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  • 1.
    Al-Maqdasi, Zainab
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Joffe, Roberts
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Ouarga, Ayoub
    High Throughput Multidisciplinary Research Laboratory, Mohammed VI Polytechnic University (UM6P), Lot 660—Hay Moulay Rachid, 43150 Benguerir, Morocco.
    Emami, Nazanin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Chouhan, Shailesh Singh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Landström, Anton
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hajlane, Abdelghani
    Laboratory of Crystallography and Materials Sciences, National Graduate School of Engineering of Caen, 6 Boulevard Maréchal Juin, 14000 Caen, France.
    Conductive Regenerated Cellulose Fibers for Multi-Functional Composites: Mechanical and Structural Investigation2021In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 14, no 7, article id 1746Article in journal (Refereed)
    Abstract [en]

    Regenerated cellulose fibers coated with copper via electroless plating process are investigated for their mechanical properties, molecular structure changes, and suitability for use in sensing applications. Mechanical properties are evaluated in terms of tensile stiffness and strength of fiber tows before, during and after the plating process. The effect of the treatment on the molecular structure of fibers is investigated by measuring their thermal stability with differential scanning calorimetry and obtaining Raman spectra of fibers at different stages of the treatment. Results show that the last stage in the electroless process (the plating step) is the most detrimental, causing changes in fibers’ properties. Fibers seem to lose their structural integrity and develop surface defects that result in a substantial loss in their mechanical strength. However, repeating the process more than once or elongating the residence time in the plating bath does not show a further negative effect on the strength but contributes to the increase in the copper coating thickness, and, subsequently, the final stiffness of the tows. Monitoring the changes in resistance values with applied strain on a model composite made of these conductive tows show an excellent correlation between the increase in strain and increase in electrical resistance. These results indicate that these fibers show potential when combined with conventional composites of glass or carbon fibers as structure monitoring devices without largely affecting their mechanical performance.

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  • 2.
    Di Mauro, Alessandro
    et al.
    Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via S. Sofia 64, 95123 Catania.
    Landström, Anton
    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.
    Impellizzeri, Giuliana
    Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via Monteroni, 73100 Lecce.
    Privitera, Vittorio
    Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via S. Sofia 64, 95123 Catania, Italy.
    Epifani, Mauro
    Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via Monteroni, 73100 Lecce, Italy.
    Surface Modification by Vanadium Pentoxide Turns Oxide Nanocrystals into Powerful Adsorbents of Methylene Blue2019In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 533, p. 369-374Article in journal (Refereed)
    Abstract [en]

    Hypothesis: If nanocrystals of such semiconductor as SnO2 and TiO2, which are not known as powerful adsorbents, have their surface modified by layer of V2O5, how will the adsorption properties be affected? Answering this question would provide a new set of surface properties to be designed by surface engineering of oxide nanocrystals.

    Experiments: SnO2 and TiO2 colloidal nanocrystals were prepared by coupling sol-gel and solvothermal synthesis. By co-processing with V chloroalkoxide and subsequent heat-treatment at 400-500 °C, surface deposition of V2O5 layers was obtained. The methylene blue adsorption onto the prepared materials was tested and compared with the pure oxide supports. Cycling of the materials and analysis of the adsorption process was also investigated.

    Findings: The V-modified nanocrystals extracted ∼ 80% methylene blue from 1.5 x 10-5 M aqueous solution after 15 min only, contrarily to pure materials, which took up only 30% of the dye even after 120 min. Comparison with pure commercial V2O5 showed that the peculiar adsorption properties were imparted by the surface deposition of the V2O5-like layers. This report demonstrates that new classes of adsorbing materials can be conceived by suitably coupling different metal oxides.

