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Active Sites in H-Mordenite Catalysts Probed by NMR and FTIR. Catalysts 2023. [DOI: 10.3390/catal13020344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Mordenites are widely used in catalysis and environmental protection. The catalytic properties of mordenite are largely determined by the composition of its crystal framework, i.e., the SiO2/Al2O3 molar ratio (MR), and the cationic form. In H-mordenites, the most important characteristic becomes the structure and distribution of acid sites, which depends on the number and distribution of Al tetrahedra in the framework. In the present work, the local structure of these centers in H-mordenite catalysts with a nominal MR varied from 9.9 to 19.8 was studied in detail using a combination of magic angle spinning nuclear magnetic resonance (MAS NMR) and Fourier transform infrared spectroscopy (FTIR). 27Al MAS NMR indicates the presence of extra-framework Al in most of the studied samples that results in a higher real MR of the zeolitic framework compared to the nominal value. Concentrations of Lewis and Brønsted acid sites, as well as of silanol groups were estimated by elemental analysis, NMR, and FTIR spectroscopy. The values of site concentrations obtained from band intensities of adsorbed CO and those of OH groups are compared with the amount of framework and extra-framework aluminum. The advantages and restrictions of different methods of active site characterization are discussed.
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Krylova EA, Shelyapina MG, Mazur A, Baranov DA, Tsyganenko AA, Petranovskii VP. LOCAL STRUCTURE OF PROTONATED MORDENITES WITH SiO2/Al2O3 ≈ 15 PROBED BY MULTINUCLEAR NMR. J STRUCT CHEM+ 2022. [DOI: 10.1134/s0022476622060105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Hasegawa T, Yamasaki N, Asakura Y, Ueda T, Yin S. Ce(iv)-centered charge-neutral perovskite layers topochemically derived from anionic [CeTa 2O 7] - layers. Chem Sci 2021; 12:15016-15027. [PMID: 34909142 PMCID: PMC8612395 DOI: 10.1039/d1sc03053a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 10/13/2021] [Indexed: 11/30/2022] Open
Abstract
Layered perovskites have been extensively investigated in many research fields, such as electronics, catalysis, optics, energy, and magnetics, because of the fascinating chemical properties that are generated by the specific structural features of perovskite frameworks. Furthermore, the interlayers of these structures can be chemically modified through ion exchange to form nanosheets. To further expand the modification of layered perovskites, we have demonstrated an advance in the new structural concept of layered perovskite "charge-neutral perovskite layers" by manipulating the perovskite layer itself. A charge-neutral perovskite layer in [CeIVTa2O7] was synthesized through a soft chemical oxidative reaction based on anionic [CeIIITa2O7]- layers. The Ce oxidation state for the charge-neutral [CeIVTa2O7] layers was found to be tetravalent by X-ray absorption fine structure (XAFS) analysis. The atomic arrangements were determined through scattering transmission electron microscopy and extended XAFS (EXAFS) analysis. The framework structure was simulated through density functional theory (DFT) calculations, the results of which were in good agreement with those of the EXAFS spectra quantitative analysis. The anionic [CeIIITa2O7]- layers exhibited optical absorption in the near infrared (NIR) region at approximately 1000 nm, whereas the level of NIR absorption decreased in the [CeIVTa2O7] charge-neutral layer due to the disappearance of the Ce 4f electrons. In addition, the chemical reactivity of the charge-neutral [CeIVTa2O7] layers was investigated by chemical reduction with ascorbic acid, resulting in the reduction of the [CeIVTa2O7] layers to form anionic [CeIIITa2O7]- layers. Furthermore, the anionic [CeIIITa2O7]- layers exhibited redox activity which the Ce in the perovskite unit can be electrochemically oxidized and reduced. The synthesis of the "charge-neutral" perovskite layer indicated that diverse features were generated by systematically tuning the electronic structure through the redox control of Ce; such diverse features have not been found in conventional layered perovskites. This study could demonstrate the potential for developing innovative, unique functional materials with perovskite structures.
