NANOCARBON IN JAPAN SPOTLIGHT Catching up with carbon Japan fights to stay on top of a field it pioneered. BY TIM HORNYAK n September last year, a handful of Nagoya University. “It was the most exciting the stability and strength to build complex researchers were sitting around a com- moment I ever had in my life.” molecules — into new materials with useful puter monitor in chemist Kenchiro Itami’s Itami thinks he has good reason to be so properties, and it has built a strong industrial Ilab at Japan’s Nagoya University as one loaded excited. “The discovery of a new form of car- sector from those basic research efforts. a file showing the results of an X-ray crystal- bon has always opened up new science and But in the past decade or so, Japan has found lography scan. Within seconds, the room technology — fullerenes are a great example,” itself beset by international competition, as erupted: scientists were on their feet, cheering he says, referring to the all-carbon molecular progress in the field has shifted abroad. Now, and exchanging high fives. In front of them spheres created by scientists at Rice University Japanese researchers are fighting to maintain was a 3D representation of a carbon nanobelt in Houston, Texas, in 1985. their global prominence. — a new molecule of carbon that the team Chemists have indeed tried many things had successfully synthesized after 12 years of when it comes to constructing exotic forms, NO SMALL PEDIGREE ILLUSTRATION BY PETER HORVATH; PHOTOS: GETTY PHOTOS: HORVATH; PETER BY ILLUSTRATION painstaking effort. or allotropes, of carbon: nanobelts are only the The history of nanocarbons is nearly as intricate “Without these data, we couldn’t prove its latest and it’s significant that a Japanese team as the structures themselves. Smiths have structure 100%,” says Itami, director of the made them. The country has enjoyed a rich his- forged carbon with metal to make sharp, resil- Institute of Transformative Bio-Molecules at tory of manipulating carbon — an atom with ient weapons for thousands of years, with ©2017 Mac millan Publishers Li mited, part of Spri nger Nature. All 7ri gDECEMBERhts reserved. 2017 | VOL 552 | NATURE | S45 SPOTLIGHT NANOCARBON IN JAPAN some astonishing results: a 2006 analysis nanotube yarn originally designed for light- known as Vantablack comprises millions of of Damascus sabre steel from the seventeenth weight data cables was re-engineered for use vertically aligned nanotubes, each with a diam- century1 revealed that the material contains in space. NASA scientists think that the yarn eter of about 20 nanometres. The nanotubes microstructures such as carbon nanotubes — — 200 times stronger and 5 times more elas- absorb 99.96% of incident radiation, according lattices of carbon atoms arranged to create a tic than steel — could significantly lower the to Vantablack’s developers, Surrey NanoSystems pipe with a diameter of 0.7–50 nanometres. overall mass of a spacecraft. in Newhaven, UK. That makes Vantablack the Modern synthesis of carbon nanotubes is Itami’s carbon nanobelt is, essentially, the darkest synthetic substance in the world. As widely attributed to Japanese scientists Mor- single repeating unit of a relatively tiny car- such, it could be used to protect telescopes from inobu Endo and Sumio Iijima. When Endo bon nanotube (see ‘Nanocarbon molecules: a stray light, making it easier to see faint stars, or was working at the French National Centre glossary’). But the simplicity of the nanobelt is to improve the optical performance of satellites, for Scientific Research (CNRS) in the 1970s, misleading — synthesizing one is supremely dif- among other applications. he synthesized carbon fibres that featured ficult owing to the high degree of strain placed And in 2013, researchers at Stanford Univer- hollow tubes arranged in concentric sheets on the 12 benzene rings that must be joined sity in California reported6 that they had made a like the rings of a tree. Sixteen years later, together to create the belt. basic computer from carbon-nanotube transis- Iijima published a letter in Nature entitled tors and simple electronic circuits. The device ‘Helical microtubules of graphitic carbon’; he drew attention as a possible replacement for sili- is often cited as the scientist who discovered con and as a way to facilitate the development of carbon nanotubes2. EXCELLENT CHEMISTS ever-smaller transistors. But who first made the discovery is still a topic of discussion. A 2006 editorial in AND PHYSICISTS ARE BARRIERS TO ENTRY Carbon3 suggested that Russian scientists The promise of nanotubes has been some- L. V. Radushkevich and V. M. Lukyanovich STILL IN JAPAN what overshadowed by their potential should be credited for their 1952 paper4, BUT THE TREND health dangers. The Japanese government which reported that “carbon filaments could has been evaluating nanotubes for possible be hollow and have a nanometre-size diam- FOR TRAINING carcinogenic effects, and some scientists eter”. The paper, published in Russian, was