  • 3.
    Di Mauro, Alessandro
    et al.
    CNR-IMM, Via S. Sofia 64, 95123 Catania, Italy.
    Natile, Marta Maria
    Istituto di Chimica della Materia Condensata e Tecnologie per l’Energia, Consiglio Nazionale delle Ricerche (ICMATE-CNR) and Dipartimento di Scienze Chimiche, Università di Padova, Via F. Marzolo 1, 35131 Padova, Italy.
    Landström, Anton
    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.
    Ferroni, Matteo
    Department of Information Engineering, University of Brescia, Via Branze, Brescia, Italy. CNR-IMM, Via Gobetti, Bologna, Italy.
    Privitera, Vittorio
    CNR-IMM, Via S. Sofia 64, 95123 Catania, Italy.
    Impellizzeri, Giuliana
    CNR-IMM, Via S. Sofia 64, 95123 Catania, Italy.
    Epifani, Mauro
    CNR-IMM, Via Monteroni c/o Campus Universitario, 73100 Lecce, Italy.
    Visible Light Photodegradation of Dyes and Paracetamol by Direct Sensitization Mechanism onto Metallic MoO2 Nanocrystals2021In: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 413, article id 113258Article in journal (Refereed)
    Abstract [en]

    MoO2 nanocrystals were prepared by solvothermal treatment of a Mo chloromethoxide at 250 °C in oleic acid. The monoclinic MoO2 phase, with a mean crystallite size of 29 nm, formed through reduction of molybdenum bronzes. The as-prepared MoO2 nanocrystals were free from organics, allowing their use in photodegradation tests of organic pollutants (methylene blue, rhodamine B, paracetamol), without any preliminary purification treatment of the nanocrystals. It was found that MoO2 was an efficient adsorbent of methylene blue (43 mg g-1 for 1.5 × 10−4 M concentration) in the dark and an efficient photodegradation catalyst under visible light (all methylene blue removed from the solution after 240 min). From the analysis of the combined photodegradation tests of rhodamine B and paracetamol, it was clarified that direct sensitization was responsible for photodegradation. This finding was related to the work function value of metallic MoO2, placed at more negative values if compared with other metallic materials.

  • 4.
    Epifani, Mauro
    et al.
    Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via Monteroni, Lecce, Italy.
    Kaciulis, Saulius
    Istituto per lo Studio dei Materiali Nanostrutturati, ISMN–CNR, Roma, Italy.
    Mezzi, Alessio
    Istituto per lo Studio dei Materiali Nanostrutturati, ISMN–CNR, Roma, Italy.
    Zhan, Ting
    Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, Spain.
    Arbiol, Jordi
    Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC BIST, Campus UAB, Barcelona, Catalonia, Spain. ICREA, Barcelona, Catalonia, Spain.
    Siciliano, Pietro
    Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via Monteroni, Lecce, Italy.
    Landström, Anton
    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.
    Moumen, Abderrahim
    Department of Information Engineering, Brescia University, Brescia, Italy.
    Comini, Elisabetta
    Department of Information Engineering, Brescia University, Brescia, Italy.
    Xiangfeng, Chu
    School of Chemistry and Chemical Engineering, Anhui University of Technology, Maanshan, Anhui, PR China.
    Rhodium as efficient additive for boosting acetone sensing by TiO2 nanocrystals: Beyond the classical view of noble metal additives2020In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 319, article id 128338Article in journal (Refereed)
    Abstract [en]

    Anatase TiO2 nanocrystals were prepared by solvothermal synthesis and modified by in- situ generated Rh nanoparticles, with a starting nominal Rh:Ti atomic concentration of 0.01 and 0.05. After heat-treatment at 400 °C the TiO2 host was still in the anatase crystallographic phase, embedding Rh nanoparticles homogeneously distributed and whose surface had been oxidized to Rh2O3, as established by X-ray diffraction, Transmission Electron Microscopy and X-ray Photoelectron spectroscopy. Moreover, Rh seemed also homogeneously distributed in elemental form or as Rh2O3 nanoclusters. The acetone sensing properties of the resulting materials were enhanced by Rh addition, featuring a response increase of one order of magnitude at the best operating temperature of 300 °C. Moreover, Rh addition enlarged the detection range down to 10 ppm whereas pure TiO2 was not able of giving an appreciable response already at a concentration as high as 50 ppm. From the sensing data, the enhancement of the sensor response was attributed to the finely dispersed Rh species and not to the oxidized Rh nanocrystals.

