Luca Braglia

Luca Braglia
IOM-CNR, Sincrotrone Trieste · APE-HE Beamline

PhD Chemistry and Material Science

About

35
Publications
4,729
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524
Citations
Additional affiliations
March 2014 - present
Southern Federal University
Position
  • PhD Student

Publications

Publications (35)
Article
This work presents an original approach to preparing pure and Ni-doped CeO2 nanoparticles (NPs) that can be directly drop-casted on a substrate or calcined to form powders. The reduction of the NPs in H2 is very different than the one usually anticipated for supported Ni–CeO2 catalysts. In situ soft X-ray absorption and infrared spectroscopies reve...
Article
Full-text available
The structural, electronic, and magnetic properties of Sr-hole-doped epitaxial La1-x Sr x MnO3 (0.15 ≤ x ≤ 0.45) thin films deposited using the molecular beam epitaxy technique on 4° vicinal STO (001) substrates are probed by the combination of X-ray diffraction and various synchrotron-based spectroscopy techniques. The structural characterizations...
Article
The ever-growing demand for Li-ion batteries requires high-capacity electrode materials that should also be environmentally benign, Co-free, secure and durable, to achieve an optimal compromise between sustainability and functional performances....
Article
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...
Article
Full-text available
Although Ziegler–Natta (ZN) catalysts play a major role in the polyolefin market, a true understanding of their properties at the molecular level is still missing. In particular, there is a lack of knowledge on the electronic properties of Ti sites. Theoretical calculations predict that the electron density of the Ti sites in the precatalysts corre...
Article
Preferential oxidation of CO (COPrOx) is a catalytic reaction targeting the removal of trace amounts of CO from hydrogen-rich gas mixtures. Non-noble metal catalysts, such as Cu and Co, can be equally active to Pt for the reaction; however, their commercialization is limited by their poor stability. We have recently shown that CoO is the most activ...
Article
Solid oxide photoelectrochemical cells (SOPECs) with inorganic ion-conducting electrolytes provide an alternative solution for light harvesting and conversion. Exploring potential photoelectrodes for SOPECs and understanding their operation mechanisms are crucial for continuously developing this technology. Here, ceria-based thin films were newly e...
Article
Full-text available
THORONDOR is a data treatment software with a graphical user interface (GUI) accessible via the browser-based Jupyter notebook framework. It aims to provide an interactive and user-friendly tool for the analysis of NEXAFS spectra collected during in situ experiments. The program allows on-the-fly representation and quick correction of large dataset...
Article
Ti silicates, and in particular Titanium Silicalite‐1 (TS‐1), are nowadays important catalysts for several partial oxidation reactions in the presence of aqueous H 2 O 2 as oxidant. Despite the numerous studies dealing with this material, some fundamental aspects are still unfathomed. In particular, the structure and the catalytic role of defective...
Article
The structure of titanium defective sites in TS‐1 is disclosed by deciphering the experimental results from electronic spectroscopies (UV/Vis, K‐edge XAS and L2,3‐edge NEXAFS) on the basis of quantum mechanical simulation of the spectroscopic observables. Within six considered models, isolated Ti sites with hexacoordinated geometry are revealed as...
Article
Full-text available
Ambient pressure operando soft X-ray absorption spectroscopy (soft-XAS) was applied to study the reactivity of hydroxylated SnO2 nanoparticles towards reducing gases. H2 was first used as a test case, showing that gas phase and surface states can be simultaneously probed: soft-XAS at the O K-edge gains sensitivity towards the gas phase, while at th...
Article
Full-text available
The mechanisms of CO oxidation on the Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O high entropy oxide were studied by means of operando soft X-ray absorption spectroscopy. We found that Cu is the active metal, and that Cu(II) can be rapidly reduced to Cu(I) by CO when the temperature is larger than 130 °C. Co and Ni do not have any role in this respect. The Cu(II) o...
Article
Implementation of in-situ and operando experimental set-ups for bridging the pressure gap in characterization techniques based on monitoring of photoelectron emission has made significant achievements at several beamlines at Elettra synchrotron facility. These set-ups are now operational and have been successfully used to address unsolved issues ex...
Article
The redox process of pretreated Co3O4 thin film coatings have been studied by ambient pressure soft X-ray absorption spectroscopy. The Co3O4 coatings were composed of nanoparticles of about 10 nm of size as prepared by pulsed laser deposition. The thin film coatings were pretreated in He or in H2 up to 150° Celsius prior to exposure to the reactive...
Article
Functionalization of metal-organic frameworks (MOFs) with noble metals is a promising way for producing new versatile catalysts that will combine the outstanding porosity and specific surface area of MOFs with high catalytic activity of metals. Here, we present a comparative study of two metal-organic frameworks with UiO-67 topology, functionalized...
Article
Full-text available
Treatment of MOF-5 with NbCl4(THF)2 in acetonitrile leads to incorporation of Nb(IV) centers in a fashion that diverges from the established cation metathesis reactivity of this iconic material. A combination of X-ray absorption spectroscopy analysis and reactivity studies altogether supported by density functional theory computational studies docu...
