The 2022 World Conference on Carbon was held at Imperial College London in early July. Given the tumultuous time, it felt remarkable to be sitting in the introductory lecture and welcomed by Prof. Geoff Fowler. It was especially remarkable for me as I had travelled on one of the longest flights in the world from Perth to London (17 hours) to be there. Here are some of my thoughts from my great week in London.
Carbon for a Cleaner Future
The theme for this year's conference was "Carbon for a Cleaner Future", which is an apt theme for a world in need of carbon to rapidly decarbonise. We heard from excellent plenary speakers including Prof. Novoselov on graphene, Prof. Bandosz on the chemical effects within porous carbon, Prof. Conchi Ania on lighting up nanoporous carbons for catalysts, Prof. Marc Monthioux on carbons mimicking water droplets on a spider's web and Prof. Milo Shaffer on assembling scalable nanocarbons! I filled many more pages of notes from other excellent speakers and presenters throughout the conference.
Industry at the cutting edge
Another highlight was meeting and hearing talks from industrial scientists at the cutting edge of carbon science. It was remarkable to see the work on reducing the power and degradation of graphite furnaces from Dr Timm Ohnweiler at Carbolite furnaces.
Brian Kelly award
I was very grateful to receive the Brian Kelly Award from Prof. Fowler at the beginning of the conference. The work for which I was awarded the prize is close to that of Prof. Kelly's. In 1981, he wrote,
"The material presented shows that graphitisation is not a simple process, and it is not well understood." Brian Kelly, Physics of Graphite, 1981
Here is the personal story of the discussions and collaborations from past Carbon conferences that led to the work I presented in London.
In 2017, at the Melbourne Carbon Conference, I met Dr Nigel Marks, Dr Irene Suarez-Martinez and Dr Carla de Tomas from the Carbon Group at Curtin University in Perth, Australia. I was in the middle of my PhD on soot/carbon black formation at the University of Cambridge but became fascinated by the disordered carbon structures the Carbon Group had prepared using molecular dynamics simulations that were able to capture all of the features in glassy and porous carbons. I visited Perth briefly and started to work on these structures with the group, employing some novel visualisation approaches of 3D printing and analysing the structures using a mesh. We managed to find a common nanostructure between the glassy and porous carbons. These disordered carbons also contained an excess of saddle-shaped (net-negative Gaussian) curvature [
Martin, Jacob W., et al. "Topology of disordered 3D graphene networks." Physical Review Letters 123.11 (2019): 116105.]. The stacking order in the glassy carbon could then be explained by the sheets winding up to form screw-like defects that enabled a fullerene-like structure to be stacked in particular regions. This provided a potential explanation for the transition from porous carbon to impervious glassy carbon as well as the isotropic properties of the material.
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| Model of disordered carbons |
I presented this work at the 2019 Carbon Conference in Lexington, USA and was very happy to receive the student prize for the talk. It was the SFEC French Carbon Award talk that drew my attention to graphite. Dr Philippe Ouzilleau spoke about the formation of graphite through a thermodynamic model that was done with Prof. Marc Monthioux and others [
Ouzilleau, Philippe, et al. "Why some carbons may or may not graphitize? The point of view of thermodynamics." Carbon 149 (2019): 419-435.]. They firstly showed that graphitisation is a second-order phase transition with a critical temperature around Tc=2550 K. Secondly, they suggested the presence of annealable topological defects in graphite that give rise to the phase transition while in non-graphitising carbons other non-annealable topological defects are present that are unable to be removed.
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| Carbon Group at Curtin University (Ms Kate Putman, Mr Jason Fogg, Dr Irene Suarez-Martinez, Dr Jacob Martin, Dr Nigel Marks) |
The Atomic Absorption Spectrometer (AAS) was invented in Australia by Alan Walsh at CSIRO in the 1950s. It works by vaporising metals that then absorb light and it is often used for environmental metal tests such as detecting lead contamination. Vaporisation was originally achieved in a flame, however, a small graphite tube furnace has mainly replaced the flame. This small joule heated graphite furnace has been extensively developed since the 1960s to ramp up extremely rapidly (~3000 °C/s) and have power control to reproducibly control the temperature. Both time and temperature are critical to control for reproducible measurements. These ramp rates far exceed those for conventional graphite furnaces, which require at least an hour to reach >2500 °C. Given the precise control over the time and temperature, it was the perfect instrument to study graphitisation kinetics and so the Carbon Group worked with GBC Scientific, one of the original Australian companies to commercialise the AAS, to have a custom tube furnace provided.
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| Dr Irene Suarez-Martinez and Mr Jason Fogg operating the GBC graphite tube furnace. |
This new furnace provided a means to address the problem posed by Prof. Brian Kelly in 1981 for studying graphite.
"The proper study of the variation of a property (of graphite) with time at temperature is difficult because of the necessity to raise the specimen temperature rapidly to very high levels, and the difficulties associated with very high temperature measurements."
