Keith Paton Email and Phone Number

I am working on developing chemical metrology tools for graphene, to allow rapid measurement of the functionalisation of liquid-phase exfoliated few-layer graphene. As well as established techniques such as raman spectroscopy and UV-vis spectroscopy, I am also developing terahertz time-domain spectroscopy as a metrology tool for characterisation of graphene quality.

I worked on the exfoliation of new inorganic layered materials, including ZrSe2, HfS2 and HfSe2. By optimising the exfoliation and separation process it has been possible to measure photoluminescence from many of these materials in the liquid phase, allowing the (direct) optical band-gap to be characterised. The results from this survey of materials properties was used to identify promising materials for devices for our collaborators to focus on developing large-area growth methods

I was embedded within the research group of Prof. Jonathan Coleman to develop a scalable method to produce high-quality graphene materials. By developing the liquid phase exfoliation approach pioneered by Prof. Coleman, a method based on shear mixing has been developed, and shown to be scalable to large volumes. This technology has been successfully transferred to Thomas Swan’s manufacturing site in Consett, UK where a pilot-scale rig has been installed.During this time, I also worked on a project to optimise the electrical conductivity of graphene films, using vacuum filtration as the standard method of film formation. Alternative film formation methods were also investigated, including spray coating and spin coating highlighting the importance of flake morphology on the final conductivity achieved.Alongside this, I was closely involved in the development of high-throughput characterisation of flake sizes produced by liquid-phase exfoliation. These metrics are based on UV-vis spectroscopy to measure the mean flake thickness directly in the liquid-phase. Easy-to-apply metrics were also obtained from raman spectroscopy of filtered films.

My role was to provide technical support to the carbon nanomaterials division. This included setting-up a process control system, as well as planning and executing research project to improve the process and reliability of the process. I was responsible for establishing a new lab-scale process for a brand new grade of nanotubes, which is now in the process of being commercialised. I also had responsibility for liaising with the quality control department to improve test methods. In particular, I provided technical expertise during commissioning of a raman spectrometer, helping to establish test protocols.

My research examined the effect of microwave frequency electromagnetic radiation on dispersions of carbon nanotubes. In particular I used a calorimetric method to quantify the energy absorption of multiwalled carbon nanotubes. I showed that the energy absorption was due to induced currents in the nanotube network, and a percolation-like dependence was observed with increasing concentration. I further showed that the addition of very small concentrations of nanotubes is sufficient to significantly reduce the time taken to heat polyethylene to allow processing. This is able to offer significant savings in energy costs for processing polymers over current techniques.