Search results for "Exfoliation joint"
showing 10 items of 43 documents
Exfoliation of Alpha-Germanium: A Covalent Diamond-Like Structure
2021
2D materials have opened a new field in materials science with outstanding scientific and technological impact. A largely explored route for the preparation of 2D materials is the exfoliation of layered crystals with weak forces between their layers. However, its application to covalent crystals remains elusive. Herein, a further step is taken by introducing the exfoliation of germanium, a narrow-bandgap semiconductor presenting a 3D diamond-like structure with strong covalent bonds. Pure α-germanium is exfoliated following a simple one-step procedure assisted by wet ball-milling, allowing gram-scale fabrication of high-quality layers with large lateral dimensions and nanometer thicknesses.…
Functionalisation of MoS2 2D layers with diarylethene molecules
2021
Functionalisation of two dimensional (2D) materials with stimuli-responsive molecules has been scarcely investigated. Here, MoS2 layers obtained by chemical exfoliation are covalently and non-covalently functionalised using two photoswitchable diarylethene derivatives under their open- and closed-ring isomers. The choice of these light-responsive molecules is based on their excellent thermal irreversibility and fatigue resistance. The characterisation of the resultant molecular/2D heterostructures proves the successful anchoring of the molecules by both approaches as well as the influence that the driving interaction has in the photoswitching behaviour of the diarylethene isomers after thei…
Proton-conducting zirconium phosphate/poly(vinyl acetate)/glycerine gel electrolytes
2003
This work reports on a proton gel electrolyte composed of zirconium phosphate (ZP) particles suspended in a poly(vinyl acetate)/glycerine matrix. The material was studied by X-ray powder diffraction, differential scanning calorimetry, impedance spectroscopy, and spectrophotometry. It had a proton conductivity of 1–0.1 mS/cm at room temperature and remained stable and transparent up to at least 110 °C; it therefore appears suitable for uses in electrochromic devices. The structure of the ZP powder and of the gel is discussed in terms of water removal from interplanar spaces by heating or exfoliation. It is suggested that an exfoliation of the layered structure of ZP by intercalation of glyce…
Liquid phase exfoliation of carbonate-intercalated layered double hydroxides.
2019
Direct exfoliation of a carbonate layered double hydroxide (LDH) has been achieved by using a novel horn-probe sonic tip, avoiding the development of time-consuming anion-exchange reactions. The most suitable solvents were chosen based on the Hildebrand solubility parameters and the thickness of the exfoliated nanosheets confirmed unambiguously the successful delamination.
Influence of the covalent grafting of organic radicals to graphene on its magnetoresistance
2013
Graphene was obtained by direct exfoliation of graphite in o-dichlorobenzene (oDCB) or benzylamine, and further functionalized with 4,4′-[(1,3-dioxo-1,3-propanediyl)bis(oxy)]bis[2,2,6,6-tetramethyl-1-piperidinyloxy] (1-TEMPO) organic radicals by using the Bingel–Hirsch cyclopropanation reaction. Here, the use of different solvents permits variation of the density of radicals anchored to the carbon layers. Covalent grafting is unambiguously demonstrated by TGA, μ-Raman, XPS and EPR measurements, which also rule out spurious physisorption. Our transport measurements indicate that the conduction mechanism varies as a function of the density of radicals grafted to the carbon layers. Moreover, t…
2D magnetic MOFs with micron-lateral size by liquid exfoliation
2020
The isolation in large amounts of high-quality flakes of 2D MOFs remains a challenge. In this work, we develop a liquid exfoliation procedure to obtain nanosheets for a whole family of Fe-based magnetic MOFs, MUV-1-X. High-quality crystalline layers with lateral sizes of 8 µm and thicknesses of 4 nm, which keep the structural integrity and magnetic properties, are obtained.
Raman Spectra of ZrS2 and ZrSe2 from Bulk to Atomically Thin Layers
2016
In the race towards two-dimensional electronic and optoelectronic devices, semiconducting transition metal dichalcogenides (TMDCs) from group VIB have been intensively studied in recent years due to the indirect to direct band-gap transition from bulk to the monolayer. However, new materials still need to be explored. For example, semiconducting TMDCs from group IVB have been predicted to have larger mobilities than their counterparts from group VIB in the monolayer limit. In this work we report the mechanical exfoliation of ZrX2 (X = S, Se) from bulk down to the monolayer and we study the dimensionality dependence of the Raman spectra in ambient conditions. We observe Raman signal from bul…
Self-Assembly of 1D/2D Hybrid Nanostructures Consisting of a Cd(II) Coordination Polymer and NiAl-Layered Double Hydroxides
2015
The preparation and characterization of a novel hybrid material based on the combination of a 2D-layered double hydroxide (LDH) nanosheets and a 1D-coordination polymer (1D-CP) has been achieved through a simple mixture of suspensions of both building blocks via an exfoliation/restacking approach. The hybrid material has been thoroughly characterized demonstrating that the 1D-CP moieties are intercalated as well as adsorbed on the surface of the LDH, giving rise to a layered assembly with the coexistence of the functionalities of their initial constituents. This hybrid represents the first example of the assembly of 1D/2D nanomaterials combining LDH with CP and opens the door for a plethora…
Accelerated weathering of PP based nanocomposites: Effect of the presence of maleic anhydryde grafted polypropylene
2013
Polymer nanocomposites are currently a topic of great interest. The increasing importance they are gaining also in the standpoint of industrial applications, is giving concerns regarding their environmental stability and, in general, their behaviour in outdoor applications, under direct solar irradiation. Papers available in the literature have highlighted the different influences of different nanosized fillers, in particular clay-based nanofillers; however, few data are available regarding other nanosized fillers. Furthermore, the research on polymer nanocomposites has clearly pointed out that the use of compatibilizers is required to improve the mechanical performance and the dispersion o…
Liquid phase exfoliation of antimonene: systematic optimization, characterization and electrocatalytic properties
2019
Antimonene, a novel group 15 two-dimensional material, is attracting great attention due to its outstanding physical and chemical properties. Despite its thermodynamic stability, the pronounced covalent character of the interlayer interactions imposes severe limitations on its exfoliation into mono- and few-layer. Here, we develop a systematic study of liquid phase exfoliation (LPE) with the aim to optimize antimonene production in terms of concentration and dimensional anisotropy, investigating the most relevant experimental factors affecting the exfoliation: pre-processing of pristine antimony, solvent selection based on Hansen solubility parameters and ultrasound conditions. Moreover, ex…