Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India.
Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India.
Ultrason Sonochem. 2020 May;63:104976. doi: 10.1016/j.ultsonch.2020.104976. Epub 2020 Jan 18.
In this work, a cost-effective and facile method was adopted for the fabrication of graphene oxide nanoscrolls (GONS) by low frequency (20 kHz) ultrasonication with tunable dimensions. The graphene oxide (GO) was synthesized by modified Hummer's method using synthetic graphite as a base material. Later, GO suspension (0.05 g L) were made using methanol as solvent and subjected to different ultrasonication conditions. It was found that GO sheets curls themselves into nanoscrolls by overcoming the energy barrier for scrolling with the help of bubble cavitation energy provided by ultrasonication. Also, the effect of ultrasonication power (100-150 W) for irradiation time (0.5-3 h) over the GONS dimensions were investigated. The spiral wounded GONS structures were shown using electron microscopy. Raman Spectroscopy, Thin-film X-Ray Diffraction, Energy Dispersive X-Ray, FT Infrared Spectroscopic analysis were also done to endorse GONS formation. Factors affecting GONS formation such as sonication power and solvent selection were studied as scrolling of GO sheets are strongly dependent on sonication parameters and solvent characteristics. It was found that GONS length varies inversely with irradiation time for identical power density. Also, a solvent with relatively large Hansen solubility parameter, lower dipole movement and less negative value of zeta potential support GONS formation of longer length. Raman analysis overlays the rapid oxygen-defect site cleavage mechanism. The obtained GONS unlocks further developments in various engineering applications like adsorption, drug delivery and filtration membrane.
在这项工作中，采用了一种经济有效的简便方法，通过低频（20 kHz）超声处理来制备具有可调尺寸的氧化石墨烯纳米卷（GONS）。氧化石墨烯（GO）是通过使用合成石墨作为基础材料的改进的 Hummer 法合成的。随后，将 GO 悬浮液（0.05 g L）用甲醇作为溶剂，并在不同的超声条件下进行处理。研究发现，GO 片在超声提供的空化气泡能量的帮助下克服卷曲的能量障碍，从而自行卷曲成纳米卷。此外，还研究了超声功率（100-150 W）对辐照时间（0.5-3 h）对 GONS 尺寸的影响。通过电子显微镜观察到了螺旋形缠绕的 GONS 结构。还进行了拉曼光谱、薄膜 X 射线衍射、能量色散 X 射线、傅里叶变换红外光谱分析，以证实 GONS 的形成。研究了影响 GONS 形成的因素，如超声功率和溶剂选择，因为 GO 片的卷曲强烈依赖于超声参数和溶剂特性。研究发现，在相同的功率密度下，GONS 的长度与辐照时间成反比。此外，具有较大 Hansen 溶解度参数、较低偶极矩和较小的 ζ 电位负值的溶剂有利于形成较长长度的 GONS。拉曼分析揭示了快速氧缺陷位断裂机制。所得到的 GONS 为各种工程应用（如吸附、药物输送和过滤膜）的进一步发展提供了可能。