  • 5.
    Landström, Anton
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Nanostructured Metal Oxide Semiconductors for Functional Applications2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is about nanostructured metal oxides, their properties, and some of their applications. Semiconducting metal oxides like TiO2, ZnO,and SnO2 have a wide band gap, which means they absorb UV light andgenerate electron-hole pairs. These charge carriers can be harnessed andused for a variety of purposes, such as electricity generation in solar cells,hydrogen production by means of photolysis and electrolysis, andenvironmental remediation by mineralizing pollutants in photocatalyticreactions. However, they are typically not very efficient when comparedwith e.g. noble metals in catalysis or silicon in solar cells , and so a widevariety of strategies have been employed to remedy their weaknesses.Such strategies include structuring the materials at the nanoscale, and thefabrication of composite materials and heterostructures.In this work, some advanced hybrid materials have been studied,composed of metal oxide and various additives, such as reduced grapheneoxide (rGO), other metal oxides, and flavonoids. The materials have beenextensively characterized in order to determine how these additives affectthe processes going on in some of the mentioned applications. Thestudied systems include rGO-ZnO, SnO2-ZnO, Rh-TiO2, MoO2, SiO2coupled to 3-hydroxyflavone and 7-hydroxyflavone, and 3-hydroxyflavone-TiO2.Particles of ZnO-encapsulated rGO exhibited a good photocatalyticactivity towards the degradation of rhodamine B and phenol, but it wasfound that the main determinant of the performance was the quality ofthe semiconductor component as opposed to any favorable interactionsbetween ZnO and rGO. However, the incorporation of rGO could stillalmost double the observed performance, which was attributed to apassivation of the defects in the metal oxide host, as well as a beneficialimpact of electrochemical properties such as charge transfer resistance anddouble-layer capacitance of the resulting material.Core-shell nanoparticles consisting of a SnO2 core and a ZnO shell weresuccessfully synthesized and employed as photocatalyst and as photoanodein dye-sensitized solar cells (DSSCs). The ZnO shell improved theperformance in both photocatalysis and DSSCs by nearly a factor of two,due to a combination of the favorable properties of the two metal oxides ,and the formation of a heterojunction in the interface between them.Rhodium as an additive to TiO2 nanocrystals proved to effectivelyimprove the response in gas sensing experiments. The rhodium exhibitedcomplex speciation, however, being distributed as a homogeneouscoating of Rh(III) as well as nanocrystals of elemental rhodium,highlighting the need for deep characterization in this class of materials.Metallic MoO2 nanocrystals were synthesized and tested in photocatalysis.Due to their electronic nature, they cannot support photocatalysisaccording to the traditional reaction scheme, because metals cannotgenerate electron-hole pairs. However, they still exhibited significantphotocatalytic activity towards methylene blue, rhodamine B, andparacetamol. This was attributed to a direct sensitization mechanismwhere the dye is photoexcited and undergoes electron transfer, madepossible due to the comparatively low work function in MoO2. This alsoenables it to assist in the degradation of non-absorbing molecules in thesolution. 3-hydroxyflavone (3HF) and 7-hydroxyflavone (7HF) were combinedwith MCM-41 silica nanoparticles via a post-doping procedure, and theirphotophysics characterized by steady-state and time-resolvedspectroscopic techniques. Both flavonoid-coated nanoparticles turned outto be highly fluorescent and stable when exposed to air at roomtemperature, showing that organic fluorophore-based solid-state emitterscan be obtained by simple methods. Furthermore, 3HF was coupled toTiO2 nanoparticles with a similarly simple adsorption procedure. In thiscase the result was a chemisorption of the flavonoid, which appears to bevery similar to a chelation of the metal ions in the metal oxide substrate.The fluorescence in the resulting materials is nearly completely quenched,but when a nanometer-thin layer of Al2O3 is applied on the TiO2, it isinstead strongly enhanced. This work therefore represents a rather noveland facile way to produce flavonoid-metal complexes.

