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  • 1. An, Rong
    et al.
    Laaksonen, Aatto
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Luleå University of Technology, Sweden; “Petru Poni” Institute of Macromolecular Chemistry, Romania; Nanjing Tech University, China.
    Wu, Muqiu
    Zhu, Yudan
    Shah, Faiz Ullah
    Lu, Xiaohua
    Ji, Xiaoyan
    Atomic force microscopy probing interactions and microstructures of ionic liquids at solid surfaces2022Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 14, nr 31, s. 11098-11128Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Ionic liquids (ILs) are room temperature molten salts that possess preeminent physicochemical properties and have shown great potential in many applications. However, the use of ILs in surface-dependent processes, e.g. energy storage, is hindered by the lack of a systematic understanding of the IL interfacial microstructure. ILs on the solid surface display rich ordering, arising from coulombic, van der Waals, solvophobic interactions, etc., all giving near-surface ILs distinct microstructures. Therefore, it is highly important to clarify the interactions of ILs with solid surfaces at the nanoscale to understand the microstructure and mechanism, providing quantitative structure-property relationships. Atomic force microscopy (AFM) opens a surface-sensitive way to probe the interaction force of ILs with solid surfaces in the layers from sub-nanometers to micrometers. Herein, this review showcases the recent progress of AFM in probing interactions and microstructures of ILs at solid interfaces, and the influence of IL characteristics, surface properties and external stimuli is thereafter discussed. Finally, a summary and perspectives are established, in which, the necessities of the quantification of IL-solid interactions at the molecular level, the development of in situ techniques closely coupled with AFM for probing IL-solid interfaces, and the combination of experiments and simulations are argued.

  • 2. Asfaw, Habtom D.
    et al.
    Roberts, Matthew R.
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Younesi, Reza
    Valvo, Mario
    Nyholm, Leif
    Edstrom, Kristina
    Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance2014Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, nr 15, s. 8804-8813Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sot-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm(-2) at 0.1 mA cm(-2) (lowest rate) and 1.1 mA h cm(-2) at 6 mA cm(-2) (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

  • 3.
    Brandt, Erik G.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Agosta, Lorenzo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Lyubartsev, Alexander P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Reactive wetting properties of TiO2 nanoparticles predicted by ab initio molecular dynamics simulations2016Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, nr 27, s. 13385-13398Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Small-sized wet TiO2 nanoparticles have been investigated by ab initio molecular dynamics simulations. Chemical and physical adsorption of water on the TiO2-water interface was studied as a function of water content, ranging from dry nanoparticles to wet nanoparticles with monolayer coverage of water. The surface reactivity was shown to be a concave function of water content and driven by surface defects. The local coordination number at the defect was identified as the key factor to decide whether water adsorption proceeds through dissociation or physisorption on the surface. A consistent picture of TiO2 nanoparticle wetting at the microscopic level emerges, which corroborates existing experimental data and gives further insight into the molecular mechanisms behind nanoparticle wetting. These calculations will facilitate the engineering of metal oxide nanoparticles with a controlled catalytic water activity.

  • 4. Disch, Sabrina
    et al.
    Wetterskog, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Hermann, Raphael P.
    Korolkov, Denis
    Busch, Peter
    Boesecke, Peter
    Lyon, Olivier
    Vainio, Ulla
    Salazar-Alvarez, German
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Brueckel, Thomas
    Structural diversity in iron oxide nanoparticle assemblies as directed by particle morphology and orientation2013Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 5, nr 9, s. 3969-3975Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mesostructure of ordered arrays of anisotropic nanoparticles is controlled by a combination of packing constraints and interparticle interactions, two factors that are strongly dependent on the particle morphology. We have investigated how the degree of truncation of iron oxide nanocubes controls the mesostructure and particle orientation in drop cast mesocrystal arrays. The combination of grazing incidence small-angle X-ray scattering and scanning electron microscopy shows that mesocrystals of highly truncated cubic nanoparticles assemble in an fcc-type mesostructure, similar to arrays formed by iron oxide nanospheres, but with a significantly reduced packing density and displaying two different growth orientations. Strong satellite reflections in the GISAXS pattern indicate a commensurate mesoscopic superstructure that is related to stacking faults in mesocrystals of the anisotropic nanocubes. Our results show how subtle variation in shape anisotropy can induce oriented arrangements of nanoparticles of different structures and also create mesoscopic superstructures of larger periodicity.

