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  • 1.
    Alberoni, Chiara
    et al.
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, Italy.
    Barroso-Martín, Isabel
    Departamento de Química Inorgánica, Cristalografía y Mineralogía (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain.
    Infantes-Molina, Antonia
    Departamento de Química Inorgánica, Cristalografía y Mineralogía (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain.
    Rodríguez-Castellón, Enrique
    Departamento de Química Inorgánica, Cristalografía y Mineralogía (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain.
    Talon, Aldo
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, Italy.
    Zhao, Haiguang
    Qingdao University – College of Physics & State Key Laboratory of Bio-Fibers and Eco-Textiles, 308 Ningxia Road, Qingdao 266071, P. R. China.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, Italy.
    Moretti, Elisa
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, Italy.
    Ceria doping boosts methylene blue photodegradation in titania nanostructures2021In: Materials Chemistry Frontiers, E-ISSN 2052-1537, Vol. 5, no 11, p. 4138-4152Article in journal (Refereed)
    Abstract [en]

    Ceria-doped titania photocatalysts (ceria loading 0.25–5.0 wt%) were synthesized by hydrothermal methods for water remediation. Nanotubes (CeTNTx) and nanoparticles (CeTNPx) were obtained. Ceria doping was applied to tune the electronic properties of nanostructured titania, boosting its photocatalytic activity. CeTNT nanostructures contained anatase as the only titania phase, whereas the CeTNP series consisted of both anatase and rutile polymorphs. The Ce addition induced a decrease in the energy gap, allowing enhancement of visible light harvesting. The photodegradation of methylene blue, MB, in aqueous solution was chosen to study the influence of the morphology and the ceria loading on the photocatalytic response, under UV and solar light. Both CeO2–TiO2 nanoparticles and nanotubes were found to be very active under UV light. The highest MB degradation rates were obtained for the 0.25 wt% CeO2 doping, for both nanotubes and nanoparticles (0.123 and 0.146 min−1, respectively), able to photodegrade completely the dye after 120 min. The two samples are stable after a 3-cycle reusability test. The photo-response under simulated solar light confirmed that doping titania with ceria allows harvesting visible light absorption, enhancing its photoactivity. A maximum efficiency of 85% under simulated sunlight at a degradation rate of 0.054 min−1 was obtained. Transient photoluminescence confirmed that MB acts as a charge scavenger for the composite system. These results pointed out ceria-doped titania nanostructures as a promising class of photocatalysts for the degradation of dyes and other hazardous organic compounds in wastewater.

  • 2.
    Cailotto, Simone
    et al.
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy; CSGI − Italian Research Center for Colloids and Surface Science, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019 Firenze, Italy.
    Massari, Daniele
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy; CSGI − Italian Research Center for Colloids and Surface Science, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019 Firenze, Italy.
    Gigli, Matteo
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy; CSGI − Italian Research Center for Colloids and Surface Science, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019 Firenze, Italy.
    Campalani, Carlotta
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy.
    Bonini, Massimo
    CSGI − Italian Research Center for Colloids and Surface Science, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019 Firenze, Italy; Department of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019 Firenze, Italy.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy.
    Selva, Maurizio
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy.
    Perosa, Alvise
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy.
    Crestini, Claudia
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy; CSGI − Italian Research Center for Colloids and Surface Science, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019 Firenze, Italy.
    N-Doped Carbon Dot Hydrogels from Brewing Waste for Photocatalytic Wastewater Treatment2022In: ACS Omega, E-ISSN 2470-1343, Vol. 7, no 5, p. 4052-4061Article in journal (Refereed)
    Abstract [en]

    The brewery industry annually produces huge amounts of byproducts that represent an underutilized, yet valuable, source of biobased compounds. In this contribution, the two major beer wastes, that is, spent grains and spent yeasts, have been transformed into carbon dots (CDs) by a simple, scalable, and ecofriendly hydrothermal approach. The prepared CDs have been characterized from the chemical, morphological, and optical points of view, highlighting a high level of N-doping, because of the chemical composition of the starting material rich in proteins, photoluminescence emission centered at 420 nm, and lifetime in the range of 5.5–7.5 ns. With the aim of producing a reusable catalytic system for wastewater treatment, CDs have been entrapped into a polyvinyl alcohol matrix and tested for their dye removal ability. The results demonstrate that methylene blue can be efficiently adsorbed from water solutions into the composite hydrogel and subsequently fully degraded by UV irradiation.

  • 3.
    Campalani, Carlotta
    et al.
    Department of Molecular Sciences and Nanosystems, Università Ca’ Foscari di Venezia, Via Torino 155, 30172 Venezia Mestre, Italy.
    Cattaruzza, Elti
    Department of Molecular Sciences and Nanosystems, Università Ca’ Foscari di Venezia, Via Torino 155, 30172 Venezia Mestre, Italy.
    Zorzi, Sandro
    Department of Molecular Sciences and Nanosystems, Università Ca’ Foscari di Venezia, Via Torino 155, 30172 Venezia Mestre, Italy.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Università Ca’ Foscari di Venezia, Via Torino 155, 30172 Venezia Mestre, Italy.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Matthews, Lauren
    The European Synchrotron Radiation Facility, 38043 Grenoble CEDEX 9, France.
    Capron, Marie
    The European Synchrotron Radiation Facility, 38043 Grenoble CEDEX 9, France; Partnership for Soft Condensed Matter PSCM, ESRF The European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble CEDEX 9, France.
    Mondelli, Claudia
    CNR-IOM, Institut Laue Langevin, 71, Avenue des Martyrs, 38042 Grenoble CEDEX 9, France.
    Selva, Maurizio
    Department of Molecular Sciences and Nanosystems, Università Ca’ Foscari di Venezia, Via Torino 155, 30172 Venezia Mestre, Italy.
    Perosa, Alvise
    Department of Molecular Sciences and Nanosystems, Università Ca’ Foscari di Venezia, Via Torino 155, 30172 Venezia Mestre, Italy.
    Biobased Carbon Dots: From Fish Scales to Photocatalysis2021In: Nanomaterials, E-ISSN 2079-4991, Vol. 11, no 2, article id 524Article in journal (Refereed)
    Abstract [en]

    The synthesis, characterization and photoreduction ability of a new class of carbon dots made from fish scales is here described. Fish scales are a waste material that contains mainly chitin, one of the most abundant natural biopolymers, and collagen. These components make the scales rich, not only in carbon, hydrogen and oxygen, but also in nitrogen. These self-nitrogen-doped carbonaceous nanostructured photocatalyst were synthesized from fish scales by a hydrothermal method in the absence of any other reagents. The morphology, structure and optical properties of these materials were investigated. Their photocatalytic activity was compared with the one of conventional nitrogen-doped carbon dots made from citric acid and diethylenetriamine in the photoreduction reaction of methyl viologen.

  • 4.
    Enrichi, Francesco
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma.
    Belmokhtar, Saloua
    Laboratoire des Technologies Innovantes, LTI, Université Abdelmalek Essâadi, Tanger.
    Benedetti, Alvise
    Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Mestre, Venezia.
    Bouajaj, Adel
    Laboratoire des Technologies Innovantes, LTI, Université Abdelmalek Essâadi, Tanger.
    Cattaruzza, E.
    Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia.
    Coccetti, F.
    Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma.
    Colusso, Elena
    Dipartimento di Ingegneria Industriale (DII), Università degli Studi di Padova.
    Ferrari, M.
    Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma.
    Ghamgosar, Pedram
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gonella, Francesco
    Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma.
    Karlsson, Maths
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology.
    Martucci, Alessandro
    Dipartimento di Ingegneria Industriale (DII), Università degli Studi di Padova.
    Ottini, Riccardo
    Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Mestre, Venezia.
    Riello, Pietro
    Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Mestre, Venezia.
    Righini, Giancarlo C.
    Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma.
    Trave, Enrico
    Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Mestre, Venezia.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Zur, Lidia Z.
    Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Roma.
    Ag nanoaggregates as efficient broadband sensitizers for Tb3+ ions in silica-zirconia ion-exchanged sol-gel glasses and glass-ceramics2018In: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 84, p. 668-674Article in journal (Refereed)
    Abstract [en]

