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Enrichi, F., Cattaruzza, E., Finotto, T., Riello, P., Righini, G. C., Trave, E. & Vomiero, A. (2020). Ag-Sensitized NIR-Emitting Yb3+-Doped Glass-Ceramics. Applied Sciences, 10(6), Article ID 2184.
Open this publication in new window or tab >>Ag-Sensitized NIR-Emitting Yb3+-Doped Glass-Ceramics
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2020 (English)In: Applied Sciences, E-ISSN 2076-3417, Vol. 10, no 6, article id 2184Article in journal (Refereed) Published
Abstract [en]

The optical photoluminescent (PL) emission of Yb3+ ions in the near infrared (NIR) spectral region at about 950–1100 nm has many potential applications, from photovoltaics to lasers and visual devices. However, due to their simple energy-level structure, Yb3+ ions cannot directly absorb UV or visible light, putting serious limits on their use as light emitters. In this paper we describe a broadband and efficient strategy for sensitizing Yb3+ ions by Ag codoping, resulting in a strong 980 nm PL emission under UV and violet-blue light excitation. Yb-doped silica–zirconia–soda glass–ceramic films were synthesized by sol-gel and dip-coating, followed by annealing at 1000 °C. Ag was then introduced by ion-exchange in a molten salt bath for 1 h at 350 °C. Different post-exchange annealing temperatures for 1 h in air at 380 °C and 430 °C were compared to investigate the possibility of migration/aggregation of the metal ions. Studies of composition showed about 1–2 wt% Ag in the exchanged samples, not modified by annealing. Structural analysis reported the stabilization of cubic zirconia by Yb-doping. Optical measurements showed that, in particular for the highest annealing temperature of 430 °C, the potential improvement of the material’s quality, which would increase the PL emission, is less relevant than Ag-aggregation, which decreases the sensitizers number, resulting in a net reduction of the PL intensity. However, all the Ag-exchanged samples showed a broadband Yb3+ sensitization by energy transfer from Ag aggregates, clearly attested by a broad photoluminescence excitation spectra after Ag-exchange, paving the way for applications in various fields, such as solar cells and NIR-emitting devices.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
sol–gel, silica–zirconia, glass–ceramics, Ag nanoaggregates, Yb3+ ions, energy transfer, downshifting, photoluminescence
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-78468 (URN)10.3390/app10062184 (DOI)2-s2.0-85082668413 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-14 (alebob)

Available from: 2020-04-14 Created: 2020-04-14 Last updated: 2020-04-22Bibliographically approved
Gilzad Kohan, M., Concina, I. & Vomiero, A. (2020). All-oxide solar cells. In: Francesco Enrichi and Giancarlo C. Righini (Ed.), Solar Cells and Light Management: Materials, Strategies and Sustainability (pp. 229-246). Elsevier
Open this publication in new window or tab >>All-oxide solar cells
2020 (English)In: Solar Cells and Light Management: Materials, Strategies and Sustainability / [ed] Francesco Enrichi and Giancarlo C. Righini, Elsevier, 2020, p. 229-246Chapter in book (Other academic)
Abstract [en]

One of the most intensively investigated directions in the field of photovoltaics is the development of technologies able to provide vacuum-free and low-cost solar cells with decent efficiency, based on earth-abundant and environmentally friendly materials. Solar cells based on oxide materials are a promising candidate for the purpose, being most of the investigated oxides comparatively more stable than most of solar cell technologies alternative to silicon, and composed of harmless materials. While oxides can exhibit high extinction coefficient in the visible and near-infrared spectral region, guaranteeing full absorption of sunlight, the main factor limiting efficiency in such kind of p–n junction devices is the low hole mobility in the p-type oxide, which represents the main challenge to be overcome to make this technology competitive. This chapter illustrates the latest results in the field, including integration of nanowire geometries as viable solution toward fast charge transport and collection.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
All-oxide solar cells, Heterostructured oxide nanowires, Oxide nanowire solar cells, p–n oxide heterojunctions, p-type oxide nanowires
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-78845 (URN)10.1016/B978-0-08-102762-2.00006-9 (DOI)2-s2.0-85084168271 (Scopus ID)
Note