Article
In the last decade the appearance of progressively more sophisticated codes, together with the increased computational capabilities, has made XANES a spectroscopic technique able to quantitatively confirm (or discard) a structural model, thus becoming a new fundamental diagnostic tool in catalysis, where the active species are often diluted metal c...
Article
Although X-ray absorption spectroscopy (XAS) has become an indispensable tool in characterization of solid-state materials, it is less of a staple in molecular chemistry of niobium. Scattering X-ray techniques remain relatively unexplored for the systematic study of molecular niobium compounds. Here, we use XAS to probe the niobium environment in c...
Article
Full-text available
A setup for fluorescence-detected X-ray absorption spectroscopy (XAS) with sub-second time resolution has been developed. This technique allows chemical speciation of low-concentrated materials embedded in highly absorbing matrices, which cannot be studied using transmission XAS. Using this setup, the reactivity of 1.5 wt% Pt/CeO 2 catalyst was stu...
Article
Functionalization of metal-organic frameworks with metal nanoparticles (NPs) is a promising way for producing advanced materials for catalytic applications. We present synthesis and in situ characterization of palladium NPs encapsulated inside functionalized UiO-67 metal-organic framework. The initial structure was synthesized with 10% of PdCl2bpyd...
Article
Partial substitution of ZnII by MnII in Zn4O(terephthalate)3 (MOF-5) leads to a distorted all-oxygen ligand field supporting a single MnII site, whose structure was confirmed by Mn K-edge X-ray absorption spectroscopy. The MnII ion at the MOF-5 node engages in redox chemistry with a variety of oxidants. With tBuSO2PhIO, it produces a putative MnIV-...
Chapter
In this chapter, we introduce MOFs as the new class of crystalline porous materials of remarkable potentialities. We underline the flexibility in the realization of different MOFs and the fact that they are ideal materials for performing X-ray absorption experiments at the metal K or L3 edges in transmission mode. A selection of relevant results ap...
Article
Full-text available
An X-ray absorption spectroscopy study of the UiO-67 Pt functionalized metal organic frameworks (MOFs) demonstrates that in proper conditions, at least two types of catalytically active sites can be formed in the cavities of the MOF: isolated Pt-complexes and Pt nanoparticles (Pt-NPs). Both pre-made linker synthesis (PMLS) and post-synthesis functi...
Article
Operando sensitive spectroscopic techniques were employed for investigating the changes in the molecular structure of the Cr sites in the CrVI/SiO2 Phillips catalyst during ethylene polymerization. Practically, the most arduous barrier to be overcome was the separation of the chromates reduction carried by ethylene from the subsequent polymerizatio...
Article
Full-text available
CO2 hydrogenation was carried out over Pt-containing UiO-67 Zr-MOFs at T = 220–280 °C and ambient pressure, with H2/CO2 = 0.2–9 and contact times, τ = 0.004–0.01 gcat×min×ml−1. The catalysts were characterized by XRD, N2 adsorption, FESEM, TEM and HRTEM, dissolution-NMR, CO chemisorption, IR spectroscopy and TGA. A positive correlation was observed...
Article
The exceptional thermal and chemical stability of the UiO-66, -67 and -68 classes of isostructural MOFs [J. Am. Chem. Soc., 2008, 130, 13850] makes them ideal materials for functionalization purposes aimed at introducing active centres for potential application in heterogeneous catalysis. We previously demonstrated that a small fraction (up to 10%)...
Article
In situ and operando XAS spectroscopic methods were applied to monitor the variations in the oxidation state and in the local structure of the chromium sites in a 2.0Cr/SiO2-DHS catalyst during propane dehydrogenation under non-oxidative and different oxidative conditions. The spectroscopic data have been compared to the catalytic performances. Alt...
Article
The exceptional thermal stability of the UiO-67/68-family MOFs makes them ideal candidates to explore post-synthetic functionalization routes aiming to the heterogenization of homogeneous catalysts. We previously demonstrated that a small fraction of the linkers in the UiO-67 MOF can be replaced by bipyridine-dicarboxylate (bpydc) moieties exhibiti...
Article
The exceptional thermal and chemical stability of UiO-66, -67 and -68 class of isostructural MOFs [J. Am. Chem. Soc., 2008, 130, 13850] makes them ideal materials for functionalization purposes aimed in introducing active centres for potential application in heterogeneous catalysis. We previously demonstrated that a small fraction (up to 10%) of th...
Article
A peculiar property of ceria is the ease to form oxygen vacancies, producing reactive sites or facilitating ionic diffusion. For these reasons ceria promotes catalytic activities for a number of important reactions when it is used as a support for transition metals. In our work we study the temporal evolution of oxygen vacancies formation by time-r...
Article
We synthesized UiO-67 metal-organic-frameworks (MOFs) functionalized with different transition metals (Rh, Ir). Using EXAFS we verified that the synthesis has been successful. Furthermore, we observed the change of local environment while varying of metal site. XAS spectroscopy is the most informative technique to characterize these kind of materia...
Article
We synthesized UiO-67 Metal Organic Frameworks (MOFs) functionalized with bpydcPt(II)Cl2 and bpydcPt(IV)Cl4 complexes (bpydc = bipyridine-dicarboxylate), as attractive candidates for the heterogenization of homogeneous catalytic reactions. Pt L3-edge XAFS experiments allowed us to thoroughly characterize these materials, in the local environment of...