    In this paper we report the study of down-shifting silica-zirconia glass and glass-ceramic films doped by Tb3+ ions and Ag nanoaggregates, which combine the typical spectral properties of the rare-earth-ions with the broadband sensitizing effect of the metal nanostructures. Na-Tb co-doped silica-zirconia samples were obtained by a modified sol-gel route. Dip-coating deposition followed by annealing for solvent evaporation and matrix densification were repeated several times, obtaining a homogeneous crack-free film. A final treatment at 700 °C or 1000 °C was performed to control the nanoscale structural properties of the samples, resulting respectively in a glass (G) or a glass-ceramic (GC), where tetragonal zirconia nanocrystals are surrounded by an amorphous silica matrix. Ag introduction was then achieved by ion-exchange in a molten salt bath, followed by annealing in air to control the migration and aggregation of the metal ions. The comparison of the structural, compositional and optical properties are presented for G and GC samples, providing evidence of highly efficient photoluminescence enhancement in both systems, slightly better in G than in GC samples, with a remarkable increase of the green Tb3+ PL emission at 330 nm excitation: 12 times for G and 8 times for GC samples. Furthermore, after Ag-exchange, the shape of Tb3+ excitation resembles the one of Ag ions/nanoaggregates, with a broad significant absorption in the whole UV-blue spectral region. This broadband enhanced downshifting could find potential applications in lighting devices and in PV solar cells.

  • 5.
    Ferraro, Valentina
    et al.
    Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Via Torino 155, I-30170 Mestre, VE, Italy. Consorzio Interuniversitario Reattività Chimica e Catalisi (CIRCC), via Celso Ulpiani 27, 70126 Bari, Italy.
    Bortoluzzi, Marco
    Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Via Torino 155, I-30170 Mestre, VE, Italy. Consorzio Interuniversitario Reattività Chimica e Catalisi (CIRCC), via Celso Ulpiani 27, 70126 Bari, Italy.
    Castro, Jesús
    Departamento de Química Inorgánica, Universidade de Vigo, Facultade de Química, Edificio de Ciencias Experimentais, 36310 Vigo, Galicia, Spain.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Via Torino 155, I-30170 Mestre, VE, Italy.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Luminescent Cu(I) complex with bis(indazol-1-yl)phenylmethane as chelating ligand2020In: Inorganic Chemistry Communications, ISSN 1387-7003, E-ISSN 1879-0259, Vol. 116, article id 107894Article in journal (Refereed)
    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.

  • 6.
    Fomekong, Roussin Lontio
    et al.
    Department of High-Temperature and Functional Coatings, Institute of Materials Research, German Aerospace Center, Cologne, Germany.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Enrichi, Francesco
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Italy.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Italy.
    Saruhan, Bilge
    Department of High-Temperature and Functional Coatings, Institute of Materials Research, German Aerospace Center, Cologne, Germany.
    Impact of Oxalate Ligand in Co-Precipitation Route on Morphological Properties and Phase Constitution of Undoped and Rh-Doped BaTiO3 Nanoparticles2019In: Nanomaterials, E-ISSN 2079-4991, Vol. 9, no 12, article id 1697Article in journal (Refereed)
    Abstract [en]

    In order to design and tailor materials for a specific application like gas sensors, the synthesis route is of great importance. Undoped and rhodium-doped barium titanate powders were successfully synthesized by two routes; oxalate route and classic route (a modified conventional route where solid-state reactions and thermal evaporation induced precipitation takes place). Both powders were calcined at different temperatures. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX) and Brunauer-Emmet-Teller (BET) analyses are employed to identify the phases and polymorphs, to determine the morphology, the chemical composition and the specific surface area of the synthesized materials, respectively. The so-called oxalate route yields pure BaTiO3 phase for undoped samples at 700 °C and 900 °C (containing both cubic and tetragonal structures), while the classic route-synthesized powder contains additional phases such as BaCO3, TiO2 and BaTi2O5. Samples of both synthesis routes prepared by the addition of Rh contain no metallic or oxide phase of rhodium. Instead, it was observed that Ti was substituted by Rh at temperatures 700 °C and 900 °C and there was some change in the composition of BaTiO3 polymorph (increase of tetragonal structure). Heat-treatments above these temperatures show that rhodium saturates out of the perovskite lattice at 1000 °C, yielding other secondary phases such as Ba3RhTi2O9 behind. Well-defined and less agglomerated spherical nanoparticles are obtained by the oxalic route, while the classic route yields particles with an undefined morphology forming very large block-like agglomerates. The surface area of the synthesized materials is higher with the oxalate route than with the classic route (4 times at 900 °C). The presence of the oxalate ligand with its steric hindrance that promotes the uniform distribution and the homogeneity of reactants could be responsible for the great difference observed between the powders prepared by two preparation routes.

  • 7.
    Ghamgosar, Pedram
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Rigoni, Federica
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gilzad Kohan, Mojtaba
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Morales, Edgar Abarca
    Luleå University of Technology.
    Mazzaro, Raffaello
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Morandi, Vittorio
    Institute for Microelectronics and Microsystems Section of Bologna , National Research Council , Bologna , Italy..
    Almqvist, Nils
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Self-Powered Photodetectors Based on Core-Shell ZnO-Co3O4 Nanowire Heterojunctions2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 26, p. 23454-23462Article in journal (Refereed)
    Abstract [en]

    Self-powered photodetectors operating in the UV–visible–NIR window made of environmentally friendly, earth abundant, and cheap materials are appealing systems to exploit natural solar radiation without external power sources. In this study, we propose a new p–n junction nanostructure, based on a ZnO–Co3O4 core–shell nanowire (NW) system, with a suitable electronic band structure and improved light absorption, charge transport, and charge collection, to build an efficient UV–visible–NIR p–n heterojunction photodetector. Ultrathin Co3O4 films (in the range 1–15 nm) were sputter-deposited on hydrothermally grown ZnO NW arrays. The effect of a thin layer of the Al2O3 buffer layer between ZnO and Co3O4 was investigated, which may inhibit charge recombination, boosting device performance. The photoresponse of the ZnO–Al2O3–Co3O4 system at zero bias is 6 times higher compared to that of ZnO–Co3O4. The responsivity (R) and specific detectivity (D*) of the best device were 21.80 mA W–1and 4.12 × 1012 Jones, respectively. These results suggest a novel p–n junction structure to develop all-oxide UV–vis photodetectors based on stable, nontoxic, low-cost materials.

  • 8.
    Ghamgosar, Pedram
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Rigoni, Federica
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Dobryden, Iliya
    Division of Surface and Corrosion Science, KTH Royal Institute of Technolog.
    Gilzad Kohan, Mojtaba
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Pellegrino, Anna Lucia
    Dipartimento Scienze Chimiche, Università degli Studi di Catania, INSTM UdR-Catania.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Almqvist, Nils
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Malandrino, Graziella
    Dipartimento Scienze Chimiche, Università degli Studi di Catania, INSTM UdR-Catania.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    ZnO-Cu2O core-shell nanowires as stable and fast response photodetectors2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 51, p. 308-316Article in journal (Refereed)
    Abstract [en]

    In this work, we present all-oxide p-n junction core-shell nanowires (NWs) as fast and stable self-powered photodetectors. Hydrothermally grown n-type ZnO NWs were conformal covered by different thicknesses (up to 420 nm) of p-type copper oxide layers through metalorganic chemical vapor deposition (MOCVD). The ZnO NWs exhibit a single crystalline Wurtzite structure, preferentially grown along the [002] direction, and energy gap Eg=3.24 eV. Depending on the deposition temperature, the copper oxide shell exhibits either a crystalline cubic structure of pure Cu2O phase (MOCVD at 250 °C) or a cubic structure of Cu2O with the presence of CuO phase impurities (MOCVD at 300 °C), with energy gap of 2.48 eV. The electrical measurements indicate the formation of a p-n junction after the deposition of the copper oxide layer. The core-shell photodetectors present a photoresponsivity at 0 V bias voltage up to 7.7 µA/W and time response ≤0.09 s, the fastest ever reported for oxide photodetectors in the visible range, and among the fastest including photodetectors with response limited to the UV region. The bare ZnO NWs have slow photoresponsivity, without recovery after the end of photo-stimulation. The fast time response for the core-shell structures is due to the presence of the p-n junctions, which enables fast exciton separation and charge extraction. Additionally, the suitable electronic structure of the ZnO-Cu2O heterojunction enables self-powering of the device at 0 V bias voltage. These results represent a significant advancement in the development of low-cost, high efficiency and self-powered photodetectors, highlighting the need of fine tuning the morphology, composition and electronic properties of p-n junctions to maximize device performances.

