| 1. |
- Cole, Jordan, et al.
(författare)
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In situ XPS of competitive CO2/H2O absorption in an ionic liquid
- 2023
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Ingår i: JPhys Materials. - 2515-7639. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- Superbasic ionic liquids (SBILs) are being investigated as potential carbon dioxide (CO2) gas capture agents, however, the presence of H2O in the flue stream can inhibit the uptake of CO2. In this study a thin film of the SBIL trihexyltetradecylphosphonium 1,2,4-triazolide ([P66614][124Triz]) was deposited onto rutile TiO2 (110) using in situ electrospray deposition and studied upon exposure to CO2 and H2O using in situ near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS). The molar uptake ratio of gas in the electrosprayed SBIL (n gas :n IL) was calculated to be 0.3:1 for CO2, 0.7:1 for H2O, and 0.9:1 for a CO2/H2O mixture. NAP-XPS taken at two different depths reveals that the competitive absorption of CO2 and H2O in [P66614][124Triz] varies with sampling depth. A greater concentration of CO2 absorbs in the bulk layers, while more H2O adsorbs/absorbs at the surface. The presence of H2O in the gas mixture does not inhibit the absorption of CO2. Measurements taken during exposure and after the removal of gas indicate that CO2 absorbed in the bulk does so reversibly, whilst CO2 adsorbed/absorbed at the surface does so irreversibly. This is contrary to the fully reversible CO2 reaction shown for bulk ionic liquids (ILs) in literature and suggests that irreversible absorption of CO2 in our highly-structured thin films is largely attributed to reactions at the surface. This has potential implications on IL gas capture and thin film IL catalysis applications.
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| 2. |
- Goyal, A., et al.
(författare)
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Mechanochemical synthesis of stable, quantum-confined CsPbBr3perovskite nanocrystals with blue-green emission and high PLQY
- 2022
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Ingår i: JPhys Materials. - : IOP Publishing. - 2515-7639. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- Cesium lead halides are a family of bright, visible-light emitting materials with near-unity photoluminescence quantum yield (PLQY) in nanocrystals (NCs). The usual way to achieve visible light-emission tunability is by mixing halides, which often leads to phase separation and poor stability. While the NCs should also show size-dependent PL emission, reports on strong quantum confinement in these materials are scarce. Here, we report the synthesis of quantum-confined cesium lead bromide (CsPbBr3) NCs via a facile, environment-friendly, and scalable high-energy mechanochemical synthesis route. The PLQY measured is ∼85%, even after 90 days of synthesis, and the emission wavelength is shifted from green, 520 nm, to blue, 460 nm by quantum confinement in NCs of size 3-5 nm. Micro-PL optical spectroscopy and atomic force microscopy confirm the size tunability of PL on a single-dot scale. Our work demonstrates the potential of mechanochemical synthesis in the medium-scale production of bright luminescent quantum-confined NCs that could be extended to other materials as well.
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| 3. |
- Poletti, Fabrizio, et al.
(författare)
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Electrochemical sensing of glucose by chitosan modified graphene oxide
- 2020
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Ingår i: JPhys Materials. - : IOP Publishing. - 2515-7639. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Graphene oxide (GO) coated electrodes provide an excellent platform for enzymatic glucose sensing, induced by the presence of glucose oxidase and an electrochemical transduction. Here, we show that the sensitivity of GO layers for glucose detection redoubles upon blending GO with chitosan (GO+Ch) and increases up to eight times if covalent binding of chitosan to GO (GO-Ch) is exploited. In addition, the conductivity of the composite material GO-Ch is suitable for electrochemical applications without the need of GO reduction, which is generally required for GO based coatings. Covalent modification of GO is achieved by a standard carboxylic activation/amidation approach by exploiting the abundant amino pendants of chitosan. Successful functionalization is proved by comparison with an ad-hoc synthesized control sample realized by using non-activated GO as precursor. The composite GO-Ch was deposited on standard screen-printed electrodes by a drop-casting approach. Comparison with a chitosan-GO blend and with pristine GO demonstrated the superior reliability and efficiency of the electrochemical response for glucose as a consequence of the high number of enzyme binding sites and of the partial reduction of GO during the carboxylic activation synthetic step.
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| 4. |
- Barrat, Jean-Louis, et al.
