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Yu X, Cheng Y, Li Y, Polo-Garzon F, Liu J, Mamontov E, Li M, Lennon D, Parker SF, Ramirez-Cuesta AJ, Wu Z. Neutron Scattering Studies of Heterogeneous Catalysis. Chem Rev 2023. [PMID: 37315192 DOI: 10.1021/acs.chemrev.3c00101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Understanding the structural dynamics/evolution of catalysts and the related surface chemistry is essential for establishing structure-catalysis relationships, where spectroscopic and scattering tools play a crucial role. Among many such tools, neutron scattering, though less-known, has a unique power for investigating catalytic phenomena. Since neutrons interact with the nuclei of matter, the neutron-nucleon interaction provides unique information on light elements (mainly hydrogen), neighboring elements, and isotopes, which are complementary to X-ray and photon-based techniques. Neutron vibrational spectroscopy has been the most utilized neutron scattering approach for heterogeneous catalysis research by providing chemical information on surface/bulk species (mostly H-containing) and reaction chemistry. Neutron diffraction and quasielastic neutron scattering can also supply important information on catalyst structures and dynamics of surface species. Other neutron approaches, such as small angle neutron scattering and neutron imaging, have been much less used but still give distinctive catalytic information. This review provides a comprehensive overview of recent advances in neutron scattering investigations of heterogeneous catalysis, focusing on surface adsorbates, reaction mechanisms, and catalyst structural changes revealed by neutron spectroscopy, diffraction, quasielastic neutron scattering, and other neutron techniques. Perspectives are also provided on the challenges and future opportunities in neutron scattering studies of heterogeneous catalysis.
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Affiliation(s)
- Xinbin Yu
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37381, United States
| | - Yongqiang Cheng
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Yuanyuan Li
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37381, United States
| | - Felipe Polo-Garzon
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37381, United States
| | - Jue Liu
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Eugene Mamontov
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Meijun Li
- Manufacturing Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - David Lennon
- School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Stewart F Parker
- ISIS Pulsed Neutron and Muon Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, United Kingdom
| | - Anibal J Ramirez-Cuesta
- Neutron Technologies Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Zili Wu
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37381, United States
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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Bridges CA, Martins ML, Jafta CJ, Sun XG, Paranthaman MP, Liu J, Dai S, Mamontov E. Dynamics of Emim + in [Emim][TFSI]/LiTFSI Solutions as Bulk and under Confinement in a Quasi-liquid Solid Electrolyte. J Phys Chem B 2021; 125:5443-5450. [PMID: 34003647 DOI: 10.1021/acs.jpcb.1c02383] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quasi-liquid solid electrolytes are a promising alternative for next-generation Li batteries. These systems combine the safety of solid electrolytes with the desired properties of liquids and are typically formed by solutions of Li salts in ionic liquids incorporated into solid matrices. Here, we present a fundamental understanding of the transport properties in solutions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][TFSI]), either in bulk form or incorporated in a boron nitride (BN) matrix. We performed a series of quasi-elastic neutron scattering experiments that, given the high incoherent neutron scattering cross section of hydrogen, allowed us to focus on the Emim+ dynamics. First, [Emim][TFSI]/LiTFSI solutions (0.5 and 2.5 mol·kg-1) were investigated and we show how the increase in the concentration reduces the Emim+ mobility and increases the activation energy of their long-range motions. Then, the 0.5 mol·kg-1 solution was incorporated into the BN matrix and we report that the diffusivities of the Emim+ cations that remain mobile under confinement are highly accelerated in comparison with the bulk sample and the activation energy of these motions is drastically reduced. We present the experimental evidence that this effect is related to the content of the Emim+ cations immobilized near the surfaces of the BN pores.
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Affiliation(s)
- C A Bridges
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - M L Martins
- Neutron Scattering Division, Oak Ridge National Laboratory, P.O. Box 2008 MS6455, Oak Ridge, Tennessee 37831, United States
| | - C J Jafta
- Electrification and Energy Infrastructures, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - X G Sun
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - M P Paranthaman
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - J Liu
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - S Dai
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - E Mamontov
- Neutron Scattering Division, Oak Ridge National Laboratory, P.O. Box 2008 MS6455, Oak Ridge, Tennessee 37831, United States
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Chen XC, Sacci RL, Osti NC, Tyagi M, Wang Y, Keum JK, Dudney NJ. Study of the Segmental Dynamics and Ion Transport of Solid Polymer Electrolytes in the Semi-crystalline State. Front Chem 2021; 8:592604. [PMID: 33520929 PMCID: PMC7838558 DOI: 10.3389/fchem.2020.592604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 11/30/2020] [Indexed: 11/13/2022] Open
Abstract
Solid polymer electrolytes are promising in fulfilling the requirements for a stable lithium metal anode toward higher energy and power densities. In this work, we investigate the segmental dynamics, ionic conductivity, and crystallinity of a polymer electrolyte consisting of poly(ethylene oxide) (PEO) and lithium triflate salt, in the semi-crystalline state. Using quasi-elastic neutron scattering, the segmental dynamics of PEO chains confined between the crystalline lamellae is quantified, using Cole-Cole analysis. We show that the structural relaxation time, τ0, of PEO equilibrated near room temperature is six-fold longer than the same sample that had just cooled down to room temperature. This corresponds to a three-fold smaller ionic conductivity in the equilibrated condition. This work reveals that the segmental dynamics of semi-crystalline polymer electrolytes is very sensitive to thermal history. We demonstrate that quasi-elastic neutron scattering can be used to characterize the ion transport and segmental dynamics in the semi-crystalline state.