  • 9.
    Gilzad Kohan, Mojtaba
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mazzaro, Raffaello
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. CNR-IMM, Area della Ricerca di Bologna, Bologna, Italy.
    Morandi, Vittorio
    CNR-IMM, Area della Ricerca di Bologna, Bologna, Italy.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Plasma assisted vapor solid deposition of Co3O4 tapered nanorods for energy applications2019In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 46, p. 26302-26310Article in journal (Refereed)
    Abstract [en]

    Self-standing, 1-dimensional (1D) structures of p-type metal oxide (MOx) have been the focus of considerable attention, due to their unique properties in energy storage and solar light conversion. However, the practical performance of p-type MOx is intrinsically limited by their interfacial defects and strong charge recombination losses. Single crystalline assembly can significantly reduce recombination at interface and grain boundaries. Here, we present a one-step route based on plasma assisted physical vapor deposition (PVD), for the rational and scalable synthesis of single crystalline 1D vertically aligned Co3O4 tapered nanorods (NRs). The effect of PVD parameters (deposition pressure, temperature and duration) in tuning the morphology, composition and crystalline structure of resultant NRs is investigated. Crystallographic data obtained from X-ray diffraction and high-resolution transmission electron microscopy (TEM) indicated the single crystalline nature of NRs with [111] facet preferred orientation. The NRs present two optical band gaps at about 1.48 eV and 2.1 eV. Current–voltage (I–V) characteristic of the Co3O4 NRs electrodes, 400 nm long, present two times higher current density at −1 V forward bias, compared to the benchmarking thin film counterpart. These array structures exhibit good electrochemical performance in lithium-ion adsorption–desorption processes. Among all, the longest Co3O4 NRs electrodes delivers a 1438.4 F g−1 at current density of 0.5 mA cm−2 and presents 98% capacitance retention after 200 charge–discharge cycles. The very low values of charge transfer resistance (Rct = 5.2 Ω for 400 nm long NRs) of the NRs testifies their high conductivity. Plasma assisted PVD is demonstrated as a facile technique for synthesizing high quality 1D structures of Co3O4, which can be of interest for further development of different desirable 1D systems based on transition MOx.

  • 10.
    Gilzad Kohan, Mojtaba
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Solomon, Getachew
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Yusupov, Khabib
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, Venezia, Mestre, 30172 Italy.
    Vertically aligned Co3O4 nanorods as a platform for inverted all‐oxide heterojunctions2021In: Nano Select, E-ISSN 2688-4011, Vol. 2, no 5, p. 967-978Article in journal (Refereed)
    Abstract [en]

    Direct stacking of n‐type and p‐type metal oxide (MOx) semiconductors is one of the appealing directions toward low cost and environmentally friendly photovoltaics (PVs). However, the main shortcoming, hindering the PV performance of MOx heterojunction devices is attributed to the tradeoff between light absorption and maximized carrier extraction in p‐type MOx. In this work, we demonstrate that the nanorod (NR) geometry of Co3O4 light absorber with a nearly ideal bandgap of ∼1.48 eV, can remove this hurdle through strong internal light trapping of adjacent one‐dimensional (1D) structure and enhanced carrier mobility. The inverted n‐on‐p configuration of the core‐shell 1D heterojunction, obtained by depositing a thin TiO2 n‐type layer, resulted in enlarged charge generation compared to the typical p‐on‐n counterpart device. Fine‐tuning of Co3O4 NRs length, permits PV investigation of the heterojunctions with respect to absorber layers thickness. The optimized Co3O4 NRs/TiO2 heterojunction (30 nm Co3O4 NR length) presented a record high open circuit photovoltage (Voc) of (0.52 ± 0.03) V under 1 sun irradiation. Impedance analysis of the heterojunctions, indicates formation of the p+‐p depletion. The presented work can highlight some vital venues to enhance photoconversion efficiency of the all‐oxide heterojunctions while introducing a pioneer contender as inverted (n‐on‐p) MOx heterojunction.

  • 11.
    Gilzad Kohan, Mojtaba
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Camellini, Andrea
    Dipartimento di Energia, Politecnico di Milano, Via G. Ponzio 34/3, Milano I-20133, Italy .
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Rossi, Margherita Zavelani
    Dipartimento di Energia, Politecnico di Milano, Via G. Ponzio 34/3, Milano I-20133, Italy; IFN-CNR, piazza L. Da Vinci 32, 20133 Milano, Italy .
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy .
    Optical field coupling in ZnO nanorods decorated with silver plasmonic nanoparticles2021In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 9, no 43, p. 15452-15462Article in journal (Refereed)
    Abstract [en]

    Characterizing carrier redistribution due to optical field modulation in a plasmonic hot-electron/semiconductor junction can be used to raise the framework for harnessing the carrier decay of plasmonic metals in more efficient conversion systems. In this work we comprehensively studied the carrier redistribution mechanisms of a 1-dimensional (1D) metal-semiconductor Schottky architecture, holding the dual feature of a hot-electron plasmonic system and a simple metal/semiconductor junction. We obtained a strongly enhanced external quantum efficiency (EQE) of the plasmonic Ag decorated ZnO semiconductor in both the band-edge region of ZnO and the corresponding plasmonic absorption profile of the Ag NPs (visible region). Simultaneously, the insertion of an insulating Al2O3 intermediate layer between Ag NPs and ZnO resulted in a parallel distinction of the two main non-radiative carrier transfer mechanisms of plasmonic NPs, i.e. direct electron transfer (DET) and plasmonic induced resonance energy transfer (PIRET). The multi-wavelength transient pump-probe spectroscopy indicated the very fast plasmonic radiative transfer dynamics of the system in <500 fs below 389 nm. We demonstrate a 13% increase of photogenerated current in ZnO upon visible irradiation as a result of non-radiative plasmonic hot-electron injection from Ag NPs. Overall, our device encompasses several effective solutions for designing a plasmonic system featuring non-radiative electron-electron plasmonic dephasing and high photoconversion efficiencies.

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  • 12.
    Kumar, Pankaj
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, Venezia Mestre, Italy.
    CuSCN as a hole transport layer in an inorganic solution-processed planar Sb2S3 solar cell, enabling carbon-based and semitransparent photovoltaics2022In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 10, no 43, p. 16273-16282Article in journal (Refereed)
    Abstract [en]

    Sb2S3 is an emerging inorganic photovoltaic absorber material with attractive properties such as high absorption coefficient, stability, earth-abundance, non-toxicity, and low-temperature solution processability. Furthermore, with a bandgap of ca. 1.7 eV, it can also be used in semitransparent or tandem solar cell applications. Here, an inorganic wide-bandgap hole transport layer (HTL), copper thiocyanate (CuSCN), is used in an Sb2S3 solar cell employing a simple planar geometry. The compact and highly transparent CuSCN HTL was compatible with the low-cost, blade-coated carbon/Ag electrode and a semitransparent solar cell device. With Au and carbon/Ag electrodes, chemical bath deposited Sb2S3 solar cells achieved power conversion efficiencies (PCEs) of 1.75% and 1.95%, respectively. At the same time, a preliminary semitransparent Sb2S3 device with an ultrathin Au (similar to 15 nm) electrode showed a good average visible transmittance (AVT) of 26.7% at a PCE of 1.65%.

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  • 13.
    Kumar, Pankaj
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, Venezia, 30172, Mestre, Italy.
    Recent Progress in Materials and Device Design for Semitransparent Photovoltaic Technologies2023In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 13, no 39, article id 2301555Article, review/survey (Refereed)
    Abstract [en]

    Semitransparent photovoltaic (STPV) solar cells offer an immense opportunity to expand the scope of photovoltaics to special applications such as windows, facades, skylights, and so on. These new opportunities have encouraged researchers to develop STPVs using traditional thin-film solar cell technologies (amorphous-Si, CdTe, and CIGS or emerging solar cells (organic, perovskites, and dye-sensitized). There are considerable improvements in both power conversion efficiency (PCE) and semitransparency of these STPV devices. This review studies the device structure of state-of-the-art STPV devices and thereby analyzes the different approaches toward maximizing the product of PCE and average visible transmittance. The origins of PCE losses during the opaque-to-semitransparent transition in the different STPV technologies are discussed. In addition, critical practical aspects relevant to all STPV devices, such as compatibility of the top transparent electrode with the device structure, buffer layer optimization, light management engineering, scale-up, and stability, are also reported. This overview is expected to facilitate researchers across different technologies to identify and overcome the challenges toward achieving higher light utilization efficiencies in STPVs.

