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Nifant'ev I, Komarov P, Sadrtdinova G, Safronov V, Kolosov N, Ivchenko P. Mechanistic Insights of Ethylene Polymerization on Phillips Chromium Catalysts. Polymers (Basel) 2024; 16:681. [PMID: 38475365 DOI: 10.3390/polym16050681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024] Open
Abstract
Silica-supported chromium oxide catalysts, also named Phillips chromium catalysts (PCCs), provide more than half of the world's production of high- and medium-density polyethylenes. PCCs are usually prepared in the Cr(VI)/SiO2 form, which is subjected to reductive activation. It has been explicitly proven that CO reduces Cr(VI) to Cr(II) species that initiate ethylene polymerization; ethylene activates Cr(VI) sites as well, but the nature of the catalytic species is complicated by the presence of the ethylene oxidation products. It is widely accepted that the catalytic species are of a Cr(III)-alkyl nature, but this common assumption faces the challenge of "extra" hydrogen: the formation of similar species under the action of even-electron reducing agents requires an additional H atom. Relatively recently, it was found that saturated hydrocarbons can also activate CrOx/SiO2, and alkyl fragments turn out to be bonded with a polyethylene chain. In recent years, there have been numerous experimental and theoretical studies of the structure and chemistry of PCCs at the different stages of preparation and activation. The use of modern spectral methods (such as extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES), and others); operando IR, UV-vis, EPR, and XAS spectroscopies; and theoretical approaches (DFT modeling, machine learning) clarified many essential aspects of the mechanisms of CrOx/SiO2 activation and catalytic behavior. Overall, the Cosse-Arlman mechanism of polymerization on Cr(III)-alkyl centers is confirmed in many works, but its theoretical support required the development of nontrivial and contentious mechanistic concepts of Cr(VI)/SiO2 or Cr(II)/SiO2 activation. On the other hand, conflicting experimental data continue to be obtained, and certain mechanistic concepts are being developed with the use of outdated models. Strictly speaking, the main question of what type of catalytic species, Cr(II), Cr(III), or Cr(IV), comes into polymerization still has not received an unambiguous answer. The role of the chemical nature of the support-through the prism of the nature, geometry, and distribution of the active sites-is also not clear in depth. In the present review, we endeavored to summarize and discuss the recent studies in the field of the preparation, activation, and action of PCCs, with a focus on existing contradictions in the interpretation of the experimental and theoretical results.
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Affiliation(s)
- Ilya Nifant'ev
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
- Department of Chemistry, M.V. Lomonosov Moscow University, 1-3 Leninskie Gory, 119991 Moscow, Russia
| | - Pavel Komarov
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
| | - Guzelia Sadrtdinova
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
- Faculty of Chemistry, National Research University Higher School of Economics, Myasnitskaya St. 20, 101100 Moscow, Russia
| | | | | | - Pavel Ivchenko
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
- Department of Chemistry, M.V. Lomonosov Moscow University, 1-3 Leninskie Gory, 119991 Moscow, Russia
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2
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Niederquell A, Vraníková B, Kuentz M. Study of Disordered Mesoporous Silica Regarding Intrinsic Compound Affinity to the Carrier and Drug-Accessible Surface Area. Mol Pharm 2023; 20:6301-6310. [PMID: 37948648 DOI: 10.1021/acs.molpharmaceut.3c00690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
There is increasing research interest in using mesoporous silica for the delivery of poorly water-soluble drugs that are stabilized in a noncrystalline form. Most research has been done on ordered silica, whereas far fewer studies have been published on using nonordered mesoporous silica, and little is known about intrinsic drug affinity to the silica surface. The present mechanistic study uses inverse gas chromatography (IGC) to analyze the surface energies of three different commercially available disordered mesoporous silica grades in the gas phase. Using the more drug-like probe molecule octane instead of nitrogen, the concept of a "drug-accessible surface area" is hereby introduced, and the effect on drug monolayer capacity is addressed. In addition, enthalpic interactions of molecules with the silica surface were calculated based on molecular mechanics, and entropic energy contributions of volatiles were estimated considering molecular flexibility. These free energy contributions were used in a regression model, giving a successful comparison with experimental desorption energies from IGC. It is proposed that a simplified model for drugs based only on the enthalpic interactions can provide an affinity ranking to the silica surface. Following this preformulation research on mesoporous silica, future studies may harness the presented concepts to guide formulation scientists.
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Affiliation(s)
- Andreas Niederquell
- Department of Pharmaceutical Technology, Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203, 500 05 Hradec Králové, Czech Republic
- School of Life Sciences FHNW, Institute for Pharma Technology, University of Applied Sciences and Arts Northwestern Switzerland, Hofackerstr. 30, 4132 Muttenz, Switzerland
| | - Barbora Vraníková
- Department of Pharmaceutical Technology, Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203, 500 05 Hradec Králové, Czech Republic
| | - Martin Kuentz
- School of Life Sciences FHNW, Institute for Pharma Technology, University of Applied Sciences and Arts Northwestern Switzerland, Hofackerstr. 30, 4132 Muttenz, Switzerland
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3
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Peng L, Hsu CC, Xiao C, Bonn D, Weber B. Controlling Macroscopic Friction through Interfacial Siloxane Bonding. PHYSICAL REVIEW LETTERS 2023; 131:226201. [PMID: 38101386 DOI: 10.1103/physrevlett.131.226201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 10/12/2023] [Indexed: 12/17/2023]
Abstract
Controlling macroscopic friction is crucial for numerous natural and industrial applications, ranging from forecasting earthquakes to miniaturizing semiconductor devices, but predicting and manipulating friction phenomena remains a challenge due to the unknown relationship between nanoscale and macroscopic friction. Here, we show experimentally that dry friction at multiasperity Si-on-Si interfaces is dominated by the formation of interfacial siloxane (Si─O─Si) bonds, the density of which can be precisely regulated by exposing plasma-cleaned silicon surfaces to dry nitrogen. Our results show how the bond density can be used to quantitatively understand and control the macroscopic friction. Our findings establish a unique connection between the molecular scale at which adhesion occurs, and the friction coefficient that is the key macroscopic parameter for industrial and natural tribology challenges.
