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BETA
Brena, Barbara
Alternative names
Publications (10 of 65) Show all publications
Brumboiu, I. E., Haldar, S., Lüder, J., Eriksson, O., Herper, H. C., Brena, B. & Sanyal, B. (2019). Ligand effects on the linear response Hubbard U: The case of transition metal phthalocyanines. Journal of Physical Chemistry A, 123(14), 3214-3222
Open this publication in new window or tab >>Ligand effects on the linear response Hubbard U: The case of transition metal phthalocyanines
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2019 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 123, no 14, p. 3214-3222Article in journal (Refereed) Published
Abstract [en]

It is established that density functional theory (DFT) + U is a better choice compared to DFT for describing the correlated electron metal center in organometallics. The value of the Hubbard U parameter may be determined from linear response, either by considering the response of the metal site alone or by additionally considering the response of other sites in the compound. We analyze here in detail the influence of ligand shells of increasing size on the U parameter calculated from the linear response for five transition metal phthalocyanines. We show that the calculated multiple-site U is larger than the single-site U by as much as 1 eV and the ligand atoms that are mainly responsible for this difference are the isoindole nitrogen atoms directly bonded to the central metal atom. This suggests that a different U value may be required for computations of chemisorbed molecules compared to physisorbed and gas-phase cases.

National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-300117 (URN)10.1021/acs.jpca.8b11940 (DOI)000464768100011 ()30892039 (PubMedID)
Funder
Swedish Research Council, 2014-3776Swedish Research Council, 2016-05366Swedish Research Council, 2017-05447Knut and Alice Wallenberg Foundation, KAW-2013.0020Swedish National Infrastructure for Computing (SNIC)
Available from: 2016-08-02 Created: 2016-08-02 Last updated: 2019-05-15Bibliographically approved
Saak, C.-M., Unger, I., Brena, B., Caleman, C. & Björneholm, O. (2019). Site-specific X-ray induced dynamics in liquid methanol. Physical Chemistry, Chemical Physics - PCCP (28), 15478-15486
Open this publication in new window or tab >>Site-specific X-ray induced dynamics in liquid methanol
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2019 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, no 28, p. 15478-15486Article in journal (Refereed) Published
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-391082 (URN)10.1039/C9CP02063B (DOI)
Available from: 2019-08-18 Created: 2019-08-18 Last updated: 2019-08-18
Zhou, Y., Pondick, J. V., Silva, J. L., Woods, J. M., Hynek, D. J., Matthews, G., . . . Cha, J. J. (2019). Unveiling the Interfacial Effects for Enhanced Hydrogen Evolution Reaction on MoS2/WTe2 Hybrid Structures. Small, 15(19), Article ID 1900078.
Open this publication in new window or tab >>Unveiling the Interfacial Effects for Enhanced Hydrogen Evolution Reaction on MoS2/WTe2 Hybrid Structures
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2019 (English)In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 15, no 19, article id 1900078Article in journal (Refereed) Published
Abstract [en]

