Roll up graphene "universal" carbon nanotubes or change the future

In the 30 years since the discovery of carbon nanotubes, my country's research level has basically kept pace with the world's advanced level, and has led the world in some fields. Carbon nanotube conductive agent has changed the situation that China's lithium battery enterprises rely on imports of conductive agents. Carbon nanotube films have been successfully used in high-end outdoor warm clothing and medical rehabilitation industries. Integrated circuits and display backplane driving devices based on semiconductor carbon nanotubes have also been developed......

Recently, Jiangsu Tiannai Technology Co., Ltd. (hereinafter referred to as Tiannai Technology), the largest carbon nanotube manufacturer in China, issued an announcement stating that it is expected to achieve a net profit of 0.11 billion -0.15 billion yuan in the first half of 2021, an increase of 235.41-357.37 year-on-year.%. The rapid growth of performance is attributed to the carbon nanotube conductive agent developed by the company, which has changed the situation that China's lithium battery enterprises rely on imports of conductive agents.

Since its discovery, carbon nanotubes have set off a global research boom. In recent years, the global accelerated mining of carbon nanotube technology landing approach, the relevant technological breakthroughs continue.

A tube of meter length and nanometer diameter

As the most important element of life, "carbon" has always played a pivotal role in the evolution of life and the provision of energy. In 1985, the C60 of the "football" structure attracted the attention of the world as soon as it was discovered. In 1991, Japanese physicist Iijima Chengnan observed carbon nanotubes in carbon materials prepared by arc method, which started the upsurge of carbon nanotube research.

"Structurally, carbon nanotubes can be vividly seen as hollow tubular structures made of single-layer or multi-layer graphene seamlessly curled." Li Qingwen, a researcher at Suzhou Institute of nanotechnology and nano bionics, Chinese Academy of Sciences (hereinafter referred to as Suzhou Institute of nano), told science and technology daily.

Carbon nanotubes are like a slender hair, its length can reach the meter level, but the diameter can be as small as nanometer scale. How are such elongated nano-tubular structures prepared?

The carbon nanotubes first discovered by Chengnan Iijima were produced by the arc discharge method. At present, carbon nanotubes have been developed by laser ablation, chemical vapor deposition (CVD), solid-phase pyrolysis and other preparation methods. Among them, the CVD method is widely used because of its low cost, good controllability and easy large-scale preparation.

Li Qingwen said that when carbon nanotubes are prepared by CVD, carbon atoms are adsorbed, diffused, dissolved and saturated on the surface of the catalyst to form carbon nanotubes. As the nucleation site of carbon nanotubes, the catalyst plays a decisive role in the diameter, wall number and chirality of carbon nanotubes. The structure design of catalyst and the regulation of growth conditions are important ways to realize the controllable growth of carbon nanotubes.

As an important member of the nano-carbon material family, carbon nanotubes are known as "universal substrates" for their excellent mechanical, electrical and thermal properties, and have great application prospects in the fields of structural and functional integrated composite materials, battery electrodes, integrated circuits, sensors, and electric heating devices.

Smolly, the 1996 Nobel Prize winner in chemistry and the discoverer of fullerenes, believes that carbon nanotubes are the strongest, stiffest and hardest materials that people can make, and they are also the best conductors of heat and electricity.

"The strength of carbon nanotubes is 100 times that of steel with the same volume, but the weight is only 1/6-1/7 of steel." Li Qingwen explained that carbon nanotubes have an aspect ratio of more than 106, so they are also called super fibers.

The peculiarity of carbon nanotubes lies in their special electrical properties. According to their different structures, carbon nanotubes can exhibit metallic and semiconducting properties, which lays the foundation for the development of new electronic devices.

China's research has reached the world's advanced level

Carbon nanotubes have been studied for 30 years. Li Qingwen believes that the research level of Chinese scientists in carbon nanotubes is basically on par with the world's advanced level, and is at the world's leading level in some fields.

