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Blachucki, W., Czapla-Masztafiak, J., Sá, J. & Szlachetko, J. (2019). A laboratory-based double X-ray spectrometer for simultaneous X-ray emission and X-ray absorption studies. Journal of Analytical Atomic Spectrometry, 34(7), 1409-1415
Öppna denna publikation i ny flik eller fönster >>A laboratory-based double X-ray spectrometer for simultaneous X-ray emission and X-ray absorption studies
2019 (Engelska)Ingår i: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 34, nr 7, s. 1409-1415Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

X-ray spectroscopy studies are usually performed using synchrotron radiation sources, which offer bright, coherent, energy-tuneable and monochromatic light. However, the application of synchrotron-based Xray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) is directly constrained by the limited, infrequent access to central facilities. With the advent of new technological solutions in the field of X-ray sources, optics and detectors, the development of efficient and compact laboratory X-ray spectroscopy systems is possible. A permanent laboratory-based setup offers the advantages of low cost and easy accessibility and, therefore, more flexibility in the preparation and scheduling of measurements. Herein, we report a laboratory X-ray setup allowing simultaneous XES and XAS measurements. The double von Hamos spectrometer performances are demonstrated by concurrent K beta XES and K-edge XAS measurements done for 3d elements.

Ort, förlag, år, upplaga, sidor
Royal Society of Chemistry, 2019
Nationell ämneskategori
Atom- och molekylfysik och optik
Identifikatorer
urn:nbn:se:uu:diva-390902 (URN)10.1039/c9ja00159j (DOI)000474289100021 ()
Tillgänglig från: 2019-08-19 Skapad: 2019-08-19 Senast uppdaterad: 2019-08-19Bibliografiskt granskad
Goncalves, L. C. P., Mansouri, H. R., PourMehdi, S., Abdellah, M., Fadiga, B. S., Bastos, E. L., . . . Rudroffe, F. (2019). Boosting photobioredox catalysis by morpholine electron donors under aerobic conditions. Catalysis Science & Technology, 9(10), 2682-2688
Öppna denna publikation i ny flik eller fönster >>Boosting photobioredox catalysis by morpholine electron donors under aerobic conditions
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2019 (Engelska)Ingår i: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, nr 10, s. 2682-2688Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Light-driven reduction of flavins, e.g. FAD or FMN, by sacrificial electron donors emerged as a convenient method to promote biocatalytic transformations. However, flavin activation has been restricted to oxygen-free conditions to prevent enzyme deactivation caused by reactive oxygen species (ROS). Herein, we show that the photoreduction of FMN by morpholines, including 3-(N-morpholino)propanesulfonic acid (MOPS), lessens the deactivation of the enoate reductase XenB from Pseudomonas sp. during the stereoselective asymmetric enzymatic reduction of a model ,-unsaturated diketone under aerobic conditions, leading to a 91% GC-yield and a stereoselectivity greater than 94%. The kinetic stability of the thermolabile XenB was increased by more than 20-fold in MOPS buffer compared to that in Tris-HCl buffer, and a pronounced positive effect on the transition midpoint temperature was observed. The reactive form of the FMN photocatalyst is stabilized by the formation of a (3)[FMN--MOPS+] ensemble, which reduces the formation of hydrogen peroxide and other ROS in the presence of oxygen. These results contribute to broaden the application of photobiocatalytic transformations using flavin-dependent reductases.

Ort, förlag, år, upplaga, sidor
Royal Society of Chemistry, 2019
Nationell ämneskategori
Biokemi och molekylärbiologi
Identifikatorer
urn:nbn:se:uu:diva-390605 (URN)10.1039/c9cy00496c (DOI)000472455800023 ()
Tillgänglig från: 2019-08-13 Skapad: 2019-08-13 Senast uppdaterad: 2019-08-13Bibliografiskt granskad
Shylin, S. I., Pavliuk, M. V., D'Amario, L., Mamedov, F., Sá, J., Berggren, G. & Fritsky, I. O. (2019). Efficient visible light-driven water oxidation catalysed by an iron(IV) clathrochelate complex. Chemical Communications, 55(23), 3335-3338
Öppna denna publikation i ny flik eller fönster >>Efficient visible light-driven water oxidation catalysed by an iron(IV) clathrochelate complex
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2019 (Engelska)Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, nr 23, s. 3335-3338Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

A water-stable FeIV clathrochelate complex catalyzes fast and homogeneous photochemical oxidation of water to dioxygen with a turnover frequency of 2.27 s−1 and a maximum turnover number of 365. An FeV intermediate generated under catalytic conditions is trapped and characterised using EPR and Mössbauer spectroscopy.

