Lab profile: Marc Monthioux, CEMES, France

Carbon: the right stuff

Carbon is vital to our modern daily life in ways that are barely appreciated. The material has long been of interest because of its unprecedented properties and behavior, says Marc Monthioux, who leads the Nanostructured Carbons team at the Center for Materials Preparation and Structural Studies (CEMES) in France. The discovery of new carbon materials like nanotubes, buckyballs, and graphene has sparked a research boom in recent decades.

Marc has dedicated his career to carbon in all its forms, starting with petroleum products and coals, then carbon-containing ceramics, carbon fibers, and carbon-containing composites, and finally the modern era of nanocarbons (fullerenes, nanotubes, and graphene). He has served as chair of the French Carbon Society and the European Carbon Association, and has been editor of the journal Carbon for the past 13 years.

His team is part of a three-team group, Multiscale, Multifunctional Materials (M3), at CEMES, which is itself part of the National Physics Institute – one of the ten Institutes making up the National Center for Scientific Research (CNRS), the largest governmental research agency in France.

Materials Today spoke to Marc about his team and his aims to build devices to probe the properties of nanostructured carbons and demonstrate their superiority over existing materials in myriad applications. 

How long has your team been running?

The M3 group has been in existence less than a year as the lab was recently reorganized, but the Nanostructured Carbons team has existed at CEMES for about 20 years and is the remains of what was Agnès Oberlin’s lab, of whom every carbon scientist has heard. She was as important for carbon materials, carbonization mechanisms, and transmission electron microscopy (TEM) as Millie Dresselhaus at Massachusetts Institute of Technology is for nanocarbons and Raman spectroscopy. Oberlin retired in 1993 and I was appointed as director of the lab. However, the 1990s saw the end of the era of small labs and the rise of large, multi-group labs near university campuses. So I left the small University of Pau and moved the lab to Toulouse – which is famous worldwide as the home of Airbus – joining CEMES in 1995.

How many staff makes up your team?

The whole team is around 10-15 people. We have specialists in nanostructured carbons and Raman spectroscopy (Professor Puech), Raman and nanocarbon-containing polymer matrix composites (Professor W. Bacsa), EELS and carbon materials (Professor V. Serin) and me, who basically works on any kind of carbon materials with transmission electron microscopy (TEM) as my main investigation tool. We are also lucky enough to have an assistant-engineer devoted to the group, L. Noé, who helps with filled-nanotube synthesis, specimen preparation, and routine TEM investigation. And then we have our cortege of PhD students, postdocs, and visiting scientists.

What are the major themes of research in your team? How does this complement other groups at CEMES?

I have always known carbon as a hot topic, since the 1980s when I started and well before then in the 1950s because of the need to understand graphite as part of the post-war development of nuclear power.

But let’s face it: we are opportunists! You have to be, nowadays, where funding is mostly provided through governmental and European research agencies. So we mostly work on topics that give us a reasonable chance of being funded. Mostly but not only!

We have had two main themes of research running for several years: one is what I call carbon meta-nanotubes (i.e. carbon nanotubes transformed upon filling, coating, doping, decorating, substitution, or functionalization); and the other is carbon nanocones, which are unique and exciting carbon objects with amazing properties that we prepare by what I used to call ‘time-of-flight chemical vapor deposition’.

Both material types are being investigated for their potential applications: for example, carbon nanocones as electron emitters and near-field microscopy probes; and carbon meta-nanotubes as electronic device components. As carbon (meta)nanotubes are materials of interest for the aeronautic industry, we also work on the physics of carbon-containing polymer-matrix composites, such as the mechanisms of nanocarbon diffusion in the polymer and electron conductivity.

From the methodology point of view, we are currently focusing our efforts on finding for new paradigms exploiting both XRD and Raman spectra. We have also just started on an exciting project to install and run our own tip-enhanced Raman spectroscopy (TERS) equipment, which is a very powerful tool for investigating individual nano-objects.

CEMES is a nice frame to work in because it has groups dedicated to advanced TEM, near-field microscopy, molecular electronics, alloys, magnetism, optical spectroscopies and so on. Because of the nano-sized dimension of our objects and the kind of physical-chemical phenomena we wish to investigate, as well as the versatility of nanocarbons for applications, we happen to interact with most of the groups at CEMES.

How and why did you come to work in these areas?

I have been working on carbon materials since I started my career as a scientist: carbon precursors such as heavy petroleum products first, then coals and kerogens, carbon-containing ceramics, carbon fibers, and carbon-containing composites. When the era of nanocarbons (fullerenes, then nanotubes, then graphene) began in the early nineties, it was a natural move to get involved.

What has been your highest impact/most influential work to date?

Based on the number of citations, I would say the discovery of nano-peapods that I made (along with D. Luzzi and B. Smith) when I was a NATO visiting scientist at University of Pennsylvania. Nano-peapods are single-wall carbon nanotubes (SWCNTs) whose inner cavity is stuffed with fullerene molecules. When I say ‘stuffed’, I mean it: filling rates can be close to 90%!

This work was important because it demonstrated that the inner cavity of SWCNTs could host foreign materials, which started a new research area based on in-SWCNT synthesis and nanochemistry, as part of what I call ‘carbon meta-nanotubes’.

What facilities and equipment does your team have?

