The Mechanism of Cavitation-Induced Scission of Single-Walled Carbon Nanotubes

Hennrich, Frank; Krupke, Ralph; Arnold, Katharina; Stütz, Jan A. Rojas; Lebedkin, Sergei; Koch, Thomas; Schimmel, Thomas; Kappes, Manfred M.

doi:10.1021/jp065262n

Cited by 246 publications

(272 citation statements)

References 34 publications

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“…Thus, the efficiency of SWNT suspension increased for longer sonication times. The length of nanotubes in an ultrasonicated sample scales as t -0.5 , as demonstrated in ref 165, and so shorter SWNTs were most likely produced with longer ultrasonication times. The estimated lengths of the SWNTs used in single molecule studies in this dissertation were 100-500 nm, and the average length measured for DNAwrapped samples used in Chapter 5 was ~380 nm.…”

Section: Recommended Sample Preparation Conditionsmentioning

confidence: 80%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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Single-walled carbon nanotubes (SWNTs) are cylindrical graphitic molecules that have remained at the forefront of nanomaterials research since 1991, largely due to their exceptional and unusual mechanical, electrical, and optical properties. The motivation for understanding how nanotubes interact with light (i.e., SWNT photophysics) is both fundamental and applied. Individual nanotubes may someday be used as superior near-infrared fluorophores, biological tags and sensors, and components for ultrahigh-speed optical communications systems. Establishing an understanding of basic nanotube photophysics is intrinsically significant and should enable the rapid development of such innovations. Unlike conventional molecules, carbon nanotubes are synthesized as heterogeneous samples, composed of molecules with different diameters, chiralities, and lengths. Because a nanotube can be either metallic or semiconducting depending on its particular molecular structure, SWNT samples are also mixtures of conductors and semiconductors. Early progress in understanding the optical characteristics of SWNTs was limited because nanotubes aggregate when synthesized, causing a mixing of the energy states of different nanotube structures. Recently, significant improvements in sample preparation have made it possible to isolate individual nanotubes, enabling many advances in characterizing their optical properties. In this Account, single-molecule confocal microscopy and spectroscopy were implemented to study the fluorescence from individual nanotubes. Single-molecule measurements naturally circumvent the difficulties associated with SWNT sample inhomogeneities. Intrinsic SWNT photoluminescence has a simple narrow Lorentzian line shape and a polarization dependence, as expected for a one-dimensional system. Although the local environment heavily influences the optical transition wavelength and intensity, single nanotubes are exceptionally photostable. In fact, they have the unique characteristic that their single molecule fluorescence intensity remains constant over time; SWNTs do not “blink” or photobleach under ambient conditions. In addition, transient absorption spectroscopy was used to examine the relaxation dynamics of photoexcited nanotubes and to elucidate the nature of the SWNT excited state. For metallic SWNTs, very fast initial recovery times (300–500 fs) corresponded to excited-state relaxation. For semiconducting SWNTs, an additional slower decay component was observed (50–100 ps) that corresponded to electron–hole recombination. As the excitation intensity was increased, multiple electron–hole pairs were generated in the SWNT; however, these e−h pairs annihilated each other completely in under 3 ps. Studying the dynamics of this annihilation process revealed the lifetimes for one, two, and three e−h pairs, which further confirmed that the photoexcitation of SWNTs produces not free electrons but rather one-dimensional bound electron–hole pairs (i.e., excitons). In summary, nanotube photophysics is a rapidly developing area o...