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  • 14.
    Leduc, Jennifer
    et al.
    University of Cologne, Institute of Inorganic Chemistry, University of Cologne, 50939, Cologne, Germany.
    Goenuellue, Yakup
    University of Cologne, Institute of Inorganic Chemistry, University of Cologne, 50939, Cologne, Germany.
    Ghamgosar, Pedram
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mouzon, Johanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Choi, Heechae
    University of Cologne, Institute of Inorganic Chemistry, University of Cologne, 50939, Cologne, Germany.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Grosch, Matthias
    University of Cologne, Institute of Inorganic Chemistry, University of Cologne, 50939, Cologne, Germany.
    Mathur, Sanjay
    University of Cologne, Institute of Inorganic Chemistry, University of Cologne, 50939, Cologne, Germany.
    Electronically-Coupled Phase Boundaries in α‑Fe2O3/Fe3O4 Nanocomposite Photoanodes for Enhanced Water Oxidation2019In: ACS APPLIED NANO MATERIALS, E-ISSN 2574-0970, Vol. 2, no 1, p. 334-342Article in journal (Refereed)
    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.

  • 15.
    Lontio Fomekong, Roussin
    et al.
    Higher Teacher Training College, University of Yaounde I, P.O.BOX 47, Yaounde, Cameroon. Department of High-Temperature and Functional Coatings, Institute of Materials Research, German Aerospace Center (DLR), 51147, Cologne, Germany.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Frohnhoven, Robert
    Institute of Inorganic Chemistry, University of Cologne, Greinstraße 6, 50939, Cologne, Germany.
    Ludwig, Tim
    Institute of Inorganic Chemistry, University of Cologne, Greinstraße 6, 50939, Cologne, Germany.
    Mathur, Sanjay
    Institute of Inorganic Chemistry, University of Cologne, Greinstraße 6, 50939, Cologne, Germany.
    Saruhan, Bilge
    Department of High-Temperature and Functional Coatings, Institute of Materials Research, German Aerospace Center (DLR), 51147, Cologne, Germany.
    Self-decoration of Barium Titanate with Rhodium-NP via a facile co-precipitation route for NO sensing in hot gas environment2021In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 338, article id 129848Article in journal (Refereed)
    Abstract [en]

    There is an urgent need to develop real-time gas sensors capable of detection under hot-gas (> 400 °C) flow, for applications such as exhaust emission control. In this context, Rh-doped BaTiO3 has been prepared by a co-precipitation route and heat-treated at 900 °C under 2% hydrogen to obtain in-situ Rh-nanoparticle decoration of submicron BaTiO3 particles. X-ray diffraction, Raman, and X-Ray photoelectron spectrometry analysis confirm the presence of Barium Titanate phases and the substitution of Ti4+ by Rh3+. According to the analytic evidence, thermal hydrogen treatment leads probably to Rhodium diffusion out of titanate lattice, yielding a self-decoration of the nano-sized Barium Titanate particles. Further NO-sensing tests revealed that the sensors produced by deposition of this in-situ Rh-loaded BaTiO3 on the interdigitated electrodes (IDE) yield a significant increase of selectivity and response (∼18 % for 200 ppm NO) towards NO, for the first time, under a hot-gas environment reaching up to 900 °C as synthetic humid air being the carrier gas. The calculated response and recovery times are reasonable, and observed reproducibility confirms suitability to practical applications. Relying on the carried investigations, this good sensing performance can be explained by the creation of excessive oxygen vacancies resulting from Rhodium's surface diffusion. Moreover, it is to claim that excellent catalytic activity of Rhodium plays a key role in enhancing NO-sensing performance.

  • 16.
    Mases, Mattias
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Weir, Samuel T.
    Lawrence Livermore National Laboratory.
    Evans, William J.
    Lawrence Livermore National Laboratory.
    Volkova, Yana
    Ural State University.
    Tebenkov, Alexander
    Ural State University.
    Babushkin, Alexey N.
    Ural State University.
    Vohra, Yogesh K.
    University of Alabama at Birmingham.
    Samudrala, G.
    University of Alabama at Birmingham.
    Soldatov, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    In situ electrical conductivity and Raman study of C60 tetragonal polymerat high pressures up to 30 GPa2010In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 274, no 11/12, p. 3068-3071Article in journal (Refereed)
    Abstract [en]

    Theory predicts that tetragonal polymeric C60 will undergo a phase transition into a metallic phase at pressures around 20 GPa. Raman and structural experiments at high pressures confirmed formation of a new phase above 20 GPa although the question about its electrical properties was still open. We report on the first simultaneous in situ study of vibrational and electrical properties of two-dimensional (2D) tetragonal C60 polymer at pressures up to 30 GPa in a diamond anvil cell (DAC) specially designed for this purpose. Our results reveal an anomaly in Raman spectra and a drop in electrical resistance of the sample at 20-25 GPa. We tentatively associate this anomalous behaviour with a phase transition into the conductive phase although its metallic character is yet to be proven.At high pressures the Raman spectra exhibit a high degree of disorder. Upon pressure release the order was partially restored and, more importantly, a significant amount of the initial 2D polymeric phase was recovered.

  • 17.
    Prikhna, T.
    et al.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Gawalek, W.
    Institut für Photonische Technologien, Jena, 07745, Germany.
    Savchuk, Y.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Soldatov, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Sokolovsky, V.
    Ben-Gurion University of Negev, P.O.B. 653, Beer-Sheva, 84105, Israel.
    Eisterer, M.
    Atominstitut, Vienna University of Technology, 1020, Vienna, Austria.
    Weber, H.W.
    Atominstitut, Vienna University of Technology, 1020, Vienna, Austria.
    Noudem, J.
    CNRS UMR 6508, CNRS/CRISMAT, 6, Bd du Maréchal Juin, 14050, Caen, France.
    Serga, M.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Turkevich, V.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Tompsic, M.
    Hyper Tech Research, Inc., 1275 Kinnear Road, Columbus, Columbus, OH, 43212, USA.
    Tkach, V.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Danilenko, N.
    Institute for Problems in Material Science of the National Academy of Sciences of Ukraine, 3 Krzhizhanovsky Street, Kiev, 03680, Ukraine.
    Goldacker, W.
    Institut für Technische Physik, 3640, Forschungszentrum Karlsruhe, Karlsruhe, 76021, Germany.
    Karau, F.
    H.C. Starck GmbH, Goslar, 38642, Germany.
    Fesenko, I.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Rindfleisch, M.
    Hyper Tech Research, Inc., 1275 Kinnear Road, Columbus, OH, 43212, USA.
    Dellith, J.
    Institut für Photonische Technologien, Jena, 07745, Germany.
    Wendt, M.
    Institut für Photonische Technologien, Jena, 07745, Germany.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Meerovich, V.
    Ben-Gurion University of Negev, P.O.B. 653, Beer-Sheva, 84105, Israel.
    Dub, S.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Moshchil, V.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Sergienko, N.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Kozyrev, A.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Habisreuther, T.
    Institut für Photonische Technologien, Jena, 07745, Germany.
    Schmidt, C.
    Institut für Photonische Technologien, Jena, 07745, Germany.
    Litzkendorf, D.
    Institut für Photonische Technologien, Jena, 07745, Germany.
    Nagorny, P.
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev, 04074, Ukraine.
    Sverdun, V.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Effects of high pressure on the physical properties of MgB22011In: Journal of Superconductivity and Novel Magnetism, ISSN 1557-1939, E-ISSN 1557-1947, Vol. 24, no 5, p. 137-150Article in journal (Refereed)
    Abstract [en]

    The synthesis of MgB2-based materials under high pressure gave the possibility to suppress the evaporation of magnesium and to obtain near theoretically dense nanograined structures with high superconducting, thermal conducting, and mechanical characteristics: critical current densities of 1.8-1.0×106 A/cm2 in the self-field and 103 A/cm2 in a magnetic field of 8 T at 20 K, 5-3×105 A/cm2 in self-field at 30 K, the corresponding critical fields being Hc2=15 T at 22 K and irreversible fields Hirr=13 T at 20 K, and Hirr=3.5 T at 30 K, thermal conduction of 53±2 W/(m{dot operator}K), the Vickers hardness HV=10.12±0.2 GPa under a load of 148.8 N and the fracture toughness K1 C=7.6±2.0 MPa{dot operator}m0.5 under the same load, the Young modulus E=213 GPa. Estimation of quenching current and AC losses allowed the conclusion that high-pressure-prepared materials are promising for application in transformer-type fault current limiters working at 20-30 K.

