Formation of Graphene Oxide Nanoscrolls in Organic Solvents: Toward Scalable Device Fabrication

Abstract

In this work, formation of graphene oxide (GO) nanoscrolls in organic solvents was investigated upon dispersing GO nanosheets in organic solvents by sonication. It was found that, in some of the organic solvents, the single-layer GO sheets can effectively curl onto themselves to form the nanoscrolls that then sediment under gravity from the dispersion media. The sedimentation was monitored by UV−vis spectroscopy when the GO suspensions were left aside for different time periods after the sonication. The nanoscrolls were separated and characterized by transmission electron microscopy (TEM) and electron diffraction (ED). A typical solvent with such scroll-forming function is pyridine, where 82% of the GO sheets form the GO nanoscrolls and undergo the sedimentation. Scroll formation is also observed for N,N-dimethylformamide (DMF), methanol, ethanol, isopropyl alcohol, acetic acid, and isobutyric acid, but the yields vary with the solvents. The scrolls formed in pyridine suspension show the average length over 20 μm, interlayer spacing of 0.6 nm, and average diameters of 186 and 192 nm for the two types of the GO samples used here. The scrolls formed in the other solvents show different average lengths and diameters governed by the properties of the solvents. The average lengths of the formed scrolls reflect the tendency of the GO sheets to curl into scrolls in the solvents, while the average number of the included sheets per scroll depends on the sedimentation rate in the suspensions. The scrolling behavior and mechanism are rationalized and elucidated by considering dipole moment, ζ potential, and Hansen solubility parameters of the solvents. Based on the above understanding, the GO scrolls with controllable lengths and diameters can be efficiently fabricated by selecting a suitable solvent, and are expected for applications in hydrogen storage, gas sensing devices, actuators, lubrication materials, and others.

Surface-Modified Ultrathin InSe Nanosheets with Enhanced Stability and Photoluminescence for High-Performance Optoelectronics

“…The high flexibility of the exfoliated InSe nanosheets makes them promising building blocks for constructing 1D architectures, which has been demonstrated by a class of 2D nanosheets, such as TMDs, graphene, and graphene oxide. − As expected, distinct M-InSe nanoscrolls were produced from the as-prepared nanosheets, showing a hollow tube-like structure with diameters of 0.5–6.4 μm and lengths of 20–90 μm (Figure S13). A schematic illustration of the nanoscroll preparation process is shown in Figure a, following the solvent-assisted self-assembly. , An ultrathin nanosheet in the act of rolling was confirmed to be a monolayer according to the thickness of ∼1.1 nm extracted from the AFM image (Figure b).…”

Influence of graphene nanoscrolls on the crystallization behavior and nano‐mechanical properties of polylactic acid

“…Unlike multiwalled nanotubes, GNSs possess an open morphology since the edges of their scrolled sheets are not fused . Scroll formation is controlled by two opposing energy contributions, where bending of the graphene sheets causes the elastic energy to increase, resulting in interactions in overlapping regions of the graphene sheet to reduce the free energy . The van der Waals and π‐π interactions between overlapping layers prevent GNSs from unrolling back into their planar morphology.…”

“…6 Scroll formation is controlled by two opposing energy contributions, where bending of the graphene sheets causes the elastic energy to increase, resulting in interactions in overlapping regions of the graphene sheet to reduce the free energy. 7 The van der Waals and π-π interactions between overlapping layers prevent GNSs from unrolling back into their planar morphology. Studies have shown that graphene as a nanofiller can increase the mechanical and thermal properties of polymers.…”

“…This is evident because of the dark layers overlapped on the lighter ones. Scrolling of GNPs is described as a result of self-assembly, which involves ultrasonication of the solvent-intercalated layer of graphene that enabled self-scrolling 4,7,29. As seen inFigure 1E-H, the scrolling of GNPs into GNS exhibits well-defined concentric geometries produced by the fine tuning of GNPs.…”

Boron nitride nanoscrolls: Structure, synthesis, and applications

“…Solvent-phase exfoliation of bulk BN can obtain single and multi-layer BNS in a highly polar solvent medium, such as N-methylpyrrolidone (NMP) [79,80] and dimethylformamide (DMF) [81]. However, it is essential that the energy required to exfoliate BN must be comparable to the solvent-BN interaction for exfoliation to occur first followed by scroll initiation later.…”