110) Surfaces: A DFT + <i>U</i> Study. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2018. [DOI: 10.1380/ejssnt.2018.267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Tada K, Maeda Y, Koga H, Okumura M. TiO2 Crystal Structure Dependence of Low-temperature CO Oxidation Catalyzed by Au/TiO2. CHEM LETT 2018. [DOI: 10.1246/cl.170989] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Kohei Tada
- Research Institute of Electrochemical Energy, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
| | - Yasushi Maeda
- Research Institute of Electrochemical Energy, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
| | - Hiroaki Koga
- Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, 1-30 Goryo Ohara, Nishikyo, Kyoto 615-8245, Japan
| | - Mitsutaka Okumura
- Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, 1-30 Goryo Ohara, Nishikyo, Kyoto 615-8245, Japan
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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Affiliation(s)
- Nicholas T. Daugherty
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - John Bacsa
- X-ray Crystallography Center, Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Joseph P. Sadighi
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
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Tada K, Koga H, Hayashi A, Kondo Y, Kawakami T, Yamanaka S, Okumura M. Theoretical Clarification of the Coexistence of Cl Effects on Au/TiO2: The Interaction between Au Clusters and the TiO2 Surface, and the Aggregation of Au Clusters on the TiO2 Surface. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2017. [DOI: 10.1246/bcsj.20160359] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Kohei Tada
- Department of Energy and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Hiroaki Koga
- Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520
| | - Akihide Hayashi
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Yudai Kondo
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Takashi Kawakami
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Shusuke Yamanaka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Mitsutaka Okumura
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
- Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520
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11
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Rapid removal and decomposition of gaseous acetaldehyde by the thermo- and photo-catalysis of gold nanoparticle-loaded anatase titanium(IV) oxide. J Colloid Interface Sci 2015; 456:161-5. [PMID: 26122796 DOI: 10.1016/j.jcis.2015.06.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/28/2015] [Accepted: 06/11/2015] [Indexed: 11/20/2022]
Abstract
Gold nanoparticles (NPs) with a mean particle size ranging from 2.1 to 7.4 nm were loaded on anatase TiO2 particles (Au/TiO2) by the heating temperature-varied deposition precipitation technique. This study has shown that Au/TiO2 with Au particle size <3 nm and TiO2 surface area >50 m(2) g(-1) can be a promising environmental catalyst for the rapid removal and decomposition of gaseous acetaldehyde in a closed space. The Au loading on TiO2 causes a drastic enhancement of the acetaldehyde adsorption in the dark, and the adsorption amount increases as the Au particle size decreases. This result originates from the thermocatalytic activity of Au/TiO2 for the oxidation of acetaldehyde to acetic acid under ambient conditions. The resulting acetic acid spontaneously moves to the TiO2 surface due to the great adsorptivity for the carboxyl group. Consequently, the acetaldehyde adsorption amount strongly depends on the TiO2 surface area in addition to the Au particle size. UV-light irradiation of acetaldehyde (or acetate)-adsorbed Au/TiO2 leads to the complete decomposition to carbon dioxide by the high photocatalytic activity of anatase TiO2.
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12
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Nikawa T, Naya SI, Kimura T, Tada H. Rapid removal and subsequent low-temperature mineralization of gaseous acetaldehyde by the dual thermocatalysis of gold nanoparticle-loaded titanium(IV) oxide. J Catal 2015. [DOI: 10.1016/j.jcat.2015.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Park JW, Shumaker-Parry JS. Strong resistance of citrate anions on metal nanoparticles to desorption under thiol functionalization. ACS NANO 2015; 9:1665-82. [PMID: 25625548 DOI: 10.1021/nn506379m] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Thiols are widely utilized to functionalize metal nanoparticles, including ubiquitous citrate-stabilized gold nanoparticles (AuNPs), for fundamental studies and biomedical applications. For more than two decades, citrate-to-thiol ligand exchange has been used to introduce functionality to AuNPs in the 5-100 nm size regime. Contrary to conventional assumptions about the completion of ligand exchange processes and formation of a uniform self-assembled monolayer (SAM) on the NP surface, coadsorption of thiols with preadsorbed citrates as a mixed layer on AuNPs is demonstrated. Hydrogen bonding between carboxyl moieties primarily is attributed to the strong adsorption of citrate, leading to the formation of a stabilized network that is challenging to displace. In these studies, adsorbed citrates, probed by Fourier transform infrared and X-ray photoelectron spectroscopy (XPS) analyses, remain on the surface following thiol addition to the AuNPs, whereas acetoacetate anions are desorbed. XPS quantitative analysis indicates that the surface density of alkyl and aryl thiolates for AuNPs with an average diameter of ∼40 nm is 50-65% of the value of a close-packed SAM on Au(111). We present a detailed citrate/thiolate coadsorption model that describes this final mixed surface composition. Intermolecular interactions between weakly coordinated oxyanions, such as polyprotic carboxylic acids, can lead to enhanced stability of the metal-ligand interactions, and this needs to be considered in the surface modification of metal nanoparticles by thiols or other anchor groups.
