1
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Che Q, Ghiasi M, Braglia L, Peerlings MLJ, Mauri S, Torelli P, de Jongh P, de Groot FMF. Operando Soft X-ray Absorption of LaMn 1-x Co x O 3 Perovskites for CO Oxidation. ACS Catal 2024; 14:11243-11251. [PMID: 39114095 PMCID: PMC11301621 DOI: 10.1021/acscatal.4c03259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 07/09/2024] [Accepted: 07/09/2024] [Indexed: 08/10/2024]
Abstract
We employed operando soft X-ray absorption spectroscopy (XAS) to monitor the changes in the valence states and spin properties of LaMn1-x Co x O3 catalysts subjected to a mixture of CO and O2 at ambient pressure. Guided by simulations based on charge transfer multiplet theory, we quantitatively analyze the Mn and Co 2p XAS as well as the oxygen K-edge XAS spectra during the reaction process. The Mn sites are particularly sensitive to the catalytic reaction, displaying dynamics in their oxidation state. When Co doping is introduced (x ≤ 0.5), Mn oxidizes from Mn2+ to Mn3+ and Mn4+, while Co largely maintains a valence state of Co2+. In the case of LaCoO3, we identify high-spin and low-spin Co3+ species combined with Co2+. Our investigation underscores the importance to consider the spin and valence states of catalyst materials under operando conditions.
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Affiliation(s)
- Qijun Che
- Materials
Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Mahnaz Ghiasi
- Materials
Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Luca Braglia
- AREA
Science Park, Padriciano
99, I-34149 Trieste, Italy
| | - Matt L. J. Peerlings
- Materials
Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Silvia Mauri
- CNR-Istituto
Officina dei Materiali, 34149 Trieste, Italy
| | - Piero Torelli
- CNR-Istituto
Officina dei Materiali, 34149 Trieste, Italy
| | - Petra de Jongh
- Materials
Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Frank M. F. de Groot
- Materials
Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
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2
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Mauri S, Calligaro R, Pauletti CF, Camellone MF, Boaro M, Braglia L, Fabris S, Piccinin S, Torelli P, Trovarelli A. Low-Temperature Methane Activation Reaction Pathways over Mechanochemically-Generated Ce 4+/Cu + Interfacial Sites. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2403028. [PMID: 38860552 DOI: 10.1002/smll.202403028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/27/2024] [Indexed: 06/12/2024]
Abstract
Methane is a valuable resource and its valorization is an important challenge in heterogeneous catalysis. Here it is shown that CeO2/CuO composite prepared by ball milling activates methane at a temperature as low as 250 °C. In contrast to conventionally prepared catalysts, the formation of partial oxidation products such as methanol and formaldehyde is also observed. Through an in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and operando Near Edge X-Ray Absorption Fine Structure Spectroscopy (NEXAFS) approach, it can be established that this unusual reactivity can be attributed to the presence of Ce4+/Cu+ interfaces generated through a redox exchange between Ce3+ and Cu2+ atoms facilitated by the mechanical energy supplied during milling. DFT modeling of the electronic properties confirms the existence of a charge transfer mechanism. These results demonstrate the effectiveness and distinctiveness of the mechanical approach in creating unique and resilient interfaces thereby enabling the optimization and refining of CeO2/CuO catalysts in methane activation reactions.