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  • 6.
    Landström, Anton
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gradone, Alessandro
    National Research Council, Institute for Microelectronics and Microsystems, Via Piero Gobetti 101, 40129, Bologna, Italy. Department of Chemistry “G. Ciamician”, University of Bologna, Via Francesco Selmi 2, 40126, Bologna, Italy.
    Mazzaro, Raffaello
    National Research Council, Institute for Microelectronics and Microsystems, Via Piero Gobetti 101, 40129, Bologna, Italy.
    Morandi, Vittorio
    National Research Council, Institute for Microelectronics and Microsystems, Via Piero Gobetti 101, 40129, Bologna, Italy.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Reduced graphene oxide-ZnO hybrid composites as photocatalysts: The role of nature of the molecular target in catalytic performance2021In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 47, no 14, p. 19346-19355Article in journal (Refereed)
    Abstract [en]

    Spurred by controversial literature findings, we enwrapped reduced graphene oxide (rGO) in ZnO hierarchical microstructures (rGO loadings spanning from 0.01 to 2 wt%) using an in situ synthetic procedure. The obtained hybrid composites were carefully characterized, aiming at shining light on the possible role of rGO on the claimed increased performance as photocatalysts. Several characterization tools were exploited to unveil the effect exerted by rGO, including steady state and time resolved photoluminescence, electron microscopies and electrochemical techniques, in order to evaluate the physical, optical and electrical features involved in determining the catalytic degradation of rhodamine B and phenol in water.

    Several properties of native ZnO structures were found changed upon the rGO enwrapping (including optical absorbance, concentration of native defects in the ZnO matrix and double-layer capacitance), which are all involved in determining the photocatalytic performance of the hybrid composites. The findings discussed in the present work highlight the high complexity of the field of application of graphene-derivatives as supporters of semiconducting metal oxides functionality, which has to be analyzed through a multi-parametric approach.

  • 7.
    Landström, Anton
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Leccese, Silvia
    Laboratoire de Réactivité de Surface UMR CNRS 7197, Sorbonne Université, 4 Place Jussieu, F-75005, Paris, France.
    Abadian, Hagop
    Laboratoire de Réactivité de Surface UMR CNRS 7197, Sorbonne Université, 4 Place Jussieu, F-75005, Paris, France.
    Lambert, Jean-François
    Laboratoire de Réactivité de Surface UMR CNRS 7197, Sorbonne Université, 4 Place Jussieu, F-75005, Paris, France.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Protti, Stefano
    PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 10, I-27100, Pavia, Italy.
    Seitsonen, Ari Paavo
    Département de Chimie, Ecole Normale Supérieure, 24 Rue Lhomond, F-75005, Paris, France; Paris Sciences et Lettres Université, Sorbonne Université et Centre National Du Recherche Scientifique (CNRS), F-75005, Paris, France.
    Mezzetti, Alberto
    Laboratoire de Réactivité de Surface UMR CNRS 7197, Sorbonne Université, 4 Place Jussieu, F-75005, Paris, France.
    Fluorescent silica MCM-41 nanoparticles based on flavonoids: Direct post-doping encapsulation and spectral characterization2021In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 185, Part A, article id 108870Article in journal (Refereed)
    Abstract [en]

    Flavones and flavonols are naturally-occurring organic molecules with interesting biological, chemical and photophysical properties. In recent years their interaction with silica surfaces has received increasing attention. In this work, the flavonol 3-hydroxyflavone (3HF) and the flavone 7-hydroxyflavone (7HF) have been encapsulated in MCM-41 mesoporous silica nanoparticles (NP) via a post-doping procedure, and their photophysics characterized by both steady state and time-resolved spectroscopic techniques. Both flavonoid-doped NPs resulted to be highly fluorescent, even after two months of exposure to air at room temperature. UV light irradiation results in a moderate decrease of the fluorescence quantum yield. Complementary UV-Vis and fluorescence experiments of 3HF and 7HF in solutions and TD-DFT calculations to simulate absorption and emission spectra have been carried out in order to better rationalize the exact nature of the emitting species. Whereas for 3HF-doped NPs the tautomer emission in the green predominates, the fluorescence of 7HF-doped NPs is likely to arise from the cationic or the phototautomeric form of the flavonoid. The results show that organic fluorophore-based fluorescent silica NPs can be easily obtained by a post-doping procedure and represent a first step towards the development of a simple strategy for the encapsulation in MCM-41 NPs of flavonoids and other organic molecules.

