| 1. |
- Amombo Noa, Francoise Mystere, 1988, et al.
(författare)
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A hexagon based Mn(ii) rod metal-organic framework - structure, SF 6 gas sorption, magnetism and electrochemistry
- 2023
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1364-548X .- 1359-7345. ; 59:15, s. 2106-2109
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Tidskriftsartikel (refereegranskat)abstract
- A manganese(ii) metal-organic framework based on the hexatopic hexakis(4-carboxyphenyl)benzene, cpb6−: [Mn3(cpb)(dmf)3], was solvothermally prepared showing a Langmuir area of 438 m2 g−1, rapid uptake of sulfur hexafluoride (SF6) as well as electrochemical and magnetic properties, while single crystal diffraction reveals an unusual rod-MOF topology.
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| 2. |
- Gebauer, Denis, et al.
(författare)
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A transparent hybrid of nanocrystalline cellulose and amorphous calcium carbonate nanoparticles
- 2011
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Ingår i: NANOSCALE. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 3:9, s. 3563-3566
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Tidskriftsartikel (refereegranskat)abstract
- Nanocellulose hybrids are promising candidates for biodegradable multifunctional materials. Hybrids of nanocrystalline cellulose (NCC) and amorphous calcium carbonate (ACC) nanoparticles were obtained through a facile chemical approach over a wide range of compositions. Controlling the interactions between NCC and ACC results in hard, transparent structures with tunable composition, homogeneity and anisotropy.
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| 3. |
- Wicklein, Bernd, et al.
(författare)
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Functional hybrids based on biogenic nanofibrils and inorganic nanomaterials
- 2013
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 1:18, s. 5469-5478
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Tidskriftsartikel (refereegranskat)abstract
- This feature article reviews some of the recent work on the fabrication of functional hybrids based on biogenic nanofibers and inorganic nanomaterials with an emphasis on their functional properties and suggested potential applications. We also discuss some of the work oriented towards the formation of ordered materials in the pursuit of achieving a hierarchical construction. Besides the academic interest in biogenic nanomaterials, it is anticipated that the use of natural, abundant nanomaterials, e.g., cellulose, chitin, collagen, and silk, could provide affordable functional nanomaterials in developing countries.
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| 4. |
- Yu, Xiaowen, et al.
(författare)
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Electrocatalytic Glycerol Oxidation with Concurrent Hydrogen Evolution Utilizing an Efficient MoOx/Pt Catalyst
- 2021
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 17:44
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Tidskriftsartikel (refereegranskat)abstract
- Glycerol electrolysis affords a green and energetically favorable route for the production of value-added chemicals at the anode and H2 production in parallel at the cathode. Here, a facile method for trapping Pt nanoparticles at oxygen vacancies of molybdenum oxide (MoOx) nanosheets, yielding a high-performance MoOx/Pt composite electrocatalyst for both the glycerol oxidation reaction (GOR) and the hydrogen evolution reaction (HER) in alkaline electrolytes, is reported. Combined electrochemical experiments and theoretical calculations reveal the important role of MoOx nanosheets for the adsorption of glycerol molecules in GOR and the dissociation of water molecules in HER, as well as the strong electronic interaction with Pt. The MoOx/Pt composite thus significantly enhances the specific mass activity of Pt and the kinetics for both reactions. With MoOx/Pt electrodes serving as both cathode and anode, two-electrode glycerol electrolysis is achieved at a cell voltage of 0.70 V to reach a current density of 10 mA cm−2, which is 0.90 V less than that required for water electrolysis.
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| 5. |
- Wang, Liping, et al.
(författare)
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Carbon aerogels from bacterial nanocellulose as anodes for lithium ion batteries
- 2014
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:34, s. 17549-17554
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Tidskriftsartikel (refereegranskat)abstract
- Carbon aerogels with large open pores and high surface area are fabricated via pyrolysis of a readily available natural resource, e. g., bacterial nanocellulose (BNC) aerogels. Freeze-drying of the BNC hydrogels is used to preserve the 3D open network structure upon calcination whereas using Fe(III) improves the yield and H/C ratio. These carbon aerogels are explored as anodes in lithium ion batteries where it is shown that they deliver superior capacity retention and rate performance compared to other carbon-based materials.