ISBN för värdpublikation: 978-0-08-102762-2

Available from: 2020-05-11 Created: 2020-05-11 Last updated: 2020-05-11Bibliographically approved
Amin, S., Tahira, A., Solangi, A. R., Mazzaro, R., Ibupoto, Z. H., Fatima, A. & Vomiero, A. (2020). Functional Nickel Oxide Nanostructures for Ethanol Oxidation in Alkaline Media. Electroanalysis, 32(5), 1052-1059
Open this publication in new window or tab >>Functional Nickel Oxide Nanostructures for Ethanol Oxidation in Alkaline Media
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2020 (English)In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 32, no 5, p. 1052-1059Article in journal (Refereed) Published
Abstract [en]

Nickel oxide (NiO) nanostructures are employed in the basic medium for the oxidation of ethanol. A variety of NiO nanostructures are synthesized by wet chemical growth method, using different hydroxide (OH−) ion sources, particularly from ammonia, hexamethylenetetramine, urea and sodium hydroxide. The use of urea as (OH−) ion source results in flower‐like NiO structures composed by extremely thin nanowalls (thickness lower than 10 nm,), which demonstrated to be the most active for ethanol oxidation. All the samples exhibit NiO cubic phase, and no other impurity was detected. The cyclic voltammetry (CV) curves of NiO nanostructures were found linear over the concentration range 0.1–3.5 mM (R2=0.99) of ethanol, with the limit of detection estimated to be 0.013 mM for ethanol. The NiO nanostructures exhibit a selective signal towards ethanol oxidation in the presence of different members of alcohol family. The proposed NiO nanostructures showed a significant practicality for the reproducible and sensitive determination of ethanol from brandy, whisky, mixture of brandy and rum, and vodka samples. The nanomaterial was used as a surface modifying agent for the glassy carbon electrode and it showed a stable electro‐oxidation activity for the ethanol for 16 days. These findings indicate that the presented NiO nanomaterial can be applied in place of noble metals for ethanol sensing and other environmental applications (like fuel cells).

Place, publisher, year, edition, pages
John Wiley & Sons, 2020
Keywords
NiO nanostructures, (OH−) ion source, ethanol oxidation, alkaline media
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-77972 (URN)10.1002/elan.201900662 (DOI)000507436500001 ()2-s2.0-85078019459 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-05-26 (alebob)

Available from: 2020-03-05 Created: 2020-03-05 Last updated: 2020-05-26Bibliographically approved
Botella, P., Enrichi, F., Vomiero, A., Muñoz-Santiuste, J. E., Garg, A. B., Arvind, A., . . . Errandonea, D. (2020). Investigation on the Luminescence Properties of InMO4 (M = V5+, Nb5+, Ta5+) Crystals Doped with Tb3+ or Yb3+ Rare Earth Ions. ACS omega, 5(5), 2148-2158
Open this publication in new window or tab >>Investigation on the Luminescence Properties of InMO(M = V5+, Nb5+, Ta5+) Crystals Doped with Tb3+ or Yb3+ Rare Earth Ions
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2020 (English)In: ACS omega, ISSN 2470-1343, Vol. 5, no 5, p. 2148-2158Article in journal (Refereed) Published
Abstract [en]