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Affiliation(s)
- Liang Peng
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Chao-Chun Hsu
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| | - Chen Xiao
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Advanced Research Center for Nanolithography (ARCNL), Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - Daniel Bonn
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Bart Weber
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Advanced Research Center for Nanolithography (ARCNL), Science Park 106, 1098 XG Amsterdam, The Netherlands
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4
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Vörös D, Angeletti A, Franchini C, Mai S, González L. Adsorption of 4-( N, N-Dimethylamino)-4'-nitrostilbene on an Amorphous Silica Glass Surface. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:22964-22974. [PMID: 38053626 PMCID: PMC10694811 DOI: 10.1021/acs.jpcc.3c05552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 11/03/2023] [Accepted: 11/03/2023] [Indexed: 12/07/2023]
Abstract
Stilbenes are a compelling class of organic photoswitches with a high degree of tunability that sensitively depend on their environment. In this study, we investigate the adsorption properties of 4-(N,N-dimethylamino)-4'-nitrostilbene (DANS), a push-pull stilbene, on amorphous silica glass. Plane-wave density functional theory (DFT) calculations are used to understand how the trans and cis isomers of DANS interact with the amorphous surface and which are the most preferred modes of adsorption. Our calculations revealed that the O-H···O hydrogen bonds between the nitro group and hydroxyl groups of the silica surface dominate the intramolecular interaction. In addition to hydrogen bonding, O-H···π interactions with the aromatic ring and double bond play a critical role in adsorption, whereas C-H···O interactions are present, but contribute little. Therefore, both isomers of DANS favor parallel orientations such that not only the functional groups but also the aromatic parts can strongly interact with the glass surface.
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Affiliation(s)
- Dóra Vörös
- Institute
of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
- Vienna
Doctoral School in Physics, University of
Vienna, Boltzmanngasse
5, 1090 Vienna, Austria
| | - Andrea Angeletti
- Computational
Materials Physics, Faculty of Physics, University
of Vienna, Kolingasse
14-16, 1090 Vienna, Austria
- Vienna
Doctoral School in Physics, University of
Vienna, Boltzmanngasse
5, 1090 Vienna, Austria
| | - Cesare Franchini
- Computational
Materials Physics, Faculty of Physics, University
of Vienna, Kolingasse
14-16, 1090 Vienna, Austria
- Department
of Physics and Astronomy ’Augusto Righi’, Alma Mater Studiorum—Università di Bologna, Bologna 40127, Italy
| | - Sebastian Mai
- Institute
of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
| | - Leticia González
- Institute
of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria
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5
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Moeini B, Pinder JW, Avval TG, Jacobsen C, Brongersma HH, Průša S, Bábík P, Vaníčková E, Argyle MD, Strohmeier BR, Jones B, Shollenberger D, Bell DS, Linford MR. Controlling the surface silanol density in capillary columns and planar silicon via the self-limiting, gas-phase deposition of tris(dimethylamino)methylsilane, and quantification of surface silanols after silanization by low energy ion scattering. J Chromatogr A 2023; 1707:464248. [PMID: 37598532 DOI: 10.1016/j.chroma.2023.464248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 07/25/2023] [Accepted: 07/27/2023] [Indexed: 08/22/2023]
Abstract
Surface silanols (Si-OH) play a vital role on fused silica surfaces in chromatography. Here, we used an atmospheric-pressure, gas-phase reactor to modify the inner surface of a gas chromatography, fused silica capillary column (0.53 mm ID) with a small, reactive silane (tris(dimethylamino)methylsilane, TDMAMS). The deposition of TDMAMS on planar witness samples around the capillary was confirmed with X-ray photoelectron spectroscopy (XPS), ex situ spectroscopic ellipsometry (SE), and wetting. The number of surface silanols on unmodified and TDMAMS-modified native oxide-terminated silicon were quantified by tagging with dimethylzinc (DMZ) via atomic layer deposition (ALD) and counting the resulting zinc atoms with high sensitivity-low energy ion scattering (HS-LEIS). A bare, clean native oxide - terminated silicon wafer has 3.66 OH/nm2, which agrees with density functional theory (DFT) calculations from the literature. After TDMAMS modification of native oxide-terminated silicon, the number of surface silanols decreases by a factor of ca. 10 (to 0.31 OH/nm2). Intermediate surface testing (IST) was used to characterize the surface activities of functionalized capillaries. It suggested a significant deactivation/passivation of the capillary with some surface silanols remaining; the modified capillary shows significant deactivation compared to the native/unmodified fused silica tubing. We believe that this methodology for determining the number of residual silanols on silanized fused silica will be enabling for chromatography.
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Affiliation(s)
- Behnam Moeini
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Joshua W Pinder
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Tahereh G Avval
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Collin Jacobsen
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Hidde H Brongersma
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, the Netherlands
| | - Stanislav Průša
- Institute of Physical Engineering, Brno University of Technology, Technická 2, Brno 616 69, Czech Republic; CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Pavel Bábík
- Institute of Physical Engineering, Brno University of Technology, Technická 2, Brno 616 69, Czech Republic; CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Elena Vaníčková
- Institute of Physical Engineering, Brno University of Technology, Technická 2, Brno 616 69, Czech Republic; CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Morris D Argyle
- Department of Chemical Engineering, Brigham Young University, Provo, UT 84602, USA
| | - Brian R Strohmeier
- Materials Group, Avery Dennison Corp., 8080 Norton Parkway, Mentor, OH 44060, USA
| | - Brian Jones
- Restek Corporation, 110 Benner Circle, Bellefonte, PA 16823, USA
| | | | - David S Bell
- Restek Corporation, 110 Benner Circle, Bellefonte, PA 16823, USA
| | - Matthew R Linford
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
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Shayesteh Zadeh A, Khan SA, Vandervelden C, Peters B. Site-Averaged Ab Initio Kinetics: Importance Learning for Multistep Reactions on Amorphous Supports. J Chem Theory Comput 2023; 19:2873-2886. [PMID: 37093705 DOI: 10.1021/acs.jctc.3c00160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Single-atom centers on amorphous supports include catalysts for polymerization, partial oxidation, metathesis, hydrogenolysis, and more. The disordered environment makes each site different, and the kinetics exponentially magnifies these differences to make ab initio site-averaged kinetics calculations extremely difficult. This work extends the importance learning algorithm for efficient and precise site-averaged kinetics estimates to ab initio calculations and multistep reaction mechanisms. Specifically, we calculate site-averaged proton transfer relaxation rates on an ensemble of cluster models representing Brønsted acid sites on silica-alumina. We include direct and water-assisted proton transfer pathways and simultaneously estimate the water adsorption and activation enthalpies for forward and backward proton transfers. We use density functional theory (DFT) to obtain a site-averaged rate, somewhat like a turnover frequency, for the proton transfer relaxation rate. Finally, we show that importance learning can provide orders-of-magnitude acceleration over standard sampling methods for site-averaged rate calculations in cases where the rate is dominated by a few highly active sites.