  • 5.
    Estrader, Marta
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). University of Barcelona, Spain.
    Lopez-Ortega, Alberto
    Golosovsky, Igor V.
    Estrade, Sonia
    Roca, Alejandro G.
    Salazar-Alvarez, German
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Lopez-Conesa, Lluis
    Tobia, Dina
    Winkler, Elin
    Ardisson, Jose D.
    Macedo, Waldemar A. A.
    Morphis, Andreas
    Vasilakaki, Marianna
    Trohidou, Kalliopi N.
    Gukasov, Arsen
    Mirebeau, Isabelle
    Makarova, O. L.
    Zysler, Roberto D.
    Peiro, Francesca
    Baro, Maria Dolors
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Nogues, Josep
    Origin of the large dispersion of magnetic properties in nanostructured oxides: FexO/Fe3O4 nanoparticles as a case study2015Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, nr 7, s. 3002-3015Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The intimate relationship between stoichiometry and physicochemical properties in transition-metal oxides makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct relationship between structure-morphology and functionalities is often complicated. In this regard, in the FexO/Fe3O4 system a largely unexplained broad dispersion of magnetic properties has been observed. Here we show, thanks to a comprehensive multi-technique approach, a clear correlation between the magneto-structural properties in large (45 nm) and small (9 nm) FexO/Fe3O4 core/shell nanoparticles that can explain the spread of magnetic behaviors. The results reveal that while the FexO core in the large nanoparticles is antiferromagnetic and has bulk-like stoichiometry and unit-cell parameters, the FexO core in the small particles is highly non-stoichiometric and strained, displaying no significant antiferromagnetism. These results highlight the importance of ample characterization to fully understand the properties of nanostructured metal oxides.

  • 6.
    Faure, Bertrand
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wetterskog, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Gunnarsson, Klas
    Josten, Elisabeth
    Hermann, Raphael P.
    Brueckel, Thomas
    Andreasen, Jens Wenzel
    Meneau, Florian
    Meyer, Mathias
    Lyubartsev, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Salazar-Alvarez, German
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Svedlindh, Peter
    2D to 3D crossover of the magnetic properties in ordered arrays of iron oxide nanocrystals2013Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 5, nr 3, s. 953-960Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The magnetic 2D to 3D crossover behavior of well-ordered arrays of monodomain gamma-Fe2O3 spherical nanoparticles with different thicknesses has been investigated by magnetometry and Monte Carlo (MC) simulations. Using the structural information of the arrays obtained from grazing incidence small-angle X-ray scattering and scanning electron microscopy together with the experimentally determined values for the saturation magnetization and magnetic anisotropy of the nanoparticles, we show that MC simulations can reproduce the thickness-dependent magnetic behavior. The magnetic dipolar particle interactions induce a ferromagnetic coupling that increases in strength with decreasing thickness of the array. The 2D to 3D transition in the magnetic properties is mainly driven by a change in the orientation of the magnetic vortex states with increasing thickness, becoming more isotropic as the thickness of the array increases. Magnetic anisotropy prevents long-range ferromagnetic order from being established at low temperature and the nanoparticle magnetic moments instead freeze along directions defined by the distribution of easy magnetization directions.

  • 7.
    Guccini, Valentina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Wallenberg Wood Science Center, Sweden.
    Yu, Shun
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Wallenberg Wood Science Center, Sweden.
    Agthe, Michael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Gordeyeva, Korneliya
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Trushkina, Yulia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Fall, Andreas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Schütz, Christina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Salazar-Alvarez, German
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Wallenberg Wood Science Center, Sweden.
    Inducing nematic ordering of cellulose nanofibers using osmotic dehydration2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 48, s. 23157-23163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The formation of nematically-ordered cellulose nanofiber (CNF) suspensions with an order parameter f(max) approximate to 0.8 is studied by polarized optical microscopy, small-angle X-ray scattering (SAXS), and rheological measurements as a function of CNF concentration. The wide range of CNF concentrations, from 0.5 wt% to 4.9 wt%, is obtained using osmotic dehydration. The rheological measurements show a strong entangled network over all the concentration range whereas SAXS measurements indicate that at concentrations >1.05 wt% the CNF suspension crosses an isotropic-anisotropic transition that is accompanied by a dramatic increase of the optical birefringence. The resulting nanostructures are modelled as mass fractal structures that converge into co-existing nematically-ordered regions and network-like regions where the correlation distances decrease with concentration. The use of rapid, upscalable osmotic dehydration is an effective method to increase the concentration of CNF suspensions while partly circumventing the gel/glass formation. The facile formation of highly ordered fibers can result in materials with interesting macroscopic properties.