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Affiliation(s)
- Silvia Mauri
- TASC Laboratory, CNR- Istituto Officina dei Materiali, Trieste, 34149, Italy
| | - Rudy Calligaro
- Dipartimento Politecnico and INSTM, Università degli Studi di Udine, Via del Cotonificio 108, Udine, 33100, Italy
| | - Carlo Federico Pauletti
- Physics Department, Università degli Studi di Trieste, Via Alfonso Valerio 2, Trieste, 34127, Italy
| | | | - Marta Boaro
- Dipartimento Politecnico and INSTM, Università degli Studi di Udine, Via del Cotonificio 108, Udine, 33100, Italy
| | - Luca Braglia
- TASC Laboratory, CNR- Istituto Officina dei Materiali, Trieste, 34149, Italy
- AREA Science Park, Padriciano 99, Trieste, I-34149, Italy
| | - Stefano Fabris
- TASC Laboratory, CNR- Istituto Officina dei Materiali, Trieste, 34149, Italy
| | - Simone Piccinin
- TASC Laboratory, CNR- Istituto Officina dei Materiali, Trieste, 34149, Italy
| | - Piero Torelli
- TASC Laboratory, CNR- Istituto Officina dei Materiali, Trieste, 34149, Italy
| | - Alessandro Trovarelli
- Dipartimento Politecnico and INSTM, Università degli Studi di Udine, Via del Cotonificio 108, Udine, 33100, Italy
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3
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Vismara R, Terruzzi S, Maspero A, Grell T, Bossola F, Sironi A, Galli S, Navarro JAR, Colombo V. CO 2 Adsorption in a Robust Iron(III) Pyrazolate-Based MOF: Molecular-Level Details and Frameworks Dynamics From Powder X-ray Diffraction Adsorption Isotherms. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2209907. [PMID: 36735860 DOI: 10.1002/adma.202209907] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/10/2023] [Indexed: 06/18/2023]
Abstract
Understanding adsorption processes at the molecular level, with multi-technique approaches, is nowadays at the frontier of porous materials research. In this work it is shown that with a proper data treatment, in situ high-resolution powder X-ray diffraction (HR-PXRD) at variable temperature and gas pressure can reveal atomic details of the accommodation sites, the framework dynamics as well as thermodynamic information (isosteric heat of adsorption) of the CO2 adsorption process in the robust iron(III) pyrazolate-based MOF Fe2(BDP)3 [H2BDP = 1,4-bis(1H-pyrazol-4-yl)benzene]. Highly reliable "HR-PXRD adsorption isotherms" can be constructed from occupancy values of CO2 molecules. The "HR-PXRD adsorption isotherms" accurately match the results of conventional static and dynamic gas sorption experiments and Monte Carlo simulations. These results are indicative of the impact of the molecular-level behavior on the bulk properties of the system under study and of the potential of the presented multi-technique approach to understand adsorption processes in metal-organic frameworks.
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Affiliation(s)
- Rebecca Vismara
- Dipartimento di Scienza e Alta Tecnologia, Università degli Studi dell'Insubria, Via Valleggio 11, Como, 22100, Italy
- Departamento de Química Inorgánica, Universidad de Granada, Av. Fuentenueva S/N, Granada, 18071, Spain
| | - Stephanie Terruzzi
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, Milano, 20133, Italy
| | - Angelo Maspero
- Dipartimento di Scienza e Alta Tecnologia, Università degli Studi dell'Insubria, Via Valleggio 11, Como, 22100, Italy
| | - Toni Grell
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, Milano, 20133, Italy
| | - Filippo Bossola
- CNR - Istituto di Scienze e Tecnologie Chimiche "Giulio Natta", Via Golgi 19, Milan, 20133, Italy
| | - Angelo Sironi
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, Milano, 20133, Italy
| | - Simona Galli
- Dipartimento di Scienza e Alta Tecnologia, Università degli Studi dell'Insubria, Via Valleggio 11, Como, 22100, Italy
- Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via Giusti 9, Firenze, 50121, Italy
| | - Jorge A R Navarro
- Departamento de Química Inorgánica, Universidad de Granada, Av. Fuentenueva S/N, Granada, 18071, Spain
| | - Valentina Colombo
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, Milano, 20133, Italy
- CNR - Istituto di Scienze e Tecnologie Chimiche "Giulio Natta", Via Golgi 19, Milan, 20133, Italy
- Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via Giusti 9, Firenze, 50121, Italy
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4
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Li X, Wang S, Guo J, Wu Z, Guo C, Cai S, Deng M. Core-Hole Excitation Spectra of the Oxides and Hydrates of Fullerene C 60 and Azafullerene C 59N. Molecules 2024; 29:609. [PMID: 38338353 PMCID: PMC10856231 DOI: 10.3390/molecules29030609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 01/18/2024] [Accepted: 01/24/2024] [Indexed: 02/12/2024] Open
Abstract
The interaction of fullerenes and their derivatives with environmental molecules such as oxygen or water was crucial for the rational design of low-dimensional materials and devices. In this paper, the near-edge X-ray absorption fine structure (NEXAFS), X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy (XPS) shake-up satellites were employed to distinguish the oxides and hydrates of the fullerene C60 and azafullerene C59N families. The study includes various isomers, such as the open [5,6] and closed [6,6] isomers of C60O, C60H(OH), C60-O-C60, C60H-O-C60H, C59N(OH) and C59N-O-C59N, based on density functional theory. These soft X-ray spectra offered comprehensive insights into the molecular orbitals of these azafullerene molecular groups. The oxygen K-edge NEXAFS, carbon and oxygen K-edge XPS shake-up satellite spectra provided valuable tools for distinguishing oxides or hydrates of fullerene C60 and azafullerene C59N. Our findings could significantly benefit the development of fullerene functional molecular materials and expand the application scope of soft X-ray spectroscopy as a molecular fingerprinting tool for the fullerene family.