  • 18.
    Prikhna, Tatiana
    et al.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Noudem, Jacques
    CNRS/CRISMAT.
    Gawalek, Wolfgang
    Institut für Photonische Technologien, Jena.
    Mamalis, Athanasios G.
    National Technical University of Athens.
    Soldatov, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Savchuk, Yaroslav
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Moshchil, Viktor
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Eisterer, Michael
    Atomic Institute of Austrian Universities.
    Weber, Harald W
    Atomic Institute of Austrian Universities.
    Dub, Sergey
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Habisreuther, Tobias
    Institut für Photonische Technologien, Jena.
    Dellith, Jan
    Institut für Photonische Technologien, Jena.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Schmidt, Christa
    Institut für Photonische Technologien, Jena.
    Karau, Friedrich
    H.C. Starck GmbH, Goslar.
    Dittrich, Ulrich
    H.C. Starck GmbH, Goslar.
    Vajda, Istvan
    Budapest University of Technology and Economics.
    Sergienko, Nina
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Sokolovsky, Vladimir
    Ben-Gurion University of Negev.
    Litzkendorf, Doris
    Institut für Photonische Technologien, Jena.
    Chaud, Xavier
    CNRS/CRETA, 25, Avenue des Martyrs.
    Sverdun, Vladimir
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Kuznietsov, Roman
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Spark plasma synthesis and sintering of superconducting MgB 2-based materials2012In: Applied Electromagnetic Engineering for Magnetic, Superconducting and Nano Materials: Selected Peer Reviewed Papers from the Selected Peer-reviewed Papers from the Seventh Japanese-mediterranean and Central European Workshop / [ed] A.G. Mamalis; A. Kaladas; M. Enokizono, Trans Tech Publications Inc., 2012, p. 42437-Conference paper (Refereed)
    Abstract [en]

    Superconducting (SC) and mechanical properties of spark plasma (or SPS) produced MgB 2 -based materials allow their efficient applications in fault current limiters, superconducting electromotors, pumps, generators, magnetic bearings, etc. The synthesized from Mg and B at 50 MPa, 1050 °C for 30 min material has a density of 2.52 g/cm 3, critical current density, j c = 7.1·10 5 A/cm 2 at 10 K , 5.4·10 5 A/cm 2 at 20 K, and 9·10 4 A/cm 2 at 35 K in zero magnetic field; at 20 K its field of irreversibility B irr(20)=7 T and upper critical field B c2(20)=11 T; microhardness H V=10.5 GPa and fracture toughness K 1C =1.7 MPa·m 1/2 at 4.9 N-load. SPS-manufactured in- situ MgB 2- based materials usually have somewhat higher j c than sintered ex-situ. The pressure variations from 16 to 96 MPa during the SPS-process did not affect material SC characteristics significantly; the j c at 10-20 K was slightly higher and the material density was higher by 11%, when pressures of 50-96 MPa were used. The structure of SPS-produced MgB 2 material contains Mg-B-O inclusions and inclusions of higher borides (of compositions near MgB 4, MgB 7, MgB 12, MgB 17, MgB 20), which can be pinning centers. The presence of higher borides in the MgB 2 structure can be revealed by the SEM and Raman spectroscopy.

  • 19.
    Prikhna, Tatjana A.
    et al.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Gawalek, Wolfgang
    Institut für Photonische Technologien, Jena.
    Goldacker, Wilfried
    Karlsruhe Institute of Technology.
    Savchuk, Yaroslav M.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Noudem, Jacques
    CNRS/CRISMAT/ISMRA.
    Soldatov, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Eisterer, Mikhael
    TU Wien-Atominstitut, Vienna University of Technology Institute of Atomic and Subatomic Physics.
    Weber, Hárakd W.
    TU Wien-Atominstitut, Vienna University of Technology Institute of Atomic and Subatomic Physics.
    Sokolovsky, Vladimir
    Ben-Gurion University of Negev.
    Serga, Maxim
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Dub, Sergey N.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Wendt, Michael
    Institut für Photonische Technologien, Jena.
    You, Shujie
    Sergienko, Nina V.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Moshchil, Viktor E.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Tkash, Vasiliy N.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Dellith, Jan
    Institut für Photonische Technologien, Jena.
    Karau, Friedrich
    H.C. Starck GmbH, Goslar.
    Tomsic, Mikhael
    Hyper Tech Research, Inc., 1275 Kinnear Road, Columbus.
    Shmidt, Shrista
    Institut für Photonische Technologien, Jena.
    Fresenko, Igor P.
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    Habisreuther, Tobias
    Institut für Photonische Technologien, Jena.
    Litzkendorf, Doris
    Institut für Photonische Technologien, Jena.
    Meerovich, Viktor
    Ben-Gurion University of Negev.
    Sverdun, Vladimir
    Institute for Superhard Materials, National Academy of Sciences of Ukraine.
    High-pressure synthesized nanostructural MgB2 materials with high performance of superconductivity, suitable for fault current limitation and other applications2011In: IEEE transactions on applied superconductivity (Print), ISSN 1051-8223, E-ISSN 1558-2515, Vol. 21, no 3, p. 2694-2697Article in journal (Refereed)
    Abstract [en]

    A variety of samples made via different routes were investigated. Samples are nanostructured (average grain sizes are about 20 nm). The advantage of high-pressure (HP)-manufactured (2 GPa, 800-1050 degrees C, 1 h) MgB2 bulk is the possibility to get almost theoretically dense (1-2% porosity) material with very high critical current densities reaching at 20 K, in 0-1 T j(c) = 1.2 - 1.0 . 10(6) A/cm(2) (with 10% SiC doping) and j(c) = 9.2 - 7.3 10(5) A/cm(2) (without doping). Mechanical properties are also very high: fracture toughness up to 4.4 +/- 0.04 MPa . m(0.5) and 7.6 +/- 2.0 MPa . m(0.5) at 148.8 N load for MgB2 undoped and doped with 10% Ta, respectively. The HP-synthesized material at moderate temperature (2 GPa, 600 degrees C, 1 h) from B with high amount of impurity C (3.15%) and H (0.87%) has j(c) = 10(3) A/cm(2) in 8 T field at 20 K, highest irreversibility fields (at 18.4 K H-irr = 15 T) and upper critical fields (at 22 K H-C2 = 15 T) but 17% porosity. HP materials with stoichiometry near MgB12 can have T-c = 37 K and j(c) = 6 . 10(4) A/cm(2) at 0 T and H-irr = 5 T at 20 K. The spark plasma synthesized (SPS) material (50 MPa, 600-1050 degrees C 1.3 h, without additions), demonstrated at 20 K, in 0-1 T j(c) = 4.5 - 4 10(5) A/cm(2). Dispersed inclusions of higher magnesium borides, which are usually present in MgB2 structure and obviously create new pinning centers can be revealed by Raman spectroscopy (for the first time a spectrum of MgB7 was obtained). Tests of quench behavior, losses on MgB2 rings and material thermal conductivity show promising properties for fault current limiters. Due to high critical fields, the material can be used for magnets