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Affiliation(s)
- Takuya Hasegawa
- Institute of Multidisciplinary Research for Advanced Material (IMRAM), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai 980-8577 Japan +81-22-217-5598 +81-22-217-5598
| | - Naoki Yamasaki
- Department of Marine Resource Science, Faculty of Agriculture and Marine Science, Kochi University Nankoku 783-8502 Japan
| | - Yusuke Asakura
- Institute of Multidisciplinary Research for Advanced Material (IMRAM), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai 980-8577 Japan +81-22-217-5598 +81-22-217-5598
| | - Tadaharu Ueda
- Department of Marine Resource Science, Faculty of Agriculture and Marine Science, Kochi University Nankoku 783-8502 Japan
- Center for Advanced Marine Core Research, Kochi University Nankoku 783-8520 Japan
| | - Shu Yin
- Institute of Multidisciplinary Research for Advanced Material (IMRAM), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai 980-8577 Japan +81-22-217-5598 +81-22-217-5598
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1H NMR Study of the HCa 2Nb 3O 10 Photocatalyst with Different Hydration Levels. Molecules 2021; 26:molecules26195943. [PMID: 34641487 PMCID: PMC8512110 DOI: 10.3390/molecules26195943] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/14/2021] [Accepted: 09/28/2021] [Indexed: 11/23/2022] Open
Abstract
The photocatalytic activity of layered perovskite-like oxides in water splitting reaction is dependent on the hydration level and species located in the interlayer slab: simple or complex cations as well as hydrogen-bonded or non-hydrogen-bonded H2O. To study proton localization and dynamics in the HCa2Nb3O10·yH2O photocatalyst with different hydration levels (hydrated—α-form, dehydrated—γ-form, and intermediate—β-form), complementary Nuclear Magnetic Resonance (NMR) techniques were applied. 1H Magic Angle Spinning NMR evidences the presence of different proton containing species in the interlayer slab depending on the hydration level. For α-form, HCa2Nb3O10·1.6H2O, 1H MAS NMR spectra reveal H3O+. Its molecular motion parameters were determined from 1H spin-lattice relaxation time in the rotating frame (T1ρ) using the Kohlrausch-Williams-Watts (KWW) correlation function with stretching exponent β = 0.28: Ea=0.2102 eV, τ0=9.01 × 10−12 s. For the β-form, HCa2Nb3O10·0.8H2O, the only 1H NMR line is the result of an exchange between lattice and non-hydrogen-bonded water protons. T1ρ(1/T) indicates the presence of two characteristic points (224 and 176 K), at which proton dynamics change. The γ-form, HCa2Nb3O10·0.1H2O, contains bulk water and interlayer H+ in regular sites. 1H NMR spectra suggest two inequivalent cation positions. The parameters of the proton motion, found within the KWW model, are as follows: Ea=0.2178 eV, τ0=8.29 × 10−10 s.
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Atri S, Tomar R. A Review on the Synthesis and Modification of Functional Inorganic‐Organic‐Hybrid Materials via Microwave‐Assisted Method. ChemistrySelect 2021. [DOI: 10.1002/slct.202102030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Shalu Atri
- Department of Chemistry Faculty of Science SGT University Gurugram Haryana 122505 India
| | - Ravi Tomar
- Department of Chemistry Faculty of Science SGT University Gurugram Haryana 122505 India
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Synthesis of n-Alkoxy Derivatives of Layered Perovskite-Like Niobate HCa2Nb3O10 and Study of Their Photocatalytic Activity for Hydrogen Production from an Aqueous Solution of Methanol. Catalysts 2021. [DOI: 10.3390/catal11080897] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A series of hybrid inorganic–organic niobates HCa2Nb3O10×ROH, containing n-alkoxy groups of primary alcohols (R = Me, Et, Pr, Bu, Hx, and Dc) grafted in the interlayer space, has been studied for the first time in relation to photocatalytic hydrogen generation from a model 1 mol % aqueous solution of methanol under ultraviolet irradiation. Photocatalytic activity was measured both for bare samples and for their composites with Pt nanoparticles as a cocatalyst. The advanced measurement scheme allowed monitoring the volume concentration of a sample in a suspension during the experiment, its pH, and possible exfoliation of layered compounds into nanolayers. In the series of n-alkoxy derivatives, the maximum rate of hydrogen evolution was achieved over a Pt-loaded ethoxy derivative HCa2Nb3O10×EtOH/Pt. Its apparent quantum efficiency of 20.6% in the 220–350 nm range was found not to be caused by changes in the light absorption region or specific surface area upon ethanol grafting. Moreover, the amounts of hydrogen released during the measurements significantly exceeded those of interlayer organic components, indicating that hydrogen is generated from the reaction solution rather than from the hybrid material.