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Affiliation(s)
- Xiong Li
- College of Big Data and Information Engineering, Guizhou University, Guiyang 550025, China; (X.L.); (S.W.)
- School of Science, East China University of Technology, Nanchang 330013, China
| | - Shuyi Wang
- College of Big Data and Information Engineering, Guizhou University, Guiyang 550025, China; (X.L.); (S.W.)
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang 550018, China;
| | - Jingdong Guo
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang 550018, China;
| | - Ziye Wu
- School of Information, Guizhou University of Finance and Economics, Guiyang 550025, China; (Z.W.); (C.G.)
| | - Changrui Guo
- School of Information, Guizhou University of Finance and Economics, Guiyang 550025, China; (Z.W.); (C.G.)
| | - Shaohong Cai
- School of Information, Guizhou University of Finance and Economics, Guiyang 550025, China; (Z.W.); (C.G.)
- Department of Resources and Environment, Moutai Institute, Renhuai 564507, China
| | - Mingsen Deng
- School of Information, Guizhou University of Finance and Economics, Guiyang 550025, China; (Z.W.); (C.G.)
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5
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Tofoni A, Tavani F, Vandone M, Braglia L, Borfecchia E, Ghigna P, Stoian DC, Grell T, Stolfi S, Colombo V, D’Angelo P. Full Spectroscopic Characterization of the Molecular Oxygen-Based Methane to Methanol Conversion over Open Fe(II) Sites in a Metal-Organic Framework. J Am Chem Soc 2023; 145:21040-21052. [PMID: 37721732 PMCID: PMC10540213 DOI: 10.1021/jacs.3c07216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Indexed: 09/19/2023]
Abstract
Iron-based enzymes efficiently activate molecular oxygen to perform the oxidation of methane to methanol (MTM), a reaction central to the contemporary chemical industry. Conversely, a very limited number of artificial catalysts have been devised to mimic this process. Herein, we employ the MIL-100(Fe) metal-organic framework (MOF), a material that exhibits isolated Fe sites, to accomplish the MTM conversion using O2 as the oxidant under mild conditions. We apply a diverse set of advanced operando X-ray techniques to unveil how MIL-100(Fe) can act as a catalyst for direct MTM conversion. Single-phase crystallinity and stability of the MOF under reaction conditions (200 or 100 °C, CH4 + O2) are confirmed by X-ray diffraction measurements. X-ray absorption, emission, and resonant inelastic scattering measurements show that thermal treatment above 200 °C generates Fe(II) sites that interact with O2 and CH4 to produce methanol. Experimental evidence-driven density functional theory (DFT) calculations illustrate that the MTM reaction involves the oxidation of the Fe(II) sites to Fe(III) via a high-spin Fe(IV)═O intermediate. Catalyst deactivation is proposed to be caused by the escape of CH3• radicals from the relatively large MOF pore cages, ultimately resulting in the formation of hydroxylated triiron units, as proven by valence-to-core X-ray emission spectroscopy. The O2-based MTM catalytic activity of MIL-100(Fe) in the investigated conditions is demonstrated for two consecutive reaction cycles, proving the MOF potential toward active site regeneration. These findings will desirably lay the groundwork for the design of improved MOF catalysts for the MTM conversion.