Nyckelord
Artificial photosynthesis, water oxidation, iron catalyst, photochemical water oxidation, electrochemical water oxidation
Nationell ämneskategori
Fysikalisk kemi
Forskningsämne
Kemi med inriktning mot fysikalisk kemi
Identifikatorer
urn:nbn:se:uu:diva-379606 (URN)10.1039/C9CC00229D (DOI)000461397500002 ()30801592 (PubMedID)
Forskningsfinansiär
EU, Horisont 2020, 778245Svenska institutet
Tillgänglig från: 2019-03-18 Skapad: 2019-03-18 Senast uppdaterad: 2019-04-12Bibliografiskt granskad
Pavliuk, M. V., Alvarez, S. G., Hattori, Y., Messing, M. E., Czapla-Masztafiak, J., Szlachetko, J., . . . Sá, J. (2019). Hydrated Electron Generation by Excitation of Copper Localized Surface Plasmon Resonance. Journal of Physical Chemistry Letters, 10(8), 1743-1749
Öppna denna publikation i ny flik eller fönster >>Hydrated Electron Generation by Excitation of Copper Localized Surface Plasmon Resonance
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2019 (Engelska)Ingår i: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 10, nr 8, s. 1743-1749Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Hydrated electrons are important in radiation chemistry and charge transfer reactions, with applications that include chemical damage of DNA, catalysis, and signaling. Conventionally, hydrated electrons are produced by pulsed radiolysis, sonolysis, two-ultraviolet-photon laser excitation of liquid water, or photodetachment of suitable electron donors. Here we report a method for the generation of hydrated electrons via single-visible-photon excitation of localized surface plasmon resonances (LSPRs) of supported sub-3 nm copper nanoparticles in contact with water. Only excitations at the LSPR maximum resulted in the formation of hydrated electrons, suggesting that plasmon excitation plays a crucial role in promoting electron transfer from the nanoparticle into the solution. The reactivity of the hydrated electrons was confirmed via proton reduction and concomitant H-2 evolution in the presence of a Ru/TiO2 catalyst.

Ort, förlag, år, upplaga, sidor
AMER CHEMICAL SOC, 2019
Nationell ämneskategori
Fysikalisk kemi Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:uu:diva-383191 (URN)10.1021/acs.jpclett.9b00792 (DOI)000465507700014 ()30920838 (PubMedID)
Forskningsfinansiär
VetenskapsrådetStiftelsen Olle Engkvist Byggmästare
Anmärkning

De två första författarna delar förstaförfattarskapet.

Tillgänglig från: 2019-07-24 Skapad: 2019-07-24 Senast uppdaterad: 2019-07-24Bibliografiskt granskad
Blachucki, W., Kayser, Y., Czapla-Masztafiak, J., Guo, M., Juranic, P., Kavcic, M., . . . Szlachetko, J. (2019). Inception of electronic damage of matter by photon-driven post-ionization mechanisms. Structural Dynamics, 6(2), Article ID 024901.
Öppna denna publikation i ny flik eller fönster >>Inception of electronic damage of matter by photon-driven post-ionization mechanisms
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2019 (Engelska)Ingår i: Structural Dynamics, ISSN 2329-7778, Vol. 6, nr 2, artikel-id 024901Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

"Probe-before-destroy" methodology permitted diffraction and imaging measurements of intact specimens using ultrabright but highly destructive X-ray free-electron laser (XFEL) pulses. The methodology takes advantage of XFEL pulses ultrashort duration to outrun the destructive nature of the X-rays. Atomic movement, generally on the order of >50 fs, regulates the maximum pulse duration for intact specimen measurements. In this contribution, we report the electronic structure damage of a molecule with ultrashort X-ray pulses under preservation of the atoms' positions. A detailed investigation of the X-ray induced processes revealed that X-ray absorption events in the solvent produce a significant number of solvated electrons within attosecond and femtosecond timescales that are capable of coulombic interactions with the probed molecules. The presented findings show a strong influence on the experimental spectra coming from ionization of the probed atoms' surroundings leading to electronic structure modification much faster than direct absorption of photons. This work calls for consideration of this phenomenon in cases focused on samples embedded in, e.g., solutions or in matrices, which in fact concerns most of the experimental studies.

