High-rate production of few-layer graphene by high-power probe sonication

Arao, Yoshihiko; Kubouchi, Masatoshi

doi:10.1016/j.carbon.2015.08.108

Cited by 73 publications

(44 citation statements)

References 36 publications

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“…This is attributed to several factors. One is the reduction of the initial graphite concentration in the LPE process; in general, the graphene concentration is in proportion to the inputted graphite concentration [43]. The initial graphite concentration decreased from 3 to 2.63 g/L at the second cycle, which should correspond to an approximately 12.3% reduction in graphene concentration at the second cycle.…”

Section: Recycling Of Sedimentmentioning

confidence: 99%

Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling

et al. 2019

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Functionalization of graphite is crucial for efficient and effective exfoliation to graphene. When negative charges are fixed to the edges of natural graphite, the resulting anionic graphite shows negative charging in a polar solvent. This enhanced negative charging is assumed to contribute the exfoliation of graphite during liquid-phase exfoliation (LPE). In this study, we prepared large anionic graphite flakes (~10 μm) by salt-assisted ball milling, as well as natural graphite flakes of the same size for comparison. During the LPE process, centrifugation speed and solvent type have dominant effects on graphene concentration and quality (e.g., size and thickness), so we investigated these factors for anionic graphite flakes in detail. The anionic graphite showed higher exfoliation efficiency in every type of solvent (isopropanol, methyl ethyl ketone, acetone, and water-based cosolvent) compared with the natural graphite. Monolayer graphene, with an average size of 80–200 nm, was obtained with relatively high yield (>10%) at only 3 min of sonication. The small size of graphene was due to edge fragmentation during the LPE process. The recyclability of the sediment and the characterization of the exfoliated powders for anionic graphene were also investigated.

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Section: Recycling Of Sedimentmentioning

confidence: 99%

Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling

et al. 2019

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“…After reduction, the obtained material is sonicated for 1 h and filtrated to obtain rGO powder. Nevertheless, the procedures involving extended sonication have limited scalability using an extensive sonication time, which may induce basal/edge defects, a small lateral size, and high-cost production [34]. Recently, Garino et al [35] reported a microwave-assisted fast synthesis of rGO co-doped with manganese and nitrogen through a green approach.…”

Section: Introductionmentioning

confidence: 99%

Toward Large-Scale Production of Oxidized Graphene

et al. 2020

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The oxidative exfoliation of graphite is a promising approach to the large-scale production of graphene. Conventional oxidation of graphite essentially facilitates the exfoliation process; however, the oxidation procedure releases toxic gases and requires extensive, time-consuming steps of washing and reduction to convert exfoliated graphene oxide (GO) into reduced graphene oxide (rGO). Although toxic gases can be controlled by modifying chemical reactions, filtration, dialysis, and extensive sonication are unfavorable for large-scale production. Here, we report a complete, scalable, and green synthesis of GO, without NaNO3, followed by reduction with citric acid (CA). This approach eliminates the generation of toxic gases, simplifies the washing steps, and reduces the time required to prepare rGO. To validate the proposed method, we present spectroscopical and morphological studies, using energy-dispersive X-ray spectroscopy (EDS), UV-visible spectroscopy, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Thermal gravimetric analysis (TGA) is used to analyze the thermal properties of GO and rGO. This eco-friendly method proposes a complete guideline protocol toward large-scale production of oxidized graphene, with potential applications in supercapacitors, fuel cells, composites, batteries, and biosensors.

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“…de‐agglomeration and long‐term stability of nanosuspensions. The first problem has been considerably addressed by using proper liquid medium and process such as probe‐sonication for optimum time by few researchers . Other issue of long‐term stability of nanosuspensions is not adequately addressed yet, and this could be a reason for non‐successful commercialisation of such oils with suspended NPs.…”

Section: Introductionmentioning

confidence: 99%

Effect of dispersant on nano‐PTFE: Striking the balance between stability and tribo‐performance

Dubey

Bijwe

Ramakumar

2018

Lubrication Science

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Nanoparticles (NPs) of PTFE (polytetrafluoroethylene) in suspension formwere reported as very efficient extreme pressure (EP) additive in 150 N API Group II oil in our earlier work. The less stability of a nanosuspension due to agglomeration of NPs beyond 3 wt%, however, was a major issue, which needed to be addressed for its possible industrial exploitation in lubricants.Using another additive, eg polyisobutylene succinimide (PIBSI), as a dispersant appeared to be a plausible solution. Its inclusion (1 wt%) increased the stability of the oil by a factor of 4. It was necessary to investigate, however, whether it influenced other properties synergistically or antagonistically. The present paper highlights the positive and negative aspects of inclusion of PIBSI on the tribo-performance (EP and anti-wear) of the nano-PTFE-based oils. A series of nano-PTFE oils (1%-6%) stabilised with PIBSI (1%) were developed and evaluated for EP and anti-wear performance. The PIBSI-PTFE combination clearly showed antagonistic behaviour due to competition for film formation on the surfaces. However, with an increase in concentration of NPs, the film formation mechanism was dominated by them. Scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy were used for the examination of the topography and surface chemistry of the protective films formed on the steel specimens. KEYWORDS 4-ball tester, nanolubricant, nano-PTFE in oil, PIBSI dispersant, surface analysis, weld load

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High-rate production of few-layer graphene by high-power probe sonication

Cited by 73 publications

References 36 publications

Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling

Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling

Toward Large-Scale Production of Oxidized Graphene

Effect of dispersant on nano‐PTFE: Striking the balance between stability and tribo‐performance

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