Using the MoS2-WTe2 heterostructure as a model system combined with electrochemical microreactors and density function theory calculations, it is shown that heterostructured contacts enhance the hydrogen evolution reaction (HER) activity of monolayer MoS2. Two possible mechanisms are suggested to explain this enhancement: efficient charge injection through large-area heterojunctions between MoS2 and WTe2 and effective screening of mirror charges due to the semimetallic nature of WTe2. The dielectric screening effect is proven minor, probed by measuring the HER activity of monolayer MoS2 on various support substrates with dielectric constants ranging from 4 to 300. Thus, the enhanced HER is attributed to the increased charge injection into MoS2 through large-area heterojunctions. Based on this understanding, a MoS2/WTe2 hybrid catalyst is fabricated with an HER overpotential of -140 mV at 10 mA cm(-2), a Tafel slope of 40 mV dec(-1), and long stability. These results demonstrate the importance of interfacial design in transition metal dichalcogenide HER catalysts. The microreactor platform presents an unambiguous approach to probe interfacial effects in various electrocatalytic reactions.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
electrochemical microreactors, heterostructures, hydrogen evolution reaction, interfacial effects, MoS2, WTe2 hybrid
National Category
Physical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-390541 (URN)10.1002/smll.201900078 (DOI)000472198100006 ()30957970 (PubMedID)
Funder
Swedish Research CouncilStandUp
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-08-12Bibliographically approved
Balatsky, A. V., Brena, B., Herper, H. C. & Sanyal, B. (2018). Functional Dirac Materials: Status and Perspectives. Physica Status Solidi. Rapid Research Letters, 12(11), Article ID 1870334.
Open this publication in new window or tab >>Functional Dirac Materials: Status and Perspectives
2018 (English)In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 12, no 11, article id 1870334Article in journal, Editorial material (Other academic) Published
Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-372954 (URN)10.1002/pssr.201870334 (DOI)000450130300001 ()
Available from: 2019-01-15 Created: 2019-01-15 Last updated: 2019-01-15Bibliographically approved
Farronato, M., Lüder, J., Longo, D., Cruguel, H., Bouvet, M., Brena, B. & Witkowski, N. (2018). High Tolerance of Double-Decker Phthalocyanine toward Molecular Oxygen. The Journal of Physical Chemistry C, 122(35), 20244-20251
Open this publication in new window or tab >>High Tolerance of Double-Decker Phthalocyanine toward Molecular Oxygen
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2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 35, p. 20244-20251Article in journal (Refereed) Published
Abstract [en]

Because organic electronics suffer from degradation-inducing oxidation processes, oxygen-tolerant organic molecules could solve this issue and be integrated to improve the stability of devices during operation. In this work, we investigate how lutetium double-decker phthalocyanine (LuPc2) reacts toward molecular oxygen and we report microscopic details of its interaction with LuPc2 film by combining X-ray photoemission spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and density functional theory. Surprisingly, LuPc2 molecules are found to weakly physisorb below 120 K and appear rather inert to molecular oxygen at more elevated temperatures. We are able to draw a microscopic picture at low temperature, in which oxygen molecules stick on top of the pyrrolic carbon of LuPc2. Our work sheds light on a class of semiconducting molecules, namely, double-decker phthalocyanines, which present a high tolerance toward molecular oxygen, opening promising perspectives for the design of stable materials to be applied in the next generation of organic-based electronic devices operating under ambient conditions.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-365654 (URN)10.1021/acs.jpcc.8b04084 (DOI)000444355400020 ()
Funder
Knut and Alice Wallenberg FoundationEU, FP7, Seventh Framework Programme, 607232 THINFACESwedish Research Council, 2014-3776Swedish National Infrastructure for Computing (SNIC)
Available from: 2018-11-16 Created: 2018-11-16 Last updated: 2018-11-16Bibliographically approved
Zhang, T., Brumboiu, I. E., Grazioli, C., Guarnaccio, A., Coreno, M., de Simone, M., . . . Puglia, C. (2018). Lone-Pair Delocalization Effects within Electron Donor Molecules: The Case of Triphenylamine and Its Thiophene-Analog. The Journal of Physical Chemistry C, 122(31), 17706-17717
Open this publication in new window or tab >>Lone-Pair Delocalization Effects within Electron Donor Molecules: The Case of Triphenylamine and Its Thiophene-Analog
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2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 31, p. 17706-17717Article in journal (Refereed) Published
Abstract [en]

Triphenylamine (TPA) and its thiophene-analog, N,N-diphenyl-2-thiophenamine (DPTA), are both well-known as electron-donating molecules implemented in optoelectronic devices such as organic solar cells and LEDs. Comprehensive valence and core level photoelectron spectroscopy, as well as near edge X-ray absorption spectroscopy (NEXAFS), measurements have been performed on gas phase TPA and DPTA. The experimental results have been compared to density functional theory calculations, providing a detailed description of the molecular electronic structure. Specifically, the C 1s photoelectron lines of both TPA and DPTA were resolved in the different C atom contributions and their binding energies explained as the result of two counter-acting effects: (1) the electronegativity of the nitrogen atom (and sulfur atom in DPTA) and (2) the the N (and S in DPTA) lone-pair electrons. In addition, the C K-edge NEXAFS spectrum of DPTA reveals that the lowest unoccupied molecular orbital (LUMO) energy position is affected differently if the core hole site is on the phenyl compared to the thiophene ring. The electron-donating properties of these two molecules are largely explained by the significant contribution of the N lone-pair electrons (p(z)) to the highest occupied molecular orbital. The contribution to the LUMO and to the empty density of states of the sulfur of the thiophene ring in DPTA explains the better performance of donor-pi-acceptor molecules containing this moiety and implemented in photoenergy conversion devices.

