Muthoosamy Kasturi, Manickam Sivakumar
Nanotechnology and Advanced Materials (NATAM), Faculty of Engineering, University of Nottingham Malaysia Campus (UNMC), 43500 Semenyih, Selangor, Malaysia.
Nanotechnology and Advanced Materials (NATAM), Faculty of Engineering, University of Nottingham Malaysia Campus (UNMC), 43500 Semenyih, Selangor, Malaysia; Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham Malaysia Campus (UNMC), 43500 Semenyih, Selangor, Malaysia.
Ultrason Sonochem. 2017 Nov;39:478-493. doi: 10.1016/j.ultsonch.2017.05.019. Epub 2017 May 15.
Sonochemistry, an almost a century old technique was predominantly employed in the cleaning and extraction processes but this tool has now slowly gained tremendous attention in the synthesis of nanoparticles (NPs) where particles of sub-micron have been produced with great stability. Following this, ultrasonication techniques have been largely employed in graphene synthesis and its dispersion in various solvents which would conventionally take days and offers poor yield. Ultrasonic irradiation allows the production of thin-layered graphene oxide (GO) and reduced graphene oxide (RGO) of up to 1nm thickness and can be produced in single layers. With ultrasonic treatment, reactions were made easy whereby graphite can be directly exfoliated to graphene layers. Oxidation to GO can also be carried out within minutes and reduction to RGO is possible without the use of any reducing agents. In addition, various geometry of graphene can be produced such as scrolled graphene, sponge or foam graphene, smooth as well as those with rough edges, each serving its own unique purpose in various applications such as supercapacitor, catalysis, biomedical, etc. In ultrasonic-assisted reaction, deposition of metal NPs on graphene was more homogeneous with custom-made patterns such as core-shell formation, discs, clusters and specific deposition at the edges of graphene sheets. Graphene derivatives with the aid of ultrasonication are the perfect catalyst for various organic reactions as well as an excellent adsorbent. Reactions which used to take hours and days were significantly reduced to minutes with exceedingly high yields. In a more recent approach, sonophotocatalysis was employed for the combined effect of sonication and photocatalysis of metal deposited graphene. The system was highly efficient in organic dye adsorption. This review provides detailed fundamental concepts of ultrasonochemistry for the synthesis of graphene, its dispersion, exfoliation as well as its functionalization, with great emphasis only based on recent publications. Necessary parameters of sonication such as frequency, power input, sonication time, type of sonication as well as temperature and dual-frequency sonication are discussed in great length to provide an overview of the resultant graphene products.
声化学是一项有着近百年历史的技术，主要应用于清洗和萃取过程，但如今这项技术在纳米颗粒（NPs）合成中逐渐受到极大关注，在此过程中已制备出具有高稳定性的亚微米级颗粒。在此之后，超声技术在石墨烯合成及其在各种溶剂中的分散方面得到了广泛应用，传统方法通常需要数天时间且产率较低。超声辐照能够制备出厚度达1nm的薄层氧化石墨烯（GO）和还原氧化石墨烯（RGO），并且可以制成单层。通过超声处理，反应变得容易，石墨能够直接剥离成石墨烯层。氧化成GO也能在几分钟内完成，且无需使用任何还原剂就能还原成RGO。此外，还能制备出各种几何形状的石墨烯，如卷曲石墨烯、海绵状或泡沫状石墨烯、边缘光滑以及边缘粗糙的石墨烯，它们在超级电容器、催化、生物医学等各种应用中都有各自独特的用途。在超声辅助反应中，金属纳米颗粒在石墨烯上的沉积更加均匀，可形成定制图案，如核壳结构、圆盘、团簇以及在石墨烯片边缘的特定沉积。借助超声处理的石墨烯衍生物是各种有机反应的理想催化剂，也是出色的吸附剂。过去需要数小时甚至数天的反应，如今能显著缩短至几分钟，且产率极高。在最近的一种方法中，声光催化被用于金属沉积石墨烯的超声和光催化联合作用。该系统在有机染料吸附方面效率极高。本综述详细介绍了用于石墨烯合成、分散、剥离及其功能化的超声化学基本概念，重点仅基于近期的出版物。详细讨论了超声处理的必要参数，如频率、功率输入、超声处理时间、超声类型以及温度和双频超声，以概述所得的石墨烯产物。
