Investigation of tip sonication effects on structural quality of graphene nanoplatelets (GNPs) for superior solvent dispersion
Investigation of tip sonication effects on structural quality of graphene nanoplatelets (GNPs) for superior solvent dispersion
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DOI：
10.1016/j.ultsonch.2018.03.007
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发表时间：
2018-07-01
影响因子：
8.4
通讯作者：
Sarfraz, Mansoor
中科院分区：
文献类型：
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作者：
Baig, Zeeshan;Mamat, Othman;Sarfraz, Mansoor
石墨烯的优异性能和结构的独特性，如果能使其均匀分散，可以提高纳米复合材料的性能。尖端超声辅助石墨烯溶剂分散已成为一种有效的方法，但它会导致石墨烯结构的显著降解。本研究旨在通过在三种不同振幅（60%、80%和100%）下改变超声处理时间和各自的能量来评估尖端超声处理对石墨烯纳米片中sp（2）碳结构特征的参数影响。该研究对于确定合适的参数以在溶剂分散后获得具有非常理想的纵横比的高质量和无缺陷的石墨烯以用于复合材料增强至关重要。通过拉曼光谱的定量方法被用来找到在尖端超声参数的影响下演化的石墨烯的缺陷率和横向尺寸。结果表明，缺陷率是稳定的，并且随着GNP的持续增加，沿着随着向纳米结晶阶段I的转变，在所有振幅下超声处理长达60分钟。在所有振幅下均清晰观察到剥落，以及由于大量片材的尺寸显著减小而导致的片材重新堆叠。最后，相当大的GNP碎片发生在超声处理过程中增加的振幅和时间，证实了减少sp（2）域（La）和薄片大小。这也验证了石墨烯中边缘型缺陷的形成。令人信服的是，较低的振幅和时间（高达60分钟）产生更好的结果，为低缺陷含量和较大的颗粒尺寸，如量化的拉曼分析。
The exceptional properties of graphene and its structural uniqueness can improve the performance of nano composites if it can attain the uniform dispersion. Tip sonication assisted graphene solvent dispersion has been emerged as an efficient approach but it can cause significant degradation of graphene structure. This study aimed to evaluate the parametric influence of tip sonication on the characteristics of sp(2) carbon structure in graphene nanoplatelets by varying the sonication time and respective energy at three different amplitudes (60%, 80% and 100%). The study is essential to identify appropriate parameters so as to achieve high-quality and defect-free graphene with a highly desirable aspect ratio after solvent dispersion for composite reinforcement. Quantitative approach via Raman spectroscopy is used to find the defect ratio and lateral size of graphene evolved under the effect of tip sonication parameters. Results imply that the defect ratio is steady and increases continually with GNPs, along with the transformation to the nano-crystalline stage I up to 60 min sonication at all amplitudes. Exfoliation was clearly observed at all amplitudes together with sheet re-stacking due to considerable size reduction of sheets with large quantity. Finally, considerable GNPs fragmentation occurred during sonication with increased amplitude and time as confirmed by the reduction of sp(2) domain (La) and flake size. This also validates the formation of edge-type defect in graphene. Convincingly, lower amplitude and time (up to 60 min) produce better results for a low defect content and larger particle size as quantified by Raman analysis.