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Affiliation(s)
- Alessandro Tofoni
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
| | - Francesco Tavani
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
| | - Marco Vandone
- Dipartimento
di Chimica & UdR INSTM di Milano, Università
degli Studi di Milano, Via Golgi 19, 20133 Milan, Italy
| | - Luca Braglia
- CNR-Istituto
Officina dei Materiali, TASC, 34149 Trieste, Italy
| | - Elisa Borfecchia
- Dipartimento
di Chimica & UdR INSTM di Torino, Università
di Torino, Via P. Giuria
7, 10125 Turin, Italy
| | - Paolo Ghigna
- Dipartimento
di Chimica, Università di Pavia, V.le Taramelli 13, I-27100 Pavia, Italy
| | - Dragos Costantin Stoian
- The Swiss-Norwegian
Beamlines (SNBL), European Synchrotron Radiation Facility, BP 220, 38043 Grenoble, France
| | - Toni Grell
- Dipartimento
di Chimica & UdR INSTM di Milano, Università
degli Studi di Milano, Via Golgi 19, 20133 Milan, Italy
| | - Sara Stolfi
- CNR-Istituto
Officina dei Materiali, TASC, 34149 Trieste, Italy
| | - Valentina Colombo
- Dipartimento
di Chimica & UdR INSTM di Milano, Università
degli Studi di Milano, Via Golgi 19, 20133 Milan, Italy
- CNR
− SCITEC − Istituto di Scienze e Tecnologie Chimiche
“Giulio Natta”, Via Golgi 19, 20133 Milan, Italy
| | - Paola D’Angelo
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
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6
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Tavani F, Busato M, Braglia L, Mauri S, Torelli P, D’Angelo P. Caught while Dissolving: Revealing the Interfacial Solvation of the Mg 2+ Ions on the MgO Surface. ACS APPLIED MATERIALS & INTERFACES 2022; 14:38370-38378. [PMID: 35968677 PMCID: PMC9412945 DOI: 10.1021/acsami.2c10005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Interfaces between water and materials are ubiquitous and are crucial in materials sciences and in biology, where investigating the interaction of water with the surface under ambient conditions is key to shedding light on the main processes occurring at the interface. Magnesium oxide is a popular model system to study the metal oxide-water interface, where, for sufficient water loadings, theoretical models have suggested that reconstructed surfaces involving hydrated Mg2+ metal ions may be energetically favored. In this work, by combining experimental and theoretical surface-selective ambient pressure X-ray absorption spectroscopy with multivariate curve resolution and molecular dynamics, we evidence in real time the occurrence of Mg2+ solvation at the interphase between MgO and solvating media such as water and methanol (MeOH). Further, we show that the Mg2+ surface ions undergo a reversible solvation process, we prove the dissolution/redeposition of the Mg2+ ions belonging to the MgO surface, and we demonstrate the formation of octahedral [Mg(H2O)6]2+ and [Mg(MeOH)6]2+ intermediate solvated species. The unique surface, electronic, and structural sensitivity of the developed technique may be beneficial to access often elusive properties of low-Z metal ion intermediates involved in interfacial processes of chemical and biological interest.
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Affiliation(s)
- Francesco Tavani
- Dipartimento
di Chimica, Università di Roma “La
Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
| | - Matteo Busato
- Dipartimento
di Chimica, Università di Roma “La
Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
| | - Luca Braglia
- CNR
- Istituto Officina dei Materiali, TASC, I-34149 Trieste, Italy
| | - Silvia Mauri
- CNR
- Istituto Officina dei Materiali, TASC, I-34149 Trieste, Italy
- Dipartimento
di Fisica, Università di Trieste, Via A. Valerio 2, 34127 Trieste, Italy
| | - Piero Torelli
- CNR
- Istituto Officina dei Materiali, TASC, I-34149 Trieste, Italy
| | - Paola D’Angelo
- Dipartimento
di Chimica, Università di Roma “La
Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
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7
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Frateloreto F, Tavani F, Di Berto Mancini M, Del Giudice D, Capocasa G, Kieffer I, Lanzalunga O, Di Stefano S, D’Angelo P. Following a Silent Metal Ion: A Combined X-ray Absorption and Nuclear Magnetic Resonance Spectroscopic Study of the Zn 2+ Cation Dissipative Translocation between Two Different Ligands. J Phys Chem Lett 2022; 13:5522-5529. [PMID: 35695810 PMCID: PMC9234980 DOI: 10.1021/acs.jpclett.2c01468] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 06/09/2022] [Indexed: 06/15/2023]
Abstract
The dissipative translocation of the Zn2+ ion between two prototypical coordination complexes has been investigated by combining X-ray absorption and 1H NMR spectroscopy. An integrated experimental and theoretical approach, based on state-of-the-art Multivariate Curve Resolution and DFT based theoretical analyses, is presented as a means to understand the concentration time evolution of all relevant Zn and organic species in the investigated processes, and accurately characterize the solution structures of the key metal coordination complexes. Specifically, we investigate the dissipative translocation of the Zn2+ cation from hexaaza-18-crown-6 to two terpyridine moieties and back again to hexaaza-18-crown-6 using 2-cyano-2-phenylpropanoic acid and its para-chloro derivative as fuels. Our interdisciplinary approach has been proven to be a valuable tool to shed light on reactive systems containing metal ions that are silent to other spectroscopic methods. These combined experimental approaches will enable future applications to chemical and biological systems in a predictive manner.
