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07/23/2017 HYU News > Academics


Vitalization in Detecting NO2 in Daily Life

Professor Kim Hyoun-woo (Division of Material Science and Engineering)


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As environmental pollution is deteriorating, various hazardous gas face people unrecognizably in their daily lives. Professor Kim Hyoun-woo of the Division of Material Science and Engineering is an active researcher in various sensors that could help identify various gas, humidity, or even radiation. His recent paper “Enhancement of gas sensing properties by the functionalization of ZnO-branched SnO2 nanowires with Cr2O3 nanoparticles” proposes another effective method of detecting a particular gas, NO2.
Kim expaining the nanostructure of his paper.

His research aimed for an effective NO2 detecting nanostructure, which is a structure made from molecules. NO2, also called as nitrogen dioxide, is required to be detected since it can be found relatively easily through the atmosphere even when it is a toxic, air-contaminant gas. Kim mentioned “Once a practical method through this nanostructure is constructed, I wish people can be easily detect this toxic gas.”

This nanostructure is composed of three different substances. First of all, a SnO2 (tin oxide) nanowire is required. A nanowire is a nanostructure of an extreme, fine line which has a diameter of one nanometer (10−9 meters). Next, ZnO (zinc oxide) nanowires are branched on the SnO2 nanowire. Then the last substance, which are Cr2O3 (chromium oxide) nanoparticles, would grow on the ZnO nanowires. With a completed nanostructure, detecting NO2 become possible.
An illustration of Cr2O-functionalized ZnO branched SnOnanowires. (photo courtesy of Kim)

This nanostructure mentioned in his paper is highly sensitive, which makes it a significant structure. A current always flows within a structure, and a resistance is made whenever there is a current. However, the resistance differs when there is an inflow of another gas. The external gas takes away the electron in the structure, therefore heightening the resistance of the structure. The sensitivity is determined through resistance within the sensor. When the sensitivity is elevated, a structure can perceive more NO2 than the one with low sensitivity even when there’s a same amount in the air.

The nanostructure mentioned in the paper is indeed a unique technology. However, Kim also mentioned the insufficiency of this nanostructure. In order to detect NO2, this gas needs to be heated in an extremely high temperature; in the case of the paper, 300’C. Therefore, there is a difficulty for people to sense the gas in the current stance. Kim mentioned that he wants to improve this difficulty through further research. He is currently working on methods that could allow this nanostructure to detect NO2 in a room temperature.

Kim wishes to develop a practical nanostructure.

Kim is an enthusiastic researcher. He constantly works on structures that could benefit people in their daily lives. He is striving for extreme-high sensitivity in his structures so that people could quickly recognize and react to the contamination. Kim mentioned “I want to make a structure that can be commercialized. A lot of the inventions disappear due to the lack of cost competency or efficiency. I wish to contribute to the promotion of mankind welfare.”

On Jung-yun
Photos by Kim Youn-soo
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