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Affiliation(s)
- Armin Shayesteh Zadeh
- Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Salman A Khan
- Delaware Energy Institute (DEI), University of Delaware, Newark, Delaware 19711, United States
| | | | - Baron Peters
- Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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7
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Yaacoub L, Dutta I, Werghi B, Chen BWJ, Zhang J, Hamad EA, Ling Ang EP, Pump E, Sedjerari AB, Huang KW, Basset JM. Formic Acid Dehydrogenation via an Active Ruthenium Pincer Catalyst Immobilized on Tetra-Coordinated Aluminum Hydride Species Supported on Fibrous Silica Nanospheres. ACS Catal 2022. [DOI: 10.1021/acscatal.2c04137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Layal Yaacoub
- Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Indranil Dutta
- Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Baraa Werghi
- Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Benjamin W. J. Chen
- Agency for Science, Technology, and Research, Institute of High Performance Computing, 1 Fusionopolis Way, #16−16 Connexis, Singapore 138632, Singapore
| | - Jia Zhang
- Agency for Science, Technology, and Research, Institute of High Performance Computing, 1 Fusionopolis Way, #16−16 Connexis, Singapore 138632, Singapore
| | - Edy Abou Hamad
- Imaging and Characterization Department, KAUST Core Labs, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
| | - Eleanor Pei Ling Ang
- Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Eva Pump
- Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Anissa Bendjeriou Sedjerari
- Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Kuo-Wei Huang
- Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Agency for Science, Technology, and Research, Institute of Materials Research and Engineering and Institute of Sustainability for Chemicals, Energy and Environment, Singapore 138634, Singapore
| | - Jean-Marie Basset
- Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Institut de Recherche de Chimie Paris, 11 Rue Pierre et Marie Curie, Cedex 05 75231, Paris
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8
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Xu Y, LiBretto NJ, Zhang G, Miller JT, Greeley J. First-Principles Analysis of Ethylene Oligomerization on Single-Site Ga 3+ Catalysts Supported on Amorphous Silica. ACS Catal 2022. [DOI: 10.1021/acscatal.1c05936] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yinan Xu
- Davidson School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Nicole J. LiBretto
- Davidson School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Guanghui Zhang
- Davidson School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
- State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning Province 116024, P.R. China
| | - Jeffrey T. Miller
- Davidson School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Jeffrey Greeley
- Davidson School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
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9
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Huang C, Liu Z, Liu B, Terano M, Jin Y. Computational Insights into the Multisite Nature of the Phillips CrO x/SiO 2 Catalyst for Ethylene Polymerization: The Perspective of Chromasiloxane Ring Size and F Modification. ACS Catal 2022. [DOI: 10.1021/acscatal.1c04998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Cuimin Huang
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, Guangzhou 510630, People’s Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510630, People’s Republic of China
| | - Zhen Liu
- State Key Laboratory of Chemical Engineering, School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, People’s Republic of China
| | - Boping Liu
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, Guangzhou 510630, People’s Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510630, People’s Republic of China
| | - Minoru Terano
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Yulong Jin
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, Guangzhou 510630, People’s Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510630, People’s Republic of China
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10
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Chen CH, Mentink-Vigier F, Trébosc J, Goldberga I, Gaveau P, Thomassot E, Iuga D, Smith ME, Chen K, Gan Z, Fabregue N, Métro TX, Alonso B, Laurencin D. Labeling and Probing the Silica Surface Using Mechanochemistry and 17 O NMR Spectroscopy*. Chemistry 2021; 27:12574-12588. [PMID: 34131984 PMCID: PMC8410671 DOI: 10.1002/chem.202101421] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Indexed: 01/21/2023]
Abstract
In recent years, there has been increasing interest in developing cost‐efficient, fast, and user‐friendly 17O enrichment protocols to help to understand the structure and reactivity of materials by using 17O NMR spectroscopy. Here, we show for the first time how ball milling (BM) can be used to selectively and efficiently enrich the surface of fumed silica, which is widely used at industrial scale. Short milling times (up to 15 min) allowed modulation of the enrichment level (up to ca. 5 %) without significantly changing the nature of the material. High‐precision 17O compositions were measured at different milling times by using large‐geometry secondary‐ion mass spectrometry (LG‐SIMS). High‐resolution 17O NMR analyses (including at 35.2 T) allowed clear identification of the signals from siloxane (Si−O−Si) and silanols (Si−OH), while DNP analyses, performed by using direct 17O polarization and indirect 17O{1H} CP excitation, agreed with selective labeling of the surface. Information on the distribution of Si−OH environments at the surface was obtained from 2D 1H−17O D‐HMQC correlations. Finally, the surface‐labeled silica was reacted with titania and using 17O DNP, their common interface was probed and Si−O−Ti bonds identified.
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Affiliation(s)
- Chia-Hsin Chen
- ICGM, Univ Montpellier, CNRS, ENSCM, Montpellier, France
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee, FL, USA
| | - Julien Trébosc
- Univ. Lille, CNRS, INRAE, Centrale Lille, Univ. Artois, FR 2638 - IMEC - Institut Michel-Eugène Chevreul, 59000, Lille, France
| | - Ieva Goldberga
- ICGM, Univ Montpellier, CNRS, ENSCM, Montpellier, France
| | | | - Emilie Thomassot
- Université de Lorraine, CRPG, CNRS UMR 7358, Vandœuvre-lès-Nancy, France
| | - Dinu Iuga
- Department of Physics, University of Warwick, CV4 7AL, Coventry, UK
| | - Mark E Smith
- Vice-Chancellor's Office and Department of Chemistry, Highfield Campus, University of Southampton, SO17 1BJ, Southampton, UK
| | - Kuizhi Chen
- National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee, FL, USA
| | - Zhehong Gan
- National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee, FL, USA
| | | | | | - Bruno Alonso
- ICGM, Univ Montpellier, CNRS, ENSCM, Montpellier, France
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11
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Vandervelden C, Jystad A, Peters B, Caricato M. Predicted Properties of Active Catalyst Sites on Amorphous Silica: Impact of Silica Preoptimization Protocol. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.1c01849] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Craig Vandervelden
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Amy Jystad
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Baron Peters
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Department of Chemistry and Biochemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Marco Caricato
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
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12
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Bistafa C, Surblys D, Kusudo H, Yamaguchi Y. Water on hydroxylated silica surfaces: Work of adhesion, interfacial entropy, and droplet wetting. J Chem Phys 2021; 155:064703. [PMID: 34391348 DOI: 10.1063/5.0056718] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In the last few years, much attention has been devoted to the control of the wettability properties of surfaces modified with functional groups. Molecular dynamics (MD) simulation is one of the powerful tools for microscopic analysis providing visual images and mean geometrical shapes of the contact line, e.g., of nanoscale droplets on solid surfaces, while profound understanding of wetting demands quantitative evaluation of the solid-liquid (SL) interfacial tension. In the present work, we examined the wetting of water on neutral and regular hydroxylated silica surfaces with five different area densities of OH groups ρA OH, ranging from a non-hydroxylated surface to a fully hydroxylated one through two theoretical methods: thermodynamic integration (TI) and MD simulations of quasi-two-dimensional equilibrium droplets. For the former, the work of adhesion needed to quasi-statically strip the water film off the solid surface was computed by the phantom wall TI scheme to evaluate the SL interfacial free energy, whereas for the latter, the apparent contact angle θapp was calculated from the droplet density distribution. The theoretical contact angle θYD and the apparent one θapp, both indicating the enhancement of wettability by an increase in ρA OH, presented good quantitative agreement, especially for non-hydroxylated and highly hydroxylated surfaces. On partially hydroxylated surfaces, in which θYD and θapp slightly deviated, the Brownian motion of the droplet was suppressed, possibly due to the pinning of the contact line around the hydroxyl groups. Relations between work of adhesion, interfacial energy, and entropy loss were also analyzed, and their influence on the wettability was discussed.