  • 8.
    Limaye, Mukta
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Royal Institute of Technology, Sweden; Indian Institute of Science Education & Research, India.
    Schütz, Christina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Royal Institute of Technology, Sweden.
    Kriechbaum, Konstantin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wohlert, Jakob
    Bacsik, Zoltán
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wohlert, Malin
    Xia, Wei
    Pléa, Mama
    Dembele, Cheick
    Salazar-Alvarez, German
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Royal Institute of Technology, Sweden.
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Functionalization and patterning of nanocellulose films by surface-bound nanoparticles of hydrolyzable tannins and multivalent metal ions2019Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, nr 41, s. 19278-19284Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inspired by the Bogolanfini dyeing technique, we report how flexible nanofibrillated cellulose (CNF) films can be functionalized and patterned by surface-bound nanoparticles of hydrolyzable tannins and multivalent metal ions with tunable colors. Molecular dynamics simulations show that gallic acid (GA) and ellagic acid (EA) rapidly adsorb and assemble on the CNF surface, and atomic force microscopy confirms that nanosized GA assemblies cover the surface of the CNF. CNF films were patterned with tannin-metal ion nanoparticles by an in-fibre reaction between the pre-impregnated tannin and the metal ions in the printing ink. Spectroscopic studies show that the Fe-III/II ions interact with GA and form surface-bound, stable GA-Fe-III/II nanoparticles. The functionalization and patterning of CNF films with metal ion-hydrolyzable tannin nanoparticles is a versatile route to functionalize films based on renewable materials and of interest for biomedical and environmental applications.

  • 9. Lindenbeck, Lucie
    et al.
    Beele, Björn B.
    Morsali, Mohammad
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Budnyk, Serhiy
    Frauscher, Marcella
    Chen, Jianhong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Sipponen, Mika H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Slabon, Adam
    Rodrigues, Bruno V. M.
    MoS2 nanoflower-decorated lignin nanoparticles for superior lubricant properties2023Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, nr 20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lignin has been, for a long time, treated as a low-value waste product. To change this scenario, high-value applications have been recently pursued, e.g., the preparation of hybrid materials with inorganic components. Although hybrid inorganic-based materials can benefit from the reactive lignin phenolic groups at the interface, often responsible for optimizing specific properties, this is still an underexplored field. Here, we present a novel and green material based on the combination of hydroxymethylated lignin nanoparticles (HLNPs) with molybdenum disulfide (MoS2) nanoflowers grown via a hydrothermal route. By bringing together the lubricant performance of MoS2 and the structural stability of biomass-based nanoparticles, a MoS2-HLNPs hybrid is presented as a bio-derived additive for superior tribological performances. While FT-IR analysis confirmed the structural stability of lignin after the hydrothermal growth of MoS2, TEM and SEM micrographs revealed a homogeneous distribution of MoS2 nanoflowers (average size of 400 nm) on the HLNPs (average size of 100 nm). Regarding the tribological tests, considering a pure oil as reference, only HLNPs as bio-derived additives led to a reduction in the wear volume of 18%. However, the hybrid of MoS2-HLNPs led to a considerably higher reduction (71%), pointing out its superior performance. These results open a new window of opportunity for a versatile and yet underexplored field that can pave the way for a new class of biobased lubricants.

  • 10. Liu, Ben
    et al.
    Yao, Huiqin
    Daniels, Robert A.
    Song, Wenqiao
    Zheng, Haoquan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Jin, Lei
    Suib, Steven L.
    He, Jie
    A facile synthesis of Fe3C@mesoporous carbon nitride nanospheres with superior electrocatalytic activity2016Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, nr 10, s. 5441-5445Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report a colloidal amphiphile-templating approach to preparing nanosized Fe3C encapsulated within mesoporous nitrogen-doped carbon nanospheres (Fe3C@mCN). The obtained Fe3C@mCN hybrids having a high surface area and ultrafine Fe3C nanocrystals exhibited superior activity and durability for oxygen reduction.

  • 11.
    Liu, Yingxin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). KTH, Sweden.
    Agthe, Michael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Salajková, Michaela
    Gordeyeva, Korneliya
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Guccini, Valentina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). KTH, Sweden.
    Fall, Andreas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Salazar-Alvarez, Germán
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). KTH, Sweden.
    Schütz, Christina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). KTH, Sweden.
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Assembly of cellulose nanocrystals in a levitating drop probed by time-resolved small angle X-ray scattering2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 38, s. 18113-18118Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Assembly of bio-based nano-sized particles into complex architectures and morphologies is an area of fundamental interest and technical importance. We have investigated the assembly of sulfonated cellulose nanocrystals (CNC) dispersed in a shrinking levitating aqueous drop using time-resolved small angle X-ray scattering (SAXS). Analysis of the scaling of the particle separation distance (d) with particle concentration (c) was used to follow the transition of CNC dispersions from an isotropic state at 1-2 vol% to a compressed nematic state at particle concentrations above 30 vol%. Comparison with SAXS measurements on CNC dispersions at near equilibrium conditions shows that evaporation-induced assembly of CNC in large levitating drops is comparable to bulk systems. Colloidal states with d vs. c scalings intermediate between isotropic dispersions and unidirectional compression of the nematic structure could be related to the biphasic region and gelation of CNC. Nanoscale structural information of CNC assembly up to very high particle concentrations can help to fabricate nanocellulose-based materials by evaporative methods.

