Technology capable of mass production of colored pure single-walled carbon nanotubes

The mystery is that

Fine-tuning preparation process

-And a small amount of carbon dioxide.

Single-walled carbon nanotubes (SWNTs) or graphene sheets with atomic thickness are rolled into different sizes and shapes, which have many uses in electronic devices and new touch screen devices.

In essence, carbon nanotubes are usually black or dark gray.

In a research paper published by the American Chemical Society (JACS), researchers at Aalto University proposed a method to control the preparation of carbon nanotube films so that they appear in different colors, such as green, brown or silver gray.

These researchers believe that this is the first time to produce colored carbon nanotubes by direct synthesis. Using their invention, the color is directly induced in the preparation process, instead of using a series of purification techniques on the finally synthesized carbon nanotubes.

Through direct synthesis, a large number of clean sample materials can be produced, and at the same time, the damage to the products during purification can be avoided, which makes it the most attractive method for application.

"In theory, these colored films can be used to make multi-color touch screens or solar cells that can display new optical characteristics." Professor Esco Kauppinen of Aalto University said.

It is a feat in itself to make the carbon structure show color. The basic technology needed to realize coloring also means fine control of nanotube structure.

Kauppinen and his team's unique method is to use metal and carbon aerosols, which enables them to carefully manipulate and control the nanotube structure directly from the preparation process.

"To some extent, generating carbon nanotubes is like planting trees: we need seeds, nutrients and solar energy. For us, iron aerosol nanoparticles play the role of catalyst or seed, CO is the source of carbon, and the heat generated by nutrients and reactors above 850℃. " Dr. Jiang Hua, a senior scientist at Aalto University, said.

The team led by Professor Kauppinen has used these resources in wonderful production methods for a long time. In order to increase their research, they recently did an experiment in which a small amount of carbon dioxide was added in the preparation process.

"As a grafting material, carbon dioxide can be used to regulate the growth of carbon nanotubes of various colors." Dr. Jiang said.

Using advanced electron diffraction technology, these researchers can find out the precise atomic scale structure of thin films. They found that they have a very narrow chiral distribution, which means that the orientation of the honeycomb lattice on the tube wall is almost the same throughout the sample. Chirality more or less determines the electrical properties of carbon nanotubes and their colors.

The method developed by Aalto University is expected to be a simple and highly scalable method for preparing carbon nanotube films with high yield.

"Usually, you have to choose between mass production and good control of the structure of carbon nanotubes. Based on our breakthrough, we can take care of both. " Dr. Zhang Qiang, a postdoctoral graduate student of the team, said with confidence.

Follow-up research has begun.

"We want to know the science of how adding carbon dioxide can adjust the structure of nanotubes and produce color. Our goal is to achieve complete control over the generation process so that single-walled carbon nanotubes can be used as building blocks for the next generation of nano-electronic devices. " Professor Kauppinen said.

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