In the basic research of carbon nanotubes, Zhang Jin's team and Li Yan's team of Peking University have made important contributions in the synthesis of carbon nanotubes with controllable conductivity and the synthesis and separation of single-handed carbon nanotubes. Peng Lianmao's team at Peking University has made significant progress in carbon nanotube electronic devices. In the application of carbon nanotubes, the Wei Fei team of Tsinghua University has made great achievements in the preparation of carbon nanotubes, high-strength carbon nanotube fibers, and carbon nanotube conductive additives.

As the national team of nanomaterials research in my country, Suzhou Nano Institute has been carrying out research work on the controllable preparation and cutting-edge applications of carbon nanotubes since 2007, and has published more than 300 high-level papers. Many major achievements have been made in the separation of electronic-grade single-walled carbon nanotubes, the large-scale preparation of carbon nanotube fibers and films, carbon nanotube composite materials and the application of energy devices.

In 2013, the world's smallest "computer" with parallel single-walled carbon nanotubes as the main components was born. In the past two years, the performance and size of carbon nanotube electronic devices have been broken through again and again.

How to obtain high-purity, high-quality semiconducting single-walled carbon nanotubes is a prerequisite for electronic-grade applications.

Li Qingwen told reporters that her team achieved high-concentration separation of semiconducting single-walled carbon nanotubes with a purity of more than 99.99 percent in 2018, as well as efficient screening of some single-handed carbon nanotubes. On this basis, they cooperated with other domestic colleges and universities to jointly realize the development of integrated circuits and display backplane driving devices based on semiconductor carbon nanotubes.

Carbon nanotubes, called super fibers, are made into fibers and films, which have excellent flexibility, electrical conductivity and thermal conductivity compared with traditional high-performance fiber and film materials.

After years of research, Li Qingwen's team has achieved continuous preparation of kilometer-level continuous carbon nanotube fibers, breaking through the dry scale preparation technology of 10,000 square meters of carbon nanotube films.

At the same time, researchers at Suzhou Nano Institute have developed a new type of carbon nanotube composite material with a carbon nanotube content of more than 60% using highly oriented carbon nanotube films, and its strength is more than twice that of carbon fiber composite materials. A new process of electrothermal curing of carbon nanotube films has been developed, which is expected to bring new design strategies for on-line repair of composite materials and wing deicing.

Carbon nanotube research results accelerate landing

Carbon nanotubes, known as "black gold", have been predicted by scientists to become one of the magical materials that "completely change the 21st century.

As the leading enterprise of carbon nanotubes in China, Tiannai Technology has successfully developed a unique catalytic reaction process to realize the continuous production of carbon nanotubes with a production capacity of up to 1,000 tons. In the past two years, Tiannai Technology's carbon nanotube conductive agent product shipments and sales have ranked first in the industry, changing the situation that my country's lithium battery companies rely on imports for conductive agents.

The use of lithium battery conductive agent is only the tip of the iceberg of the industrialization of carbon nanotubes.

As a national strategic emerging material, carbon nanotube materials are also widely used in conductive plastics, lightweight high-strength composite materials, broadband lightweight electromagnetic shielding, impact protection, smart materials, electronic devices and so on. Among them, the market prospects of carbon nanotube-based heating films, conductive plastics, composite materials and other materials are getting better and better.

"While strengthening cutting-edge exploration, we are actively carrying out research and development on the application of carbon nanotubes, developing lightweight carbon nanotube/metal composite wire technology, as well as lightweight cables for satellites. The developed carbon nanotube heated thermal clothing has been used by a number of international brands and has become one of the products of the Winter Olympics." Li Qingwen said. Based on the team's technology, Suzhou Jedi Nano Technology Co., Ltd. has realized the industrialization of carbon nanotube films with a production capacity of 100000 square meters per year, and successfully developed the application of this product in high-end outdoor warm clothing and medical rehabilitation.

"As an emerging material, carbon nanotubes may also be expanded to be used in conductive plastics, semiconductor devices, lightweight high-strength composite materials, broadband lightweight electromagnetic shielding, impact protection, smart devices and other fields in the future, and are expected to bring these fields. Revolutionary development." Li Qingwen said.