Nationell ämneskategori
Atom- och molekylfysik och optik Fysikalisk kemi
Identifikatorer
urn:nbn:se:uu:diva-383884 (URN)10.1063/1.5090332 (DOI)000466710000011 ()31041363 (PubMedID)
Forskningsfinansiär
Knut och Alice Wallenbergs Stiftelse, KAW-2013.0020
Tillgänglig från: 2019-05-29 Skapad: 2019-05-29 Senast uppdaterad: 2019-05-29Bibliografiskt granskad
Goncalves, L. C. P., Mansouri, H. R., Bastos, E. L., Abdellah, M., Fadiga, B. S., Sá, J., . . . Mihovilovic, M. D. (2019). Morpholine-based buffers activate aerobic photobiocatalysis via spin correlated ion pair formation. Catalysis Science & Technology, 9(6), 1365-1371
Öppna denna publikation i ny flik eller fönster >>Morpholine-based buffers activate aerobic photobiocatalysis via spin correlated ion pair formation
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2019 (Engelska)Ingår i: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, nr 6, s. 1365-1371Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The use of enzymes for synthetic applications is a powerful and environmentally-benign approach to increase molecular complexity. Oxidoreductases selectively introduce oxygen and hydrogen atoms into myriad substrates, catalyzing the synthesis of chemical and pharmaceutical building blocks for chemical production. However, broader application of this class of enzymes is limited by the requirements of expensive cofactors and low operational stability. Herein, we show that morpholine-based buffers, especially 3-(N-morpholino)propanesulfonic acid (MOPS), promote photoinduced flavoenzyme-catalyzed asymmetric redox transformations by regenerating the flavin cofactor via sacrificial electron donation and by increasing the operational stability of flavin-dependent oxidoreductases. The stabilization of the active forms of flavin by MOPS via formation of the spin correlated ion pair (3)[flavin(-)-MOPS+] ensemble reduces the formation of hydrogen peroxide, circumventing the oxygen dilemma under aerobic conditions detrimental to fragile enzymes.

Ort, förlag, år, upplaga, sidor
ROYAL SOC CHEMISTRY, 2019
Nationell ämneskategori
Fysikalisk kemi
Identifikatorer
urn:nbn:se:uu:diva-381585 (URN)10.1039/c8cy02524j (DOI)000462662100003 ()
Tillgänglig från: 2019-04-12 Skapad: 2019-04-12 Senast uppdaterad: 2019-04-12Bibliografiskt granskad
Hattori, Y., Abdellah, M., Meng, J., Zheng, K. & Sá, J. (2019). Simultaneous Hot Electron and Hole Injection upon Excitation of Gold Surface Plasmon. Journal of Physical Chemistry Letters, 10(11), 3140-3146
Öppna denna publikation i ny flik eller fönster >>Simultaneous Hot Electron and Hole Injection upon Excitation of Gold Surface Plasmon
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2019 (Engelska)Ingår i: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 10, nr 11, s. 3140-3146Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We have successfully investigated the simultaneous injection of hot electrons and holes upon excitation of gold localized surface plasmon resonance (LSPR). The studies were performed on all-solid-state plasmonic system composed of titanium dioxide (TiO2)/poly(3,4-ethylenedioxythiophene) :poly(styrenesulfonic acid) (PEDOT:PSS) p-n junctions with gold nanoparticles (Au NPs). The study revealed that both charge carriers are transferred within 200 fs to the respective charge acceptors, exhibiting a free carrier transport behavior. We also confirmed that the transfer of charge carriers are accompanied by change in the initial relaxation dynamics of Au NPs.

Nationell ämneskategori
Fysikalisk kemi
Identifikatorer
urn:nbn:se:uu:diva-389600 (URN)10.1021/acs.jpclett.9b01085 (DOI)000471079400075 ()31117685 (PubMedID)
Forskningsfinansiär
Vetenskapsrådet
Tillgänglig från: 2019-07-24 Skapad: 2019-07-24 Senast uppdaterad: 2019-07-24Bibliografiskt granskad
Wojtaszek, K., Wach, A., Czapla-Masztafiak, J., Tyrala, K., Sá, J., Özer, L. Y., . . . Szlachetko, J. (2019). The influence of nitrogen doping on the electronic structure of the valence and conduction band in TiO2. Journal of Synchrotron Radiation, 26, 145-151
Öppna denna publikation i ny flik eller fönster >>The influence of nitrogen doping on the electronic structure of the valence and conduction band in TiO2
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2019 (Engelska)Ingår i: Journal of Synchrotron Radiation, ISSN 0909-0495, E-ISSN 1600-5775, Vol. 26, s. 145-151Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

X-ray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) provide a unique opportunity to probe both the highest occupied and the lowest unoccupied states in matter with bulk sensitivity. In this work, a combination of valence-to-core XES and pre-edge XAS techniques are used to determine changes induced in the electronic structure of titanium dioxide doped with nitrogen atoms. Based on the experimental data it is shown that N-doping leads to incorporation of the p-states on the occupied electronic site. For the conduction band, a decrease in population of the lowest unoccupied d-localized orbitals with respect to the d-delocalized orbitals is observed. As confirmed by theoretical calculations, the N p-states in TiO2 structure are characterized by higher binding energy than the O p-states which gives a smaller value of the band-gap energy for the doped material.