  • 20.
    Prikhna, Tetiana
    et al.
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Gawalek, Wolfgang
    Instistut für Photonische Techologien, Jena, D-07745, Germany.
    Savchuk, Yaroslav
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Serga, Maxim
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Habisreuther, Tobias
    Instistut für Photonische Techologien, Jena, D-07745, Germany.
    Soldatov, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Eisterer, Michael
    Vienna University of Technology, Atominstitut, 1020 Viennea, Austria.
    Weber, Harald W.
    Vienna University of Technology, Atominstitut, 1020 Viennea, Austria.
    Noudem, Jacques
    CNR/CRISMAT, 6, Bd du Maréchal Juin, CNRS UMR 6508, 14050, Caen, France.
    Sokolovsky, Vladimir
    Ben-Gurion Universityof the Negev, P.O.B. 653, Beer-Sheva 8410,5 Israel.
    Karau, Friedrich
    H.C. Starck GmbH, Goslar 38642, Germany.
    Dellith, Jan
    Instistut für Photonische Techologien, Jena, D-07745, Germany.
    Wendt, Michael
    Instistut für Photonische Techologien, Jena, D-07745, Germany.
    Tompsic, Mikhael
    Hyper Tech research, Inc. 1275 Kinnear Road Columbus, OH 43212, USA.
    Tkach, Vasiliy
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Danilenko, Nikolay
    Institute for Problems in Material Science of the Nationel Academy o Sciences of Ukraine, 3 Krzhizhanovsky Street, Kiev, 03680, Ukraine.
    Fesenko, Igor
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Dub, Sergey N.
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Moshchil, Vladimir
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Sergienko, Nina
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Schmidt, Christa
    Instistut für Photonische Techologien, Jena, D-07745, Germany.
    Litzkendorf, Doris
    Instistut für Photonische Techologien, Jena, D-07745, Germany.
    Nagorny, Peter
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Sverdun, Vladimir
    Institute for Superhard Materials of the National Academy of Sciences of Ukraine, Kiev 04074, Ukraine.
    Vajda, Istvan
    Budapest University of Technology and Echonomics, Budapest, Hungary 1111 Budapest, Egry Jozsef u. 18. Hungary.
    Kósa, Janos
    Budapest University of Technology and Echonomics, Budapest, Hungary 1111 Budapest, Egry Jozsef u. 18. Hungary.
    The effect of oxygen distribution inhomogeneity and presence of higher borides on the critical current density improvement of nanostructural MgB22010In: Advances in Science and Technology, ISSN 1662-0356, Vol. 75, p. 161-166Article in journal (Refereed)
    Abstract [en]

    MgB2-based nanostructural materials with rather high oxygen concentration (5-14 wt.%) and dispersed grains of higher borides (MgB12, MgB7) high-pressure (2 GPa or 30 MPa) synthesized (in-situ) or sintered (ex-situ) demonstrated high superconducting characteristics (critical current density, jc, up to 1.8-1.0106 A/cm2 in the self magnetic field and 103 in 8 T field at 20 K, 3-1.5105 A/cm2 in the self field at 35 K, upper critical field up to HC2 = 15 T at 22 K, field of irreversibility Hirr =13 T at 20 K). The additives (Ti, SiC) and synthesis or sintering temperature can affect the segregation of oxygen and formation of oxygen-enriched Mg-B-O inclusions in the material structure, thus reducing the amount of oxygen in the material matrix as well as the formation of higher borides grains, which affects an increase of the critical current density. The record high HC2 and Hirr have been registered for the material high-pressure (2 GPa) synthesized from Mg and B at 600 oC having 17% porosity and more than 7 wt.% of oxygen. The attained values of the critical current, AC losses and thermal conductivity make the materials promising for application for fault current limiters and electromotors. The structural and superconducting (SC) characteristics of the material with matrix close to MgB12 in stoichiometry has been studied and the SC transition Tc=37 K as well as jc= 5×104 A/cm2 at 20 K in the self field were registered, its Raman spectrum demonstrated metal-like behavior.

  • 21.
    Solomon, Getachew
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gilzad Kohan, Mojtaba
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vagin, Mikhail
    Department of Science and Technology, Laboratory of Organic Electronics, Linköping University, SE-601 74 Norrköping, Sweden.
    Rigoni, Federica
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy.
    Mazzaro, Raffaello
    CNR-Institute of Microelectronics and Microsystem (IMM), Section of Bologna Via Piero Gobetti 101, Bologna 40129, Italy.
    Natile, Marta Maria
    Institute of Condensed Matter Chemistry and Technologies for Energy (ICMATE), National Research Council (CNR) and Department of Chemical Sciences, University of Padova, Via Francesco Marzolo, 1, 35131 Padova PD, Italy.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Morandi, Vittorio
    CNR-Institute of Microelectronics and Microsystem (IMM), Section of Bologna Via Piero Gobetti 101, Bologna 40129, Italy.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy.
    Decorating vertically aligned MoS2 nanoflakes with silver nanoparticles for inducing a bifunctional electrocatalyst towards oxygen evolution and oxygen reduction reaction2021In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 81, article id 105664Article in journal (Refereed)
    Abstract [en]

    Catalysts capable of improving the performance of oxygen evolution reaction (OER) and oxygen reduction reactions (ORR) are essential for the advancement of renewable energy technologies. Herein, Ag-decorated vertically aligned MoS2 nanoflakes are developed via magnetron co-sputtering and investigated as electrocatalyst towards OER and ORR. Due to the presence of silver, the catalyst shows more than 1.5 times an increase in the roughness-normalized rate of OER, featuring a very low Tafel slope (58.6 mv dec−1), thus suggesting that the catalyst surface favors the thermodynamics of hydroxyl radical (OH•) adsorption with the deprotonation steps being the rate-determining steps. The improved performance is attributed to the strong interactions between OOH intermediates and the Ag surface which reduces the activation energy. Rotating ring disk electrode (RRDE) analysis shows that the net disk currents on the Ag-MoS2 sample are two times higher at 0.65 V compared to MoS2, demonstrating the co-catalysis effect of silver doping. Based on the rate constant values, Ag-MoS2 proceeds through a mixed 4 electron and a 2 + 2 serial route reduction mechanism, in which the ionized hydrogen peroxide is formed as a mobile intermediate. The presence of silver decreases the electron transfer number and increases the peroxide yield due to the interplay of a 2 + 2 electron reduction pathway. A 2.5–6 times faster conversion rate of peroxide to OH- observed due to the presence of silver, indicating its effective cocatalyst nature. This strategy can help in designing a highly active bifunctional catalyst that has great potential as a viable alternative to precious-metal-based catalysts.Graphica

  • 22.
    Solomon, Getachew
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mazzaro, Raffaello
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Natile, Marta Maria
    CNR-Institute of Condensed Matter Chemistry and Technologies for Energy (ICMATE), Department of Chemical Sciences, University of Padova, Padova , Italy.
    Morandi, Vittorio
    CNR-Institute of Microelectronics and Microsystem (IMM), Bologna, Italy.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Ag2S/MoS2 Nanocomposites Anchored on Reduced Graphene Oxide: Fast Interfacial Charge Transfer for Hydrogen Evolution Reaction2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 25, p. 22380-22389Article in journal (Refereed)
    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.

  • 23.
    Tahira, Aneela
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Ibupoto, Zafar
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Dr. M.A Kazi Institute of Chemistry University of Sindh Jamshoro, Sindh, Pakistan.
    Mazzaro, Raffaello
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Istituto per la Microelettronica ed i Microsistemi, Consiglio Nazionale delle Ricerche (IMM-CNR), Bologna, Italy.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Morandi, Vittorio
    Istituto per la Microelettronica ed i Microsistemi, Consiglio Nazionale delle Ricerche (IMM-CNR), Bologna, Italy.
    Natile, Marta Maria
    Università di Padova, Padova, Italy.
    Vagin, Mikhail
    Linköping University, Norrköping, Sweden.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Ca’ Foscari University Venice, Venice, Italy.
    Advanced Electrocatalysts for Hydrogen Evolution Reaction Based on Core–Shell MoS2/TiO2 Nanostructures in Acidic and Alkaline Media2019In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 2, no 3, p. 2053-2062Article in journal (Refereed)
    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.

