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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)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: 2019-12-09Bibliographically approved
Tahira, A., Ibupoto, Z., Mazzaro, R., You, S., Morandi, V., Natile, M. M., . . . Vomiero, A. (2019). Advanced Electrocatalysts for Hydrogen Evolution Reaction Based on Core–Shell MoS2/TiO2 Nanostructures in Acidic and Alkaline Media. ACS APPLIED ENERGY MATERIALS, 2(3), 2053-2062
Open this publication in new window or tab >>Advanced Electrocatalysts for Hydrogen Evolution Reaction Based on Core–Shell MoS2/TiO2 Nanostructures in Acidic and Alkaline Media
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2019 (English)In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 3, p. 2053-2062Article in journal (Refereed) Published
Abstract [en]

Hydrogen production as alternative energy source is still a challenge due to the lack of efficient and inexpensive catalysts, alternative to platinum. Thus, stable, earth abundant, and inexpensive catalysts are of prime need for hydrogen production via hydrogen evolution reaction (HER). Herein, we present an efficient and stable electrocatalyst composed of earth abundant TiO2 nanorods decorated with molybdenum disulfide thin nanosheets, a few nanometers thick. We grew rutile TiO2 nanorods via the hydrothermal method on conducting glass substrate, and then we nucleated the molybdenum disulfide nanosheets as the top layer. This composite possesses excellent hydrogen evolution activity in both acidic and alkaline media at considerably low overpotentials (350 mV and 700 mV in acidic and alkaline media, respectively) and small Tafel slopes (48 and 60 mV/dec in acidic and alkaline conditions, respectively), which are better than several transition metal dichalcogenides, such as pure molybdenum disulfide and cobalt diselenide. A good stability in acidic and alkaline media is reported here for the new MoS2/TiO2 electrocatalyst. These results demonstrate the potential of composite electrocatalysts for HER based on earth abundant, cost-effective, and environmentally friendly materials, which can also be of interest for a broader range of scalable applications in renewable energies, such as lithium sulfur batteries, solar cells, and fuel cells.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
acidic, alkaline, catalyst, hydrogen evolution reaction, MoS2, TiO2
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-73610 (URN)10.1021/acsaem.8b02119 (DOI)000462944700053 ()2-s2.0-85064810223 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-04-12 (oliekm)

Available from: 2019-04-12 Created: 2019-04-12 Last updated: 2019-06-24Bibliographically approved
Solomon, G., Mazzaro, R., You, S., Natile, M. M., Morandi, V., Concina, I. & Vomiero, A. (2019). Ag2S/MoS2 Nanocomposites Anchored on Reduced Graphene Oxide: Fast Interfacial Charge Transfer for Hydrogen Evolution Reaction. ACS Applied Materials and Interfaces, 11(25), 22380-22389
Open this publication in new window or tab >>Ag2S/MoS2 Nanocomposites Anchored on Reduced Graphene Oxide: Fast Interfacial Charge Transfer for Hydrogen Evolution Reaction
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 25, p. 22380-22389Article in journal (Refereed) Published
Abstract [en]

Hydrogen evolution reaction through electrolysis holds great potential as a clean, renewable, and sustainable energy source. Platinum-based catalysts are the most efficient to catalyze and convert water into molecular hydrogen; however, their large-scale application is prevented by scarcity and cost of Pt. In this work, we propose a new ternary composite of Ag2S, MoS2, and reduced graphene oxide (RGO) flakes via a one-pot synthesis. The RGO support assists the growth of two-dimensional MoS2 nanosheets partially covered by silver sulfides as revealed by high-resolution transmission electron microscopy. Compared with the bare MoS2 and MoS2/RGO, the Ag2S/MoS2 anchored on the RGO surface (the ternary system Ag2S/MoS2/RGO) demonstrated a high catalytic activity toward hydrogen evolution reaction (HER). Its superior electrochemical activity toward HER is evidenced by the positively shifted (−190 mV vs reversible hydrogen electrode (RHE)) overpotential at a current density of −10 mA/cm2 and a small Tafel slope (56 mV/dec) compared with a bare and binary system. The Ag2S/MoS2/RGO ternary catalyst at an overpotential of −200 mV demonstrated a turnover frequency equal to 0.38 s–1. Electrochemical impedance spectroscopy was applied to understand the charge-transfer resistance; the ternary sample shows a very small charge-transfer resistance (98 Ω) at −155 mV vs RHE. Such a large improvement can be attributed to the synergistic effect resulting from the enhanced active site density of both sulfides and to the improved electrical conductivity at the interfaces between MoS2 and Ag2S. This ternary catalyst opens up further optimization strategies to design a stable and cheap catalyst for hydrogen evolution reaction, which holds great promise for the development of a clean energy landscape.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
electrocatalyst, hydrogen evolution, silver sulfide, molybdenum sulfide, reduced graphene oxide
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-75551 (URN)10.1021/acsami.9b05086 (DOI)000473251100036 ()2-s2.0-85068008830 (Scopus ID)
Note

