An artist’s representation of the 3D graphene pyramid.
An artist’s representation of the 3D graphene pyramid.

Researchers from Finland and Taiwan have discovered how graphene, a single-atom-thick layer of carbon, can be forged into three-dimensional (3D) objects using laser light. As a demonstration of this novel technique, they fabricated a pyramid with a height of 60 nm, which is about 200 times larger than the thickness of a single graphene sheet but still small enough to fit easily on a single strand of hair.

The research was supported by the Academy of Finland and the Ministry of Science and Technology of the Republic of China, and reported in a paper in Nano Letters.

Graphene was first isolated from graphite in 2004, and researchers have since found that it possesses a range of interesting properties, including great strength and high electrical conductivity. Because of this, graphene is being investigated for use in advanced electronic and optoelectronic devices, such as transistors, photodetectors and sensors. Now, researchers have shown that graphene can also be used to build 3D objects.

“We call this technique optical forging, since the process resembles forging metals into 3D shapes with a hammer. In our case, a laser beam is the hammer that forges graphene into 3D shapes,” explains Mika Pettersson, who led the experimental team at the Nanoscience Center of the University of Jyväskylä in Finland. “The beauty of the technique is that it’s fast and easy to use; it doesn’t require any additional chemicals or processing. Despite the simplicity of the technique, we were very surprised initially when we observed that the laser beam induced such substantial changes on graphene. It took a while to understand what was happening.”

“At first, we were flabbergasted. The experimental data simply made no sense,” says Pekka Koskinen, who is also at the Nanoscience Center of the University of Jyväskylä and was responsible for the theory. “But gradually, by close interplay between experiments and computer simulations, the actuality of 3D shapes and their formation mechanism started to become clear.”

“When we first examined the irradiated graphene, we were expecting to find traces of chemical species incorporated into the graphene, but we couldn’t find any,” says Wei Yen Woon from the National Synchrotron Radiation Research Center in Taiwan, who led the experimental group that carried out X-ray photoelectron spectroscopy at the synchrotron. “After some more careful inspections, we concluded that it must be purely structural defects, rather than chemical doping, that are responsible for such dramatic changes on graphene.

The novel 3D graphene is stable and it has electronic and optical properties that differ from normal 2D graphene. Optically-forged graphene could help in fabricating 3D architectures for graphene-based devices.

This story is adapted from material from the Academy of Finland, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.