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| 6. |
- White, Jai, et al.
(författare)
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Electrodeposited PdNi on a Ni rotating disk electrode highly active for glycerol electrooxidation in alkaline conditions
- 2022
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 403
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Tidskriftsartikel (refereegranskat)abstract
- The development of alcohol-based electrolysis to enable the concurrent production of hydrogen with low electricity consumption still faces major challenges in terms of the maximum anodic current density achievable. Whilst noble metals enable a low electrode potential to facilitate alcohol oxidation, the deactivation of the catalyst at higher potentials makes it difficult for the obtained anodic current density to compete with water electrolysis. In this work the effect of significant parameters such as mass transport, glycerol and OH- concentration and electrolyte temperature on the glycerol electrooxidation reaction (GEOR) in alkaline conditions on a bimetallic catalyst PdNi/Ni-RDE (Pd0.9Ni0.1) has been studied to discern experimental conditions which maximise achievable anodic current density before deactivation occurs. The ratio of NaOH:glycerol in the electrolyte highly affects the rate of the GEOR. A maximum current density of 793 mA cm(-2) at-0.125 V vs. Hg/HgO through steady state polarisation curves was achieved at a moderate and intermediate rotation rate of 500 RPM in a 2 M NaOH and 1 M glycerol (ratio of 2) electrolyte at 80 & DEG;C. Shown here is a method of catalyst reactivation for enabling the longterm use of the PdNi/Ni-RDE for electrolysis at optimal conditions for extended periods of time (3 h at 300 mA cm(-2) and 10 h at 100 mA cm(-2)). Through scanning electron microscopy (SEM), X-ray photon electron spectroscopy (XPS) and X-ray diffraction (XRD) it is shown that the electrodeposition of Pd and Ni forms an alloy and that after 10 h of electrolysis the catalyst has chemical and structural stability. This study provides details on parameters significant to the maximising of the GEOR current density and the minimising of the debilitating effect that deactivation has on noble metal based electrocatalysts for the GEOR.
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| 7. |
- White, Jai, et al.
(författare)
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Glycerol Electrooxidation at Industrially Relevant Current Densities Using Electrodeposited PdNi/Nifoam Catalysts in Aerated Alkaline Media
- 2023
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 170:8
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Tidskriftsartikel (refereegranskat)abstract
- Through glycerol electrooxidation, we demonstrate the viability of using a PdNi catalyst electrodeposited on Ni foam to facilitate industrially relevant rates of hydrogen generation while concurrently providing valuable organic chemicals as glycerol oxidation products. This electrocatalyst, in a solution of 2 M NaOH and 1 M glycerol at 80 °C, enabled current densities above 2000 mA cm−2 (in a voltammetric sweep) to be obtained in atmospheres of both air and N2. Repeated potential cycling under an aerated atmosphere to these exceptional current densities indicated a high stability of the catalyst. Through steady state polarisation curves, 1000 mA cm−2 was reached below an anodic potential of 0.8 V vs RHE. Chronoamperometry showed glycerate and lactate being the major oxidation products, with increased selectivity for lactate at the expense of glycerate in aerated systems. Aerated atmospheres were demonstrated to consistently increase the apparent Faradaic efficiency to >100%, as determined by the concentration of oxidation products in solution. The excellent performance of PdNi/Ni in aerated solutions suggests that O2 removal from the electrolyte is not needed for an industrial glycerol electrooxidation process, and that combining electrochemical and chemical glycerol oxidation, in the presence of dissolved O2, presents an important process advantage.
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| 8. |
- Agthe, Michael, et al.