  • 12. Lu, Can
    et al.
    Drichel, Andreas
    Chen, Jianhong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Enders, Florian
    Rokicińska, Anna
    Kuśtrowski, Piotr
    Dronskowski, Richard
    Boldt, Klaus
    Slabon, Adam
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Sensibilization of p-NiO with ZnSe/CdS and CdS/ZnSe quantum dots for photoelectrochemical water reduction2021Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 13, nr 2, s. 869-877Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Core/shell quantum dots (QDs) paired with semiconductor photocathodes for water reduction have rarely been implemented so far. We demonstrate the integration of ZnSe/CdS and CdS/ZnSe QDs with porous p-type NiO photocathodes for water reduction. The QDs demonstrate appreciable enhancement in water-reduction efficiency, as compared with the bare NiO. Despite their different structure, both QDs generate comparable photocurrent enhancement, yielding a 3.8- and 3.2-fold improvement for the ZnSe/CdS@NiO and CdS/ZnSe@NiO system, respectively. Unraveling the carrier kinetics at the interface of these hybrid photocathodes is therefore critical for the development of efficient photoelectrochemical (PEC) proton reduction. In addition to examining the carrier dynamics by the Mott–Schottky technique and electrochemical impedance spectroscopy (EIS), we performed theoretical modelling for the distribution density of the carriers with respect to electron and hole wave functions. The electrons are found to be delocalized through the whole shell and can directly actuate the PEC-related process in the ZnSe/CdS QDs. The holes as the more localized carriers in the core have to tunnel through the shell before injecting into the hole transport layer (NiO). Our results emphasize the role of interfacial effects in core/shell QDs-based multi-heterojunction photocathodes.

  • 13. Lu, Can
    et al.
    Jothi, Palani R.
    Thersleff, Thomas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Budnyak, Tetyana M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Rokicinska, Anna
    Yubuta, Kunio
    Dronskowski, Richard
    Kustrowski, Piotr
    Fokwa, Boniface P. T.
    Slabon, Adam
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Nanostructured core-shell metal borides-oxides as highly efficient electrocatalysts for photoelectrochemical water oxidation2020Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 12, nr 5, s. 3121-3128Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Oxygen evolution reaction (OER) catalysts are critical components of photoanodes for photoelectrochemical (PEC) water oxidation. Herein, nanostructured metal boride MB (M = Co, Fe) electrocatalysts, which have been synthesized by a Sn/SnCl2 redox assisted solid-state method, were integrated with WO3 thin films to build heterojunction photoanodes. As-obtained MB modified WO3 photoanodes exhibit enhanced charge carrier transport, amended separation of photogenerated electrons and holes, prolonged hole lifetime and increased charge carrier density. Surface modification of CoB and FeB significantly enhances the photocurrent density of WO3 photoanodes from 0.53 to 0.83 and 0.85 mA cm(-2), respectively, in transient chronoamperometry (CA) at 1.23 V vs. RHE (V-RHE) under interrupted illumination in 0.1 M Na2SO4 electrolyte (pH 7), corresponding to an increase of 1.6 relative to pristine WO3. In contrast, the pristine MB thin film electrodes do not produce noticeable photocurrent during water oxidation. The metal boride catalysts transform in situ to a core-shell structure with a metal boride core and a metal oxide (MO, M = Co, Fe) surface layer. When coupled to WO3 thin films, the CoB@CoOx nanostructures exhibit a higher catalytic enhancement than corresponding pure cobalt borate (Co-B-i) and cobalt hydroxide (Co(OH)(x)) electrocatalysts. Our results emphasize the role of the semiconductor-electrocatalyst interface for photoelectrodes and their high dependency on materials combination.

  • 14. Luo, Jinghui
    et al.
    Wärmlander, Sebastian K. T. S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Yu, Chien-Hung
    Muhammad, Kamran
    Gräslund, Astrid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Abrahams, Jan Pieter
    The A beta peptide forms non-amyloid fibrils in the presence of carbon nanotubes2014Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, nr 12, s. 6720-6726Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carbon nanotubes have specific properties that make them potentially useful in biomedicine and biotechnology. However, carbon nanotubes may themselves be toxic, making it imperative to understand how carbon nanotubes interact with biomolecules such as proteins. Here, we used NMR, CD, and ThT/fluorescence spectroscopy together with AFM imaging to study pH-dependent molecular interactions between single walled carbon nanotubes (SWNTs) and the amyloid-beta (A beta) peptide. The aggregation of the A beta peptide, first into oligomers and later into amyloid fibrils, is considered to be the toxic mechanism behind Alzheimer's disease. We found that SWNTs direct the A beta peptides to form a new class of beta-sheet-rich yet non-amyloid fibrils.

