Vol.9 No.3 2017

Research paper : A super-growth method for single-walled carbon nanotube synthesis (K. Hata)−169−Synthesiology - English edition Vol.9 No.3 (2017) As of 2004 when the method was published, the vertically aligned single-wall CNT structure grew to 1.5 mm length in 10 min. This was an improvement of 500 times in length and 3,000 times in time efficiency compared to the world record at the time. The high-speed growth by the super-growth method showed that large amount of CNTs could be synthesized in a short time, and the road to full commercial production of single-walled CNTs was paved.Moreover, the single-walled CNT forests could be easily sliced off from the substrate using a blade, just like harvesting rice. The catalyst was firmly attached to the substrate, and breakage occurred at the interface of the catalyst and CNTs, and as a result, the CNTs and the catalyst could be separated. Therefore, the amount of catalysts that was mixed in the CNT products was minute, and the CNTs with carbon purity 99.98 % or more could be manufactured on the spot. This purity was 1/2,000 of the impurity concentration in the single-walled CNTs manufactured by the HiPCo method that is most widely used today. The ability to synthesize CNT products with high purity and without need of a renement process was a major advantage compared to the conventional synthesis method in using the single-walled CNTs as industrial material.2.2 Research policy that set the direction and my thoughtsSince the super-growth method was published in November 2004, I questioned myself which research to do next. I thought that ideas and what could be done were limitless, including clarification of the mechanism of water addition or the creation of some bizarre CNT structures. In fact, most of the research topics that I conceived at the time or were brewing in the laboratory were published in illustrious academic journals a few years later. The super-growth method opened the possibilities to various new kinds of research.Although I was surrounded by much exciting research potential, I did not choose my research topics at whim. That was because I gave myself some policies in selecting the research that I should engage in the future. The policies were:• to engage in research that would be useful to the world,• to engage in research that would become industrial technology that may support Japan in 10 or 20 years from now, although it may be dull at the moment,• to engage in research of which I can appreciate the results at the end of my life.Why did I give myself such research policies? This was because I had a bitter experience when I was working on surface science research. Around 2000, I was conducting research on atomic structure analysis of semiconductor surfaces using the scanning tunneling microscope at Tsukuba University, and I went to the American Vacuum Society (the largest and most authoritative society in the eld of surface science) to give a lecture presentation of my greatest nding during the preceding few years (this was later published in Physical Review Letter).[8] In a lecture hall having seating capacity of 300 that was normally filled with several hundred people, there were only ten people. Most of them were Japanese. Right before this event, the National Science Foundation (NSF) that was the research funding agency in the United States suddenly decided to cut funds to the surface science field, and researchers left this field like an ebbing tide. Until that moment I thought science was the pursuit of absolute truths to clarify nature’s mechanism and therefore it had absolute value. My experience in the US taught me that in the real world there is research that goes in and out of trend, and research is not evaluated based on absolute value.From this experience in the US, I began to think about engaging in research that was not affected by trend, and wished to do research where the results are ultimately returned and become useful in society, rather than engaging in research to clarify the ways of nature. The aforementioned three research policies were the expression of my thoughts in a somewhat abstract form.This abstract wish became a specic goal in a slide (Fig. 5) that was used for presentation for visitors from the Ministry of Economy, Trade and Industry (METI) that I was in charge of in March 2005, right after the press release of the super-growth method. Someday, when I go home, my elderly mother will be using a product that contains the super-growth CNTs, and I want to tell her, “Oh, mom. This product has CNTs in it that we developed at Tsukuba.” To say this sentence became my personal goal as a researcher. This is because when I say these words, there should be a giant CNT industry in Japan, and our research will be contributing considerably in society. I used this slide repeatedly on visits and in lectures, and I must have re-used it several hundred times, as it represents my research philosophy and goal. In retrospect, this thought and wish were the source of my power to overcome all difficulties that came one after the other, and allowed me to realize the commercial production of the super-growth method.Fig. 5 Personal goal• A slide that was created in March 2005 for my rst presentation to visitors from METI→Create new industry with nanotubesMother owns a product that uses super-growth CNTs• Product developmentApplication• Application development• Evaluation of property

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