  • 24.
    Taranova, Anastasiia
    et al.
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, 30172, Venice, Italy View author publications.
    Akbar, Kamran
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, 30172, Venice, Italy.
    Yusupov, Khabib
    Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83, Linköping, Sweden.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Polewczyk, Vincent
    Istituto Officina dei Materiali (IOM) - CNR, Laboratorio TASC, Area Science Park, S.S. 14 Km 163.5, Trieste, I-34149, Italy.
    Mauri, Silvia
    Istituto Officina dei Materiali (IOM) - CNR, Laboratorio TASC, Area Science Park, S.S. 14 Km 163.5, Trieste, I-34149, Italy; Dipartimento di Fisica, University of Trieste, via A. Valerio 2, 34127, Trieste, Italy.
    Balliana, Eleonora
    Department of Environmental Sciences, Informatics and Statistics, Ca’ Foscari University of Venice, Scientific Campus Via Torino 155/b, 30173, Venice, Italy.
    Rosen, Johanna
    Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83, Linköping, Sweden.
    Moras, Paolo
    Istituto di Struttura della Materia (ISM) - CNR, S.S. 14 Km 163.5, Trieste, I-34149, Italy.
    Gradone, Alessandro
    Istituto per la Microelettronica ed i Microsistemi (IMM) – CNR Sede di Bologna, via Gobetti 101, 40129, Bologna, Italy.
    Morandi, Vittorio
    Istituto per la Microelettronica ed i Microsistemi (IMM) – CNR Sede di Bologna, via Gobetti 101, 40129, Bologna, Italy.
    Moretti, Elisa
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, 30172, Venice, Italy.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, 30172, Venice, Italy.
    Unraveling the optoelectronic properties of CoSbx intrinsic selective solar absorber towards high-temperature surfaces2023In: Nature Communications, E-ISSN 2041-1723, Vol. 14, no 1, article id 7280Article in journal (Refereed)
    Abstract [en]

    The combination of the ability to absorb most of the solar radiation and simultaneously suppress infrared re-radiation allows selective solar absorbers (SSAs) to maximize solar energy to heat conversion, which is critical to several advanced applications. The intrinsic spectral selective materials are rare in nature and only a few demonstrated complete solar absorption. Typically, intrinsic materials exhibit high performances when integrated into complex multilayered solar absorber systems due to their limited spectral selectivity and solar absorption. In this study, we propose CoSbx (2 < x < 3) as a new exceptionally efficient SSA. Here we demonstrate that the low bandgap nature of CoSbx endows broadband solar absorption (0.96) over the solar spectral range and simultaneous low emissivity (0.18) in the mid-infrared region, resulting in a remarkable intrinsic spectral solar selectivity of 5.3. Under 1 sun illumination, the heat concentrates on the surface of the CoSbx thin film, and an impressive temperature of 101.7 °C is reached, demonstrating the highest value among reported intrinsic SSAs. Furthermore, the CoSbx was tested for solar water evaporation achieving an evaporation rate of 1.4 kg m−2 h−1. This study could expand the use of narrow bandgap semiconductors as efficient intrinsic SSAs with high surface temperatures in solar applications.

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  • 25. You, Shujie
    et al.
    Mases, Mattias
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Dobryden, Illia
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Green, Alexander A.
    Department of Materials Science and Engineering, Northwestern University, Evanston, IL.
    Hersam, Mark C.
    Department of Materials Science and Engineering, Northwestern University, Evanston, IL.
    Soldatov, Alexander
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Probing structural stability of double-walled carbon nanotubes at high non-hydrostatic pressure by Raman spectroscopy2011In: High Pressure Research, ISSN 0895-7959, E-ISSN 1477-2299, Vol. 31, no 1, p. 186-190Article in journal (Refereed)
    Abstract [en]

    Theoretical calculations predict that the collapse pressure for double-walled carbon nanotubes (DWCNTs) is proportional to 1/R3, where R is the effective or average radius of a DWCNT. In order to address the problem of CNT stability at high pressure and stress, we performed a resonance Raman study of DWCNTs dispersed in sodium cholate using 532 and 633 nm laser excitation. Raman spectra of the recovered samples show minor versus irreversible changes with increasing ID/IG ratio after exposure to high non-hydrostatic pressure of 23 and 35 GPa, respectively. The system exhibits nearly 70% pressure hysteresis in radial breathing vibrational mode signals recovery on pressure release which is twice that predicted by theory.

  • 26.
    You, Shujie
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Patelli, Alessandro
    Department of Physics and Astronomy, University of Padova, Padova, Italy.
    Ghamgosar, Pedram
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Cesca, Tiziana
    Department of Physics and Astronomy, University of Padova, Padova, Italy.
    Enrichi, Francesco
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Venezia Mestre, Italy.
    Mattei, Giovanni
    Department of Physics and Astronomy, University of Padova, Padova, Italy.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Tuning ZnO nanorods photoluminescence through atmospheric plasma treatments2019In: APL Materials, E-ISSN 2166-532X, Vol. 7, no 8, article id 08111Article in journal (Refereed)
    Abstract [en]

    Room temperature atmospheric plasma treatments are widely used to activate and control chemical functionalities at surfaces. Here, we investigated the effect of atmospheric pressure plasma jet (APPJ) treatments in reducing atmosphere (Ar/1‰ H2 mixture) on the photoluminescence (PL) properties of single crystal ZnO nanorods (NRs) grown through hydrothermal synthesis on fluorine-doped tin oxide glass substrates. The results were compared with a standard annealing process in air at 300 °C. Steady-state photoluminescence showed strong suppression of the defect emission in ZnO NRs for both plasma and thermal treatments. On the other side, the APPJ process induced an increase in PL quantum efficiency (QE), while the annealing does not show any improvement. The QE in the plasma treated samples was mainly determined by the near band-edge emission, which increased 5–6 fold compared to the as-prepared samples. This behavior suggests that the quenching of the defect emission is related to the substitution of hydrogen probably in zinc vacancies (VZn), while the enhancement of UV emission is due to doping originated by interstitial hydrogen (Hi), which diffuses out during annealing. Our results demonstrate that atmospheric pressure plasma can induce a similar hydrogen doping as ordinarily used vacuum processes and highlight that the APPJ treatments are not limited to the surfaces but can lead to subsurface modifications. APPJ processes at room temperature and under ambient air conditions are stable, convenient, and efficient methods, compared to thermal treatments to improve the optical and surface properties of ZnO NRs, and remarkably increase the efficiency of UV emission.

  • 27.
    Yusupov, Khabib
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hedman, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Tsapenko, Alexey P.
    Skolkovo Institute of Science and Technology, Moscow, Russian Federation. Department of Applied Physics, Aalto University, Espoo, Finland.
    Ishteev, A.
    Department of Functional Nanosystems and High-Temperature Materials, National University of Science and Technology “MISiS” Moscow, Russian Federation.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Khovaylo, V.
    Department of Functional Nanosystems and High-Temperature Materials, National University of Science and Technology “MISiS” Moscow, Russian Federation. National Research South Ural State University, Chelyabinsk, Russian Federation.
    Larsson, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Nasibulin, Albert G.
    Skolkovo Institute of Science and Technology, Moscow, Russian Federation. Department of Applied Physics, Aalto University, Espoo, Finland.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Venezia Mestre, Italy.
    Enhancing the thermoelectric performance of single-walled carbon nanotube-conducting polymer nanocomposites2020In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 845, article id 156354Article in journal (Refereed)
    Abstract [en]

    Harnessing energy lost in the form of heat is an important challenge today. Organic thermoelectric materials (TE) can convert lost heat into electricity at relatively low temperature. Single-walled carbon nanotubes (SWCNTs) are known to boost the TE properties of organic-based materials at room temperature (TR). However, the TE performance decreases with the increasing temperature, which restricts the working temperature region of the devices. Here, we present a three steps investigation: initially, the influence of the net of SWCNTs on TE properties of polymer matrix; secondly, creation of hybrid fillers via SWCNTs treatment with gold chloride; lastly, chemical post-treatment of obtained systems in the temperature range 325–410 K. In the process of HAuCl4 aerosolization (gold chloride treatment) on the surface of nanotubes, different ionic conformations (Au and AuCl4−) can be formed. For this reason, we performed a theoretical investigation on the influence of ionic conformations on SWCNTs on the electronic structure. Implementation of SWCNTs net into polymer matrix alongside gold chloride doping and chemical post-treatment successfully increased the power factor of the system in the temperature interval from 300 to 410 K. These results demonstrate the potential of combined approach in creation of hybrid fillers based on organic/inorganic materials with chemical post-treatment in boosting the thermoelectric performance within the whole operating temperature of polymer-based composite alongside the importance of theoretical modeling in tuning the electronic structure of composite systems through a material-by-design approach.