  • 15.
    Ma, Zili
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). RWTH Aachen University, Germany.
    Chen, Jianhong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Luo, Dongbao
    Thersleff, Thomas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Dronskowski, Richard
    Slabon, Adam
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Structural evolution of CrN nanocube electrocatalysts during nitrogen reduction reaction2020Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 12, nr 37, s. 19276-19283Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Metal nitrides have been suggested as prospective catalysts for the electrochemical nitrogen reduction reaction (NRR) in order to obtain ammonia at room temperature under ambient pressure. Herein, we report that templated chromium nitride porous microspheres built up by nanocubes (NCs) are an efficient noble-metal-free electrocatalyst for NRR. The CrN NCs catalyst exhibits both a high stability and NH(3)yield of 31.11 mu g h(-1)mg(cat.)(-1)with a Faradaic efficiency (FE) of 16.6% in 0.1 M HCl electrolyte. Complementary physical characterization techniques demonstrate partial oxidation of the pristine CrN NCs during reaction. Structural characterization by means of scanning transmission electron microscopy (STEM) combining electron energy loss spectrum (EELS) and energy dispersive X-ray spectroscopy (EDX) analysis reveals the NC structure to consist of an O-rich core and N-rich shell after NRR. This gradient distribution of nitrogen within the CrN NCs upon completed NRR is distinct to previously reported metal nitride NRR catalysts, because no significant loss of nitrogen occurs at the catalyst surface.

  • 16.
    Mayence, Arnaud
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wang, Dong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Salazar-Alvarez, German
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Oleynikov, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Probing planar defects in nanoparticle superlattices by 3D small-angle electron diffraction tomography and real space imaging2014Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, nr 22, s. 13803-13808Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate how the acquisition and processing of 3D electron diffraction data can be extended to characterize structural features on the mesoscale, and show how lattice distortions in superlattices of self-assembled spherical Pd nanoparticles can be quantified by three-dimensional small-angle electron diffraction tomography (3D SA-EDT). Transmission electron microscopy real space imaging and 3D SA-EDT reveal a high density of stacking faults that was related to a competition between fcc and hcp arrangements during assembly. Information on the orientation of the stacking faults was used to make analogies between planar defects in the superlattices and Shockley partial dislocations in metallic systems.

  • 17.
    Mayence, Arnaud
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wery, Madeleine
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wetterskog, Erik
    Svedlindh, Peter
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Interfacial strain and defects in asymmetric Fe-Mn oxide hybrid nanoparticles2016Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, nr 29, s. 14171-14177Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Asymmetric Fe-Mn oxide hybrid nanoparticles have been obtained by a seed-mediated thermal decomposition-based synthesis route. The use of benzyl ether as the solvent was found to promote the orientational growth of Mn1-xO onto the iron oxide nanocube seeds yielding mainly dimers and trimers whereas 1-octadecene yields large nanoparticles. HRTEM imaging and HAADF-STEM tomography performed on dimers show that the growth of Mn1-xO occurs preferentially along the edges of iron oxide nanocubes where both oxides share a common crystallographic orientation. Fourier filtering and geometric phase analysis of dimers reveal a lattice mismatch of 5% and a large interfacial strain together with a significant concentration of defects. The saturation magnetization is lower and the coercivity is higher for the Fe-Mn oxide hybrid nanoparticles compared to the iron oxide nanocube seeds.

  • 18. Ouyang, Wengen
    et al.
    de Wijn, Astrid S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Norwegian University of Science and Technology, Norway.
    Urbakh, Michael
    Atomic-scale sliding friction on a contaminated surface2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 14, s. 6375-6381Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using non-equilibrium molecular dynamic simulations, we investigate the effect of adsorbates on nano-scopic friction. We find that the interplay between different channels of energy dissipation at the frictional interface may lead to non-monotonic dependence of the friction force on the adsorbate surface coverage and to strongly nonlinear variation of friction with normal load (non-Amontons' behavior). Our simulations suggest that the key parameter controlling the variation of friction force with the normal load, surface coverage and temperature is the time-averaged number of adsorbates confined between the tip and the substrate. Three different regimes of temperature dependence of friction in the presence of adsorbates are predicted. Our findings point on new ways to control friction on contaminated surfaces.

