Delamination of graphite in a high pressure homogenizer

Nacken, Thomas J.; Damm, Cornelia; Walter, Johannes; Rüger, Andreas; Peukert, Wolfgang

doi:10.1039/c5ra08643d

Cited by 72 publications

(51 citation statements)

References 61 publications

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“…A significant advantage of this approach is its versatility; it has been used to exfoliate graphene, 24,[27][28][29][30][31] BN, 15 a range of TMDs 25,26,32,33 and TMOs 34,35 as well as black phosphorus [36][37][38][39][40] and a host of other 2D materials. 41,42 Another advantage is the inherent processability of nanosheet dispersions.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence from Liquid‐Exfoliated WS₂Monomers in Poly(Vinyl Alcohol) Polymer Composites

Vega‐Mayoral

Backes

Hanlon

et al. 2015

Adv Funct Materials

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While liquid phase exfoliation can be used to produce nanosheets stabilized in polymer solutions, very little is known about the resultant nanosheet size, thickness or monolayer content. Here we use semi-quantitative spectroscopic metrics based on extinction, Raman and photoluminescence (PL) spectroscopy to investigate these parameters for WS2 nanosheets exfoliated in aqueous polyvinylalcohol (PVA) solutions. By measuring Raman and PL simultaneously, we can track the monolayer content via the PL/Raman intensity ratio while varying processing conditions. We find the monolayer population to be maximized for a stabilizing polymer concentration of 2 g/L. In addition, the monolayer content can be controlled via the centrifugation conditions, exceeding 5% by mass in some cases. These techniques have allowed us to track the ratio of PL/Raman in a droplet of polymer-stabilized WS2 nanosheets as the water evaporates during composite formation. We find no evidence of nanosheet aggregation under these conditions although the PL becomes dominated by trion emission as drying proceeds and the balance of doping from PVA/water changes. Finally, we have produced bulk PVA/WS2 composites by freeze drying where >50% of the monolayers remain unaggregated, even at WS2 volume fractions as high as 10%.2

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Section: Introductionmentioning

confidence: 99%

Photoluminescence from Liquid‐Exfoliated WS₂Monomers in Poly(Vinyl Alcohol) Polymer Composites

Vega‐Mayoral

Backes

Hanlon

et al. 2015

Adv Funct Materials

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“…In order to realize large-scale production of graphene, the pressure-driven fluid dynamics (PFD) is utilized [55,56,61,69,75,78,84,86,109]. Unlike the VFD which depends on the rapidly rotating tube, PFD relies on a serial of flow channels for exfoliation.…”

Section: Pressure-driven Fluid Dynamics (Pfd)mentioning

confidence: 99%

“…These results on size distribution establish PFD as a controllable method for preparing graphene with specified size. As for the defects, only Raman results on the graphene-based films are available [86,109], which indicate low-level basal plane defects. Nevertheless, microscopic study on the individual flakes by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) is still required to get more detailed information on the atomic structure and chemical components of the basal plane of graphene prepared by PFD.…”

Section: Pressure-driven Fluid Dynamics (Pfd)mentioning

confidence: 99%

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Fluid dynamics: an emerging route for the scalable production of graphene in the last five years

Shen

2016

RSC Adv.

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Bulk applications of graphene in fields such as advanced composites, conductive ink, and energy storage require cheap and scalable graphene. Fortunately, in the last decade, liquid-phase exfoliation of graphite to give pristine graphene has been thought as a promising way to massive production of graphene at high efficiency and low cost, in terms of the cheap and abundant graphite source and a variety of cost-effective exfoliation techniques. Though many exfoliation techniques are available so far, this article will highlight the recent progress of fluid dynamics route which emerges as a promising scalable and efficient way for graphene production in the last five years. The emphasis is set on vortex fluidic devices and pressure-and mixer-driven fluid dynamics, with our perspectives on the latest progress, exfoliation mechanism, and some key issues that require further study in order to realize industrial applications.