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Affiliation(s)
- Jong-Won Park
- Department of Chemistry, University of Utah , 1400 East 315 South, RM 2020, Salt Lake City, Utah 84112, United States
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Tamura M, Tamura R, Takeda Y, Nakagawa Y, Tomishige K. Insight into the Mechanism of Hydrogenation of Amino Acids to Amino Alcohols Catalyzed by a Heterogeneous MoOx-Modified Rh Catalyst. Chemistry 2014; 21:3097-107. [DOI: 10.1002/chem.201405769] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Indexed: 01/24/2023]
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McEntee M, Tang W, Neurock M, Yates JT. Mechanistic Insights into the Catalytic Oxidation of Carboxylic Acids on Au/TiO2: Partial Oxidation of Propionic and Butyric Acid to Gold Ketenylidene through Unsaturated Acids. ACS Catal 2014. [DOI: 10.1021/cs5014255] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Monica McEntee
- Department of Chemistry, ‡Department of Chemical
Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Wenjie Tang
- Department of Chemistry, ‡Department of Chemical
Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Matthew Neurock
- Department of Chemistry, ‡Department of Chemical
Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
| | - John T. Yates
- Department of Chemistry, ‡Department of Chemical
Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
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Hermes ED, Jenness GR, Schmidt J. Decoupling the electronic, geometric and interfacial contributions to support effects in heterogeneous catalysis. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.926549] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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McEntee M, Tang W, Neurock M, Yates JT. Selective catalytic oxidative-dehydrogenation of carboxylic acids-acrylate and crotonate formation at the Au/TiO2 interface. J Am Chem Soc 2014; 136:5116-20. [PMID: 24597473 DOI: 10.1021/ja500928h] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The oxidative-dehydrogenation of carboxylic acids to selectively produce unsaturated acids at the second and third carbons regardless of alkyl chain length was found to occur on a Au/TiO2 catalyst. Using transmission infrared spectroscopy (IR) and density functional theory (DFT), unsaturated acrylate (H2C═CHCOO) and crotonate (CH3CH═CHCOO) were observed to form from propionic acid (H3CCH2COOH) and butyric acid (H3CCH2CH2COOH), respectively, on a catalyst with ∼3 nm diameter Au particles on TiO2 at 400 K. Desorption experiments also show gas phase acrylic acid is produced. Isotopically labeled (13)C and (12)C propionic acid experiments along with DFT calculated frequency shifts confirm the formation of acrylate and crotonate. Experiments on pure TiO2 confirmed that the unsaturated acids were not produced on the TiO2 support alone, providing evidence that the sites for catalytic activity are at the dual Au-Ti(4+) sites at the nanometer Au particles' perimeter. The DFT calculated energy barriers between 0.3 and 0.5 eV for the reaction pathway are consistent with the reaction occurring at 400 K on Au/TiO2.