  • 19. Rehnlund, David
    et al.
    Valvo, Mario
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Ångström, Jonas
    Sahlberg, Martin
    Edström, Kristina
    Nyholm, Leif
    Electrochemical fabrication and characterization of Cu/Cu2O multi-layered micro and nanorods in Li-ion batteries2015Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, nr 32, s. 13591-13604Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrodes composed of freestanding nano- and microrods composed of stacked layers of copper and cuprous oxide have been fabricated using a straightforward one-step template-assisted pulsed galvanostatic electrodeposition approach. The approach provided precise control of the thickness of each individual layer of the high-aspect-ratio rods as was verified by SEM, EDS, XRD, TEM and EELS measurements. Rods with diameters of 80, 200 and 1000 nm were deposited and the influence of the template pore size on the structure and electrochemical performance of the conversion reaction based electrodes in lithium-ion batteries was investigated. The multi-layered Cu2O/Cu nano-and microrod electrodes exhibited a potential window of more than 2 V, which was ascribed to the presence of a distribution of Cu2O (and Cu, respectively) nanoparticles with different sizes and redox potentials. As approximately the same areal capacity was obtained independent of the diameter of the multi-layered rods the results demonstrate the presence of an electroactive Cu2O layer with a thickness defined by the time domain of the measurements. It is also demonstrated that while the areal capacity of the electrodes decreased dramatically when the scan rate was increased from 0.1 to 2 mV s(-1), the capacity remained practically constant when the scan rate was further increased to 100 mV s(-1). This behaviour can be explained by assuming that the capacity is limited by the lithium ion diffusion rate though the Cu2O layer generated during the oxidation step. The electrochemical performance of present type of 3-D multi-layered rods provides new insights into the lithiation and delithiation reactions taking place for conversion reaction materials such as Cu2O.

  • 20. Shakya, Jyoti
    et al.
    Kang, Min-A.
    Li, Jian
    VahidMohammadi, Armin
    Tian, Weiqian
    Zeglio, Erica
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi. KTH Royal Institute of Technology and Digital Futures, Sweden; Karolinska Institute, Sweden.
    Hamedi, Mahiar Max
    2D MXene electrochemical transistors2024Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 16, nr 6, s. 2883-2893Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The solid-state field-effect transistor, FET, and its theories were paramount in the discovery and studies of graphene. In the past two decades another transistor based on conducting polymers, called organic electrochemical transistor (ECT), has been developed and largely studied. The main difference between organic ECTs and FETs is the mode and extent of channel doping; while in FETs the channel only has surface doping through dipoles, the mixed ionic-electronic conductivity of the channel material in organic ECTs enables bulk electrochemical doping. As a result, organic ECTs maximize conductance modulation at the expense of speed. To date ECTs have been based on conducting polymers, but here we show that MXenes, a class of 2D materials beyond graphene, enable the realization of electrochemical transistors (ECTs). We show that the formulas for organic ECTs can be applied to these 2D ECTs and used to extract parameters like mobility. These MXene ECTs have high transconductance values but low on-off ratios. We further show that conductance switching data measured using ECT, in combination with other in situ-ex situ electrochemical measurements, is a powerful tool for correlating the change in conductance to that of the redox state, to our knowledge, this is the first report of this important correlation for MXene films. 2D ECTs can draw great inspiration and theoretical tools from the field of organic ECTs and have the potential to considerably extend the capabilities of transistors beyond those of conducting polymer ECTs, with added properties such as extreme heat resistance, tolerance for solvents, and higher conductivity for both electrons and ions than conducting polymers. Here we show that not only conducting polymers, but also 2D MXenes can be used as materials for electrochemical transistors ECTs. MXene extend the capabilities of ECTs with properties such as extreme heat resistance, and higher conductivity/speeds.

  • 21.
    Sultan, Sahar
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    3D printed scaffolds with gradient porosity based on a cellulose nanocrystal hydrogel2018Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, nr 9, s. 4421-4431Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    3-Dimensional (3D) printing provides a unique methodology for the customization of biomedical scaffolds with respect to size, shape, pore structure and pore orientation useful for tissue repair and regeneration. 3D printing was used to fabricate fully bio-based porous scaffolds of a double crosslinked interpenetrating polymer network (IPN) from a hydrogel ink of sodium alginate and gelatin (SA/G) reinforced with cellulose nanocrystals (CNCs). CNCs provided favorable rheological properties required for 3D printing. The 3D printed scaffolds were crosslinked sequentially via covalent and ionic reactions resulting in dimensionally stable hydrogel scaffolds with pore sizes of 80-2125 m and nanoscaled pore wall roughness (visible from scanning electron microscopy) favorable for cell interaction. The 2D wide angle X-ray scattering studies showed that the nanocrystals orient preferably in the printing direction; the degree of orientation varied between 61-76%. The 3D printing pathways were optimised successfully to achieve 3-dimensional scaffolds (Z axis up to 20 mm) with uniform as well as gradient pore structures. This study demonstrates the potential of 3D printing in developing bio-based scaffolds with controlled pore sizes, gradient pore structures and alignment of nanocrystals for optimal tissue regeneration.

