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Sá, J., Garlisi, C., Palmisano, G., Czapla-Masztafiak, J., Kayser, Y. & Szlachetko, J. (2018). Differences between bulk and surface electronic structure of doped TiO2 with soft-elements (C, N and S). Materials Chemistry and Physics, 208, 281-288
Open this publication in new window or tab >>Differences between bulk and surface electronic structure of doped TiO2 with soft-elements (C, N and S)
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2018 (English)In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 208, p. 281-288Article in journal (Refereed) Published
Abstract [en]

Herein, we report a systematic study on the electronic structure of surface and bulk TiO2 doped with C, N or S. The results were attained with a semi-empirical method consisting of a combination between resonant X-ray emission spectroscopy (RXES) measurements and localized density of states (LDOS) simulations. Experimental TiO2 RXES data was used to fit FEFF code empirical parameters, and subsequently frozen for the theoretical analysis of LDOS of TiO2 doped materials. The results show significant electronic structure differences between bulk and surface doping, as well as in the nearest Ti atom electronic structure if it is located at the surface or sub-surface, with potential consequences to the photo-catalytic process. The methodology can be adapted to study other dopants, morphologies, structures and surface terminations and as well as other inorganic semiconductors.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
Keywords
TiO2 doping, Electronic structure analysis, Surface vs bulk
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-350279 (URN)10.1016/j.matchemphys.2018.01.041 (DOI)000426223800034 ()
Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2018-05-14Bibliographically approved
Bhunia, A., Johnson, B. A., Czapla-Masztafiak, J., Sá, J. & Ott, S. (2018). Formal water oxidation turnover frequencies from MIL-101(Cr) anchored Ru(bda) depend on oxidant concentration. Chemical Communications, 54, 7770-7773
Open this publication in new window or tab >>Formal water oxidation turnover frequencies from MIL-101(Cr) anchored Ru(bda) depend on oxidant concentration
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2018 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, p. 7770-7773Article in journal (Refereed) Published
Abstract [en]

The molecular water oxidation catalyst [Ru(bda)(L)(2)] has been incorporated into pyridine-decorated MIL-101(Cr) metal-organic frameworks. The resulting MIL-101@Ru materials exhibit turnover frequencies (TOFs) up to ten times higher compared to the homogenous reference. An unusual dependence of the formal TOFs on oxidant concentration is observed that ultimately arises from differing amounts of catalysts in the MOF crystals being active.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Inorganic Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-361265 (URN)10.1039/c8cc02300j (DOI)000438237700009 ()29926035 (PubMedID)
Funder
Swedish Research CouncilSwedish Energy AgencyKnut and Alice Wallenberg FoundationEU, European Research Council, ERC-CoG2015-681895_MOFcat
Note

De två första författarna delar förstaförfattarskapet.

Available from: 2018-10-11 Created: 2018-10-11 Last updated: 2018-10-11Bibliographically approved
Szlachetko, J., Kubas, A., Cieslak, A. M., Sokolowski, K., Makolski, L., Czapla-Masztafiak, J., . . . Lewinski, J. (2018). Hidden gapless states during thermal transformations of preorganized zinc alkoxides to zinc oxide nanocrystals. Materials Horizons, 5(5), 905-911
Open this publication in new window or tab >>Hidden gapless states during thermal transformations of preorganized zinc alkoxides to zinc oxide nanocrystals
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2018 (English)In: Materials Horizons, ISSN 2051-6347, E-ISSN 2051-6355, Vol. 5, no 5, p. 905-911Article in journal (Refereed) Published
Abstract [en]