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

Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved
Zur, L. Z., Armellini, C., Belmokhtar, S., Bouajaj, A., Cattaruzza, E., Chiappini, A., . . . Enrichi, F. (2019). Comparison between glass and glass-ceramic silica-hafnia matrices on the down-conversion efficiency of Tb3+/Yb3+ rare earth ions. Optical materials (Amsterdam), 87, 102-106
Open this publication in new window or tab >>Comparison between glass and glass-ceramic silica-hafnia matrices on the down-conversion efficiency of Tb3+/Yb3+ rare earth ions
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2019 (English)In: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 87, p. 102-106Article in journal (Refereed) Published
Abstract [en]

In this paper, the investigation of energy transfer efficiency in Tb3+-Yb3+ co-doped SiO2-HfO2 glass and glass-ceramic waveguides is presented. Cooperative energy transfer between these two ions allows to cut one UV or 488 nm photon in two 980 nm photons and could have important applications in improving the performance of photovoltaic solar cells. Thin films with different molar concentrations of rare earths, up to a total concentration of 21%, were prepared by a sol-gel route, using dip-coating deposition technique on SiO2 substrates. The ratio between Yb3+ and Tb3+ ions in all the prepared thin films is constant and equal to 4. The energy transfer between Tb3+ and Yb3+ ions in glass and glass-ceramic waveguides shows the higher efficiency for glass-ceramic with a maximum quantum transfer efficiency of about 190% for the sample containing 19% of rare earths.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Rare earths, Down-conversion, Energy transfer, Waveguides, Sol-gel
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-68810 (URN)10.1016/j.optmat.2018.05.008 (DOI)000457505900020 ()2-s2.0-85047221245 (Scopus ID)
Note

Konferensartikel i tidskrift

Available from: 2018-05-21 Created: 2018-05-21 Last updated: 2019-03-08Bibliographically approved
Shifa, T. A. & Vomiero, A. (2019). Confined Catalysis: Progress and Prospects in Energy Conversion. Advanced Energy Materials, 9(40), Article ID 1902307.
Open this publication in new window or tab >>Confined Catalysis: Progress and Prospects in Energy Conversion
2019 (English)In: Advanced Energy Materials, ISSN 1614-6840, Vol. 9, no 40, article id 1902307Article, review/survey (Refereed) Published
Abstract [en]

Space confined catalysis has emerged as viable strategy for achieving potent and efficient catalysts in various important reactions. It offers a means of creating unique nanoscale chemical environments partitioned from the surrounding bulk space. This gives rise to the phenomena of nanoconfinement, where the energetics and kinetics of catalytic reactions can be modulated upon confining the catalysts in a particular site. Various scaffolds have been reported so far for confinement. Among these, void spaces under the cover of 2D materials, van der Waals (vdW) gaps of layered 2D materials, nanotubes, and porous surfaces have recently won copious attention. In this review, the concept of space confinement with respect to its effect on the electronic and structural properties of a catalyst is discussed. Emphasis is devoted to the catalysis of water splitting and CO2 reduction reactions. The progress in the design and applications of space confined catalysts is then traced. Finally, a discussion of emerging issues yet to be explored for this strategy to achieve a high efficiency, and future directions with the potential to become a new hotspots are presented.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
CO2 reduction, confined catalysis, pore filling, van der Waals gaps, water splitting
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-76057 (URN)10.1002/aenm.201902307 (DOI)000485447800001 ()
Note

Validerad;2019;Nivå 2;2019-11-04 (johcin)

Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-11-04Bibliographically approved
Zairov, R., Dovzhenko, A., Sapunova, A., Voloshina, A., Tatarinov, D., Nizameev, I., . . . Mustafina, A. (2019). Dual red-NIR luminescent Eu–Yb heterolanthanide nanoparticles as promising basis for cellular imaging and sensing. Materials science & engineering. C, biomimetic materials, sensors and systems, 105, Article ID 110057.
Open this publication in new window or tab >>Dual red-NIR luminescent Eu–Yb heterolanthanide nanoparticles as promising basis for cellular imaging and sensing
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2019 (English)In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 105, article id 110057Article in journal (Refereed) Published
Abstract [en]