Projects

Projects (2)
Project
NFFA-Trieste (www.trieste.nffa.eu) is an open access infrastructure to perform experiments in nanoscience involving growth, characterization and advanced spectroscopies at synchrotron radiation and pulsed laser sources. NFFA-Trieste is the first research facility offering direct integration between nanofoundries and analytical large scale facilities. The project, therefore, offers advanced off-line tools for sample growth (PLD, MBE, PVD) and for characterization (STM, XPS, MOKE, SEM, XRD) of nanosystems, in combination with spectroscopic techniques (ARPES, Spin-ARPES, XPS, XMCD, XAS, Ambient-pressure XAS, FTIR analysis) at Elettra-Sincrotrone Trieste storage ring. From 2018 users may apply for the use of SPRINT laboratory, where pulsed laser sources are used to perform time-resolved valence band photoemission spectroscopy and spin polarization polarimetry. Moreover, from December 2020 SISSI-Bio, the Chemical and Life Sciences branch of the SISSI infrared beamline, is accessible through the NFFA-Trieste project.
Project
This project is being worked intensively in collaboration between several research groups from the Southern Federal University (Russia), University of Turin and Chimet company (Italy), ETH Zurich and Swiss Light Source (Switzerland), ESRF (France), and some others. We study different palladium-based catalysts (mostly supported nanoparticles) by synchrotron-based techniques, X-ray absorption spectroscopy being most actively applied. These studies include both fundamental investigation of phase transitions and kinetics of formation of palladium hydrides, carbides and oxides, and more applied operando studies of real industrial catalysts under relevant working conditions. For those who don't like reading papers - watch this funny video that was submitted for Dance Your PhD contest of the Science Magazines: https://www.youtube.com/watch?v=eQwk9fkJXDU