(författare)
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Soft matter roadmap
- 2024
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 2515-7639. ; 7:1
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Forskningsöversikt (refereegranskat)abstract
- Soft materials are usually defined as materials made of mesoscopic entities, often self-organised, sensitive to thermal fluctuations and to weak perturbations. Archetypal examples are colloids, polymers, amphiphiles, liquid crystals, foams. The importance of soft materials in everyday commodity products, as well as in technological applications, is enormous, and controlling or improving their properties is the focus of many efforts. From a fundamental perspective, the possibility of manipulating soft material properties, by tuning interactions between constituents and by applying external perturbations, gives rise to an almost unlimited variety in physical properties. Together with the relative ease to observe and characterise them, this renders soft matter systems powerful model systems to investigate statistical physics phenomena, many of them relevant as well to hard condensed matter systems. Understanding the emerging properties from mesoscale constituents still poses enormous challenges, which have stimulated a wealth of new experimental approaches, including the synthesis of new systems with, e.g. tailored self-assembling properties, or novel experimental techniques in imaging, scattering or rheology. Theoretical and numerical methods, and coarse-grained models, have become central to predict physical properties of soft materials, while computational approaches that also use machine learning tools are playing a progressively major role in many investigations. This Roadmap intends to give a broad overview of recent and possible future activities in the field of soft materials, with experts covering various developments and challenges in material synthesis and characterisation, instrumental, simulation and theoretical methods as well as general concepts.
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| 5. |
- Cao, Shun, et al.
(författare)
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Enhancing single photon emission through quasi-bound states in the continuum of monolithic hexagonal boron nitride metasurface
- 2021
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Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- A patterned structure of monolithic hexagonal boron nitride (hBN) on a glass substrate, which can enhance the emission of the embedded single photon emitters (SPEs), is useful for onchip single-photon sources of high-quality. Here, we design and demonstrate a monolithic hBN metasurface with quasi-bound states in the continuum mode at emission wavelength with ultrahigh Q values to enhance fluorescence emission of SPEs in hBN. Because of ultrahigh electric field enhancement inside the proposed hBN metasurface, an ultrahigh Purcell factor (3.3 x 10(4)) is achieved. In addition, the Purcell factor can also be strongly enhanced in most part of the hBN structure, which makes the hBN metasurface suitable for e.g. monolithic quantum photonics.
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| 6. |
- Ektarawong, A., et al.
(författare)
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Boron vacancy-driven thermodynamic stabilization and improved mechanical properties of AlB2-type tantalum diborides as revealed by first-principles calculations
- 2023
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Ingår i: Journal of Physics. - : IOP Publishing Ltd. - 2515-7639. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Thermodynamic stability as well as structural, electronic, and elastic properties of boron-deficient AlB2-type tantalum diborides, which is designated as alpha-TaB2-x, due to the presence of vacancies at its boron sublattice are studied via first-principles calculations. The results reveal that alpha-TaB2-x, where 0.167 less than or similar to x less than or similar to 0.25, is thermodynamically stable even at absolute zero. On the other hand, the shear and Youngs moduli as well as the hardness of stable alpha-TaB2-x are predicted to be superior as compared to those of alpha-TaB2. The changes in the relative stability and also the elastic properties of alpha-TaB2-x with respect to those of alpha-TaB2 can be explained by the competitive effect between the decrease in the number of electrons filling in the antibonding states of alpha-TaB2 and the increase in the number of broken bonds around the vacancies, both induced by the increase in the concentration of boron vacancies. A good agreement between our calculated lattice parameters, elastic moduli and hardness of alpha-TaB2-x and the experimentally measured data of as-synthesized AlB2-type tantalum diborides with the claimed composition of TaB similar to 2, available in the literature, suggests that, instead of being a line compound with a stoichiometric composition of TaB2, AlB2-type tantalum diboride is readily boron-deficient, and its stable composition in equilibrium may be ranging at least from TaB similar to 1.833 to TaB similar to 1.75. Furthermore, the substitution of vacancies for boron atoms in alpha-TaB2 is responsible for destabilization of WB2-type tantalum diboride and orthorhombic Ta2B3, predicted in the previous theoretical studies to be thermodynamically stable in the Ta-B system, and it thus enables the interpretation of why the two compounds have never been realized in actual experiments.
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| 7. |
- Gazzi, Arianna, et al.