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Affiliation(s)
- Carlos Bistafa
- Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Donatas Surblys
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Hiroki Kusudo
- Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
| | - Yasutaka Yamaguchi
- Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan
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13
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Improving the Barrier Properties of Food Packaging by Al2O3@TiO2 & Al2O3@SiO2 Nanoparticles. FOOD BIOPROCESS TECH 2021. [DOI: 10.1007/s11947-021-02635-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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14
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Zhou J, Yang Y, Zhang Y, Duan S, Zhou X, Sun W, Xu S. Sulfur in Amorphous Silica for an Advanced Room‐Temperature Sodium–Sulfur Battery. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202015932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Jiahui Zhou
- School of Minerals Processing and Bioengineering Central South University 932 Lushan Road Changsha 410083 China
| | - Yue Yang
- School of Minerals Processing and Bioengineering Central South University 932 Lushan Road Changsha 410083 China
| | - Yingchao Zhang
- Division of Chemical Engineering Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China
| | - Shuaikang Duan
- Division of Chemical Engineering Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China
| | - Xia Zhou
- Division of Chemical Engineering Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China
| | - Wei Sun
- School of Minerals Processing and Bioengineering Central South University 932 Lushan Road Changsha 410083 China
| | - Shengming Xu
- Division of Chemical Engineering Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China
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15
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Zhou J, Yang Y, Zhang Y, Duan S, Zhou X, Sun W, Xu S. Sulfur in Amorphous Silica for an Advanced Room‐Temperature Sodium–Sulfur Battery. Angew Chem Int Ed Engl 2021; 60:10129-10136. [DOI: 10.1002/anie.202015932] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/04/2021] [Indexed: 01/20/2023]
Affiliation(s)
- Jiahui Zhou
- School of Minerals Processing and Bioengineering Central South University 932 Lushan Road Changsha 410083 China
| | - Yue Yang
- School of Minerals Processing and Bioengineering Central South University 932 Lushan Road Changsha 410083 China
| | - Yingchao Zhang
- Division of Chemical Engineering Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China
| | - Shuaikang Duan
- Division of Chemical Engineering Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China
| | - Xia Zhou
- Division of Chemical Engineering Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China
| | - Wei Sun
- School of Minerals Processing and Bioengineering Central South University 932 Lushan Road Changsha 410083 China
| | - Shengming Xu
- Division of Chemical Engineering Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China
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16
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Surface Functionalization Utilizing Mesoporous Silica Nanoparticles for Enhanced Evanescent-Field Mid-Infrared Waveguide Gas Sensing. COATINGS 2021. [DOI: 10.3390/coatings11020118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This work focuses on the development of nanoparticle-based layer-by-layer (LbL) coatings for enhancing the detection sensitivity and selectivity of volatile organic compounds (VOCs) using on-chip mid-infrared (MIR) waveguides (WGs). First, we demonstrate construction of conformal coatings of polymer/mesoporous silica nanoparticles (MSNs) on the surface of Si-based WGs using the LbL technique and evaluate the coating deposition conditions, such as pH and substrate withdrawal speed, on the thickness and homogeneity of the assemblies. We then use the modified WGs to achieve enhanced sensitivity and selectivity of polar organic compounds, such as ethanol, versus non-polar ones, such as methane, in the MIR region. In addition, using density functional theory calculations, we show that such an improvement in sensing performance is achieved due to preferential adsorption of ethanol molecules within MSNs in the vicinity of the WG evanescent field.
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17
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Vandervelden CA, Khan SA, Peters B. Importance learning estimator for the site-averaged turnover frequency of a disordered solid catalyst. J Chem Phys 2020; 153:244120. [PMID: 33380094 DOI: 10.1063/5.0037450] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
For disordered catalysts such as atomically dispersed "single-atom" metals on amorphous silica, the active sites inherit different properties from their quenched-disordered local environments. The observed kinetics are site-averages, typically dominated by a small fraction of highly active sites. Standard sampling methods require expensive ab initio calculations at an intractable number of sites to converge on the site-averaged kinetics. We present a new method that efficiently estimates the site-averaged turnover frequency (TOF). The new estimator uses the same importance learning algorithm [Vandervelden et al., React. Chem. Eng. 5, 77 (2020)] that we previously used to compute the site-averaged activation energy. We demonstrate the method by computing the site-averaged TOF for a simple disordered lattice model of an amorphous catalyst. The results show that with the importance learning algorithm, the site-averaged TOF and activation energy can now be obtained concurrently with orders of magnitude reduction in required ab initio calculations.
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Affiliation(s)
- Craig A Vandervelden
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, USA
| | - Salman A Khan
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, USA
| | - Baron Peters
- Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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18
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Berro Y, Badawi M, El Haj Hassan F, Kassir M, Tielens F. Water-silanol interactions on the amorphous silica surface: A dispersion-corrected DFT investigation. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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19
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Tielens F, Gierada M, Handzlik J, Calatayud M. Characterization of amorphous silica based catalysts using DFT computational methods. Catal Today 2020. [DOI: 10.1016/j.cattod.2019.03.062] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Monroe J, Barry M, DeStefano A, Aydogan Gokturk P, Jiao S, Robinson-Brown D, Webber T, Crumlin EJ, Han S, Shell MS. Water Structure and Properties at Hydrophilic and Hydrophobic Surfaces. Annu Rev Chem Biomol Eng 2020; 11:523-557. [PMID: 32169001 DOI: 10.1146/annurev-chembioeng-120919-114657] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The properties of water on both molecular and macroscopic surfaces critically influence a wide range of physical behaviors, with applications spanning from membrane science to catalysis to protein engineering. Yet, our current understanding of water interfacing molecular and material surfaces is incomplete, in part because measurement of water structure and molecular-scale properties challenges even the most advanced experimental characterization techniques and computational approaches. This review highlights progress in the ongoing development of tools working to answer fundamental questions on the principles that govern the interactions between water and surfaces. One outstanding and critical question is what universal molecular signatures capture the hydrophobicity of different surfaces in an operationally meaningful way, since traditional macroscopic hydrophobicity measures like contact angles fail to capture even basic properties of molecular or extended surfaces with any heterogeneity at the nanometer length scale. Resolving this grand challenge will require close interactions between state-of-the-art experiments, simulations, and theory, spanning research groups and using agreed-upon model systems, to synthesize an integrated knowledge of solvation water structure, dynamics, and thermodynamics.
