World's First Discovery of Spiral Galaxy-Shaped Graphene Adsorption Layer

UNIST Research Team Finds Clue to Synthesis Method Allowing Thickness Control of Graphene for Various Applications

[Asia Economy Reporter Kim Bong-su] Domestic researchers have discovered for the first time a graphene adlayer synthesized in a spiral galaxy shape and elucidated it with a new theory.

Ulsan National Institute of Science and Technology (UNIST) announced on the 28th that the research team led by Professors Feng Ding and Jong-Hoon Lee from the Department of Materials Science and Engineering published a paper containing these research results in the international journal Advanced Materials on the 24th of last month.

An adlayer refers to another graphene layer formed underneath the original graphene layer. This research is expected to provide clues for developing synthesis methods that can control the number of graphene layers according to the intended application. Graphene is known as a two-dimensional material with a thickness of a single carbon atom. However, synthesized graphene often consists of multiple layers of carbon atoms stacked together. Its properties vary depending on the number of layers. For example, bilayer graphene can be used to create semiconductor devices that can be switched on and off, which is not possible with monolayer graphene. Instead, monolayer graphene has higher charge mobility than bilayer graphene. Therefore, developing technology to synthesize graphene with a controlled number of layers according to its use is important.

The research team improved existing probability-based modeling methods, such as kinetic Monte Carlo simulation, to analyze the cause of graphene being synthesized in a spiral form. Since such spiral structures had never been observed in graphene or other materials, existing theories had limitations in explaining this phenomenon.

According to the team’s theory, the spiral graphene grows by receiving a high concentration of carbon precursors gathered at the edges of the hexagonal graphene layer above it. During this process, the carbon precursor concentration becomes insufficient, causing the growth to take on a spiral shape. When carbon precursors are scarce, the lower graphene layer grows partially only along the edges where precursors are easily supplied, while the upper graphene layer continues to grow. Following the edge of the upper graphene layer causes the lower layer to form a spiral shape. The spiral graphene is synthesized smaller than the upper graphene layer, and this theory explains the unique phenomenon where the ‘arms’ of the spiral graphene are always in contact with the edges of the upper graphene layer. The spiral arms refer to the web-like structures radiating from the center of the spiral. Furthermore, the team succeeded in controlling the number of spiral arms by varying the concentration of graphene precursors, consistent with theoretical predictions.

Professor Feng Ding explained, “This research theoretically revealed where the carbon precursors forming the adlayer come from, providing a clue for developing new synthesis methods that control the number of graphene layers by suppressing or activating precursor supply.”

Meanwhile, Professor Jong-Hoon Lee’s research team was able to analyze the complex characteristics of spiral graphene using high-resolution transmission electron microscopy (HRTEM) technology.

This content was produced with the assistance of AI translation services.