National Category
Physical Sciences Theoretical Chemistry Condensed Matter Physics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-355118 (URN)10.1021/acs.jpcc.8b06475 (DOI)000441484600014 ()
Funder
Swedish Research Council, VR 2014-3776Carl Tryggers foundation
Note

Title in thesis list of papers: Lone Pair Delocalization Effect within Electron Donor Molecules:The Case of Triphenylamine (TPA) and Its Thiophene-Analog(DPTA)

Available from: 2018-06-29 Created: 2018-06-29 Last updated: 2018-10-15Bibliographically approved
Farronato, M., Bidermane, I., Lüder, J., Bouvet, M., Vlad, A., Jones, A., . . . Witkowski, N. (2018). New Quadratic Self-Assembly of Double-Decker Phthalocyanine on Gold(111) Surface: From Macroscopic to Microscopic Scale. The Journal of Physical Chemistry C, 122(46), 26480-26488
Open this publication in new window or tab >>New Quadratic Self-Assembly of Double-Decker Phthalocyanine on Gold(111) Surface: From Macroscopic to Microscopic Scale
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2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 46, p. 26480-26488Article in journal (Refereed) Published
Abstract [en]

Unveiling the self-organization mechanism of semiconducting organic molecules onto metallic surfaces is the first step to design hybrid devices in which the self-assembling is exploited to tailor magnetic properties. In this study, double-decker rare-earth phthalocyanines, namely, lutetium phthalocyanine (LuPc2), are deposited on Au(111) gold surface forming large-scale self-assemblies. Global and local experimental techniques, namely, grazing incidence X-ray diffraction and scanning tunneling microscopy, supplemented by density functional theory calculations with van der Waals corrections, give insight into the molecular structural arrangement of the thin film and the self organization at the surface. Our results show unambiguously that the two plateaus of the double-decker phthalocyanine present a different rotation than the isolated molecule. This is evidenced by density functional theory simulations of optimized LuPc2 monolayer showing a perfect agreement with experimental findings. Moreover, the stabilized structure of double layers reveals an eclipsed configuration of the molecules in the stacking, having the ligand plateaus parallel to the gold surface. The high crystallinity of the molecular assembly and its weak electronic coupling with the metallic substrate is expected to open new perspective in magnetic devices.

National Category
Condensed Matter Physics Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-372453 (URN)10.1021/acs.jpcc.8b08462 (DOI)000451495600021 ()
Funder
Swedish Research Council, 2014-3776EU, FP7, Seventh Framework Programme, 607232 THINFACE
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-01-07Bibliographically approved
Zhou, Y., Silva, J. L., Woods, J. M., Pondick, J. V., Feng, Q., Liang, Z., . . . Cha, J. J. (2018). Revealing the Contribution of Individual Factors to Hydrogen Evolution Reaction Catalytic Activity. Advanced Materials, 30(18), Article ID 1706076.
Open this publication in new window or tab >>Revealing the Contribution of Individual Factors to Hydrogen Evolution Reaction Catalytic Activity
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2018 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 30, no 18, article id 1706076Article in journal (Refereed) Published
Abstract [en]