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Shelyapina MG, Silyukov OI, Lushpinskaia IP, Kurnosenko SA, Mazur AS, Shenderovich IG, Zvereva IA. NMR Study of Intercalates and Grafted Organic Derivatives of H 2La 2Ti 3O 10. Molecules 2020; 25:E5229. [PMID: 33182612 PMCID: PMC7696603 DOI: 10.3390/molecules25225229] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 10/28/2020] [Accepted: 11/08/2020] [Indexed: 12/02/2022] Open
Abstract
The protonated perovskite-like titanate H2La2Ti3O10 has been used to produce organic-inorganic hybrids with simple organic molecules: methylamine, methanol, monoethanolamine, and n-butylamine. The optimal pathways for the preparation of such hybrids are summarized. Solid-state NMR, combined with thermal analysis, Raman, and IR spectroscopy, has been applied to determine the bonding type in the obtained organic-inorganic hybrids. It has been found that, in the methanolic hybrid, the organic residues are covalently bound to the inorganic matrix. In contrast, in the methylamine and n-butylamine hybrids, the organic molecules are intercalated into the inorganic matrix in cationic forms. The structure of the monoethanolamine hybrid is composite and includes both the covalently bound and intercalated organic species.
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Affiliation(s)
- Marina G. Shelyapina
- Department of Nuclear Physics Research Methods, Saint-Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia;
| | - Oleg I. Silyukov
- Institute of Chemistry, Saint-Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia; (O.I.S.); (S.A.K.); (I.A.Z.)
| | - Irina P. Lushpinskaia
- Department of Nuclear Physics Research Methods, Saint-Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia;
- Magnetic Resonance Research Center, Saint-Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia;
| | - Sergey A. Kurnosenko
- Institute of Chemistry, Saint-Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia; (O.I.S.); (S.A.K.); (I.A.Z.)
| | - Anton S. Mazur
- Magnetic Resonance Research Center, Saint-Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia;
| | - Ilya G. Shenderovich
- Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, 93040 Regensburg, Germany;
| | - Irina A. Zvereva
- Institute of Chemistry, Saint-Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia; (O.I.S.); (S.A.K.); (I.A.Z.)
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Strategy for Modifying Layered Perovskites toward Efficient Solar Light-Driven Photocatalysts for Removal of Chlorinated Pollutants. Catalysts 2020. [DOI: 10.3390/catal10060637] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We have explored an efficient strategy to enhance the overall photocatalytic performances of layered perovskites by increasing the density of hydroxyl group by protonation. The experimental procedure consisted of the slow replacement of interlayer Rb+ cation of RbLaTa2O7 Dion-Jacobson (DJ) perovskite by H+ via acid treatment. Two layered perovskites synthesized by mild (1200 °C for 18 h) and harsh (950 and 1200 °C, for 36 h) annealing treatment routes were used as starting materials. The successful intercalation of proton into D-J interlayer galleries was confirmed by FTIR spectroscopy, thermal analyses, ion chromatography and XPS results. In addition, the ion-exchange route was effective to enlarge the specific surface area, thus enhancing the supply of photocharges able to participate in redox processes involved in the degradation of organic pollutants. HLaTa_01 protonated layered perovskite is reported as a efficient photocatalyst for photomineralization of trichloroethylene (TCE) to Cl− and CO2 under simulated solar light. The enhanced activity is attributed to combined beneficial roles played by the increased specific surface area and high density of hydroxyl groups, leading to an efficiency of TCE mineralization of 68% moles after 5 h of irradiation.
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Minich IA, Silyukov OI, Gak VV, Borisov EV, Zvereva IA. Synthesis of Organic-Inorganic Hybrids Based on Perovskite-like Bismuth Titanate H 2K 0.5Bi 2.5Ti 4O 13·H 2O and n-Alkylamines. ACS OMEGA 2020; 5:8158-8168. [PMID: 32309726 PMCID: PMC7161038 DOI: 10.1021/acsomega.0c00424] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/18/2020] [Indexed: 06/11/2023]
Abstract
New organic-inorganic hybrids have been synthesized by the intercalation of n-alkylamines (methylamine, ethylamine, n-propylamine, n-butylamine, n-hexylamine, and n-octylamine) into the structure of the protonated and hydrated form of the perovskite-like layered titanate H2K0.5Bi2.5Ti4O13·H2O (HKBT4·H2O). The possibility of the synthesis of the hybrid materials was studied in a wide range of conditions. It was found that interlayer water plays a crucial role in the formation of intercalated hybrids. The obtained compounds were characterized with powder X-ray diffraction analysis; Raman, IR, and NMR spectroscopies; thermogravimetry (TG), TG coupled with mass spectrometry, and CHN analyses; and scanning electron microscopy. It was suggested that the intercalated n-alkylamines exist in the form of alkylammonium ions forming a paraffin-like bilayer with an average tilting angle of ∼77.5°. The obtained HKBT4×RNH2 compounds contain 0.4-0.7 n-alkylamine molecules per formula unit as well as the varied amount of intercalated water. By gentle heating, they can be obtained as dehydrated forms, which are thermally stable up to 250 °C.