  • 8.
    Landström, Anton
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Seitsonen, Ari Paavo
    Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, F-75005, Paris, France; Paris Sciences et Lettres Université, Sorbonne Université et Centre National du Recherche Scientifique (CNRS), F-75005, Paris, France.
    Leccese, Silvia
    Laboratoire de Réactivité de Surface UMR CNRS 7197, Sorbonne Université, 4 place Jussieu, F-75005 Paris, France.
    Abadian, Hagop
    Laboratoire de Réactivité de Surface UMR CNRS 7197, Sorbonne Université, 4 place Jussieu, F-75005 Paris, France.
    Lambert, Jean-François
    Laboratoire de Réactivité de Surface UMR CNRS 7197, Sorbonne Université, 4 place Jussieu, F-75005 Paris, France.
    Protti, Stefano
    PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 10, I-27100, Pavia, Italy.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mezzetti, Alberto
    Laboratoire de Réactivité de Surface UMR CNRS 7197, Sorbonne Université, 4 place Jussieu, F-75005 Paris, France.
    Electron spectroscopies of 3-hydroxyflavone and 7-hydroxyflavone in MCM-41 silica nanoparticles and in acetonitrile solutions. Experimental data and DFT/TD-DFT calculations2021In: Data in Brief, E-ISSN 2352-3409, Vol. 34, article id 106630Article in journal (Refereed)
    Abstract [en]

    The data presented here concern the photophysical characterization of luminescent MCM-41 nanoparticles doped with 3-hydroxyflavone and 7-hydroxyflavone, two fluorescent flavonoids. UV-Vis and fluorescence spectra obtained on freshly-prepared samples and aged (2 months exposed to air) samples are shown. The effect of light exposure is also studied. In parallel, experiments have been carried out in acetonitrile solutions of the two flavonoids as a term of comparison. Time-dependent density functional theory calculations have also been used to simulate UV-Vis and emission spectra of different species for both flavonoids (neutral molecule, tautomers, cationic and anionic forms), taking into account the effect of the surrounding medium (solvent). Density functional theory calculations of vibrational spectra (IR, Raman) of neutral and tautomeric species of 3HF and 7HF are also provided.

  • 9.
    Landström, Anton
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Soldatov, Alexander
    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.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Thermal Defect Modulation and Functional Performance: A Case Study on ZnO–rGO Nanocomposites2019In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 256, no 12, article id 1900239Article in journal (Refereed)
    Abstract [en]

    Herein, a reduced graphene oxide–zinc oxide (rGO–ZnO) hybrid nanocomposite (1 wt% rGO) is synthesized and heat treated at different temperatures, aimed at modulating the intrinsic bulk/surface defects naturally present in nano‐ZnO. The correlation of both the dispersion of rGO within the metal oxide scaffold and the defects present on the semiconductor crystalline lattice with the photocatalytic performance toward the degradation of a molecular dye in water is investigated and discussed. It is shown that several processes compete to determine the catalytic skill of the nanocomposite, which can be enhanced by a simple thermal treatment at moderate temperatures.

  • 10.
    Landström, Anton
    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.
    Rotta Loria, Silvia
    Zavelani Rossi, Margherita
    Mezzi, Alessio
    Kaciulis, Saulius
    Protti, Stefano
    Mezzetti, Alberto
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Chemisorption of 3-hydroxyflavone Onto TiO2 Nanoparticles: Optical and Charge Transfer PropertiesManuscript (preprint) (Other academic)
    Abstract [en]

    3-hydroxyflavone (3HF) is chemisorbed on TiO2 nanoparticle films with an Al2O3 interlayer through a facile dip coating process. The films are characterized with UV-Vis and IR absorption spectroscopy, fluorescence spectroscopy, energy-dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. The 3HF adduct is shown to bond to the substrate through the carbonyl group, resulting in a bathochromic shift in its absorption spectra similar to that observed in 3HF-metal chelates. The emission spectrum is quenched in the case of adsorption on TiO2, but strongly enhanced in the case of Al2O3, with a quantum yield (9.3%) exceeding that of uncoordinated 3HF in acetonitrile.