(författare)
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Following in Real Time the Two-Step Assembly of Nanoparticles into Mesocrystals in Levitating Drops
- 2016
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 16:11, s. 6838-6843
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Tidskriftsartikel (refereegranskat)abstract
- Mesocrystals composed of crystallographically aligned nanocrystals are present in biominerals and assembled materials which show strongly directional properties of importance for mechanical protection and functional devices. Mesocrystals are commonly formed by complex biomineralization processes and can also be generated by assembly of anisotropic nanocrystals. Here, we follow the evaporation-induced assembly of maghemite nanocubes into mesocrystals in real time in levitating drops. Analysis of time-resolved small-angle X-ray scattering data and ex situ scanning electron microscopy together with interparticle potential calculations show that the substrate-free, particle-mediated crystallization process proceeds in two stages involving the formation and rapid transformation of a dense, structurally disordered phase into ordered mesocrystals. Controlling and tailoring the particle-mediated formation of mesocrystals could be utilized to assemble designed nanoparticles into new materials with unique functions.
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| 9. |
- Boily, Jean-Francois, et al.
(författare)
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Thin Water Films at Multifaceted Hematite Particle Surfaces
- 2015
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 31:48, s. 13127-13137
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Tidskriftsartikel (refereegranskat)abstract
- Mineral surfaces exposed to moist air stabilize nanometer- to micrometer-thick water films. This study resolves the nature of thin water film formation at multifaceted hematite (alpha-Fe2O3) nanoparticle surfaces with crystallographic faces resolved by selected area electron diffraction. Dynamic vapor adsorption (DVA) in the 0-19 Torr range at 298 K showed that these particles stabilize water films consisting of up to 4-5 monolayers. Modeling of these data predicts water loadings in terms of an adsorption regime (up to 16 H2O/nm(2)) involving direct water binding to hematite surface sites, and of a condensation regime (up to 34 H2O/nm(2)) involving water binding to hematite-bound water nanodusters. Vibration spectroscopy identified the predominant hematite surface hydroxo groups (-OH, mu-OH, mu(3)-OH) through which first layer water molecules formed hydrogen bonds, as well as surface iron sites directly coordinating water molecules (i.e., as geminal eta-(OH2)(2) sites). Chemometric analyses of the vibration spectra also revealed a strong correspondence in the response of hematite surface hydroxo groups to DVA-derived water loadings. These findings point to a near-saturation of the hydrogen-bonding environment of surface hydroxo groups at a partial water vapor pressure of similar to 8 Torr (similar to 40% relative humidity). Classical molecular dynamics (MD) resolved the interfacial water structures and hydrogen bonding populations at five representative crystallographic faces expressed in these nanoparticles. Simulations of single oriented slabs underscored the individual roles of all (hydro)oxo groups in donating and accepting hydrogen bonds with first layer water in the adsorption regime. These analyses pointed to the preponderance of hydrogen bond-donating -OH groups in the stabilization of thin water films. Contributions of mu-OH and mu(3)-OH groups are secondary, yet remain essential in the stabilization of thin water films. MD simulations also helped resolve crystallographic controls on water water interactions occurring in the condensation regime. Water water hydrogen bond populations are greatest on the (001) face, and decrease in importance in the order (001) > (012) approximate to (110) > (014) >> (100). Simulations of a single (similar to 5 nm x similar to 6 nm x similar to 6 nm) nanometric hematite particle terminated by the (001), (110), (012), and (100) faces also highlighted the key roles that sites at particle edges play in interconnecting thin water films grown along contiguous crystallographic faces. Hydroxo water hydrogen bond populations showed that edges were the preferential loci of binding. These simulations also suggested that equilibration times for water binding at edges were slower than on crystallographic faces. In this regard, edges, and by extension roughened surfaces, are expected to play commanding roles in the stabilization of thin water films. Thus, in focusing on the properties of nanometric-thick water layers at hematite surfaces, this study revealed the nature of interactions between water and multifaced particle surfaces. Our results pave the way for furthering our understanding of mineral-thin water film interfacial structure and reactivity on a broader range of materials.
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| 10. |
- Guccini, Valentina, et al.
(författare)
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Inducing nematic ordering of cellulose nanofibers using osmotic dehydration
- 2018
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Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 10:48, s. 23157-23163
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Tidskriftsartikel (refereegranskat)abstract
- The formation of nematically-ordered cellulose nanofiber (CNF) suspensions with an order parameter fmax ≈ 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.
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