Ort, förlag, år, upplaga, sidor
INT UNION CRYSTALLOGRAPHY, 2019
Nyckelord
X-ray emission spectroscopy, X-ray absorption spectroscopy, electronic structure analysis, TiO2 doping
Nationell ämneskategori
Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:uu:diva-376891 (URN)10.1107/S1600577518016685 (DOI)000456025200018 ()30655479 (PubMedID)
Tillgänglig från: 2019-02-12 Skapad: 2019-02-12 Senast uppdaterad: 2019-02-12Bibliografiskt granskad
Rohr, J. A., Sá, J. & Konezny, S. J. (2019). The role of adsorbates in the green emission and conductivity of zinc oxide. COMMUNICATIONS CHEMISTRY, 2, Article ID 52.
Öppna denna publikation i ny flik eller fönster >>The role of adsorbates in the green emission and conductivity of zinc oxide
2019 (Engelska)Ingår i: COMMUNICATIONS CHEMISTRY, ISSN 2399-3669, Vol. 2, artikel-id 52Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Zinc oxide is a versatile semiconductor with an expansive range of applications including lighting, sensing and solar energy conversion. Two central phenomena coupled to its performance that remain heavily investigated are the origin of its sub-band-gap green emission and the nature of its conductivity. We report photoluminescence and dark conductivity measurements of zinc oxide nanoparticle films under various atmospheric conditions that demonstrate the vital role of adsorbates. We show that the UV emission and conductivity can be tuned reversibly by facilitating the adsorption of species that either donate or extract electrons from the conduction band. When the conductivity data are compared with photoluminescence spectra taken under the same ambient conditions, the green emission can be directly linked to surface superoxide formation, rather than surface hydroxylation or native defects such as oxygen vacancies. This demonstrates how and explains why the green emission can be controlled by surface reactivity and chemical environment.

Ort, förlag, år, upplaga, sidor
NATURE PUBLISHING GROUP, 2019
Nationell ämneskategori
Materialkemi Den kondenserade materiens fysik
Identifikatorer
urn:nbn:se:uu:diva-383837 (URN)10.1038/s42004-019-0153-0 (DOI)000467008300002 ()
Tillgänglig från: 2019-05-28 Skapad: 2019-05-28 Senast uppdaterad: 2019-05-28Bibliografiskt granskad
Bonarowska, M., Matus, K., Srebowata, A. & Sá, J. (2018). Application of silica-supported Ir and Ir-M (M=Pt, Pd, Au) catalysts for low-temperature hydrodechlorination of tetrachloromethane. Science of the Total Environment, 644, 287-297
Öppna denna publikation i ny flik eller fönster >>Application of silica-supported Ir and Ir-M (M=Pt, Pd, Au) catalysts for low-temperature hydrodechlorination of tetrachloromethane
2018 (Engelska)Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 644, s. 287-297Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Herein, it is presented a catalytic system for gas-phase hydrodechlorination of tetrachloromethane at low temperature and atmospheric pressure, using iridium supported on silica as parent catalyst. Iridium electronic configuration is suitable to catalyse the hydrodechlorination reactions, however, it has been rarely used in this reaction to date. The catalytic abilities were significantly improved when a second transition metal was added. Catalysts' stability and selectivity to the desired products (i.e. C-1-C-4 hydrocarbons) improved compared to conventional activation in hydrogen when catalysts were activated shortly with microwave irradiation. Microwave irradiation of catalysts favourably influences the homogeneity of the metallic active phase, both in terms of the size of metal crystals and the homogeneity of bimetallic systems. Addition of platinumto the 'parent' iridium catalyst improved its catalytic properties and decreased deactivation. Fresh and spent catalysts were comprehensively characterized using several techniques (BET, CO-chemisorption, XRD, XPS, electron microscopy and mass spectrometry) to determine structure-activity relationships and potential causes for catalyst deactivation. No significant changes in crystalline size or bimetallic phase composition were observed for spent catalysts (with the exception of Ir-Pd catalysts which underwent bulk carbide during the reaction).

Ort, förlag, år, upplaga, sidor
ELSEVIER SCIENCE BV, 2018
Nyckelord
Hydrodechlorination of tetrachloromethane, Iridium nanoparticles, Bimetallic catalysts, Selectivity for hydrocarbons, High stability, Microwave irradiation
Nationell ämneskategori
Fysikalisk kemi
Identifikatorer
urn:nbn:se:uu:diva-367011 (URN)10.1016/j.scitotenv.2018.06.270 (DOI)000445164000029 ()29981976 (PubMedID)
Tillgänglig från: 2018-11-28 Skapad: 2018-11-28 Senast uppdaterad: 2018-11-28Bibliografiskt granskad
Organisationer
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0003-2124-9510

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