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  • 22.
    Valencia, Luis
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Monti, Susanna
    Kumar, Sugam
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zhu, Chuantao
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Liu, Peng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Yu, Shun
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Nanocellulose/graphene oxide layered membranes: elucidating their behaviour during filtration of water and metal ions in real time2019Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, nr 46, s. 22413-22422Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deposition of a thin layer of graphene oxide onto cellulose nanofibril membranes, to form CNF-GO layered-composite membranes, dramatically enhances their wet-mechanical stability, water flux and capacity to adsorb water pollutants (P. Liu, C. Zhu and A. P. Mathew, J. Hazard. Mater., 2019, 371, 484-493). In this work, we studied in real time the behavior of these layered membranes during filtration of water and metal ion solutions by means of in situ SAXS and reactive molecular dynamics (ReaxFF) computational simulations. SAXS confirms that the GO layers limit the swelling and structural deformations of CNFs during filtration of aqueous solutions. Moreover, during filtration of metal ion solutions, the connection of the CNF-GO network becomes highly complex mass-fractal like, with an increment in the correlation length. In addition, after ion adsorption, the SAXS data revealed apparent formation of nanoparticles during the drying stage and particle size increase as a function of time during drying. The molecular dynamics simulations, on the other hand, provide a deep insight into the assembly of both components, as well as elucidating the motion of the metal ions that potentially lead to the formation of metal clusters during adsorption, confirming the synergistic behavior of GO and CNFs for water purification applications.

  • 23.
    Valencia, Luis
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Alfa Laval Tumba AB, Sweden.
    Nomena, Emma M.
    Monti, Susanna
    Rosas-Arbelaez, Walter
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Kumar, Sugam
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Bhabha Atomic Research Centre, India.
    Velikov, Krassimir P.
    Multivalent ion-induced re-entrant transition of carboxylated cellulose nanofibrils and its influence on nanomaterials' properties2020Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 12, nr 29, s. 15652-15662Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we identify and characterize a new intriguing capability of carboxylated cellulose nanofibrils that could be exploited to design smart nanomaterials with tuned response properties for specific applications. Cellulose nanofibrils undergo a multivalent counter-ion induced re-entrant behavior at a specific multivalent metal salt concentration. This effect is manifested as an abrupt increase in the strength of the hydrogel that returns upon a further increment of salt concentration. We systematically study this phenomenon using dynamic light scattering, small-angle X-ray scattering, and molecular dynamics simulations based on a reactive force field. We find that the transitions in the nanofibril microstructure are mainly because of the perturbing actions of multivalent metal ions that induce conformational changes of the nanocellulosic chains and thus new packing arrangements. These new aggregation states also cause changes in the thermal and mechanical properties as well as wettability of the resulting films, upon water evaporation. Our results provide guidelines for the fabrication of cellulose-based films with variable properties by the simple addition of multivalent ions.

  • 24.
    Volkov, Nikolai
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). University of Gothenburg, Sweden.
    Lyubartsev, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Phase transitions and thermodynamic properties of dense assemblies of truncated nanocubes and cuboctahedra2012Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 4, nr 15, s. 4765-4771Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inspired by recent advances on the self-assembly of non-spherical nanoparticles, Monte Carlo simulations of the packing and thermodynamic properties of truncated nanocubes and cuboctahedra have been performed. The ergodicity problem was overcome by a modified Wang-Landau entropic sampling algorithm and equilibrium structural and thermodynamic properties were computed over a wide density range for both non-interacting and interacting particles. We found a structural transition from a simple cubic to a rhombohedral order when the degree of truncation exceeds a value of 0.9.

  • 25. Wang, Tao
    et al.
    Shi, Li
    Tang, Jing
    Malgras, Victor
    Asahina, Shunsuke
    Liu, Guigao
    Zhang, Huabin
    Meng, Xianguang
    Chang, Kun
    He, Jianping
    Terasaki, Osamu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Yamauchi, Yusuke
    Ye, Jinhua
    A Co3O4-embedded porous ZnO rhombic dodecahedron prepared using zeolitic imidazolate frameworks as precursors for CO2 photoreduction2016Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, nr 12, s. 6712-6720Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Metal-organic frameworks (MOFs) are attracting considerable attention for their use as both the precursor and the template to prepare metal oxides or carbon-based materials. For the first time in this paper, the core-shell ZIF-8@ZIF-67 crystals are thermally converted into porous ZnO@Co3O4 composites by combining a seed-mediated growth process with a two-step calcination. The designed porous ZnO@Co3O4 composites exhibited the highest photocatalytic activity with an excellent stability for the reduction of CO2 among the commonly reported composite photocatalysts. Their superior photocatalytic performance is demonstrated to be resulting from the unique porous structure of ZnO@Co3O4 and the co-catalytic function of Co3O4 which can effectively suppress the photocorrosion of ZnO.