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Affiliation(s)
- Xi Chelsea Chen
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Robert L. Sacci
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Naresh C. Osti
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Madhusudan Tyagi
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD, United States
- Department of Materials Science and Engineering, University of Maryland, College Park, MD, United States
| | - Yangyang Wang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Jong K. Keum
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Nancy J. Dudney
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
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Stavretis SE, Mamontov E, Moseley DH, Cheng Y, Daemen LL, Ramirez-Cuesta AJ, Xue ZL. Effect of magnetic fields on the methyl rotation in a paramagnetic cobalt(ii) complex. Quasielastic neutron scattering studies. Phys Chem Chem Phys 2018; 20:21119-21126. [PMID: 30079409 DOI: 10.1039/c8cp01660g] [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
Molecular dynamics is a fundamental property of metal complexes. These dynamic processes, especially for paramagnetic complexes under external magnetic fields, are in general not well understood. Quasielastic neutron scattering (QENS) in 0-4 T magnetic fields has been used to study the dynamics of Co(acac)2(D2O)2 (1-d4, acac = acetylacetonate). At 80-100 K, rotation of the methyl groups on the acac ligands is the dominant dynamical process. This rotation is slowed down by the magnetic field increase. Rotation times at 80 K are 5.6(3) × 10-10 s at 0 T and 2.04(10) × 10-9 s at 4 T. The QENS studies suggest that methyl groups in these paramagnetic Co(ii) molecules do not behave as isolated units, which is consistent with results from earlier magnetic susceptibility studies indicating the presence of intermolecular interactions. DFT calculations show that unpaired electron spin density in 1 is dispersed to the atoms of both acac and H2O ligands. Methyl torsions in 1-d4 have also been observed at 5-100 K in inelastic neutron spectroscopy (INS). The QENS and INS results here help understand the dynamics of the compound in the solid state.
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Affiliation(s)
- Shelby E Stavretis
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
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Anunciado DB, Nyugen VP, Hurst GB, Doktycz MJ, Urban V, Langan P, Mamontov E, O'Neill H. In Vivo Protein Dynamics on the Nanometer Length Scale and Nanosecond Time Scale. J Phys Chem Lett 2017; 8:1899-1904. [PMID: 28388043 DOI: 10.1021/acs.jpclett.7b00399] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Selectively labeled GroEL protein was produced in living deuterated bacterial cells to enhance its neutron scattering signal above that of the intracellular milieu. Quasi-elastic neutron scattering shows that the in-cell diffusion coefficient of GroEL was (4.7 ± 0.3) × 10-12 m2/s, a factor of 4 slower than its diffusion coefficient in buffer solution. Internal protein dynamics showed a relaxation time of (65 ± 6) ps, a factor of 2 slower compared to the protein in solution. Comparison to the literature suggests that the effective diffusivity of proteins depends on the length and time scale being probed. Retardation of in-cell diffusion compared to the buffer becomes more significant with the increasing probe length scale, suggesting that intracellular diffusion of biomolecules is nonuniform over the cellular volume. The approach outlined here enables investigation of protein dynamics within living cells to open up new lines of research using "in-cell neutron scattering" to study the dynamics of complex biomolecular systems.
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Affiliation(s)
| | | | | | | | | | | | | | - Hugh O'Neill
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996, United States
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Angell CA, Magazù S, Migliardo F. Science for life - Recent advances in biochemical and biophysical methods. Biochim Biophys Acta Gen Subj 2016; 1861:3501-3503. [PMID: 27657805 DOI: 10.1016/j.bbagen.2016.09.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- C Austen Angell
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Salvatore Magazù
- Department of Mathematical and Informatics Sciences, Physical Sciences and Earth Sciences, University of Messina, Viale D'Alcontres 31, 98166 Messina, Italy
| | - Federica Migliardo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale D'Alcontres 31, 98166 Messina, Italy.
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