For the electrochemical hydrogen evolution reaction (HER), the electrical properties of catalysts can play an important role in influencing the overall catalytic activity. This is particularly important for semiconducting HER catalysts such as MoS2, which has been extensively studied over the last decade. Herein, on-chip microreactors on two model catalysts, semiconducting MoS2 and semimetallic WTe2, are employed to extract the effects of individual factors and study their relations with the HER catalytic activity. It is shown that electron injection at the catalyst/current collector interface and intralayer and interlayer charge transport within the catalyst can be more important than thermodynamic energy considerations. For WTe2, the site-dependent activities and the relations of the pure thermodynamics to the overall activity are measured and established, as the microreactors allow precise measurements of the type and area of the catalytic sites. The approach presents opportunities to study electrochemical reactions systematically to help establish rational design principles for future electrocatalysts.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
2D TMD materials, electrochemical microreactors, hydrogen evolution reaction, individual factors, overall performance
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-356393 (URN)10.1002/adma.201706076 (DOI)000431615100009 ()29573299 (PubMedID)
Funder
Swedish Research CouncilStandUp
Available from: 2018-07-25 Created: 2018-07-25 Last updated: 2018-07-25Bibliographically approved
Lanzilotto, V., Silva, J. L., Zhang, T., Stredansky, M., Grazioli, C., Simonov, K., . . . Puglia, C. (2018). Spectroscopic Fingerprints of Intermolecular H-Bonding Interactions in Carbon Nitride Model Compounds. Chemistry - A European Journal, 24(53), 14198-14206
Open this publication in new window or tab >>Spectroscopic Fingerprints of Intermolecular H-Bonding Interactions in Carbon Nitride Model Compounds
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2018 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 53, p. 14198-14206Article in journal (Refereed) Published
Abstract [en]

The effect of intermolecular H-bonding interactions on the local electronic structure of N-containing functional groups (amino group and pyridine-like N) that are characteristic of polymeric carbon nitride materials p-CN(H), a new class of metal-free organophotocatalysts, was investigated. Specifically, the melamine molecule, a building block of p-CN(H), was characterized by X-ray photoelectron (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The molecule was studied as a noninteracting system in the gas phase and in the solid state within a H-bonded network. With the support of DFT simulations of the spectra, it was found that the H-bonds mainly affect the N1s level of the amino group, leaving the N1s level of the pyridine-like N mostly unperturbed. This is responsible for a reduction of the chemical shift between the two XPS N1s levels relative to free melamine. Consequently, N K-edge NEXAFS resonances involving the amino N1s level also shift to lower photon energies. Moreover, the solid-state absorption spectra showed significant modification/quenching of resonances related to transitions from the amino N1s level to sigma* orbitals involving the NH2 termini.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
density functional calculations, hydrogen bonds, carbon nitrides, photoelectron spectroscopy, X-ray absorption spectroscopy
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-366732 (URN)10.1002/chem.201802435 (DOI)000445177600028 ()30009392 (PubMedID)
Funder
Carl Tryggers foundation
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-11Bibliographically approved
Zhang, T., Brumboiu, I. E., Lanzilotto, V., Luder, J., Grazioli, C., Giangrisostomi, E., . . . Puglia, C. (2017). Conclusively Addressing the CoPc Electronic Structure: A Joint Gas-Phase and Solid-State Photoemission and Absorption Spectroscopy Study. The Journal of Physical Chemistry C, 121(47), 26372-26378
Open this publication in new window or tab >>Conclusively Addressing the CoPc Electronic Structure: A Joint Gas-Phase and Solid-State Photoemission and Absorption Spectroscopy Study
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2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 47, p. 26372-26378Article in journal (Refereed) Published
Abstract [en]

The occupied and empty densities of states of cobalt phthalocyanine (CoPc) were investigated by photoelectron and X-ray absorption spectroscopies in the gas phase and in thin films deposited on a Au(111) surface. The comparison between the gas-phase results and density functional theory single-molecule simulations confirmed that the CoPc ground state is correctly described by the (2)A(1g) electronic configuration. Moreover, photon-energy-dependent valence photoemission spectra of both the gas phase and thin film confirmed the atomic character of the highest occupied molecular orbital as being derived from the organic ligand, with dominant contributions from the carbon atoms. Multiplet ligand-field theory was employed to simulate the Co L-edge X-ray absorption spectroscopy results.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-345249 (URN)10.1021/acs.jpcc.7b08524 (DOI)000417228500026 ()
Funder
Swedish Research CouncilCarl Tryggers foundation
Available from: 2018-03-09 Created: 2018-03-09 Last updated: 2018-03-09Bibliographically approved
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