| 1. |
- Ahmed, Heba, et al.
(författare)
-
Ultrafast assembly of swordlike Cu-3(1,3,5-benzenetricarboxylate)(n) metal-organic framework crystals with exposed active metal sites
- 2020
-
Ingår i: Nanoscale Horizons. - : ROYAL SOC CHEMISTRY. - 2055-6764 .- 2055-6756. ; 5:7, s. 1050-1057
-
Tidskriftsartikel (refereegranskat)abstract
- Owing to their large surface area and high uptake capacity, metal-organic frameworks (MOFs) have attracted considerable attention as potential materials for gas storage, energy conversion, and electrocatalysis. Various strategies have recently been proposed to manipulate the MOF surface chemistry to facilitate exposure of the embedded metal centers at the crystal surface to allow more effective binding of target molecules to these active sites. Nevertheless, such strategies remain complex, often requiring strict control over the synthesis conditions to avoid blocking pore access, reduction in crystal quality, or even collapse of the entire crystal structure. In this work, we exploit the hydrodynamics and capillary resonance associated with acoustically-driven dynamically spreading and nebulizing thin films as a new method for ultrafast synthesis of swordlike Cu-3(1,3,5-benzenetricarboxylate)(n) (Cu-BTC) MOFs with unique monoclinic crystal structures (P2(1)/n) distinct to that obtained via conventional bulk solvothermal synthesis, with swordlike morphologies whose lengths far exceed their thicknesses. Through pulse modulation and taking advantage of the rapid solvent evaporation associated with the high nebulisation rates, we are also able to control the thicknesses of these large aspect ratio (width and length with respect to the thickness) crystals by arresting their vertical growth, which, in turn, allows exposure of the metal active sites at the crystal surface. An upshot of such active site exposure on the crystal surface is the concomitant enhancement in the conductivity of the MOF, evident from the improvement in its current density by two orders of magnitude.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Bergendal, Erik, et al.
(författare)
-
3D texturing of the air-water interface by biomimetic self-assembly
- 2020
-
Ingår i: Nanoscale Horizons. - : Royal Society of Chemistry. - 2055-6764 .- 2055-6756. ; 5:5, s. 839-846
-
Tidskriftsartikel (refereegranskat)abstract
- A simple, insoluble monolayer of fatty acid is shown to induce 3D nanotexturing of the air-water interface. This advance has been achieved through the study of monolayers of a methyl-branched long chain fatty acid, analogous to those found on the surface of hair and wool, directly at the air-water interface. Specular neutron reflectometry combined with AFM probing of deposited monolayers shows pronounced 3D surface domains, which are absent for unbranched analogues and are attributed to hydrocarbon packing constraints. The resulting surface topographies of the water far exceed the height perturbation that can be explained by the presence of capillary waves of a free liquid surface. These have hitherto been considered the only source of perturbation of the flatness of a planar water interface under gravity in the absence of topographical features from the presence of extended, globular or particulate matter. This amounts to a paradigm shift in the study of interfacial films and opens the possibility of 3D texturing of the air-water interface.
|
|
| 6. |
- Bergendal, Erik, et al.
(författare)
-
3D texturing of the air–water interface by biomimetic self-assembly
- 2020
-
Ingår i: Nanoscale Horizons. - 2055-6764 .- 2055-6756. ; :5, s. 839-846
-
Tidskriftsartikel (refereegranskat)abstract
- A simple, insoluble monolayer of fatty acid is shown to induce 3D nanotexturing of the air–water interface. This advance has been achieved through the study of monolayers of a methyl-branched long chain fatty acid, analogous to those found on the surface of hair and wool, directly at the air–water interface. Specular neutron reflectometry combined with AFM probing of deposited monolayers shows pronounced 3D surface domains, which are absent for unbranched analogues and are attributed to hydrocarbon packing constraints. The resulting surface topographies of the water far exceed the height perturbation that can be explained by the presence of capillary waves of a free liquid surface. These have hitherto been considered the only source of perturbation of the flatness of a planar water interface under gravity in the absence of topographical features from the presence of extended, globular or particulate matter. This amounts to a paradigm shift in the study of interfacial films and opens the possibility of 3D texturing of the air–water interface.
|
|
| 7. |
- Chang, Jian, et al.