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Affiliation(s)
- Federico Frateloreto
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
| | - Francesco Tavani
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
| | - Marika Di Berto Mancini
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
| | - Daniele Del Giudice
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
| | - Giorgio Capocasa
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
| | - Isabelle Kieffer
- Observatoire
des Sciences de l’Univers de Grenoble (OSUG), Université Grenoble-Alpes, UMR
832 CNRS, Grenoble, Cedex 9 F-38041, France
- BM30/CRG-FAME, ESRF, Polygone scientifique, Grenoble, 38000, France
| | - Osvaldo Lanzalunga
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
| | - Stefano Di Stefano
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
| | - Paola D’Angelo
- Dipartimento
di Chimica, Università degli Studi
di Roma “La Sapienza”, P.le A. Moro 5, I-00185 Rome, Italy
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8
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Politano A. On the fate of high-resolution electron energy loss spectroscopy (HREELS), a versatile probe to detect surface excitations: will the Phoenix rise again? Phys Chem Chem Phys 2021; 23:26061-26069. [PMID: 34812442 DOI: 10.1039/d1cp03804d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
From its advent, high-resolution electron energy loss spectroscopy (HREELS) has emerged as one of the most versatile tools in surface science. In the last few decades, HREELS was widely used for the fundamental study of (i) chemical reactions at the surfaces of model catalysts (mostly single crystals), (ii) lattice dynamics (phonons), (iii) surface plasmons and (iv) magnons. However, HREELS has experienced a continuous decay of the number of daily users worldwide so far, due to several factors. However, the rise of Dirac materials (graphene, topological insulators, Dirac semimetals) offers new perspectives for HREELS, due to its unique features enabling ultrasensitive detection of (i) chemical modifications at their surfaces, (ii) Kohn anomalies arising from electron-phonon coupling and (iii) novel plasmonic excitations associated to Dirac-cone fermions, as well as their eventual mutual interplay with other plasmon resonances related to topologically trivial electronic states. By selected case-study examples, here we show that HREELS can uniquely probe these phenomena in Dirac materials, thus validating its outstanding relevance and its irreplaceability in contemporary solid-state physics, thus paving the way for a renewed interest. In addition, recent technological upgrades enable the combination of HREELS as an add-on to photoemission apparatuses for parallel readout of energy and momentum of surface excitations. Open issues for theoretical modelling of HREELS related to the dependence on primary electron beam energy and scattering geometry are also critically presented.