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Section: Recommended Sample Preparation Conditionsmentioning

confidence: 80%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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“…This journal is © The Royal Society of Chemistry 2014 bubbles, with radius of about one hundred of µm, that generate high strain rates in the surrounding liquid upon implosion. [1][2][3] Fig . 7 in main text shows the typical effects of treatment by sonication (Fig.…”

Section: Supporting Information Exfoliation Methodsmentioning

confidence: 99%

Fragmentation and exfoliation of 2-dimensional materials: a statistical approach

et al. 2014

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The main advantage for applications of graphene and related 2D materials is that they can be produced on large scales by liquid phase exfoliation. The exfoliation process shall be considered as a particular fragmentation process, where the 2D character of the exfoliated objects will influence significantly fragmentation dynamics as compared to standard materials. Here, we used automatized image processing of Atomic Force Microscopy (AFM) data to measure, one by one, the exact shape and size of thousands of nanosheets obtained by exfoliation of an important 2D-material, boron nitride, and used different statistical functions to model the asymmetric distribution of nanosheet sizes typically obtained.Being the resolution of AFM much larger than the average sheet size, analysis could be performed directly at the nanoscale and at the single sheet level. We find that the size distribution of the sheets at a given time follows a log-normal distribution, indicating that the exfoliation process has a "typical" scale length that changes with time and that exfoliation proceeds through the formation of a distribution of random cracks that follow Poisson statistics. The validity of this model implies that the size distribution does not depend on the different preparation methods used, but is a common feature in the exfoliation of this material and thus probably for other 2D materials.The huge scientic and technological interest for graphene has triggered in the last few years the development of a wide range of techniques to produce and process nanosheets that, having nanometric thickness and mesoscopic lateral size, shall be considered as quasi 2-dimensional (2D) objects. Besides their novel properties, even the way these 2D sheets are produced in solution, by exfoliation, 1 is an original process, still not completely understood.The exfoliation of a 2D object from a 3D bulk material is a process spanning from the nano-to meso-scale due to bubble cavitation, intercalation and disruptive fragmentation, as we described in recent work. 2 Exfoliation always yields a polydispersed range of nanosheet thickness and lateral size. When characterizing these 2D sheet solutions, their average size and size standard deviation are commonly reported, oen assuming that their size follows a "Gaussian" (a.k.a. "normal") distribution. Conversely, the experimental data show that the size distribution of these materials is highly asymmetric and nonGaussian.It is noteworthy that this asymmetry in size distribution shall be observed in very different systems such as the distribution of chemical elements in rocks, the species abundance in biology, the lengths of latent periods of infectious diseases in medicine, and the distribution of galaxies in astronomy (Fig. 1). 3,4 A better modelling of the size distribution of 2D materials is needed both from a fundamental point of view (to understand the exfoliation mechanism) and from a technological point of view (to improve the metrology of 2D materials for applications and quality control).Here, we ...

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“…However, as sonication time increased, the flake width and length decreased as t -1/2 as observed previously for nanotubes. [136] This behaviour can be used to explain the scaling of concentration with √t. We propose that the max concentration is that where the average solvent volume per flake is just the sphere defined by the flake length.…”

Section: Solventsmentioning

confidence: 99%

Liquid‐Phase Exfoliation of Nanotubes and Graphene

Coleman

2009

Adv Funct Materials

603

536

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Many applications of carbon nanotubes require the exfoliation of the nanotubes to give individual tubes in the liquid phase. This requires the dispersion, exfoliation and stabilisation of nanotubes in a variety of liquids. In this paper we review recent work in this area, focusing on results from the author's group. We begin by reviewing stabilisation mechanisms before exploring research into the exfoliation of nanotubes in solvents, by using surfactants or biomolecules and by covalent attachment of molecules.The concentration dependence of the degree of exfoliation in each case will be highlighted. In addition we will discuss research into the dispersion mechanism for each dispersant type. Most importantly we have compared dispersion quality metrics for all dispersants. From this analysis, we conclude that functionalised nanotubes can be exfoliated to the greatest degree. Finally, we review the extension of this work to the liquid phase exfoliation of graphite to give graphene.

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The Mechanism of Cavitation-Induced Scission of Single-Walled Carbon Nanotubes

Cited by 246 publications

References 34 publications

Photophysics of Individual Single-Walled Carbon Nanotubes

Photophysics of Individual Single-Walled Carbon Nanotubes

Fragmentation and exfoliation of 2-dimensional materials: a statistical approach

Liquid‐Phase Exfoliation of Nanotubes and Graphene

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