(författare)
-
Ultratough and ultrastrong graphene oxide hybrid films via a polycationitrile approach
- 2021
-
Ingår i: Nanoscale Horizons. - : Royal Society of Chemistry (RSC). - 2055-6764 .- 2055-6756. ; 6:4, s. 341-347
-
Tidskriftsartikel (refereegranskat)abstract
- Graphene oxide (GO) is a classic two dimensional (2D) building block that can be used to develop high-performance materials for numerous applications, particularly in the energy and environmental fields. Currently, the precise assembly of GO nanosheets into macroscopic nanohybrids of superior strength and toughness is desirable, and faces challenges and trade-offs. Herein, we exploited the freshly established polycationitrile method as a powerful molecular crosslinking strategy to engineer ultratough and ultrastrong GO/polymer hybrid films, in which a covalent triazine-based network was constructed in a mild condition to reinforce the interface between GO nanosheets. The tensile strength and toughness reached 585 +/- 25 MPa and 14.93 +/- 1.09 MJ m(-3), respectively, which, to the best of our knowledge, are the current world records in all GO-based hybrid films. As an added merit of the tailor-made polymer crosslinker, the high mechanical performance can be maintained in large part at an extremely high relative humidity of 98%. This emerging interface-engineering approach paves a new avenue to produce integrated strong-and-tough 2D nanohybrid materials that are useful in aerospace, artificial muscle, energy harvesting, tissue engineering and more.
|
|
| 8. |
- Chen, Wei, et al.
(författare)
-
Colloidal PbS quantum dot stacking kinetics during deposition via printing
- 2020
-
Ingår i: Nanoscale Horizons. - : Royal Society of Chemistry (RSC). - 2055-6764 .- 2055-6756. ; 5:5, s. 880-885
-
Tidskriftsartikel (refereegranskat)abstract
- Colloidal PbS quantum dots (QDs) are attractive for solution-processed thin-film optoelectronic applications. In particular, directly achieving QD thin-films by printing is a very promising method for low-cost and large-scale fabrication. The kinetics of QD particles during the deposition process play an important role in the QD film quality and their respective optoelectronic performance. In this work, the particle self-organization behavior of small-sized QDs with an average diameter of 2.88 +/- 0.36 nm is investigated for the first time in situ during printing by grazing-incidence small-angle X-ray scattering (GISAXS). The time-dependent changes in peak intensities suggest that the structure formation and phase transition of QD films happen within 30 seconds. The stacking of QDs is initialized by a templating effect, and a face-centered cubic (FCC) film forms in which a superlattice distortion is also found. A body-centered cubic nested FCC stacking is the final QD assembly layout. The small size of the inorganic QDs and the ligand collapse during the solvent evaporation can well explain this stacking behavior. These results provide important fundamental understanding of structure formation of small-sized QD based films prepared via large-scale deposition with printing with a slot die coater.
|
|
| 9. |
|
|
| 10. |
- Grossmann, Lukas, et al.
(författare)
-
Evolution of adsorption heights in the on-surface synthesis and decoupling of covalent organic networks on Ag(111) by normal-incidence X-ray standing wave
- 2022
-
Ingår i: Nanoscale Horizons. - : Royal Society of Chemistry. - 2055-6764 .- 2055-6756. ; 7:1, s. 51-62
-
Tidskriftsartikel (refereegranskat)abstract
- Structural characterization in on-surface synthesis is primarily carried out by Scanning Probe Microscopy (SPM) which provides high lateral resolution. Yet, important fresh perspectives on surface interactions and molecular conformations are gained from adsorption heights that remain largely inaccessible to SPM, but can be precisely measured with both elemental and chemical sensitivity by Normal-Incidence X-ray Standing Wave (NIXSW) analysis. Here, we study the evolution of adsorption heights in the on-surface synthesis and post-synthetic decoupling of porous covalent triazine-phenylene networks obtained from 2,4,6-tris(4-bromophenyl)-1,3,5-triazine (TBPT) precursors on Ag(111). Room temperature deposition of TBPT and mild annealing to ~150 C result in full debromination and formation of organometallic intermediates, where the monomers are linked into reticulated networks by C-Ag-C bonds. Topologically identical covalent networks comprised of triazine vertices that are interconnected by biphenyl units are obtained by a thermally activated chemical transformation of the organometallic intermediates. Exposure to iodine vapor facilitates decoupling by intercalation of an iodine monolayer between the covalent networks and the Ag(111) surface. Accordingly, Scanning Tunneling Microscopy (STM), X-ray Photoelectron Spectroscopy (XPS) and NIXSW experiments are carried out for three successive sample stages: organometallic intermediates, covalent networks directly on Ag(111) and after decoupling. NIXSW analysis facilitates the determination of adsorption heights of chemically distinct carbon species, i.e. in the phenyl and triazine rings, and also for the organometallic carbon atoms. Thereby, molecular conformations are assessed for each sample stage. The interpretation of experimental results is informed by Density Functional Theory (DFT) calculations, providing a consistent picture of adsorption heights and molecular deformations in the networks that result from the interplay between steric hindrance and surface interactions. Quantitative adsorption heights, i.e. vertical distances between adsorbates and surface, provide detailed insight into surface interactions, but are underexplored in on-surface synthesis. In particular, the direct comparison with an in situ prepared decoupled state unveils the surface influence on the network structure, and shows that iodine intercalation is a powerful decoupling strategy.
|
|