Zinc oxide (ZnO) is one of the most versatile semiconductor materials with multifarious potential applications. Easily accessible alkylzinc alkoxides have been widely exploited as single-source precursors of ZnO-based nanomaterials but their multi-step decomposition pathways have not been understood in detail. Herein, the formation mechanism of ZnO nanocrystals via solid-state thermal decomposition of a model pre-organised alkylzinc alkoxide precursor, i.e. [tBuZn(mu(3)-OtBu)](4), is elucidated using in situ valence-to-core X-ray emission (v2c-XES) and high energy resolution off-resonant spectroscopy (HEROS) in conjunction with theoretical calculations. Combination of in situ spectroscopic measurements and theoretical simulations indicates that the precursor structural evolution is initiated by the homolytic cleavage of the R-Zn bond, which leads to the formation of a transient radical ([center dot Zn(mu(3)-OR)][RZn(mu(3)-OR)](3)) species, which is responsible for the initial decomposition process. The ensuing multistep transformations involve the formation of intermediate radical zinc oxo-alkoxide clusters with gapless electronic states. Hitherto, the formation of clusters of this type has not been considered either as intermediate structures en route to a semiconductor ZnO phase or as potential species accounting for various defect states of ZnO NCs, particularly the singly charged oxygen vacancy, V-o(+).

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-365669 (URN)10.1039/c8mh00106e (DOI)000444245600013 ()
Available from: 2018-11-14 Created: 2018-11-14 Last updated: 2018-11-14Bibliographically approved
Pavliuk, M. V., Abdellah, M. & Sá, J. (2018). Hydrogen evolution with CsPbBr3 perovskite nanocrystals under visible light in solution. MATERIALS TODAY COMMUNICATIONS, 16, 90-96
Open this publication in new window or tab >>Hydrogen evolution with CsPbBr3 perovskite nanocrystals under visible light in solution
2018 (English)In: MATERIALS TODAY COMMUNICATIONS, ISSN 2352-4928, Vol. 16, p. 90-96Article in journal (Refereed) Published
Abstract [en]

Direct proton photo-reduction to molecular hydrogen with a lead-halide perovskite photosystem is presented. The concept uses CsPbBr3 nanocrystals and Ru@TiO2 nanoparticles as light harvesters and catalyst, respectively. The photo-system attains charge transfer from donor to acceptor via collision events, established via static and ultrafast spectroscopy. The photo-system exhibits a photon-to-hydrogen efficiency of ca. 0.4%, a respectable efficiency for a system relying on effective collisions for the transference of electrons.

Keywords
Inorganic perovskites nanocrystals, H-2 evolution, Ultrafast spectroscopy, Charge transfer via collision
National Category
Materials Chemistry Physical Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-364171 (URN)10.1016/j.mtcomm.2018.05.001 (DOI)000443035000012 ()
Funder
Swedish Research CouncilStiftelsen Olle Engkvist Byggmästare
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-06Bibliographically approved
Bonarowska, M., Zielinski, M., Matus, K., Sá, J. & Srebowata, A. (2018). Influence of microwave activation on the catalytic behavior of Pd-Au/C catalysts employed in the hydrodechlorination of tetrachloromethane. Reaction Kinetics, Mechanisms and Catalysis, 124(1), 375-388
Open this publication in new window or tab >>Influence of microwave activation on the catalytic behavior of Pd-Au/C catalysts employed in the hydrodechlorination of tetrachloromethane
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2018 (English)In: Reaction Kinetics, Mechanisms and Catalysis, ISSN 1878-5190, E-ISSN 1878-5204, Vol. 124, no 1, p. 375-388Article in journal (Refereed) Published
Abstract [en]

This work investigates the influence of activation by microwave irradiation on the catalytic properties of Pd-Au/C-Sibunit catalysts in the hydrodechlorination of CCl4. Pd and Pd-Au samples were thoroughly characterized by CO chemisorption, X-ray diffraction, TPHD and STEM, and used in gas phase hydrodechlorination of tetrachloromethane. The studies showed that homogenous Pd-Au alloys are formed more efficiently if short-time microwave activation is applied instead of conventional activation by H-2 reduction at 380 A degrees C. These catalysts show higher activity, stability and higher selectivity towards the desired products (C1-C5 hydrocarbons) than the catalysts activated by conventional reduction in 10%H-2/Ar flow.