Brian Kelly, Physics of Graphite, 1981
When I arrived in Perth, I suggested we look at a graphitising carbon and search for an annealable topological defect. Jason prepared samples across the graphitisation transition with varying residence times by applying multiple thermal pulses. I then took the samples to the transmission electron microscope for imaging. This new microscope had a cold field emission gun that provided atomic resolution of the graphite and clearly resolved the interplanar defects as screw dislocations that were removed with heat treatment. To find out how the screws form and are removed we performed molecular dynamics simulations to find the mechanism for their removal. There was a nice connection with the screw dislocations, as Dr Suarez-Martinez studied these in her PhD with the late Malcolm Heggie.
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| Electron microscopy and model of a screw dislocation. |
We could then probe the kinetics of graphitisation by tracking the crystallites using X-ray diffraction of the pulse heated samples. This revealed that the graphitisation kinetics were more rapid than first thought, occurring on the seconds timescale. The speed at which graphitisation occurs was the aspect that most interested those in the graphite industry at the conference. At 2500 °C, graphitisation takes a few minutes, however, above 2800 °C it takes less than 10 seconds. These insights could have significant cost savings when it comes to industrial production of graphite. Additionally, the removal of screw defects could be targeted to catalyse graphitisation.
The preprint for the work is currently online if you would like to read more. A recording of the
lecture I gave is also available online.
Nanocarbon in virtual reality and 3D printing
Alongside the presentation on graphite, I gave two other talks on the formation of soot/carbon black (recording available online) and also on the visualisations of carbon nanostructures using VR and 3D printing (recording available online).
During the lunch breaks I was able to demonstrate the virtual reality headset and show people carbon in 3D. It was a lot of fun to see people explore these computational models. We also had the opportunity to view other groups' atomistic structures that were emailed as xyz coordinates, providing a new way to engage with other peoples work.
Not yet back to normal
Many people were absent from the conference and were sadly missed. Colleagues from China and Japan could not attend due to travel restrictions in their home countries. There were also instances of scientists unable to attend due to global conflict. Dr Yuriy A. Olkhovyk from Ukraine gave an excellent recorded talk on containment of nuclear graphite at Chernobyl. I hope that these barriers will soon be removed within the Carbon community and we can all freely meet at future conferences.
However, given the situation it was remarkable what the British Carbon Society achieved in spite of terrible uncertainty. I wanted to personally thank them for bringing together an excellent conference programme, expertly planned and executed.
Molly the anthropomorphic Molymod
Another attendee sorely missed was
the late Malcolm Heggie. In memory of Malcolm and to bring his humour back to the Carbon community, Molly was reconstructed out of a Molymod molecular modelling kit.
I recall emailing Prof. Curl as an undergraduate to ask for help with a paper. I was working on whether giant fullerenes could be synthesised. He not only responded to my email but organised for someone at Rice to perform an experiment I proposed, however, it was not initially successful. I tried a different approach to heating the fullerenes to size them into giant fullerenes, which ended up working. I sent him the manuscript that was
subsequently published in Carbon. He wrote,
"Thank you for sending me your manuscript on the heat driven solid state coalescence of giant fullerenes in toluene-extracted fullerene soots. I think this paper makes significant progress in understanding this interesting and challenging subject. I am flattered by your offer to join you as an author to this paper, but have to decline. I believe that any contributions I might have made to this work are trivial."
This was followed by extensive feedback on the manuscript. He continued to help me in another projects too. I was fascinated by the lack of fullerenes in fullerene-like carbons such as charcoal. Prof. Curl emailed the late Prof. Sir Harry Kroto and Prof. Alan Marshall to organise some high resolution mass spectrometry to be done at Florida State University. These experiments demonstrated similar oxygen-containing giant fullerene-like fragments, as seen in the giant fullerene paper. This suggested that the heat treated fullerene arc-carbon and charcoal share a common nanostructure.
We published this work in Environmental Science & Technology with Prof. Curl again refusing to be on the authorship.
He also kindly wrote a letter of support for one of my fellowship applications in 2020. I hadn't even met him in person but he agree to support the science present in my application. As a young person exploring carbon science this was extraordinarily encouraging with all of my interactions with Prof. Curl demonstrated his kindness, humility and generosity to a student he had never met.
Conference dinner on the Thames
A significant highlight was having a sit-down dinner on board a river boat and having the tower bridge open for us. The cloudless sky was also a nice touch from the organising committee!
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| On board the boat with friends. |
I spent the following week in Cambridge with a Covid-induced fever, enhanced by the heat wave, but with no regrets. I can only reiterate words from Prof. Kelly that ring true also for me:
"The study of these materials has brought me considerable pleasure and the good fellowship of the 'carbon' community." Brian Kelly Physics of Graphite, 1981