We explore the potential of Tb- and Yb-doped InVO4, InTaO4, and InNbO4 for applications as phosphors for light-emitting sources. Doping below 0.2% barely change the crystal structure and Raman spectrum but provide optical excitation and emission properties in the visible and near-infrared (NIR) spectral regions. From optical measurements, the energy of the first/second direct band gaps was determined to be 3.7/4.1 eV in InVO4, 4.7/5.3 in InNbO4, and 5.6/6.1 eV in InTaO4. In the last two cases, these band gaps are larger than the fundamental band gap (being indirect gap materials), while for InVO4, a direct band gap semiconductor, the fundamental band gap is at 3.7 eV. As a consequence, this material shows a strong self-activated photoluminescence centered at 2.2 eV. The other two materials have a weak self-activated signal at 2.2 and 2.9 eV. We provide an explanation for the origin of these signals taking into account the analysis of the polyhedral coordination around the pentavalent cations (V, Nb, and Ta). Finally, the characteristic green (5D4 → 7FJ) and NIR (2F5/2 → 2F7/2) emissions of Tb3+ and Yb3+ have been analyzed and explained.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2020
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-77773 (URN)10.1021/acsomega.9b02862 (DOI)000513942200012 ()32064375 (PubMedID)2-s2.0-85079070678 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-02-19 (johcin)

Available from: 2020-02-19 Created: 2020-02-19 Last updated: 2020-04-22Bibliographically approved
Ferraro, V., Bortoluzzi, M., Castro, J., Vomiero, A. & You, S. (2020). Luminescent Cu(I) complex with bis(indazol-1-yl)phenylmethane as chelating ligand. Inorganic Chemistry Communications, 116, Article ID 107894.
Open this publication in new window or tab >>Luminescent Cu(I) complex with bis(indazol-1-yl)phenylmethane as chelating ligand
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2020 (English)In: Inorganic Chemistry Communications, ISSN 1387-7003, E-ISSN 1879-0259, Vol. 116, article id 107894Article in journal (Refereed) Published
Abstract [en]

The cationic Cu(I) complex [Cu(N^N)2]+, where N^N is bis(indazol-1-yl)phenylmethane, was synthesized as chloride or tetrafluoroborate salt by reacting CuCl or [Cu(NCCH3)4][BF4] with bis(indazol-1-yl)phenylmethane under mild conditions. The structure of [Cu(N^N)2]Cl was ascertained by single-crystal X-ray diffraction. The complex exhibited bright yellow emission upon excitation with near UV and violet light, attributed to triplet LLCT/MLCT transitions on the basis of experimental data and computational outcomes.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Cu(I), Luminescence, N-donor ligands, Indazole
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-78360 (URN)10.1016/j.inoche.2020.107894 (DOI)000530085000024 ()2-s2.0-85082419602 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-07 (alebob)

Available from: 2020-04-06 Created: 2020-04-06 Last updated: 2020-05-28Bibliographically approved
Liu, G., Mazzaro, R., Sun, C., Zhang, Y., Wang, Y., Zhao, H., . . . Vomiero, A. (2020). Role of refractive index in highly efficient laminated luminescent solar concentrators. Nano Energy, 70, Article ID 104470.
Open this publication in new window or tab >>Role of refractive index in highly efficient laminated luminescent solar concentrators
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2020 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 70, article id 104470Article in journal (Refereed) Published
Abstract [en]

As a large-area solar radiation collector, luminescent solar concentrators (LSCs) can be used as power generation units in semitransparent solar windows, modernized agricultural greenhouses and building facades. However, the external optical efficiency and long-term stability of the LSCs limit their practical applications due to the sensitivity of the emitters to the light and environmental conditions. Here, we used the concept of “laminated glass” to prepare LSCs, which consist of two waveguide layers and the quantum dots (QDs)/polymer interlayer, and we tune the refractive index of the different parts of the system to improve the external optical efficiency and stability of the LSCs, simultaneously. The waveguide layer can be glass, quartz, polymethyl methacrylate (PMMA) and other transparent materials. The CdSe/CdS core/shell QDs were used as fluorophores to prepare the interlayer of the LSCs. The external optical efficiency of the laminated LSCs is associated with the refractive index of the three layers: the closer the refractive index, the higher the ηopt. The highest external optical efficiency of 3.4% has been achieved for the laminated PMMA/QDs-polymer/PMMA LSCs, which improved ~92% compared to the single-layered CdSe/CdS based LSCs. To the best of our knowledge, this is the highest efficiency for the LSCs based on CdSe/CdS QDs. These results pave the way to realize high efficiency laminated windows as power generation units by suitably tuning the structure of the LSC, and provide the theoretical guidance for the LSCs utilized in building integrated photovoltaics.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
CdSe/CdS quantum dots, Luminescent solar concentrators, Laminated structure, Refractive index, External optical efficiency
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-78430 (URN)10.1016/j.nanoen.2020.104470 (DOI)000521052900068 ()2-s2.0-85077946805 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-09 (alebob)