Keywords
Microwave activation, Tetrachloromethane, Hydrodechlorination, Pd-Au alloys
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-353357 (URN)10.1007/s11144-018-1364-6 (DOI)000430556600026 ()
Available from: 2018-06-12 Created: 2018-06-12 Last updated: 2018-06-12Bibliographically approved
Tang, Y., Cao, X., Honarfar, A., Abdellah, M., Chen, C., Avila, J., . . . Chi, Q. (2018). Inorganic Ions Assisted the Anisotropic Growth of CsPbCl3 Nanowires with Surface Passivation Effect. ACS Applied Materials and Interfaces, 10(35), 29574-29582
Open this publication in new window or tab >>Inorganic Ions Assisted the Anisotropic Growth of CsPbCl3 Nanowires with Surface Passivation Effect
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2018 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 35, p. 29574-29582Article in journal (Refereed) Published
Abstract [en]

All-inorganic halide perovskite nanowires (NWs) exhibit improved thermal and hydrolysis stability and could thus play a vital role in nanoscale optoelectronics. Among them, blue-light-based devices are extremely limited because of the lack of a facile method to obtain high-purity CsPbCl3 NWs. Herein, we report a direct and facile method for the synthesis of CsPbCl3 NWs assisted by inorganic ions that served both as a morphology controlling agent for the anisotropic growth of nanomaterials and a surface passivation species modulating the surface of nanomaterials. This new approach allows us to obtain high-purity and size-uniform NWs as long as 500 nm in length and 20 nm in diameter with high reproducibility. X-ray photoelectron spectroscopy and ultrafast spectroscopic measurements confirmed that a reduced band gap caused by the surface species of NWs relative to nanocubes (NCs) was achieved at the photon energy of 160 eV because of the hybrid surface passivation contributed by adsorbed inorganic ions. The resulting NWs demonstrate significantly enhanced photoelectrochemical performances, 3.5-fold increase in the photocurrent generation, and notably improved stability compared to their NC counterparts. Our results suggest that the newly designed NWs could be a promising material for the development of nanoscale optoelectronic devices.

Keywords
inorganic halide perovskite, CsPbCl3 nanowires, surface passivation, photoelectrochemical cell, electron and hole injection, ultrafast spectroscopy
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-365656 (URN)10.1021/acsami.8b09113 (DOI)000444355700038 ()30088920 (PubMedID)
Funder
Swedish Research Council, 2017-05337
Available from: 2018-11-16 Created: 2018-11-16 Last updated: 2018-11-16Bibliographically approved
Hattori, Y., Abdellah, M., Rocha, I., Pavliuk, M. V., Fernandes, D. L. A. & Sá, J. (2018). Light-induced ultrafast proton-coupled electron transfer responsible for H-2 evolution on silver plasmonics. Materials Today, 21(6), 590-593
Open this publication in new window or tab >>Light-induced ultrafast proton-coupled electron transfer responsible for H-2 evolution on silver plasmonics
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2018 (English)In: Materials Today, ISSN 1369-7021, E-ISSN 1873-4103, Vol. 21, no 6, p. 590-593Article in journal (Refereed) Published
Abstract [en]

Light-driven proton-coupled electron transfer (PCET) reactions on nanoplasmonics would bring temporal control of their reactive pathways, in particular, prolong their charge separation state. Using a silver nano-hybrid plasmonic structure, we observed that optical excitation of Ag-localized surface plasmon instigated electron injection into TiO2 conduction band and oxidation of isopropanol alcoholic functionality. Femtosecond transient infrared absorption studies show that electron transfer from Ag to TiO2 occurs in ca. 650 fs, while IPA molecules near the Ag surface undergo an ultrafast bidirectional PCET step within 400 fs. Our work demonstrates that ultrafast PCET reaction plays a determinant role in prolonging charge separation state, providing an innovative strategy for visible-light photocatalysis with plasmonic nanostructures.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2018
National Category
Physical Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-362849 (URN)10.1016/j.mattod.2018.05.002 (DOI)000441765700016 ()
Funder
Swedish Research Council, 2015-03764Stiftelsen Olle Engkvist Byggmästare, 2016/367
Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2018-10-18Bibliographically approved
Ozer, L. Y., Apostoleris, H., Ravaux, F., Shylin, S. I., Mamedov, F., Lindblad, A., . . . Palmisano, G. (2018). Long-Lasting Non-hydrogenated Dark Titanium Dioxide: Medium Vacuum Anneal for Enhanced Visible Activity of Modified Multiphase Photocatalysts. ChemCatChem, 10(14), 2949-2954
Open this publication in new window or tab >>Long-Lasting Non-hydrogenated Dark Titanium Dioxide: Medium Vacuum Anneal for Enhanced Visible Activity of Modified Multiphase Photocatalysts
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2018 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 10, no 14, p. 2949-2954Article in journal (Refereed) Published
Abstract [en]