YOUNG JAPANESE have likened the tubes to asbestos in terms little-known outside the Soviet Union, and it of health risk, In 2015, one joint French–US was Japanese researchers who were responsi- SCIENTISTS IS study7 found nanotubes similar to those used ble for opening up the field to the rest of the in vehicle exhaust systems in tissue samples world. “From the beginning of the discovery, DECREASING. taken from 69 children in Paris with asthma. I was confident in the importance of nano- “These results strongly suggest that humans tubes,” says Iijima, now a chemist at Meijo are routinely exposed to nanotubes,” the University in Nagoya. authors wrote. He turned out to be right. The strength-to- The effort could well be worthwhile, however. Another roadblock to the application weight ratio of the tiny molecules is at least Nanobelts have been described as ‘dream mol- of nanotubes is price — 1 gram can cost as 30 times greater than for Kevlar, the material ecules’ by researchers, because of their potential much as US$250, around 6 times the price used in bulletproof vests. Adding nanotube roles in everything from semi conductors to of gold. Mass production would bring down fibres to just about any material — from vehi- photonics equipment. They might even serve that cost considerably, so an important area cle parts to golf-club shafts to elevator cables as “seeds” for growing “structurally well-defined in nanotube research is the development of — will strengthen it enormously. And because carbon nanotubes”, Itami and his colleagues alternatives to the expensive, high-energy they can conduct electricity better than cop- reported this year5. methods currently used, such as arc electrical per, nanotubes have given rise to products Itami hopes that carbon nanobelts will discharge and chemical vapour deposition. such as transparent conductive films and even become available to businesses in a matter of The possible effects on human health and prototype computers. months. If they do, they will be making their the high price tag may have dampened global As with many new materials, some appli- way into a commercial field that is steadily fill- enthusiasm for nanocarbon products, and cations can be unexpected. For instance, a ing up with exotic forms of carbon. A mat erial could have slowed down Japan’s academic NANOCARBON MOLECULES: A GLOSSARY Over the years, researchers have built a dizzying collection of exotic forms of carbon. Graphene NANOTUBE FULLERENE GRAPHITE NANOBELT A sheet of hexagonally arranged carbon A hollow sphere of carbon Layers of hexagonally arranged carbon stacked The single repeating unit atoms, stretched to make a pipe shape. First resembling a football. on top of one another. Graphene — a single of a tiny carbon nanotube. formally described by scientists in 1952. Synthesized in 1985. layer of this lattice — was isolated in 2004. Synthesized in 2016. S46 | NATURE | VOL 552 | 7 DECEMBER©2017 M2017ac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. ©2017 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. NANOCARBON IN JAPAN SPOTLIGHT output. The country also faces challenges scientist at Meijo University, set up Meijo Nano in terms of its academic workforce. “Excel- Carbon to manufacture nanotubes. In 2013, lent chemists and physicists are still in Japan collaboration between Meijo Nano Carbon but the trend for training young Japanese and Japan’s National Institute of Advanced scientists is decreasing because students Industrial Science and Technology (AIST) led are not motivated to pursue PhDs any more to a joint production plant that uses a tech- — instead they want to finish a master’s, as nology known as enhanced direct injection companies do not value PhDs,” says Mauricio pyrolytic synthesis. According to AIST, man- Terrones, a nanotechnologist at Pennsylva- ufacturing speeds are 100 times greater than nia State University in University Park and those achieved previously, with higher-qual- an editor at Carbon. “Therefore, Japan needs a ity end products. The company’s hope is that new policy to motivate industry to hire PhDs mass production of high-quality nanotubes from Japanese universities. In this way, the for the research and development market will next generation of chemists and physicists accelerate commercial applications. will continue to be first-class and competi- They face competition. In 2015, ZEON in tive worldwide.” Toyko began what it says was the first mass Japan’s research performance doesn’t reflect production of nanotubes using another the nuances of its relative strengths in the field. technique developed at AIST, termed Super- Japanese researchers excel in some areas, such growth. It expects to supply manufacturers of as developing chemical techniques to grow conductive and rubber materials and high- nanotubes, but underperform in others, such performance capacitors. Meanwhile, AIST as thermal engineering, says Takashi Kodama, is working with companies such as elec- a thermophysicist at the University of Tokyo.