  • 26. Wei, Xinyu
    et al.
    Fan, Qikui
    Liu, Hongpo
    Bai, Yaocai
    Zhang, Lei
    Zheng, Haoquan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Yin, Yadong
    Gao, Chuanbo
    Holey Au-Ag alloy nanoplates with built-in hotspots for surface-enhanced Raman scattering2016Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, nr 34, s. 15689-15695Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plasmonic noble metal nanocrystals with interior nanogaps have attracted great attention in surface-enhanced Raman scattering (SERS) applications due to the presence of built-in hotspots. Herein, we report a synthesis route to holey Au-Ag alloy nanoplates by controlled galvanic replacement with Ag nanoplates as the sacrificial template, a sulfite-coordinated Au(I) salt as the Au source, and polyvinylpyrrolidone (PVP) as the capping agent. PVP helps regulate the anisotropic growth of nanopores on the Ag nanoplates to afford a highly holey nanostructure, and the monovalent Au(I) salt plays a critical role in stabilizing these holey nanoplates by rapidly enriching Au in the alloy nanostructures. Numerical simulations and experimental results suggest that these holey Au-Ag alloy nanoplates possess enormous internal hotspots for high sensitivity in the SERS analysis, and high stability for excellent reliability of the analysis under many harsh conditions. We believe that this strategy is potentially applicable to the synthesis of many other types of plasmonic nanostructures with inherent nanogaps for many sensing and imaging applications.

  • 27.
    Wetterskog, Erik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Uppsala University, Sweden.
    Klapper, Alice
    Disch, Sabrina
    Josten, Elisabeth
    Hermann, Raphaël P.
    Rücker, Ulrich
    Brückel, Thomas
    Bergström, Lennart
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Salazar-Alvarez, German
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Tuning the structure and habit of iron oxide mesocrystals2016Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, nr 34, s. 15571-15580Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A precise control over the meso-and microstructure of ordered and aligned nanoparticle assemblies, i.e., mesocrystals, is essential in the quest for exploiting the collective material properties for potential applications. In this work, we produced evaporation-induced self-assembled mesocrystals with different mesostructures and crystal habits based on iron oxide nanocubes by varying the nanocube size and shape and by applying magnetic fields. A full 3D characterization of the mesocrystals was performed using image analysis, high-resolution scanning electron microscopy and Grazing Incidence Small Angle X-ray Scattering (GISAXS). This enabled the structural determination of e.g. multi-domain mesocrystals with complex crystal habits and the quantification of interparticle distances with sub-nm precision. Mesocrystals of small nanocubes (l = 8.6-12.6 nm) are isostructural with a body centred tetragonal (bct) lattice whereas assemblies of the largest nanocubes in this study (l = 13.6 nm) additionally form a simple cubic (sc) lattice. The mesocrystal habit can be tuned from a square, hexagonal to star-like and pillar shapes depending on the particle size and shape and the strength of the applied magnetic field. Finally, we outline a qualitative phase diagram of the evaporation-induced self-assembled superparamagnetic iron oxide nanocube mesocrystals based on nanocube edge length and magnetic field strength.

  • 28.
    Zhu, Chuantao
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Luleå University of Technology, Sweden.
    Soldatov, Alexander
    Mathew, Aji P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Luleå University of Technology, Sweden.
    Advanced microscopy and spectroscopy reveal the adsorption and clustering of Cu(II) onto TEMPO-oxidized cellulose nanofibers2017Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, nr 22, s. 7419-7428Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    TEMPO (2,2,6,6-tetramethylpiperidine-1-oxylradical)-mediated oxidation nanofibers (TOCNF), as a biocompatible and bioactive material, have opened up a new application of nanocellulose for the removal of water contaminants. This development demands extremely sensitive and accurate methods to understand the surface interactions between water pollutants and TOCNF. In this report, we investigated the adsorption of metal ions on TOCNF surfaces using experimental techniques atthe nano and molecular scales with Cu(II) as the target pollutant in both aqueous and dry forms. Imaging with in situ atomic force microscopy (AFM), together with a study of the physiochemical properties of TOCNF caused by adsorption with Cu(II) in liquid, were conducted using the PeakForce Quantitative NanoMechanics (PF-QNM) mode at the nano scale. The average adhesion force between the tip and the target single TOCNF almost tripled after adsorption with Cu(II) from 50 pN to 140 pN. The stiffness of the TOCNF was also enhanced because the Cu(II) bound to the carboxylate groups and hardened the fiber. AFM topography, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) mapping and X-ray photoelectron spectroscopy (XPS) indicated that the TOCNF were covered by copper nanolayers and/or nanoparticles after adsorption. The changes in the molecular structure caused by the adsorption were demonstrated by Raman and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). This methodology will be of great assistance to gain qualitative and quantitative information on the adsorption process and interaction between charged entities in aqueous medium.

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