水溶性高质量二维材料纳米片的制备及其表征

Preparation and Characterization of Water-Soluble High-Quality Two-Dimensional Material Nanosheets

近几年来,二维(2D)材料的研究,已成为纳米科学最令人兴奋的领域之一。其中液相分离具有层状结构的块体材料来制备二维材料的方法成为研究热点。相比于化学气相沉积(CVD)等自下而上的制备方法,通过块体层状材料的剥离制备二维材料及其分散液的方法具有低成本、可大规模生产的优势。在这里主要研究以液相剥离(LPE)的方法制备石墨烯(graphene)、六方氮化硼(h-BN)和四种过渡金属硫属化物(TMDs)溶液,这种水溶性的二维材料具有绿色环保、成本低等优点。使用拉曼光谱(Raman),原子力显微镜(AFM),扫描电子显微镜(SEM)等仪器对研制的层状纳米片的物质组分、表面结构等进行表征,通过紫外(UV)吸收光谱估算出不同离心转速下的浓度,最后通过电化学工作站的循环伏安法(cyclic voltammetry)测出用于MoS2纳米片电解质门控的离子液体体电容,分析可见制得的二维材料纳米片平均尺寸在400 nm左右,离子溶液的体电容为1.21 F/cm3,该体电容是研究电子器件性能的关键性参数。上述表征结果对基于水溶性二维材料纳米片的电子器件研究有着重要的科学与应用价值。

In recent years,the research on two-dimensional( 2D) materials has become one of the most exciting areas of nanoscience. Among two-dimensional material preparation methods,liquid phase exfoliating of bulk materials with layered structure to prepare two-dimensional materials has become a hot topic. Compared to the bottom-up methods such as chemical vapor deposition( CVD),the industrially scalable method of preparing 2D materials and their dispersions by peeling off the bulk layered materials allows simple,versatile and low-cost techniques. Here we mainly study the preparation of water-based graphene,hexagonal boron nitride( h-BN) and transition metal chalcogenide( TMDs) solutions with a low-cost and environmental-friendly method. The composition and surface topography of the resulting layered nanosheets have been characterized by Raman,atomic force microscopy( AFM) as well as scanning electron microscopy( SEM). Estimation of concentrations at different centrifugal speeds has been performed by ultraviolet( UV) absorption spectroscopy. Finally,cyclic voltammetry measurements were carried out to measure the volumetric capacitance of the ionic liquid in the presence of MoS2 nanosheets. The average lateral size of the two-dimensional material nanosheets is around 400 nm,and the measured volumetric capacitance of the ionic liquid is 1. 21 F/cm3,which is the key parameter for the study of the electronic devices.Our findings pave the way for the potential electronic applications of the water-soluble 2D material nanosheets.