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Affiliation(s)
- Jacob Monroe
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Mikayla Barry
- Department of Materials, University of California, Santa Barbara, California 93106, USA
| | - Audra DeStefano
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Pinar Aydogan Gokturk
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sally Jiao
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Dennis Robinson-Brown
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Thomas Webber
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
| | - Ethan J Crumlin
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Songi Han
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA; .,Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
| | - M Scott Shell
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA;
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21
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Asgar H, Semeykina V, Hunt M, Mohammed S, Kuzmenko I, Zharov I, Gadikota G. Thermally-Induced morphological evolution of spherical silica nanoparticles using in-operando X-ray scattering measurements. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2019.124260] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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22
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Love AM, Cendejas MC, Hanrahan MP, Carnahan SL, Uchupalanun P, Rossini AJ, Hermans I. Understanding the Synthesis of Supported Vanadium Oxide Catalysts Using Chemical Grafting. Chemistry 2020; 26:1052-1063. [PMID: 31703149 DOI: 10.1002/chem.201904260] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Indexed: 11/12/2022]
Abstract
The complexity of variables during incipient wetness impregnation synthesis of supported metal oxides precludes an in-depth understanding of the chemical reactions governing the formation of the dispersed oxide sites. This contribution describes the use of vapor phase deposition chemistry (also known as grafting) as a tool to systematically investigate the influence of isopropanol solvent on VO(Oi Pr)3 anchoring during synthesis of vanadium oxide on silica. The availability of anchoring sites on silica was found to depend not only on the pretreatment of the silica but also on the solvent present. H-bond donors can reduce the reactivity of isolated silanols whereas disruption of silanol nests by H-bond acceptors can turn unreactive H-bonded silanols into reactive anchoring sites. The model suggested here can inform improved syntheses with increased dispersion of metal oxides on silica.
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Affiliation(s)
- Alyssa M Love
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI, 53706, USA
| | - Melissa C Cendejas
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI, 53706, USA
| | - Michael P Hanrahan
- Department of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, IA, 50011, USA
| | - Scott L Carnahan
- Department of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, IA, 50011, USA
| | - Pajean Uchupalanun
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI, 53706, USA
| | - Aaron J Rossini
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, 53706, USA
| | - Ive Hermans
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI, 53706, USA.,Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, 53706, USA
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23
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Khan SA, Vandervelden CA, Scott SL, Peters B. Grafting metal complexes onto amorphous supports: from elementary steps to catalyst site populationsviakernel regression. REACT CHEM ENG 2020. [DOI: 10.1039/c9re00357f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We use transition state theory, kernel regression, and population balance modeling techniques to model the grafting of metal complexes onto amorphous catalyst supports.
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Affiliation(s)
- Salman A. Khan
- Department of Chemical Engineering
- University of California
- Santa Barbara
- USA
| | | | - Susannah L. Scott
- Department of Chemical Engineering
- University of California
- Santa Barbara
- USA
- Department of Chemistry & Biochemistry
| | - Baron Peters
- Department of Chemical & Biomolecular Engineering
- University of Illinois at Urbana-Champaign
- Urbana
- USA
- Department of Chemistry
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24
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Vandervelden CA, Khan SA, Scott SL, Peters B. Site-averaged kinetics for catalysts on amorphous supports: an importance learning algorithm. REACT CHEM ENG 2020. [DOI: 10.1039/c9re00356h] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We combine importance sampling and kernel regression techniques to efficiently predict site-averaged kinetics for isolated catalyst sites on amorphous supports.
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Affiliation(s)
| | - Salman A. Khan
- Department of Chemical Engineering
- University of California
- Santa Barbara
- USA
| | - Susannah L. Scott
- Department of Chemical Engineering
- University of California
- Santa Barbara
- USA
- Department of Chemistry
| | - Baron Peters
- Department of Chemical and Biomolecular Engineering
- University of Illinois at Urbana-Champaign
- Urbana
- USA
- Department of Chemistry
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25
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Wang M, Duan F, Mu X. Effect of Surface Silanol Groups on Friction and Wear between Amorphous Silica Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5463-5470. [PMID: 30925219 DOI: 10.1021/acs.langmuir.8b04291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Reactive molecular dynamics (ReaxFF) simulations are performed to explore the tribological behavior between fully hydroxylated amorphous silica (a-SiO2) surfaces as a function of surface silanol density. The results show that the interfacial friction and wear are greatly reduced by increasing surface silanol density, which originates from the suppression of the initial formation of interfacial Si-O-Si bridge bonds. Two different tribochemical reactions resulting in the formation of interfacial Si-O-Si bridge bonds are observed: i.e., one occurring between two silanol groups, which is insensitive to changes in silanol density, and the other occurring between a silanol group and a surface Si-O-Si bond, which is strongly suppressed with the increase of silanol density. We decouple the contributions of these two Si-O-Si bond formation mechanisms to the observed tribological behavior and find that the latter formation mechanism plays a dominant role. Furthermore, the changes in the geometry and structure of fully hydroxylated a-SiO2 surface caused by the increased surface silanol groups also play an important role in the tribochemical reactions and the tribological performance of the a-SiO2/a-SiO2 system. This work provides a deeper insight into the effect of surface silanol groups on the tribological behaviors of silicon-based materials.