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Affiliation(s)
- Antonio Politano
- Department of Physical and Chemical Sciences, University of L'Aquila, via Vetoio, 67100 L'Aquila, Abruzzo, Italy. .,CNR-IMM Istituto per la Microelettronica e Microsistemi, VIII strada 5, I-95121 Catania, Italy
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9
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Tavani F, Fracchia M, Tofoni A, Braglia L, Jouve A, Morandi S, Manzoli M, Torelli P, Ghigna P, D'Angelo P. Structural and mechanistic insights into low-temperature CO oxidation over a prototypical high entropy oxide by Cu L-edge operando soft X-ray absorption spectroscopy. Phys Chem Chem Phys 2021; 23:26575-26584. [PMID: 34812450 DOI: 10.1039/d1cp03946f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High entropy oxides (HEOs) are an emerging class of materials constituted by multicomponent systems that are receiving special interest as candidates for obtaining novel and desirable properties. In this study we present a detailed investigation of the relevant intermediates arising at the surface of the prototypical HEO Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O during low-temperature CO oxidation. By combining Cu L2,3-edge operando soft X-ray absorption spectroscopy (soft-XAS) with density functional theory simulations and in situ FT-IR spectroscopy, we propose that upon HEO exposure to CO at 235 °C reduced Cu(I) sites arise mostly coordinated to activated CO molecules and partly to bidentate carbonate species. When the HEO surface is then exposed to a stoichiometric mixture of CO + 1/2O2 at 250 °C, CO2 is produced while bidentate carbonate moieties remain interacting with the Cu(I) sites. We structurally characterize the carbonate and CO preferential adsorption geometries on the Cu(I) surface metal centers, and find that CO adopts a bent conformation that may energetically favor its subsequent oxidation. The unique surface, structural and electronic sensitivity of soft-XAS coupled with the developed data analysis work-flow and supported by FT-IR spectroscopy may be beneficial to characterize often elusive surface properties of systems of catalytic interest.
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Affiliation(s)
- Francesco Tavani
- Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro 5, 00185 Roma, Italy.
| | - Martina Fracchia
- Dipartimento di Chimica, Università di Pavia, Via Taramelli 16, 27100 Pavia, Italy
| | - Alessandro Tofoni
- Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro 5, 00185 Roma, Italy.
| | - Luca Braglia
- CNR - Istituto Officina dei Materiali, TASC, I-34149 Trieste, Italy
| | - Andrea Jouve
- Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Via P. Giuria 9, 10125, Torino, Italy
| | - Sara Morandi
- Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino, Italy
| | - Maela Manzoli
- Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, Via P. Giuria 9, 10125, Torino, Italy
| | - Piero Torelli
- CNR - Istituto Officina dei Materiali, TASC, I-34149 Trieste, Italy
| | - Paolo Ghigna
- Dipartimento di Chimica, Università di Pavia, Via Taramelli 16, 27100 Pavia, Italy
| | - Paola D'Angelo
- Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro 5, 00185 Roma, Italy.
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Del Giudice D, Tavani F, Di Berto Mancini M, Frateloreto F, Busato M, Oliveira De Souza D, Cenesi F, Lanzalunga O, Di Stefano S, D'Angelo P. Two Faces of the Same Coin: Coupling X-Ray Absorption and NMR Spectroscopies to Investigate the Exchange Reaction Between Prototypical Cu Coordination Complexes. Chemistry 2021; 28:e202103825. [PMID: 34850474 DOI: 10.1002/chem.202103825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Indexed: 12/21/2022]
Abstract
The satisfactory rationalization of complex reactive pathways in solution chemistry may greatly benefit from the combined use of advanced experimental and theoretical complementary methods of analysis. In this work, we combine X-Ray Absorption and 1 H NMR spectroscopies with state-of-the-art Multivariate Curve Resolution and theoretical analyses to gain a comprehensive view on a prototypical reaction involving the variation of the oxidation state and local structure environment of a selected metal ion coordinated by organic ligands. Specifically, we investigate the 2-cyano-2-phenylpropanoic acid reduction of the octahedral complex established by the Cu2+ ion with terpyridine to the tetrahedral complex formed by Cu+ and neocuproine. Through our interdisciplinary approach we gain insights into the nature, concentration time evolution and structures of the key metal (XAS measurements) and organic (1 H NMR measurements) species under reaction. We believe our method may prove to be useful in the toolbox necessary to understand the mechanisms of reactive processes of interest in solution.
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Affiliation(s)
- Daniele Del Giudice
- Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185, Rome, Italy
| | - Francesco Tavani
- Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185, Rome, Italy
| | - Marika Di Berto Mancini
- Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185, Rome, Italy
| | - Federico Frateloreto
- Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185, Rome, Italy
| | - Matteo Busato
- Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185, Rome, Italy
| | - Danilo Oliveira De Souza
- Elettra-Sincrotrone Trieste, Strada Statale 14, km 163.5 in AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - Flavia Cenesi
- Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185, Rome, Italy
| | - Osvaldo Lanzalunga
- Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185, Rome, Italy
| | - Stefano Di Stefano
- Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185, Rome, Italy
| | - Paola D'Angelo
- Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185, Rome, Italy
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