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Wednesday, September 13, 2017, 10:44
Layers of success
By Xing Yi
Wednesday, September 13, 2017, 10:44 By Xing Yi

A Chinese scientist aims to unlock the secrets of 2-D material. Xing Yi reports.

For more than a decade, Chinese physicist Zhang Yuanbo has been hunting for 2-D material in our 3-D world.

Zhang, 39, is one of the early scientists who tried to extract and analyze graphene, a carbon allotrope in the form of an atomic scale.

Graphene is hundreds of times stronger than steel.

Pioneering work on it won the Nobel Prize and opened the door to a whole new world of physics researching 2-D material.

"Scientists have since found more than 200 2-D materials," says Zhang, who works in Fudan University in Shanghai.

"The field is very active. Almost all the universities that I know pursue some kind of research related to it."

Graphene is a good conductor of electricity and the best conductor of heat among all known materials.

Scientists need time to develop and explore — too much evaluation on publishing papers will stifle their creativity

Zhang Yuanbo, Chinese physicist

It is almost transparent, yet its structure is so dense even a gas atom cannot pass through it.

Graphene and other 2-D materials are composed of known elements but they exhibit different features.

Zhang, through his collaboration with other scientists in China, managed to pin down phosphorene, a 2-D material made up of phosphorus atoms.

It is a natural semiconductor and has the potential of replacing silicon to make the microchips in computers and smartphones even smaller.

In 2014, academic journal Nature Nanotechnology published a research paper on phosphorene written by Zhang and his partners.

But there is much work to be done before phosphorene can be mass-produced, says Zhang.

Born in 1978 in a village in Xinyang, Henan province, Zhang took part in a national physics competition in high school.

He clinched the first prize in his province and that got him into Peking University.

When Zhang completed college in 2000, he was admitted to Columbia University for his PhD studies.

In 2002, he got to know his adviser Philip Kim, who was a new professor at Columbia. Kim introduced him to the field of 2-D material.

Physicist Zhang Yuanbo, one of the early scientists who tried to extract and analyze graphene, a carbon allotrope, works in his laboratory at Fudan University in Shanghai. (PHOTO BY XING YI / CHINA DAILY)

According to Zhang, Kim told him that research had been done on both carbon atoms in the shape of nanoballs and nanotubes, which are zero and one-dimensional, but little research has been done on the 2-D form of carbon.

"That sounded like exciting research to me," says Zhang.

Their first task was acquiring such a form of carbon.

Zhang found out that layers of graphite, the naturally occurring crystalline carbon, are like a stack of playing cards - different layers would slip away from each other if they were "pushed" aside.

Just like writing with a pencil, the graphite layers left on paper were the traces being left behind.

Following that line of reasoning, Zhang set up some nano pencils and tried to "write down" a few single layers of graphite.

Before Zhang and Kim could separate graphene in this way, University of Manchester researchers Andre Geim and Konstantin Novoselov, who were working in the same field, succeeded and published their paper in 2004.

Their method applied the use of adhesive tape, to "peel off" the thin layers, and their discovery helped them win the Nobel Prize in physics in 2010.

Zhang himself continued to study graphene and other 2-D materials.

Zhang and his team are at work in the lab, which he took two years to set up at Fudan University, after he completed his postdoctoral studies in the United States. (PHOTO BY XING YI / CHINA DAILY)

After earning his doctorate at Columbia, Zhang went for post-doctoral research at the University of California, Berkeley, in 2006.

Five years later, he returned to China through its Young Thousand Talents program, which recruits young scientists overseas to work and teach in the country.

"I chose Fudan University because I found that it gave me much freedom in research, and the relationship between colleagues is very good," recalls Zhang.

Zhang took two years to set up the laboratory. The university also did not pressure him to publish papers, an approach he felt was conducive for young researchers.

"Scientists need time to develop and explore - too much evaluation on publishing papers will stifle their creativity," he says.

There are now many laboratories in China that are also good enough to compete with their US counterparts, adds Zhang.

During his student days, going abroad seemed to offer the best option for aspiring scientists who wanted to further their studies, but "the situation has changed", he says.

"In the past, some might have said that scientists who returned to the motherland 'sacrificed their good life and research abroad'. But that is not the case now."

To help further address the tendency to place more value on researchers who have earned their degrees abroad, "we should also give homegrown researchers equal opportunity in applying for funds", he says.

Contact the writer at xingyi@chinadaily.com.cn

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