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Affiliation(s)
- Monica McEntee
- Department of Chemistry, University of Virginia , Charlottesville, Virginia 22904, United States
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Green IX, Tang W, Neurock M, Yates JT. Insights into catalytic oxidation at the Au/TiO(2) dual perimeter sites. Acc Chem Res 2014; 47:805-15. [PMID: 24372536 DOI: 10.1021/ar400196f] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Gold (Au) nanoparticles supported on reducible oxides such as TiO2 demonstrate exceptional catalytic activity for a wide range of gas phase oxidation reactions such as CO oxidation, olefin epoxidation, and water gas shift catalysis. Scientists have recently shifted their hypotheses on the origin of the reactivity of these materials from the unique electronic properties and under-coordinated Au sites on nanometer-sized particles to bifunctional sites at the Au-support interface. In this Account, we summarize our recent experimental and theoretical results to provide insights into the active sites and pathways that control oxidation over Au/TiO2 catalysts. We provide transmission IR spectroscopic data that show the direct involvement of the Au-Ti(4+) dual perimeter sites, and density functional theory results that connect the electronic properties at these sites to their reactivity and to plausible reaction mechanisms. We also show the importance of interfacial Au-Ti(4+) sites in adsorbing and activating O2 as a result of charge transfer from the Au into antibonding states on O2 causing di-σ interactions with interfacial Au-Ti(4+) sites. This results in apparent activation energies for O2 activation of 0.16-0.60 eV thus allowing these materials to operate over a wide range of temperatures (110-420 K) and offering the ability also to control H-H, C-H, and C-O bond scission. At low temperatures (100-130 K), adsorbed O2 directly reacts with co-adsorbed CO or H2. In addition, we observe the specific consumption of CO adsorbed on TiO2. The more strongly held CO/Au species do not react at ∼120 K due to high diffusion barriers that prevent them from reaching active interfacial sites. At higher temperatures, O2 directly dissociates to form active oxygen adatoms (O*) on Au and TiO2. These readily react with bound hydrocarbon intermediates via base-catalyzed nucleophilic attack on unsaturated C═O and C═C bonds or via activation of weakly acidic C-H or O-H bonds. We demonstrate that when the active Au-Ti(4+) sites are pre-occupied by O*, the low temperature CO oxidation rate is reduced by a factor 22. We observe similar site blocking for H2 oxidation by O2, where the reaction at 210 K is quenched by ice formation. At higher temperatures (400-420 K), the O* generated at the perimeter sites is able to diffuse onto the Au particles, which then activate weakly acidic C-H bonds and assist in C-O bond scission. These sites allow for active conversion of adsorbed acetate intermediates on TiO2 (CH3COO/TiO2) to a gold ketenylidene species (Au2═C═C═O). The consecutive C-H bond scission steps appear to proceed by the reaction with basic O* or OH* on the Au sites and C-O bond activation occurs at the Au-Ti(4+) dual perimeter sites. There is a bound-intermediate transfer from the TiO2 support to the Au sites during the course of reaction as the reactant (CH3COO/TiO2) and the product (Au2═C═C═O) are bound to different sites. We demonstrate that IR spectroscopy is a powerful tool to follow surface catalytic reactions and provide kinetic information, while theory provides atomic scale insights into the mechanisms and the active sites that control catalytic oxidation.
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Affiliation(s)
- Isabel X. Green
- Department of Chemistry, University of Washington, Seattle, Washington 98104, United States
| | - Wenjie Tang
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Matthew Neurock
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - John T. Yates
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
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Allen AD, Tidwell TT. Structure and Mechanism in Ketene Chemistry. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2014. [DOI: 10.1016/b978-0-12-800256-8.00004-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Jenness GR, Schmidt JR. Unraveling the Role of Metal–Support Interactions in Heterogeneous Catalysis: Oxygenate Selectivity in Fischer–Tropsch Synthesis. ACS Catal 2013. [DOI: 10.1021/cs4006277] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Glen R. Jenness
- Department of Chemistry and Theoretical
Chemistry Institute, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - J. R. Schmidt
- Department of Chemistry and Theoretical
Chemistry Institute, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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Green IX, McEntee M, Tang W, Neurock M, Yates JT. Direct Formation of Acetate from the Partial Oxidation of Ethylene on a Au/TiO2 Catalyst. Top Catal 2013. [DOI: 10.1007/s11244-013-0154-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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