  • 28.
    Yusupov, Khabib
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Functional Nanosystems and High-Temperature Materials National University of Science and Technology MISIS Moscow.
    Stumpf, Steffi
    Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Bogach, Aleksei
    Prokhorov General Physics Institute of the Russian Academy of Sciences.
    Martinez, Patricia M.
    NanoTech Institute University of Texas at Dallas Richardson .
    Zakhidov, Anvar
    Department of Functional Nanosystems and High-Temperature Materials National University of Science and Technology MISIS Moscow.
    Schubert, Ulrich S.
    Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena.
    Khovaylo, Vladimir V.
    Department of Functional Nanosystems and High-Temperature Materials National University of Science and Technology MISIS Moscow.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Flexible Thermoelectric Polymer Composites Based on a Carbon Nanotubes Forest2018In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 28, no 40, article id 1801246Article in journal (Refereed)
    Abstract [en]

    Polymer-based composites are of high interest in the field of thermoelectric (TE) materials because of their properties: abundance, low thermal conductivity, and nontoxicity. In applications, like TE for wearable energy harvesting, where low operating temperatures are required, polymer composites demonstrate compatible with the targeted specifications. The main challenge is reaching high TE efficiency. Fillers and chemical treatments can be used to enhance TE performance of the polymer matrix. The combined application of vertically aligned carbon nanotubes forest (VA-CNTF) is demonstrated as fillers and chemical post-treatment to obtain high-efficiency TE composites, by dispersing VA-CNTF into a poly (3,4-ethylenedioxythiophene) polystyrene sulfonate matrix. The VA-CNTF keeps the functional properties even in flexible substrates. The morphology, structure, composition, and functional features of the composites are thoroughly investigated. A dramatic increase of power factor is observed at the lowest operating temperature difference ever reported. The highest Seebeck coefficient and electrical conductivity are 58.7 μV K-1 and 1131 S cm-1, respectively. The highest power factor after treatment is twice as high in untreated samples. The results demonstrate the potential for the combined application of VA-CNTF and chemical post-treatment, in boosting the TE properties of composite polymers toward the development of high efficiency, low-temperature, flexible TEs.

  • 29.
    Yusupov, Khabib
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Functional Nanosystems and High Temperature Materials, NUST MISiS, Moscow, Russia; Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Germany.
    Zakhidov, A.
    Department of Functional Nanosystems and High Temperature Materials, NUST MISiS, Moscow, Russia; NanoTech Institute, University of Texas at Dallas, USA.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Stumpf, S.
    Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Germany; Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Germany.
    Martinez, P.M.
    NanoTech Institute, University of Texas at Dallas, USA.
    Ishteev, A.
    Department of Functional Nanosystems and High Temperature Materials, NUST MISiS, Moscow, Russia.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Khovaylo, V.
    Department of Functional Nanosystems and High Temperature Materials, NUST MISiS, Moscow, Russia; National Research South Ural State University, Chelyabinsk, Russian Federation.
    Schubert, U.
    Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Germany; Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Germany; Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Germany.
    Influence of oriented CNT forest on thermoelectric properties of polymer-based materials2018In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 741, p. 392-397Article in journal (Refereed)
    Abstract [en]

    Thermoelectric (TE) materials are highly important due to their ability to convert wasted heat energy into electricity. Among the different TE materials, organic-based or polymer-based TE systems are among the most promising due to their sustainability, non-toxicity and good electrical properties. In our research, we have investigated for the first time the application of vertically aligned carbon nanotubes forest (VA-CNTF) as a filler for TE composite; compared to unconnected carbon nanotubes (CNT), which are typically used in polymer/CNT composites, dry pulled VA-CNTF sheets have more ordered structure, which is supposed to improve the TE efficiency of the material. VA-CNTF and short unoriented multiwalled carbon nanotubes (MWCNT) were used as fillers of a polymeric matrix, to prepare TE composites. Various stacking configurations were explored by using CNTF. All the samples were examined by scanning electron microscopy (SEM), micro-Raman spectroscopy, and four-point probe electrical measurements; MWCNT-based samples were used as benchmarking systems.

    The results revealed a dramatic increase of the Seebeck coefficient up to 46 μV/K for the VA-CNTF-based sample, while the best MWCNTs-based sample (MWCNT concentration 50 wt%) provided only 21.49, which is roughly the Seebeck coefficient of pure polymer. This research represents the first application of VA-CNTF as a promising material for TE systems and demonstrates that oriented nanoforests and related CNT sheets are a very perspective material for promising developments in the field.

  • 30.
    Zhao, Haiguang
    et al.
    State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China; College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China.
    Liu, Guiju
    College of Physics, University Industry Joint Center for Ocean Observation and Broadband Communication, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China.
    You, Shujie
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Camargo, Franco V. A.
    Dipartimento di Fisica & Dipartimento di Energia, Politecnico di Milano, via G. Ponzio 34/3 and IFN-CNR, piazza L. da Vinci 32, 20133 Milano, Italy.
    Zavelani-Rossi, Margherita
    Dipartimento di Fisica & Dipartimento di Energia, Politecnico di Milano, via G. Ponzio 34/3 and IFN-CNR, piazza L. da Vinci 32, 20133 Milano, Italy.
    Wang, Xiaohan
    State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China; College of Textiles & Clothing, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China.
    Sun, Changchun
    State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China; College of Textiles & Clothing, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China.
    Liu, Bing
    State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China.
    Zhang, Yuanming
    State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China.
    Han, Guangting
    State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, No. 308 Ningxia Road, Qingdao 266071, P. R. China.
    Vomiero, Alberto
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Molecular Science and Nano Systems, Ca' Foscari University of Venice Via Torino 155, 30172 Venezia Mestre, Italy.
    Gong, Xiao
    State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, Hubei, P. R. China.
    Gram-scale synthesis of carbon quantum dots with a large Stokes shift for the fabrication of eco-friendly and high-efficiency luminescent solar concentrators2021In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 14, no 1, p. 396-406Article in journal (Refereed)
    Abstract [en]

    Luminescent solar concentrators (LSCs) are large-area sunlight collectors coupled to small area solar cells, for efficient solar-to-electricity conversion. The three key points for the successful market penetration of LSCs are: (i) removal of light losses due to reabsorption during light collection; (ii) high light-to-electrical power conversion efficiency of the final device; (iii) long-term stability of the LSC structure related to the stability of both the matrix and the luminophores. Among various types of fluorophores, carbon quantum dots (C-dots) offer a wide absorption spectrum, high quantum yield, non-toxicity, environmental friendliness, low-cost, and eco-friendly synthetic methods. However, they are characterized by a relatively small Stokes shift, compared to inorganic quantum dots, which limits the highest external optical efficiency that can be obtained for a large-area single-layer LSC (>100 cm2) based on C-dots below 2%. Herein, we report highly efficient large-area LSCs (100–225 cm2) based on colloidal C-dots synthesized via a space-confined vacuum-heating approach. This one batch reaction could produce Gram-scale C-dots with a high quantum yield (QY) (∼65%) using eco-friendly citric acid and urea as precursors. Thanks to their very narrow size distribution, the C-dots produced via the space-confined vacuum-heating approach had a large Stokes shift of 0.53 eV, 50% larger than C-dots synthesized via a standard solvothermal reaction using the same precursors with a similar absorption range. The large-area LSC (15 × 15 × 0.5 cm3) prepared by using polyvinyl pyrrolidone (PVP) polymer as a matrix exhibited an external optical efficiency of 2.2% (under natural sun irradiation, 60 mW cm−2, uncharacterized spectrum). After coupling to silicon solar cells, the LSC exhibited a power conversion efficiency (PCE) of 1.13% under natural sunlight illumination (20 mW cm−2, uncharacterized spectrum). These unprecedented results were obtained by completely suppressing the reabsorption losses during light collection, as proved by optical spectroscopy. These findings demonstrate the possibility of obtaining eco-friendly, high-efficiency, large-area LSCs through scalable production techniques, paving the way to the lab-to-fab transition of this kind of devices.

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