(författare)
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Graphene, other carbon nanomaterials and the immune system: toward nanoimmunity-by-design
- 2020
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Ingår i: JPhys Materials. - : IOP Publishing. - 2515-7639. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- Carbon-based materials (CBMs), such as graphene, nanodiamonds, carbon fibers, and carbon dots, have attracted a great deal scientific attention due to their potential as biomedical tools. Following exposure, particularly intravenous injection, these nanomaterials can be recognized by immune cells. Such interactions could be modulated by the different physicochemical properties of the materials (e.g. structure, size, and chemical functions), by either stimulating or suppressing the immune response. However, a harmonized cutting-edge approach for the classification of these materials based not only on their physicochemical parameters but also their immune properties has been missing. The European Commission-funded G-IMMUNOMICS and CARBO-IMmap projects aimed to fill this gap, developing a functional pipeline for the qualitative and quantitative immune characterization of graphene, graphene-related materials (GRMs), and other CBMs. The goal was to open breakthrough perspectives for the definition of the immune profiles of these materials. Here, we summarize our methodological approach, key results, and the necessary multidisciplinary expertise ranging across various fields, from material chemistry to engineering, immunology, toxicology, and systems biology. G-IMMUNOMICS, as a partnering project of the Graphene Flagship, the largest scientific research initiative on graphene worldwide, also complemented the studies performed in the Flagship on health and environmental impact of GRMs. Finally, we present the nanoimmunity-by-design concept, developed within the projects, which can be readily applied to other 2D materials. Overall, the G-IMMUNOMICS and CARBO-IMmap projects have provided new insights on the immune impact of GRMs and CBMs, thus laying the foundation for their safe use and future translation in medicine.
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| 8. |
- Mishra, Himanshu, et al.
(författare)
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Experimental advances in charge and spin transport in chemical vapor deposited graphene
- 2021
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 2515-7639. ; 4:4
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Forskningsöversikt (refereegranskat)abstract
- Despite structural and processing-induced imperfections, wafer-scale chemical vapor deposited (CVD) graphene today is commercially available and has emerged as a versatile form that can be readily transferred to desired substrates for various nanoelectronic and spintronic applications. In particular, over the past decade, significant advancements in CVD graphene synthesis methods and experiments realizing high-quality charge and spin transport have been achieved. These include growth of large-grain graphene, new processing methods, high-quality electrical transport with high-carrier mobility, micron-scale ballistic transport, observations of quantum and fractional quantum Hall effect, as well as the spintronic performance of extremely long spin communication over tens of micrometers at room temperature with robust spin diffusion lengths and spin lifetimes. In this short review, we discuss the progress in recent years in the synthesis of high-quality, large-scale CVD graphene and improvement of the electrical and spin transport performance, particularly towards achieving ballistic and long-distance spin transport that show exceptional promise for next-generation graphene electronic and spintronic applications.
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| 9. |
- Nocerino, E., et al.
(författare)
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Unusually large magnetic moment and tricritical behavior of the CMR compound NaCr 2 O 4 revealed with high resolution neutron diffraction and μ + SR
- 2023
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Ingår i: JPhys Materials. - 2515-7639. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- The mixed valence Cr3+/Cr4+ compound NaCr2O4, hosts a plethora of unconventional electronic properties. In the present study, muon spin rotation/relaxation ( μ + SR) and high-resolution time-of-flight neutron powder diffraction measurements were carried out on high-quality samples to clarify the complex magnetic ground state of this unique material. We identified a commensurate canted antiferromagnetic order (C-AFM) with a canting angle of the Cr spin axial vector equal to θ c = ( 8.8 ± 0.5 ) ∘ , and an estimated Cr moment μ C r C ∼ ( 4.30 ± 0.01 ) μ B . Such an unusually large value of μ C r C is compatible with the existence of high-spin Cr sites created by the presence of an unconventional negative charge transfer state in NaCr2O4. In addition to the C-AFM structure, a novel magnetic supercell was also revealed. Such supercell display an incommensurate (IC)-AFM propagation vector (0 0 1 2 − δ ), having a Cr moment μ C r I C = ( 2.20 ± 0.03 ) μ B . It is suggested that the C-AFM and IC-AFM modulations have two different electronic origins, being due to itinerant and localized contributions to the magnetic moment respectively. Finally, the direct measurement of the magnetic order parameter for the C-AFM structure provided a value of the critical exponent β = 0.245 ≈ 1 4 , suggesting a non conventional critical behavior for the magnetic phase transition in NaCr2O4
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| 10. |
- Nocerino, Elisabetta, et al.
(författare)
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Unusually large magnetic moment and tricritical behavior of the CMR compound NaCr2O4 revealed with high resolution neutron diffraction and mu(+) SR
- 2023
-
Ingår i: Journal of Physics. - : IOP Publishing. - 2515-7639. ; 6:3
-
Tidskriftsartikel (refereegranskat)abstract
- The mixed valence Cr3+/Cr4+ compound NaCr2O4, hosts a plethora of unconventional electronic properties. In the present study, muon spin rotation/relaxation (mu(+) SR) and high-resolution time-of-flight neutron powder diffraction measurements were carried out on high-quality samples to clarify the complex magnetic ground state of this unique material. We identified a commensurate canted antiferromagnetic order (C-AFM) with a canting angle of the Cr spin axial vector equal to theta
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