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“…In such conditions, hydrodynamic cavitation is also likely to occur. As for sonication, cavitation can help the exfoliation but also reduce the lateral sizes of graphene layers [26,27]. Recently [23], some authors have used high pressure homogenizers in a laminar flow regime.…”

Section: Liquid Phase Exfoliation Of 2d Materialsmentioning

confidence: 99%

Hydrodynamic Cavitation through “Labs on a Chip”: From Fundamentals to Applications

Ayela

Cherief

Colombet

et al. 2017

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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-Monitoring hydrodynamic cavitation of liquids through "labs on a chip" (i.e. microchannels with a shrinkage, such as microdiaphragms or microventuris) is an improvement in experimental approaches devoted to study the mechanisms involved in these multiphase flows. The small sizes of the reactors do not require big substructures. Flow rates of around 1 L/h make possible the characterisation of rare, toxic or expensive pure fluids or mixtures. Moreover, because of that microfluidic approach, an unique inception of the cavitation from a laminar flow regime is also possible, that provides precious databases for simulation or modelisation. Lastly, "labs on a chip" are an extremely versatile solution to perform novel experiments, as they are embeddable in tools basically designed to proceed with small samples (confocal microscopy, spectroscopy). We present here a summary of the former experiments performed by our team, concerning the fundamental aspects of hydrodynamic cavitation in a microchannel. We have recorded, with thermosensitive nanoparticles dispersed in water, the thermal signature of the growth and collapse of bubbles. We were also able to monitor the cavitation flow regime from a laminar single liquid phase. We are currently involved in applicative studies of hydrodynamic cavitation in microchannels, and preliminary results concerning liquid phase exfoliation of graphene will be also presented.Résumé -Cavitation hydrodynamique "sur puce" : Aspects fondamentaux et appliqués -L'émergence de la cavitation hydrodynamique 'sur puce' (cavitation dans des microcanaux comportant une réduction localisée de leur section de passage) est un atout pour l'étude des mécanismes impliqués dans ce type d'écoulements diphasiques. Les dimensions réduites des réacteurs s'affranchissent de l'utilisation d'infrastructures lourdes. Des débits de l'ordre du litre par heure rendent possible l'étude de fluides rares, toxiques ou coûteux, ainsi que l'étude de mélanges. De plus, cette approche microfluidique est la seule qui permet sous certaines conditions l'apparition de la cavitation à partir d'un régime d'écoulement laminaire, ce qui fournit des données expérimentales intéressantes pour la modélisation. Enfin, la dimension réduite des "laboratoires sur puce" leur permet de s'intégrer dans des schémas expérimentaux (microscopes confocaux, spectrométrie) inenvisageables à plus grande échelle. Nous présentons ici un récapitulatif de résultats récemment obtenus par notre équipe, concernant des aspects fondamentaux et appliqués au génie des procédés de la cavitation hydrodynamique sur puce. Nous avons pu détecter la signature thermique de l'évaporation et de la condensation de bulles, grâce à des nanoparticules thermofluorescentes dispersées dans l'écoulement. Nous avons également piloté la transition vers la cavitation à partir d'un écoulement laminaire. Nous présentons enfin les premiers résultats de nos travaux en cours, concernant l'exfoliation en phase liquide du graphène assistée par microcavitation.

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Delamination of graphite in a high pressure homogenizer

Cited by 72 publications

References 61 publications

Photoluminescence from Liquid‐Exfoliated WS₂Monomers in Poly(Vinyl Alcohol) Polymer Composites

Photoluminescence from Liquid‐Exfoliated WS₂Monomers in Poly(Vinyl Alcohol) Polymer Composites

Fluid dynamics: an emerging route for the scalable production of graphene in the last five years

Hydrodynamic Cavitation through “Labs on a Chip”: From Fundamentals to Applications

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Delamination of graphite in a high pressure homogenizer

Cited by 72 publications

References 61 publications

Photoluminescence from Liquid‐Exfoliated WS2Monomers in Poly(Vinyl Alcohol) Polymer Composites

Photoluminescence from Liquid‐Exfoliated WS2Monomers in Poly(Vinyl Alcohol) Polymer Composites

Fluid dynamics: an emerging route for the scalable production of graphene in the last five years

Hydrodynamic Cavitation through “Labs on a Chip”: From Fundamentals to Applications

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Product

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Photoluminescence from Liquid‐Exfoliated WS₂Monomers in Poly(Vinyl Alcohol) Polymer Composites

Photoluminescence from Liquid‐Exfoliated WS₂Monomers in Poly(Vinyl Alcohol) Polymer Composites