Abstract Multiphase TiO2 was stably modified by vacuum treatment for a dramatic improvement in visible-light absorption and photocatalytic reactivity. The samples were made of rutile-brookite, bare or N doped, and were grown on reduced graphene oxide. The stable introduction of Ti3+ species and oxygen vacancies resulting in mitigated electron?hole recombination was identified as the main responsible factor, along with a change in surface charges.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2018
Keywords
doping, photocatalysis, titanium, vacuum annealing, visible-light radiation
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-359437 (URN)10.1002/cctc.201800097 (DOI)
Available from: 2018-09-03 Created: 2018-09-03 Last updated: 2018-09-03
Gizinski, D., Blachucki, W., Srebowata, A., Zienkiewicz-Machnik, M., Goszewska, I., Matus, K., . . . Sá, J. (2018). On-the-fly Catalyst Accretion and Screening in Chemoselective Flow Hydrogenation. ChemCatChem, 10(17), 3641-3646
Open this publication in new window or tab >>On-the-fly Catalyst Accretion and Screening in Chemoselective Flow Hydrogenation
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2018 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 10, no 17, p. 3641-3646Article in journal (Refereed) Published
Abstract [en]

Herein, it is reported an on-the-fly accretion/reaction protocol to evaluate the structure-performance relationship in the chemoselective flow citral hydrogenation over Ni-based catalysts. Based on the methodology one was able to determine Ni nanoparticles ideal average size (ca. 9nm), in a rapid and facile manner. The methodology offers a simple workflow, cost-effective and adaptable strategy for process intensification and optimization.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
on-the-fly catalyst modification, structure-performance relationship, hydrogenation, flow catalysis, photon-in photon out spectroscopy
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-364239 (URN)10.1002/cctc.201800581 (DOI)000443935100003 ()
Available from: 2018-10-25 Created: 2018-10-25 Last updated: 2018-10-25Bibliographically approved
Zienkiewicz-Machnik, M., Goszewska, I., Srebowata, A., Kubas, A., Gizinski, D., Slowik, G., . . . Sá, J. (2018). Tuning nano-nickel selectivity with tin in flow hydrogenation of 6-methyl-5-hepten-2-one by surface organometallic chemistry modification. Catalysis Today, 308, 38-44
Open this publication in new window or tab >>Tuning nano-nickel selectivity with tin in flow hydrogenation of 6-methyl-5-hepten-2-one by surface organometallic chemistry modification
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2018 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 308, p. 38-44Article in journal (Refereed) Published
Abstract [en]

Chemoselective flow hydrogenation of 6-methyl-5-hepten-2-one was performed over nano-nickel catalysts. The parent catalyst composed solely of nickel nanoparticles grafted on the polymeric resin exhibited high activity and selectivity towards C=C bond saturation but its modification with small quantities of tin significantly increased its ability to perform C=O bond hydrogenation. The post-synthetic modification of the parent catalyst was achieved by surface organometallic chemistry approach and performed in the same flow micro-reactor, which was used for the catalytic studies, providing a methodology for online modification of parent catalysts.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Chemoselective flow hydrogenation, 6-methyl-5-hepten-2-one, Nano-Ni grafted on resin, Tin surface modification
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-352559 (URN)10.1016/j.cattod.2017.08.062 (DOI)000429527800005 ()
Available from: 2018-08-08 Created: 2018-08-08 Last updated: 2018-08-08Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2124-9510

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