  • 11.
    Solomon, Getachew
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Kohan, Mojtaba Gilzad
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Landström, Anton
    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, 30170 Venezia Mestre, Italy.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Semiconducting metal oxides empowered by graphene and its derivatives: Progresses and critical perspective on selected functional applications2020In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 128, no 18, article id 180905Article, review/survey (Refereed)
    Abstract [en]

    This Perspective presents and discusses the most recent advancements in the field of exploitation of hybrid nanostructured composites consisting of semiconducting metal oxides and graphene and its derivatives (graphene oxide, reduced graphene oxide, graphene quantum dots, and carbon nanotubes) in specific fields of applications, namely, photovoltaics, water splitting, photocatalysis, and supercapacitors. These hybrid materials have received remarkable attention over the last decade thanks to claimed outstanding functional optoelectronic properties, especially as for (photogenerated) charge carriers storage and transport, allowing the promotion of useful reactions and enhancement of the efficiency of several processes based on charge exchange. In situ and ex situ synthetic strategies have been applied in order to optimize the contact between the two partners and efforts have as well been devoted to investigate the best amount of carbon material to insert in the semiconductor scaffold. We provide the reader with an overview of the research carried out in the last decade, together with a critical analysis of the claimed benefits provided by the carbon materials, also highlighting the current questions waiting for the scientific community to provide an answer to.

  • 12.
    Solomon, Getachew
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Landström, Anton
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mazzaro, Raffaello
    Istituto di Microelettronica e Microsistemi-CNR (CNR, IMM), Via Piero Gobetti 101, Bologna, 95121 Italy.
    Jugovac, Matteo
    Istituto di Struttura della Materia-CNR (ISM-CNR), SS 14 Km 163,5, Trieste, 34149 Italy.
    Moras, Paolo
    Istituto di Struttura della Materia-CNR (ISM-CNR), SS 14 Km 163,5, Trieste, 34149 Italy.
    Cattaruzza, Elti
    Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia Mestre, 30172 Italy.
    Morandi, Vittorio
    Istituto di Microelettronica e Microsistemi-CNR (CNR, IMM), Via Piero Gobetti 101, Bologna, 95121 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, Venezia Mestre, 30172 Italy.
    NiMoO4@Co3O4 Core–Shell Nanorods: In Situ Catalyst Reconstruction toward High Efficiency Oxygen Evolution Reaction2021In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 11, no 32, article id 2101324Article in journal (Refereed)
    Abstract [en]

    The sluggish kinetics of the oxygen evolution reaction (OER) is the bottleneck for the practical exploitation of water splitting. Here, the potential of a core–shell structure of hydrous NiMoO4 microrods conformally covered by Co3O4 nanoparticles via atomic layer depositions is demonstrated. In situ Raman and synchrotron-based photoemission spectroscopy analysis confirms the leaching out of Mo facilitates the catalyst reconstruction, and it is one of the centers of active sites responsible for higher catalytic activity. Post OER characterization indicates that the leaching of Mo from the crystal structure, induces the surface of the catalyst to become porous and rougher, hence facilitating the penetration of the electrolyte. The presence of Co3O4 improves the onset potential of the hydrated catalyst due to its higher conductivity, confirmed by the shift in the Fermi level of the heterostructure. In particular NiMoO4@Co3O4 shows a record low overpotential of 120 mV at a current density of 10 mA cm−2, sustaining a remarkable performance operating at a constant current density of 10, 50, and 100 mA cm−2 with negligible decay. Presented outcomes can significantly contribute to the practical use of the water-splitting process, by offering a clear and in-depth understanding of the preparation of a robust and efficient catalyst for water-splitting.