Our team has no major equipment of its own. We use lab facilities, which are based on three ‘methodological feet’. CEMES was created in the 1950s to build the world’s largest TEM. Two were actually built: one in the 1950s (1.5 MeV) and another in the 1970s (3.2 MeV). Although the original microscopes are now gone, the legacy was strong expertise in TEM-related methods. We currently have seven TEMs, each dedicated to different types of investigation or developments.

The second foot is near-field microscopy, again in various modes (AFM, STM, MFM, high vacuum, low temperature, etc.); and the third, added to the lab about 10 years ago, is multi-wavelength optical spectroscopy – more specifically Raman spectroscopy. We also have a well-equipped X-ray diffraction (XRD) facility related to other XRD platforms on the university campus, so that all kinds of XRD needs can be fulfilled.

These three feet are not just technical platforms, they are the main investigation tools of the groups making up CEMES, which means that scientific expertise is always available.

Do you have a favorite piece of kit or equipment?

TEM is my main investigation tool, and always has been, except during the five years I spent at the French Institute of Petroleum, where my research was more focused on liquids. Liquids and TEM are not good friends!

What is the key to running a successful team? And successful collaborations?

For a successful collaboration, I would say there are three main ingredients: (i) inventiveness (a good idea to start with!); (ii) complementarity; and (iii) mutual trust. I may have a poor imagination, but I think the ingredients for running a successful team are the same! There is a fourth ingredient, I have to add: getting funding.

I used to say that the whole world is my lab. With the Internet, communication is so easy that you can start a collaboration in a minute. Someone somewhere in the world has the equipment or the expertise you need. Throughout my career, I have preferred to use the equipment that others have bought!

How do you plan to develop your team in the future?

CEMES is more and more involved in nanoscience. For example, CEMES is organizing the world’s first international nano-car race! All this increasing nano-expertise makes a quite pertinent scientific environment for our carbon-related topics.

We are the only team at CEMES fully dedicated to carbon, although other teams or groups occasionally work on carbon nanoforms. I like that because it means many of my lab-mates are potential collaborators in scientific fields of which my own command is poor.

Among the exciting developments we plan for the next few years are installing our TERS equipment and exploiting its investigative power on filled SWCNTs and DWCNTs; testing our new electrochemistry micro-cell for doping nanotubes individually; understanding the mechanisms of electronic doping in carbon nanotubes; investigating our carbon nanocones as probes for a variety of near-field microscopy modes; getting our carbon nanocones out of the lab by developing them as electron emitters for cold-FEG sources in commercial electron microscopes (in partnership with Hitachi High Technologies in Japan); and more! For most of those topics, we have approved dedicated budgets, so I am confident that some good science will come out.

Key publications

1. Puech P., Plewa J.-M., Mallet-Ladeira P., Monthioux M. Spatial confinement model applied to phonons in disordered graphene-based carbons. Carbon 105 (2016) 275-281.
2. Suarez-Martinez I., Mittal J., Allouche H., Pacheco M., Monthioux M., Razafinimanana M., Ewels C. P. Fullerene attachment to sharp-angle nanocones mediated by covalent oxygen bridging. Carbon 54 (2013) 149-154.
3. Monthioux M. (editor) Carbon Meta-Nanotubes : Synthesis, Properties, and Applications, Wiley-Blackwell, 2012. (ISBN 978-0-470-51282-1).
4. Shen J., Puech P., Ondarçuhu T., Escoffier W., Raquet B., Monthioux M. The effect of adsorbed species and exposure to sulfuric acid on the electrical conductance of individual single-wall carbon nanotube transistors. Carbon 50 (2012) 3953-3956.
5. Houdellier F., Masseboeuf A., Monthioux M., Hÿtch M. J. New carbon cone nanotip for use in a highly coherent cold field emission electron microscope. Carbon 50 (2012) 2037-2044.
6. Monthioux M., Allouche H., Jacobsen R. Chemical vapor deposition of pyrolytic carbon on carbon nanotubes. Part III: Formation mechanisms. Carbon 44 (2006) 3183-3194.
7. Cleuziou J.-P., Wernsdorfer W., Bouchiat V., Ondarçuhu T., Monthioux M. Carbon nanotube superconducting quantum interference device. Nature Nanotechnology 1 (2006) 53-59.
8. Monthioux M., Smith B. W., Burteaux B., Claye A., Fischer J. E., Luzzi D. E. Sensitivity of single-wall carbon nanotubes to chemical processing: an electron microscopy investigation. Carbon 39 (2001) 1251-1272.
9. Smith B. W., Monthioux M. and Luzzi D. E. Carbon nanotube encapsulated fullerenes: a unique class of hybrid materials. Chemical Physics Letters 315 (1999) 31-36.
10. Smith B. W., Monthioux M., Luzzi D. E. Encapsulated C₆₀ in carbon nanotubes. Nature 396 (1998) 323-324.
11. Jacobsen R. L., Monthioux M. Carbon beads with protruding spicules. Nature 385 (1997) 211-212.
12. Monthioux M. and Delverdier O. Thermal behavior of (organosilicon) polymer-derived ceramics. V: Main facts and trends. Journal of European Ceramic Society 16 (1996) 721-737.
13. Després J.-F. and Monthioux M. Mechanical properties of C/SiC composites as explained from their interfacial features. Journal of European Ceramic Society 15 (1995) 209-224.
14. Monthioux M., Landais P. and Monin J.C. Comparison between natural and artificial maturations of coals from Mahakam delta, Indonesia. Organic Geochemistry 8 (1985) 275-292.