The present work introduces ternary Ln(III) (Ln = Eu, Yb, Lu) complexes with thenoyltriflouro1,3-diketonate (TTA−) and phosphine oxide derivative (PhO) as building blocks for core-shell nanoparticles with both Eu(III)- or Yb(III)-centered luminescence and the dual Eu(III)-Yb(III)-centered luminescence. Solvent-mediated self-assembly of the complexes is presented herein as the procedure for formation of Eu–Lu, Eu–Yb and Yb–Lu heterometallic or homometallic cores coated by hydrophilic polystyrenesulfonate-based shells. Steady state and time resolved Eu-centered luminescence in homolanthanide and heterolanthanide Eu–Lu and Eu–Yb cores is affected by Eu → Eu and Eu → Yb energy transfer due to a close proximity of the lanthanide blocks within the core of nanoparticles. The Eu → Yb energy transfer is highlighted to be the reason for the enhancement of the NIR Yb-centered luminescence. Efficient cellular uptake, low cytotoxicity towards normal and cancer cells, and sensing ability of Eu–Yb nanoparticles on lomefloxacin additives via both red and NIR channels make them promising as cellular imaging agents and sensors.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Mixed ligand complexesHeterolanthanide nanoparticles, Dual luminescence, Energy transfer, Cellular imaging, Sensors, Fluoroquinolones
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-75610 (URN)10.1016/j.msec.2019.110057 (DOI)31546380 (PubMedID)2-s2.0-85070189572 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-08-20 (svasva)

Available from: 2019-08-20 Created: 2019-08-20 Last updated: 2019-10-09Bibliographically approved
Leduc, J., Goenuellue, Y., Ghamgosar, P., You, S., Mouzon, J., Choi, H., . . . Mathur, S. (2019). Electronically-Coupled Phase Boundaries in α‑Fe2O3/Fe3O4 Nanocomposite Photoanodes for Enhanced Water Oxidation. ACS APPLIED NANO MATERIALS, 2(1), 334-342
Open this publication in new window or tab >>Electronically-Coupled Phase Boundaries in α‑Fe2O3/Fe3O4 Nanocomposite Photoanodes for Enhanced Water Oxidation
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2019 (English)In: ACS APPLIED NANO MATERIALS, E-ISSN 2574-0970, Vol. 2, no 1, p. 334-342Article in journal (Refereed) Published
Abstract [en]

Photoelectrochemical (PEC) water splittingreactions are promising for sustainable hydrogen productionfrom renewable sources. We report here, the preparation of α-Fe2O3/Fe3O4 composite films via a single-step chemical vapordeposition of [Fe(OtBu)3]2 and their use as efficient photoanode materials in PEC setups. Film thickness and phase segregation was controlled by varying the deposition time and corroborated through cross-section Raman spectroscopy and scanning electron microscopy. The highest water oxidationactivity (0.48 mA/cm2 at 1.23 V vs RHE) using intermittent AM 1.5 G (100 mW/cm2) standard illumination was found forhybrid films with a thickness of 11 μm. This phenomenon is attributed to an improved electron transport resulting from ahigher magnetite content toward the substrate interface and an increased light absorption due to the hematite layer mainly located at the top surface of the film. The observed high efficiency of α-Fe2O3/Fe3O4 nanocomposite photoanodes is attributed to the close proximity and establishment of 3D interfaces between the weakly ferro- (Fe2O3) and ferrimagnetic (Fe3O4) oxides, which in view of their differential chemical constitution andvalence states of Fe ions (Fe2+/Fe3+) can enhance the charge separation and thus the overall electrical conductivity of the layer.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
solar water splitting, valence dynamics, magnetite, Raman, single-source CVD, heterostructures
National Category
Composite Science and Engineering Chemical Process Engineering
Research subject
Experimental Physics; Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-73139 (URN)10.1021/acsanm.8b01936 (DOI)000464491500036 ()
Note

Validerad;2019;Nivå 2;2019-03-13 (oliekm)

Available from: 2019-03-08 Created: 2019-03-08 Last updated: 2019-08-23Bibliographically approved
Borgani, R., Gilzad Kohan, M., Vomiero, A. & Haviland, D. B. (2019). Fast Multifrequency Measurement of Nonlinear Conductance. Physical Review Applied, 11(4), Article ID 044062.
Open this publication in new window or tab >>Fast Multifrequency Measurement of Nonlinear Conductance
2019 (English)In: Physical Review Applied, E-ISSN 2331-7019, Vol. 11, no 4, article id 044062Article in journal (Refereed) Published
Abstract [en]

We describe a phase-coherent multifrequency lock-in measurement technique that uses the inverse Fourier transform to reconstruct the nonlinear current-voltage characteristic of a nanoscale junction. The method provides separation of the galvanic and displacement currents in the junction and easy cancellation of the parasitic displacement current from the measurement leads. These two features allow us to overcome traditional limitations imposed by the low conductance of the junction and the high capacitance of the leads, thus providing an increase in measurement speed of several orders of magnitude. We demonstrate the method in the context of conductive atomic force microscopy, acquiring current-voltage characteristics at every pixel while scanning at standard imaging speed.

Place, publisher, year, edition, pages
American Physical Society, 2019
National Category
Other Physics Topics
Research subject
Experimental Physics
Identifiers
urn:nbn:se:ltu:diva-73933 (URN)10.1103/PhysRevApplied.11.044062 (DOI)000465185700002 ()2-s2.0-85064857475 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-05-14 (johcin)

Available from: 2019-05-14 Created: 2019-05-14 Last updated: 2019-05-14Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-2935-1165

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