  • 13.
    Solomon, Getachew
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Landström, Anton
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Rotta Loria, Silvia
    Dipartimento di Fisica, Politecnico di Milano, piazza L. da Vinci 32, 20133 Milano, Italy.
    Bolli, Eleonora
    Institute for the Study of Nanostructured Materials, ISMN-CNR, 00015 Monterotondo Stazione, Roma, Italy.
    Mezzetti, Alberto
    Laboratoire de Réactivité de Surface (LRS), Sorbonne Université, CNRS, 4 Place Jussieu, Paris 75005, France.
    Facibeni, Anna
    Dipartimento di Energia, Politecnico di Milano, via G. Ponzio 34/3, 20133 Milano, Italy; IFN-CNR, piazza L. da Vinci 32, 20133 Milano, Italy.
    Cattarin, Sandro
    Istituto di Chimica della Materia Condensata e di Tecnologie per l'Energia, ICMATE-CNR, C.so Stati Uniti 4, 35127, Padova, Italy.
    Mezzi, Alessio
    Institute for the Study of Nanostructured Materials, ISMN-CNR, 00015 Monterotondo Stazione, Roma, Italy.
    Protti, Stefano
    Photogreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 10, 27100 Pavia, Italy.
    Kaciulis, Saulius
    Institute for the Study of Nanostructured Materials, ISMN-CNR, 00015 Monterotondo Stazione, Roma, Italy.
    Zavelani-Rossi, Margherita
    Dipartimento di Energia, Politecnico di Milano, via G. Ponzio 34/3, 20133 Milano, Italy; IFN-CNR, piazza L. da Vinci 32, 20133 Milano, Italy.
    Concina, Isabella
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Tunable physics through coordination chemistry: formation on oxide surface of Ti and Al chelates with 3-hydroxyflavone capable of electron injection and light emission2022In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 51, no 48, p. 18489-18501Article in journal (Refereed)
    Abstract [en]

    The optoelectronic features of 3-hydroxyflavone (3HF) self-assembled on the surface of an n-type semiconducting metal oxide (TiO2) and an insulator (Al2O3) are herein investigated. 3HF molecules use the coordinatively unsaturated metal ions present on the oxide surface to form metal complexes, which exhibit different behaviors upon light irradiation, depending on the nature of the metal ion. Specifically, we show that the photoluminescence of the surface species can be modulated according to the chemical properties of the complex (i.e. the binding metal ion), resulting in solid-state emitters in a high quantum yield (about 15%). Furthermore, photoinduced charge injection can be promoted or inhibited, providing a multifunctional hybrid system.

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  • 14.
    Thomas, Bony
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    George, Gejo
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Landström, Anton
    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.
    Geng, Shiyu
    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.
    Sain, Mohini
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Mechanical & Industrial Engineering (MIE), University of Toronto, Toronto, Ontario M5S 3G8, Canada.
    Oksman, Kristiina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Department of Mechanical & Industrial Engineering (MIE), University of Toronto, Toronto, Ontario M5S 3G8, Canada.
    Electrochemical Properties of Biobased Carbon Aerogels Decorated with Graphene Dots Synthesized from Biochar2021In: ACS Applied Electronic Materials, E-ISSN 2637-6113, Vol. 3, no 11, p. 4699-4710Article in journal (Refereed)
    Abstract [en]

    Carbon aerogels prepared from low-cost renewable resources are promising electrode materials for future energy storage applications. However, their electrochemical properties must be significantly improved to match the commercially used high-carbon petroleum products. This paper presents a facile method for the green synthesis of carbon aerogels (CAs) from lignocellulosic materials and graphene dots (GDs) from commercially available biochar. The produced carbon aerogels exhibited a hierarchical porous structure, which facilitates energy storage by forming an electrical double-layer capacitance. Surprisingly, the electrochemical analyses of the GD-doped carbon aerogels revealed that in comparison to pristine carbon aerogels, the surface doping of GDs enhanced the electrochemical performance of carbon aerogels, which can be attributed to the combined effect from both double-layer capacitance and pseudocapacitance. Herein, we designed and demonstrated the efficacy of a supercapacitor device using our green carbon electrode as a sustainable option. These green carbon aerogels have opened a window for their practical use in designing sustainable energy storage devices. 

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