Available from: 2020-04-09 Created: 2020-04-09 Last updated: 2020-04-09Bibliographically approved
Alvi, S., Jarzabek, D. M., Gilzad Kohan, M., Hedman, D., Jenczyk, P., Natile, M. M., . . . Akhtar, F. (2020). Synthesis and Mechanical Characterization of a CuMoTaWV High-Entropy Film by Magnetron Sputtering. ACS Applied Materials and Interfaces, 12(18), 21070-21079
Open this publication in new window or tab >>Synthesis and Mechanical Characterization of a CuMoTaWV High-Entropy Film by Magnetron Sputtering
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2020 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 12, no 18, p. 21070-21079Article in journal (Refereed) Published
Abstract [en]

Development of high-entropy alloy (HEA) films is a promising and cost-effective way to incorporate these materials of superior properties in harsh environments. In this work, a refractory high-entropy alloy (RHEA) film of equimolar CuMoTaWV was deposited on silicon and 304 stainless-steel substrates using DC-magnetron sputtering. A sputtering target was developed by partial sintering of an equimolar powder mixture of Cu, Mo, Ta, W, and V using spark plasma sintering. The target was used to sputter a nanocrystalline RHEA film with a thickness of ∼900 nm and an average grain size of 18 nm. X-ray diffraction of the film revealed a body-centered cubic solid solution with preferred orientation in the (110) directional plane. The nanocrystalline nature of the RHEA film resulted in a hardness of 19 ± 2.3 GPa and an elastic modulus of 259 ± 19.2 GPa. A high compressive strength of 10 ± 0.8 GPa was obtained in nanopillar compression due to solid solution hardening and grain boundary strengthening. The adhesion between the RHEA film and 304 stainless-steel substrates was increased on annealing. For the wear test against the E52100 alloy steel (Grade 25, 700–880 HV) at 1 N load, the RHEA film showed an average coefficient of friction (COF) and wear rate of 0.25 (RT) and 1.5 (300 °C), and 6.4 × 10–6 mm3/N m (RT) and 2.5 × 10–5 mm3/N m (300 °C), respectively. The COF was found to be 2 times lower at RT and wear rate 102 times lower at RT and 300 °C than those of 304 stainless steel. This study may lead to the processing of high-entropy alloy films for large-scale industrial applications.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2020
Keywords
high-entropy alloys, magnetron sputtering, spark plasma sintering, mechanical properties, wear
National Category
Other Materials Engineering Other Physics Topics
Research subject
Experimental Physics; Engineering Materials; Applied Physics
Identifiers
urn:nbn:se:ltu:diva-78868 (URN)10.1021/acsami.0c02156 (DOI)32290645 (PubMedID)2-s2.0-85084379557 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-05-12 (alebob)

Available from: 2020-05-12 Created: 2020-05-12 Last updated: 2020-05-18Bibliographically approved
Amin, S., Tahira, A., Solangi, A., Beni, V., Morante, J., Liu, X., . . . Vomiero, A. (2019). A practical non-enzymatic urea sensor based on NiCo2O4 nanoneedles. RSC Advances, 9(25), 14443-14451
Open this publication in new window or tab >>A practical non-enzymatic urea sensor based on NiCo2O4 nanoneedles
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2019 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 25, p. 14443-14451Article in journal (Refereed) Published
Abstract [en]

We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo2O4) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 μM) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo2O4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo2O4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo2O4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co3O4. The GCE-modified electrode is highly sensitive towards urea, with a linear response (R2 = 0.99) over the concentration range 0.01–5 mM and with a detection limit of 1.0 μM. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-74362 (URN)10.1039/C9RA00909D (DOI)000468640100054 ()2-s2.0-85065663040 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-11 (johcin)

