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Colloquium: Jonathan Coleman

"Liquid phase exfoliation of van der Waals bonded nanomaterials; from tiny things to advanced applications"

Prof. Jonathan Coleman, Trinity College Dublin

Graphene is one of the most important of all nano-materials. For many applications, high quality, defect free graphene is required. However by and large it is possible to make either small quantities of high-quality graphene or a large quantities of low quality graphene. In this talk, I will describe Liquid Phase exfoliation, a method produce large quantities of high-quality, few layer graphene nanosheets. In order to make this process scalable, simplicity is a significant virtue. We have used one of the simplest chemical processing technologies, high shear mixing, to exfoliate graphite to give large quantities of graphene dispersed in liquids. Although the graphene sheets produced in this way are rather small they are virtually defect free. We have developed a basic understanding of the exfoliation process, supported by a simple mathematical model. This model predicts that even our humble kitchen blender can be used to produce exfoliated graphene. We have tested this prediction by exfoliating not only graphite, but born nitride, molybdenum disulphide and tungsten disulphide in kitchen blenders. Furthermore, we showed that the 2D nanosheets produced in this way can be used in a wide range of applications including high performance sensors, photodetectors, composites and electrodes for supercapacitors, batteries and gas evolution electrolysers. We believe that this is an important demonstration of the power of nano materials.