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Affiliation(s)
- Iana A. Minich
- Institute
of Chemistry, St. Petersburg State University, 198504 St. Petersburg, Russia
| | - Oleg I. Silyukov
- Institute
of Chemistry, St. Petersburg State University, 198504 St. Petersburg, Russia
| | - Veronika V. Gak
- Institute
of Chemistry, St. Petersburg State University, 198504 St. Petersburg, Russia
| | - Evgeny V. Borisov
- Center
for Optical and Laser Materials Research, St. Petersburg State University, 198504 St. Petersburg, Russia
| | - Irina A. Zvereva
- Institute
of Chemistry, St. Petersburg State University, 198504 St. Petersburg, Russia
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Akbarian-Tefaghi S, Wiley JB. Microwave-assisted routes for rapid and efficient modification of layered perovskites. Dalton Trans 2018; 47:2917-2924. [PMID: 29188257 DOI: 10.1039/c7dt03865h] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Recent advances in exploiting microwave radiation in the topochemical modification of layered oxide perovskites are presented. Such methods work well for rapid bulk synthetic steps used in the production of novel inorganic-organic hybrids (protonation, grafting, intercalation, and in situ click reactions), exfoliation to produce dispersed nanosheets, and post-exfoliation processing to rapidly vary nanosheet surface groups. Compared to traditional methods that often take days, microwave methods can produce quality products in as little as 1-2 h.
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Affiliation(s)
- S Akbarian-Tefaghi
- Department of Chemistry and Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148, USA.
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Lilly Thankamony AS, Wittmann JJ, Kaushik M, Corzilius B. Dynamic nuclear polarization for sensitivity enhancement in modern solid-state NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2017; 102-103:120-195. [PMID: 29157490 DOI: 10.1016/j.pnmrs.2017.06.002] [Citation(s) in RCA: 273] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/03/2017] [Accepted: 06/08/2017] [Indexed: 05/03/2023]
Abstract
The field of dynamic nuclear polarization has undergone tremendous developments and diversification since its inception more than 6 decades ago. In this review we provide an in-depth overview of the relevant topics involved in DNP-enhanced MAS NMR spectroscopy. This includes the theoretical description of DNP mechanisms as well as of the polarization transfer pathways that can lead to a uniform or selective spreading of polarization between nuclear spins. Furthermore, we cover historical and state-of-the art aspects of dedicated instrumentation, polarizing agents, and optimization techniques for efficient MAS DNP. Finally, we present an extensive overview on applications in the fields of structural biology and materials science, which underlines that MAS DNP has moved far beyond the proof-of-concept stage and has become an important tool for research in these fields.
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Affiliation(s)
- Aany Sofia Lilly Thankamony
- Institute of Physical and Theoretical Chemistry, Institute of Biophysical Chemistry, and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 7-9, 60438 Frankfurt, Germany
| | - Johannes J Wittmann
- Institute of Physical and Theoretical Chemistry, Institute of Biophysical Chemistry, and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 7-9, 60438 Frankfurt, Germany
| | - Monu Kaushik
- Institute of Physical and Theoretical Chemistry, Institute of Biophysical Chemistry, and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 7-9, 60438 Frankfurt, Germany
| | - Björn Corzilius
- Institute of Physical and Theoretical Chemistry, Institute of Biophysical Chemistry, and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 7-9, 60438 Frankfurt, Germany.
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Giannici F, Mossuto Marculescu A, Cattaneo AS, Tealdi C, Mustarelli P, Longo A, Martorana A. Covalent and Ionic Functionalization of HLN Layered Perovskite by Sonochemical Methods. Inorg Chem 2016; 56:645-653. [DOI: 10.1021/acs.inorgchem.6b02581] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Francesco Giannici
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze ed. 17, I-90128 Palermo, Italy
| | - Adriana Mossuto Marculescu
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze ed. 17, I-90128 Palermo, Italy
| | - Alice Silvia Cattaneo
- Dipartimento di Chimica Sezione di Chimica-Fisica, Università degli Studi di Pavia, Via Taramelli 16, I-2700 Pavia, Italy
| | - Cristina Tealdi
- Dipartimento di Chimica Sezione di Chimica-Fisica, Università degli Studi di Pavia, Via Taramelli 16, I-2700 Pavia, Italy
| | - Piercarlo Mustarelli
- Dipartimento di Chimica Sezione di Chimica-Fisica, Università degli Studi di Pavia, Via Taramelli 16, I-2700 Pavia, Italy
| | - Alessandro Longo
- CNR−Istituto per lo Studio dei Materiali Nanostrutturati, Via U. La Malfa, I-90146 Palermo, Italy
- Netherlands Organization for Scientific Research at ESRF, F-38043 Grenoble, France
| | - Antonino Martorana
- Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze ed. 17, I-90128 Palermo, Italy
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