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26
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Ghashghaee M, Ghambarian M. Ethene Protonation Over Silica-Grafted Metal (Cr, Mo, and W) Oxide Catalysts: A Comparative Nanocluster Modeling Study. RUSS J INORG CHEM+ 2018. [DOI: 10.1134/s0036023618160015] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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27
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Groppo E, Martino GA, Piovano A, Barzan C. The Active Sites in the Phillips Catalysts: Origins of a Lively Debate and a Vision for the Future. ACS Catal 2018. [DOI: 10.1021/acscatal.8b02521] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elena Groppo
- Department of Chemistry, NIS Centre and INSTM, University of Torino, Via Quarello 15/A, 10125 Torino, Italy
| | - Giorgia Antonina Martino
- Department of Chemistry, NIS Centre and INSTM, University of Torino, Via Quarello 15/A, 10125 Torino, Italy
| | - Alessandro Piovano
- Department of Chemistry, NIS Centre and INSTM, University of Torino, Via Quarello 15/A, 10125 Torino, Italy
| | - Caterina Barzan
- Department of Chemistry, NIS Centre and INSTM, University of Torino, Via Quarello 15/A, 10125 Torino, Italy
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28
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Nauert SL, Rosen AS, Kim H, Snurr RQ, Stair PC, Notestein JM. Evidence for Copper Dimers in Low-Loaded CuOx/SiO2 Catalysts for Cyclohexane Oxidative Dehydrogenation. ACS Catal 2018. [DOI: 10.1021/acscatal.8b02532] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Scott L. Nauert
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Andrew S. Rosen
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Hacksung Kim
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
- Department of Chemistry, Center for Catalysis and Surface Science, and Institute for Catalysis in Energy Processes, Northwestern University, Evanston, Illinois 60208, United States
| | - Randall Q. Snurr
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Peter C. Stair
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
- Department of Chemistry, Center for Catalysis and Surface Science, and Institute for Catalysis in Energy Processes, Northwestern University, Evanston, Illinois 60208, United States
| | - Justin M. Notestein
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
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29
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Li Z, Pastewka L, Szlufarska I. Chemical aging of large-scale randomly rough frictional contacts. Phys Rev E 2018; 98:023001. [PMID: 30253579 DOI: 10.1103/physreve.98.023001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Indexed: 06/08/2023]
Abstract
It has been shown that contact aging due to chemical reactions in single asperity contacts can have a significant effect on friction. However, it is currently unknown how chemically induced contact aging of friction depends on roughness that is typically encountered in macroscopic rough contacts. Here we develop an approach that brings together a kinetic Monte Carlo model of chemical aging with a contact mechanics model of rough surfaces based on the boundary element method to determine the magnitude of chemical aging in silica-silica contacts with random roughness. Our multiscale model predicts that chemical aging for randomly rough contacts has a logarithmic dependence on time. It also shows that friction aging switches from a linear to a nonlinear dependence on the applied load as the load increase. We discover that surface roughness affects the aging behavior primarily by modifying the real contact area and the local contact pressure, whereas the effect of contact morphology is relatively small. Our results demonstrate how understanding of chemical aging can be translated from studies of single asperity contacts to macroscopic rough contacts.
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Affiliation(s)
- Zhuohan Li
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison 53706-1595, USA
| | - Lars Pastewka
- Department of Microsystems Engineering, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
| | - Izabela Szlufarska
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison 53706-1595, USA
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30
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Le HLT, Goniakowski J, Noguera C, Koltsov A, Mataigne JM. Effects of surface hydroxylation on adhesion at zinc/silica interfaces. Phys Chem Chem Phys 2018; 20:15581-15588. [PMID: 29809208 DOI: 10.1039/c8cp02139b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The weak interaction between zinc and silica is responsible for the poor performance of anti-corrosive galvanic zinc coatings on modern advanced high-strength steels, which are fundamental in the automotive industry, and important for rail transport, shipbuilding, and aerospace. With the goal of identifying possible methods for its improvement, we report an ab initio study of the effect of surface hydroxylation on the adhesion characteristics of model zinc/β-cristobalite interfaces, representative of various surface hydroxylation/hydrogenation conditions. We show that surface silanols resulting from dissociative water adsorption at the most stable stoichiometric (001) and (111) surfaces prevent strong zinc-silica interactions. However, dehydrogenation of such interfaces produces oxygen-rich zinc/silica contacts with excellent adhesion characteristics. These are due to partial zinc oxidation and the formation of strong iono-covalent Zn-O bonds between zinc atoms and the under-coordinated excess anions, remnant of the hydroxylation layer. Interestingly, these interfaces appear as the most thermodynamically stable in a wide range of realistic oxygen-rich and hydrogen-lean environments. We also point out that the partial oxidation of zinc atoms in direct contact with the oxide substrate may somewhat weaken the cohesion in the zinc deposit itself. This fundamental analysis of the microscopic mechanisms responsible for the improved zinc wetting on pre-hydroxylated silica substrates provides useful guidelines towards practical attempts to improve adhesion.
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Affiliation(s)
- Ha-Linh Thi Le
- CNRS, UMR 7588, Institut des Nanosciences de Paris, F-75005 Paris, France.
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31
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Affiliation(s)
- Elisa Jimenez-Izal
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
- Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU) and Donostia International Physics Center (DIPC), 20080 Donostia, Euskadi, Spain
| | - Anastassia N. Alexandrova
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA
- California NanoSystems Institute, Los Angeles, California 90095, USA
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32
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Abstract
An in-depth knowledge of the interaction of water with amorphous silica is critical to fundamental studies of interfacial hydration water, as well as to industrial processes such as catalysis, nanofabrication, and chromatography. Silica has a tunable surface comprising hydrophilic silanol groups and moderately hydrophobic siloxane groups that can be interchanged through thermal and chemical treatments. Despite extensive studies of silica surfaces, the influence of surface hydrophilicity and chemical topology on the molecular properties of interfacial water is not well understood. In this work, we controllably altered the surface silanol density, and measured surface water diffusivity using Overhauser dynamic nuclear polarization (ODNP) and complementary silica-silica interaction forces across water using a surface forces apparatus (SFA). The results show that increased silanol density generally leads to slower water diffusivity and stronger silica-silica repulsion at short aqueous separations (less than ∼4 nm). Both techniques show sharp changes in hydration properties at intermediate silanol densities (2.0-2.9 nm-2). Molecular dynamics simulations of model silica-water interfaces corroborate the increase in water diffusivity with silanol density, and furthermore show that even on a smooth and crystalline surface at a fixed silanol density, adjusting the spatial distribution of silanols results in a range of surface water diffusivities spanning ∼10%. We speculate that a critical silanol cluster size or connectivity parameter could explain the sharp transition in our results, and can modulate wettability, colloidal interactions, and surface reactions, and thus is a phenomenon worth further investigation on silica and chemically heterogeneous surfaces.
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33
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Horowitz Y, Han HL, Soto FA, Ralston WT, Balbuena PB, Somorjai GA. Fluoroethylene Carbonate as a Directing Agent in Amorphous Silicon Anodes: Electrolyte Interface Structure Probed by Sum Frequency Vibrational Spectroscopy and Ab Initio Molecular Dynamics. NANO LETTERS 2018; 18:1145-1151. [PMID: 29251510 DOI: 10.1021/acs.nanolett.7b04688] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Fluorinated compounds are added to carbonate-based electrolyte solutions in an effort to create a stable solid electrolyte interphase (SEI). The SEI mitigates detrimental electrolyte redox reactions taking place on the anode's surface upon applying a potential in order to charge (discharge) the lithium (Li) ion battery. The need for a stable SEI is dire when the anode material is silicon as silicon cracks due to its expansion and contraction upon lithiation and delithiation (charge-discharge) cycles, consequently limiting the cyclability of a silicon-based battery. Here we show the molecular structures for ethylene carbonate (EC): fluoroethylene carbonate (FEC) solutions on silicon surfaces by sum frequency generation (SFG) vibrational spectroscopy, which yields vibrational spectra of molecules at interfaces and by ab initio molecular dynamics (AIMD) simulations at open circuit potential. Our AIMD simulations and SFG spectra indicate that both EC and FEC adsorb to the amorphous silicon (a-Si) through their carbonyl group (C═O) oxygen atom with no further desorption. We show that FEC additives induce the reorientation of EC molecules to create an ordered, up-right orientation of the electrolytes on the Si surface. We suggest that this might be helpful for Li diffusion under applied potential. Furthermore, FEC becomes the dominant species at the a-Si surface as the FEC concentration increases above 20 wt %. Our finding at open circuit potential can now initiate additive design to not only act as a sacrificial compound but also to produce a better suited SEI for the use of silicon anodes in the Li-ion vehicular industry.
