Long-term stability of superhydrophilic oxygen plasma-modified single-walled carbon nanotube network surfaces and the influence on ammonia gas detection
- Authors
- Min, Sungjoon; Kim, Joonhyub; Park, Chanwon; Jin, Joon-Hyung; Min, Nam Ki
- Issue Date
- 15-7월-2017
- Publisher
- ELSEVIER SCIENCE BV
- Keywords
- Long-term stability; NH3 sensor; Oxygen plasma modification; Superhydrophilic SWCNT; Wettability
- Citation
- APPLIED SURFACE SCIENCE, v.410, pp.105 - 110
- Indexed
- SCIE
SCOPUS
- Journal Title
- APPLIED SURFACE SCIENCE
- Volume
- 410
- Start Page
- 105
- End Page
- 110
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/82819
- DOI
- 10.1016/j.apsusc.2017.03.080
- ISSN
- 0169-4332
- Abstract
- Single-walled carbon nanotube (SWCNT) networks are subjected to a low-powered oxygen plasma for the surface modification. Changes in the surface chemical composition and the stability of the plasma treated SWCNT (p-SWCNT) with aging in air for up to five weeks are studied using X-ray photoelectron spectroscopy (XPS) and contact angle analysis. The contact angle decreases from 120 degrees of the untreated hydrophobic SWCNT to 0 degrees for the superhydrophilic p-SWCNT. Similarly, the ratio of oxygen to carbon (O:C) based on the XPS spectra increases from 0.25 to 1.19, indicating an increase in surface energy of the p-SWCNT. The enhanced surface energy is gradually dissipated and the p-SWCNT network loses the superhydrophilic surface property. However, it never revert to the original hydrophobic surface state but to a metastable hydrophilic state. The aging effect on sensitivity of the p-SWCNT network-based ammonia sensor is investigated to show the importance of the aging process for the stabilization of the p-SWCNT. The best sensitivity for monitoring NH3 gas is observed with the as-prepared p-SWCNT, and the sensitivity decreases as similar as the p-SWCNT loses its hydrophilicity with time goes by. After a large performance degradation during the aging time for about two weeks, the response characteristics including sensitivity and response time of the p-SWCNT to ammonia gas are stabilized and eventually saturated. (C) 2017 Elsevier B.V. All rights reserved.
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Collections - College of Science and Technology > Department of Electro-Mechanical Systems Engineering > 1. Journal Articles
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