Over the last decade graphene and graphene oxide-based nanomaterials have gained broad interests in research because of their unique physiochemical properties leading to remarkable electronic, optical, and mechanical properties. Graphene is the simplest form of carbon and the thinnest material consisting of only one to a few layers of graphite, while graphene oxide (GO) is obtained from a highly oxidized form of graphene molecule by using strong oxidizing agents. Both materials are being considered for a myriad of applications, with use as filtration membranes being one of the most interesting. At DMME we have focused on the characterisation of graphene using atomic force microscopy and the use of RAMAN spectroscopy which provides information such as thickness, disorder and specifically the type and extent of defects present in the graphene membrane. Furthermore, we are now looking into the synthesis of graphene oxide through a chemical route, while the GO-product is characterised via X-ray photoelectron spectroscopy.
To expand the applicability of graphene, a robust understanding of its behaviour under mechanical loading is required. The use of atomic force microscopy (AFM) to indent suspended graphene membranes, in order to measure the elastic modulus and tensile strength of graphene, will provide a better understanding of graphene as well as the experimental methods used to study the mechanical properties of such 2D nanomaterials.
Graphene is commonly described to be a single layer of graphite. A derivative of graphene is graphene oxide (GO), which bears several oxygen-containing functional groups. Apart from having its own applications in various fields it can be prepared by oxidising graphite by the Hummers’ method. In turn, GO can be reduced to graphene. The synthesis of graphene through a chemical approach is quite a challenge, and at DMME, we are trying to optimise such a preparation. Both nanomaterials have a range of promising applications: biomedical, environmental, and electronics. State of the art equipment such as XPS, AFM, Raman, and others, helps in this ongoing research.
The heavy use of plastics in today’s age has inevitably contributed to the formation of micro (<5 mm in diameter) and nano plastics (MNPs) (<100 nm in at least one dimension) in various water systems. The presence of MNPs in the environment, often originating from the degradation and breakdown of larger plastic pollutants, poses significant threats to microorganisms, plants, animals, and humans alike, with most potential hazards still under research [4]. Beyond world-wide efforts for mass clean-ups, proper recycling, and significant reduction or even total prohibition of production of new plastics, successfully eliminating the prevalence of MNPs from our water supplies would be an important corrective course of action to be followed. However, most filtration systems currently in use are unable to filter out MNPs < 20 μm.
In view of this, at DMME, research is aimed at developing 3D reduced graphene oxide foams (rGOF) to be used to filter out MNPs from polluted water systems. The physiochemical nature of the produced rGOFs is expected to allow water to pass through while selectively adsorb polymeric MNPs. A variety of synthesis routes are being explored and various characterization techniques such as optical microscopy, scanning electron microscopy, Raman spectroscopy, and Fourier-Transform Infra Red spectroscopy are supporting the research.