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Affiliation(s)
- Yonatan Horowitz
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Hui-Ling Han
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Fernando A Soto
- Department of Chemical Engineering, Texas A&M University , College Station, Texas 77843-3122, United States
| | - Walter T Ralston
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Perla B Balbuena
- Department of Chemical Engineering, Texas A&M University , College Station, Texas 77843-3122, United States
| | - Gabor A Somorjai
- Department of Chemistry, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, California 94720, United States
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34
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35
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Halbert S, Ispas S, Raynaud C, Eisenstein O. Modelling the surface of amorphous dehydroxylated silica: the influence of the potential on the nature and density of defects. NEW J CHEM 2018. [DOI: 10.1039/c7nj03922k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nature and density of defects on the amorphous dehydroxylated silica surface are studied by molecular dynamics for information on the silanol groups of pretreated silica.
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Affiliation(s)
| | - Simona Ispas
- Laboratoire Charles Coulomb (L2C)
- UMR 5221
- Univ. Montpellier
- CNRS
- Montpellier
| | | | - Odile Eisenstein
- Institut Charles Gerhardt (ICGM)
- UMR 5253
- Univ. Montpellier
- CNRS
- ENSCM
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36
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Goldsmith BR, Peters B, Johnson JK, Gates BC, Scott SL. Beyond Ordered Materials: Understanding Catalytic Sites on Amorphous Solids. ACS Catal 2017. [DOI: 10.1021/acscatal.7b01767] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Bryan R. Goldsmith
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
- Department
of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48105, United States
| | - Baron Peters
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - J. Karl Johnson
- Department
of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Bruce C. Gates
- Department
of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Susannah L. Scott
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, United States
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37
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Armelao L, Dell’Amico DB, Bellucci L, Bottaro G, Di Bari L, Labella L, Marchetti F, Samaritani S, Zinna F. Circularly Polarized Luminescence of Silica-Grafted Europium Chiral Derivatives Prepared through a Sequential Functionalization. Inorg Chem 2017; 56:7010-7018. [DOI: 10.1021/acs.inorgchem.7b00611] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lidia Armelao
- Dipartimento di Scienze
Chimiche, Università di Padova, via Marzolo 1, I-35131 Padova, Italy
- CNR ICMATE and INSTM, Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, I-35131 Padova, Italy
| | - Daniela Belli Dell’Amico
- Dipartimento di
Chimica e Chimica Industriale, Università di Pisa and CIRCC, via
Giuseppe Moruzzi 13, I-56124 Pisa, Italy
| | - Luca Bellucci
- Dipartimento di
Chimica e Chimica Industriale, Università di Pisa and CIRCC, via
Giuseppe Moruzzi 13, I-56124 Pisa, Italy
- Dipartimento di Scienze
Chimiche, Università di Padova, via Marzolo 1, I-35131 Padova, Italy
| | - Gregorio Bottaro
- CNR ICMATE and INSTM, Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, I-35131 Padova, Italy
| | - Lorenzo Di Bari
- Dipartimento di
Chimica e Chimica Industriale, Università di Pisa and CIRCC, via
Giuseppe Moruzzi 13, I-56124 Pisa, Italy
| | - Luca Labella
- Dipartimento di
Chimica e Chimica Industriale, Università di Pisa and CIRCC, via
Giuseppe Moruzzi 13, I-56124 Pisa, Italy
| | - Fabio Marchetti
- Dipartimento di
Chimica e Chimica Industriale, Università di Pisa and CIRCC, via
Giuseppe Moruzzi 13, I-56124 Pisa, Italy
| | - Simona Samaritani
- Dipartimento di
Chimica e Chimica Industriale, Università di Pisa and CIRCC, via
Giuseppe Moruzzi 13, I-56124 Pisa, Italy
| | - Francesco Zinna
- Dipartimento di
Chimica e Chimica Industriale, Università di Pisa and CIRCC, via
Giuseppe Moruzzi 13, I-56124 Pisa, Italy
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38
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Comas-Vives A, Larmier K, Copéret C. Understanding surface site structures and properties by first principles calculations: an experimental point of view! Chem Commun (Camb) 2017; 53:4296-4303. [DOI: 10.1039/c7cc01101f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Computational Chemistry is key for the molecular-level understanding of active sites in heterogeneous catalysis paving the way to the rational design and development.
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Affiliation(s)
- Aleix Comas-Vives
- Department of Chemistry and Applied Biosciences
- ETH Zürich
- CH-8093 Zürich
- Switzerland
| | - Kim Larmier
- Department of Chemistry and Applied Biosciences
- ETH Zürich
- CH-8093 Zürich
- Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences
- ETH Zürich
- CH-8093 Zürich
- Switzerland
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39
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Ewing CS, Bagusetty A, Patriarca EG, Lambrecht DS, Veser G, Johnson JK. Impact of Support Interactions for Single-Atom Molybdenum Catalysts on Amorphous Silica. Ind Eng Chem Res 2016. [DOI: 10.1021/acs.iecr.6b03558] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Abhishek Bagusetty
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
| | | | | | | | - J. Karl Johnson
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, United States
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40
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Fong A, Peters B, Scott SL. One-Electron-Redox Activation of the Reduced Phillips Polymerization Catalyst, via Alkylchromium(IV) Homolysis: A Computational Assessment. ACS Catal 2016. [DOI: 10.1021/acscatal.6b01728] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Anthony Fong
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106-5080, United States
| | - Baron Peters
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106-5080, United States
- Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106-9510, United States
| | - Susannah L. Scott
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106-5080, United States
- Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106-9510, United States
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41
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Gierada M, Michorczyk P, Tielens F, Handzlik J. Reduction of chromia–silica catalysts: A molecular picture. J Catal 2016. [DOI: 10.1016/j.jcat.2016.04.022] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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42
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Warring SL, Beattie DA, McQuillan AJ. Surficial Siloxane-to-Silanol Interconversion during Room-Temperature Hydration/Dehydration of Amorphous Silica Films Observed by ATR-IR and TIR-Raman Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:1568-76. [PMID: 26804934 DOI: 10.1021/acs.langmuir.5b04506] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Silica has been frequently studied using infrared and Raman spectroscopy due to its importance in many practical contexts where its surface chemistry plays a vital role. The majority of these studies have utilized chemical-vapor-deposited films in vacuo after high-temperature calcination. However, room-temperature hydration and dehydration of thin silica particle films has not been well characterized in spite of the importance of such films as substrates for polymer and surfactant adsorption. The present study has utilized ATR-IR spectroscopy and thin silica particle films exposed to varying humidity to clearly show reversible conversion between surface siloxanes and hydrogen-bonded silanols without the need for semiempirical peak deconvolution. The IR spectra from corresponding hydration experiments on deuterated silica films has confirmed the vibrational mode assignments. The variation of humidity over silica films formed from silica suspensions of differing pH gave IR spectra consistent with the change in the relative populations of siloxide to silanol surface groups. In addition, total internal reflection Raman spectroscopy has been used to provide further evidence of room-temperature dehydroxylation, with spectral evidence for the presence of three-membered siloxane rings when films are dehydrated under argon. The confirmation of room-temperature siloxane-to-silanol interconversion is expected to benefit understanding in many silica surface chemical contexts.