Available from: 2019-06-11 Created: 2019-06-11 Last updated: 2019-06-11Bibliographically approved
Amin, S., Tahira, A., Solangi, A., Mazzaro, R., Ibupoto, Z. & Vomiero, A. (2019). A sensitive enzyme-free lactic acid sensor based on NiO nanoparticles for practical applications. Analytical Methods, 11, 3578-3583
Open this publication in new window or tab >>A sensitive enzyme-free lactic acid sensor based on NiO nanoparticles for practical applications
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2019 (English)In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 11, p. 3578-3583Article in journal (Refereed) Published
Abstract [en]

A facile and efficient electrochemical sensing platform has been successfully exploited for the first time for the determination of lactic acid using a nickel oxide (NiO) nanoparticle-modified glassy carbon electrode (GCE). Nickel oxide nanoparticles were prepared by a chemical growth method using different quantities of arginine as a soft template. The structural and morphological properties of NiO nanoparticles were characterized by Raman spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Cyclic voltammetry (CV) was used to study the electrochemical properties of various samples. The modified electrode is highly sensitive and presents a linear response over a wide range (0.005–5 mM) of lactic acid concentrations in 0.1 M NaOH. The detection limit for the sensor was found to be 5.7 μM, and it exhibits good stability. Furthermore, the sensor shows excellent selectivity in the presence of common interfering species. The lactic acid sensor showed good viability for lactic acid analysis in real samples (milk, yogurt and red wine) and demonstrated significant advancement in sensor technology for practical applications.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-75559 (URN)10.1039/C9AY00516A (DOI)000475986600010 ()2-s2.0-85069500109 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-08-16 (johcin)

Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-19Bibliographically approved
Alvi, S. A., Ghamgosar, P., Rigoni, F., Vomiero, A. & Akhtar, F. (2019). Adaptive nanolaminate coating by atomic layer deposition. Thin Solid Films, 692, Article ID 137631.
Open this publication in new window or tab >>Adaptive nanolaminate coating by atomic layer deposition
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2019 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 692, article id 137631Article in journal (Refereed) Published
Abstract [en]

Atomic layer deposition (ALD) was used to deposit ZnO/Al2O3/V2O5 nanolaminate coatings to demonstrate a coating system with temperature adaptive frictional behaviour. The nanolaminate coating exhibited excellent conformity and crack-free coating of thickness 110 nm over Inconel 718 substrate. The ALD trilayer coating showed a hardness and elastic modulus of 12 GPa and 193 GPa, respectively. High-temperature tribology of the nanolaminate trilayer was tested against steel ball in dry sliding condition at 25 °C (room temperature, RT), 200 °C, 300 °C, and 400 °C. It was found that the nanolaminate coating showed a low coefficient of friction (COF) and wear rate at RT and 300 °C. The trilayer coating was found intact and stable at all temperatures during the friction tests. The adaptability of nanolaminate coating with the temperature was verified by performing the cyclic friction test at 300 °C and RT. The low COF and wear rate had been attributed to the (100) and (002) basal plane sliding of ZnO top layer, and the interlayer sliding of weakly bonded planes parallel to (001) plane in V2O5 bottom layer. Furthermore, even after the removal of ZnO coating during the tribotest, the bottom V2O5 layer coating stabilized the COF and wear rate at RT and 300 °C.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Atomic layer deposition, Nanolaminate coating, Tribology, High temperature, Adaptive coating
National Category
Other Physics Topics Other Materials Engineering
Research subject
Experimental Physics; Engineering Materials
Identifiers
urn:nbn:se:ltu:diva-76604 (URN)10.1016/j.tsf.2019.137631 (DOI)000499678700001 ()2-s2.0-85075506757 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-12-09 (johcin)

Available from: 2019-11-04 Created: 2019-11-04 Last updated: 2019-12-20Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-2935-1165

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