Fast and efficient shear-force assisted production of covalently functionalized oxide nanosheets

Abstract

HypothesisWhile controlled and efficient exfoliation of layered oxides often remains a time consuming challenge, the surface modification of inorganic nanosheets is of outmost importance for future applications. The functionalization of the bulk material prior to exfoliation should allow the application of tools developped for Van der Waals materials to directly produce functionalized oxide nanosheets. ExperimentsThe Aurivillius phase Bi 2 SrTa 2 O 9 is functionalized by a linear aliphatic phosphonic acid via microwave-assisted reactions. The structure of the hybrid material and the coordination of the phosphonate group is scrutinized, notably by Pair Distribution Function. This functionalized layered oxide is then exfoliated in one hour in organic solvent, using high shear force dispersion.The obtained nanosheets are characterized in suspension and as deposits to check their chemical integrity. FindingsThe covalent functionalization decreases the electrostatic cohesion between the inorganic layers leading to an efficient exfoliation in short time under shearing. The functionalization of the bulk material is preserved on the nanosheets upon exfoliation and plays a major role to enable liquid-phase exfoliation and in the stability of the resulting suspensions. This strategy is very promising for the straighforward preparation of functionalized nanosheets, paving the way for versatile design of new (multi)functional hybrid nanosheets for various potential applications.

Current State and Perspectives of Exfoliated Zeolites

“…The discussion will focus first on the methodology for proving monolayers in solution and determining their structure, while the synthetic aspects are described in the next section. This proving of the presence of monolayers in solution and characterization of their structure is based on a protocol combining the following methods: [51,96] i. SAXS for measuring interlayer d-spacing in solution, ii. in situ XRD confirming mono-dispersity and structure of the layers in solution, iii.…”

“…The discussion will focus first on the methodology for proving monolayers in solution and determining their structure, while the synthetic aspects are described in the next section. This proving of the presence of monolayers in solution and characterization of their structure is based on a protocol combining the following methods: [ 51,96 ] SAXS for measuring interlayer d‐spacing in solution, in situ XRD confirming mono‐dispersity and structure of the layers in solution, AFM to show distribution of layer thicknesses, in‐plane XRD to determine the planar unit cell, X‐ray diffraction, TEM, and ED to characterize layer structure, and flocculation reaction, e.g., with a surfactant, to show formation of multilayered composites with alternating inorganic and surfactant layers with specific d‐spacings. …”

Graphene‐Based Silicon Photonic Devices for Optical Interconnects

“…Two main categories of mechanical force-assisted liquid exfoliation methods have been developed: sonication-assisted liquid exfoliation [133,[136][137][138] and shear forceassisted liquid exfoliation. [135,[139][140][141] In sonication-assisted liquid exfoliation, graphite is chemically dispersed in a liquid medium without the use of surfactants. The dispersion is then subjected to ultrasonication in organic solvents.…”

“…Two main categories of mechanical force‐assisted liquid exfoliation methods have been developed: sonication‐assisted liquid exfoliation [ 133,136–138 ] and shear force‐assisted liquid exfoliation. [ 135,139–141 ]…”

Highly Efficient Liquid-Phase Exfoliation of Layered Perovskite-like Titanates HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd) into Nanosheets

“…Further ultrasonic treatment is supposed to generate a large number of dense bubble clusters whose powerful vibration and implosion produce severe energy boosts, mechanical shear stresses and turbulence, thus providing delamination for the layered structure [68]. Along with ultrasound, its initiation is also reported to be feasible via microwave treatment [69] and a shear-force assisted approach [70]. The intercalationsonication method allows for the achievement of high exfoliation completeness for many layered compounds.…”