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Affiliation(s)
- Suzanne L Warring
- Department of Chemistry, University of Otago , P. O Box 56, Dunedin 9054, New Zealand
| | - David A Beattie
- Future Industries Institute, University of South Australia , Mawson Lakes, Adelaide, SA 5095, Australia
| | - A James McQuillan
- Department of Chemistry, University of Otago , P. O Box 56, Dunedin 9054, New Zealand
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43
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Gierada M, Petit I, Handzlik J, Tielens F. Hydration in silica based mesoporous materials: a DFT model. Phys Chem Chem Phys 2016; 18:32962-32972. [DOI: 10.1039/c6cp05460a] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, calculable and realistic DFT models of MCM-41 material that follow temperature dependence of silanol density were developed. They can be easily applied in further studies of adsorption or as a support for catalysts.
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Affiliation(s)
- Maciej Gierada
- Faculty of Chemical Engineering and Technology
- Cracow University of Technology
- 31-155 Kraków
- Poland
| | - Ivan Petit
- Sorbonne Universités
- UPMC Univ Paris 06
- UMR 7574
- Laboratoire Chimie de la Matière Condensée
- Collège de France
| | - Jarosław Handzlik
- Faculty of Chemical Engineering and Technology
- Cracow University of Technology
- 31-155 Kraków
- Poland
| | - Frederik Tielens
- Sorbonne Universités
- UPMC Univ Paris 06
- UMR 7574
- Laboratoire Chimie de la Matière Condensée
- Collège de France
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44
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Comas-Vives A. Amorphous SiO2 surface models: energetics of the dehydroxylation process, strain, ab initio atomistic thermodynamics and IR spectroscopic signatures. Phys Chem Chem Phys 2016; 18:7475-82. [DOI: 10.1039/c6cp00602g] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Realistic amorphous SiO2 models of 2.1 × 2.1 nm with silanol densities ranging 1.1–7.2 OH per nm2 are obtained by means of ab initio calculations via the dehydroxylation of a fully hydroxylated silica surface.
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Affiliation(s)
- Aleix Comas-Vives
- ETH Zürich
- Department of Chemistry and Applied Biosciences
- CH-8093 Zürich
- Switzerland
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45
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Corno M, Delle Piane M, Monti S, Moreno-Couranjou M, Choquet P, Ugliengo P. Computational Study of Acidic and Basic Functionalized Crystalline Silica Surfaces as a Model for Biomaterial Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:6321-6331. [PMID: 26010674 DOI: 10.1021/acs.langmuir.5b01828] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In silico modeling of acidic (CH2COOH) or basic (CH2NH2) functionalized silica surfaces has been carried out by means of a density functional approach based on a gradient-corrected functional to provide insight into the characterization of experimentally functionalized surfaces via a plasma method. Hydroxylated surfaces of crystalline cristobalite (sporting 4.8 OH/nm(2)) mimic an amorphous silica interface as unsubstituted material. To functionalize the silica surface we transformed the surface Si-OH groups into Si-CH2COOH and Si-CH2NH2 moieties to represent acidic/basic chemical character for the substitution. Structures, energetics, electronic, and vibrational properties were computed and compared as a function of the increasing loading of the functional groups (from 1 to 4 per surface unit cell). Classical molecular dynamics simulations of selected cases have been performed through a Reax-FF reactive force field to assess the mobility of the surface added chains. Both DFT and force field calculations identify the CH2NH2 moderate surface loading (1 group per unit cell) as the most stable functionalization, at variance with the case of the CH2COOH group, where higher loadings are preferred (2 groups per unit cell). The vibrational fingerprints of the surface functionalities, which are the ν(C═O) stretching and δ(NH2) bending modes for acidic/basic cases, have been characterized as a function of substitution percentage in order to guide the assignment of the experimental data. The final results highlighted the different behavior of the two types of functionalization. On the one hand, the frequency associated with the ν(C═O) mode shifts to lower wavenumbers as a function of the H-bond strength between the surface functionalities (both COOH and SiOH groups), and on the other hand, the δ(NH2) frequency shift seems to be caused by a subtle balance between the H-bond donor and acceptor abilities of the NH2 moiety. Both sets of data are in general agreement with experimental measurements on the corresponding silica-functionalized materials and provide finer details for a deeper interpretation of experimental spectra.
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Affiliation(s)
- Marta Corno
- †Dipartimento di Chimica and NIS - Nanostructured Interfaces and Surfaces - Centre, Università degli Studi di Torino, via P. Giuria 7, 10125 Torino, Italy
| | - Massimo Delle Piane
- †Dipartimento di Chimica and NIS - Nanostructured Interfaces and Surfaces - Centre, Università degli Studi di Torino, via P. Giuria 7, 10125 Torino, Italy
| | - Susanna Monti
- ‡CNR Institute of Chemistry of Organometallic Compounds, Area della Ricerca, via G. Moruzzi l, I-56124 Pisa, Italy
| | - Maryline Moreno-Couranjou
- §Materials Research and Technology Department (MRT), Luxembourg Institute of Science and Technology (LIST), 5 avenue des Hauts-Fourneaux, L-4362 Esch/Alzette, Luxembourg
| | - Patrick Choquet
- §Materials Research and Technology Department (MRT), Luxembourg Institute of Science and Technology (LIST), 5 avenue des Hauts-Fourneaux, L-4362 Esch/Alzette, Luxembourg
| | - Piero Ugliengo
- †Dipartimento di Chimica and NIS - Nanostructured Interfaces and Surfaces - Centre, Università degli Studi di Torino, via P. Giuria 7, 10125 Torino, Italy
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46
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Peters B, Scott SL. Single atom catalysts on amorphous supports: A quenched disorder perspective. J Chem Phys 2015; 142:104708. [DOI: 10.1063/1.4914145] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
- Baron Peters
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
| | - Susannah L. Scott
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
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