The Change in Gas Absorption Behavior for Oxygen-Doped Carbon Nanotubes

Yung-Huang Chang ； Yuan-Tsung Chen ； Chien-Sheng Huang

《Journal of Innovative Technology》 2卷2期 (2020/09) Pp. 25-30

https://doi.org/10.29424/JIT.202009_2(2).0004

摘要

Carbon nanotubes (CNTs) have a unique one-dimensional nanostructure, along with various other useful properties. Recently they have attracted much attention for their possible application as gas sensors. Many existing CNT-based gas sensors focus on the promotion of sensitivity, selectivity, and response time, but little research has been done on the change in gas absorption behavior. This study examined the effects of oxygen doped CNTs on gas absorption behavior; the improvements in gas sensing capabilities were explored and recorded. The crystalline graphite structure of the pristine CNTs was improved via a 200°C post-treatment annealing process. After the annealing, the sensitivity of the CNTs was improved and this was attributed to the enriched oxygenated groups (C = O and O = C-O bonds) on CNT surface. Gas absorption behavior was found to change from dominant physisorption to dominant chemisorption, resulting from the enriched oxygenated groups, especially the O = C-O bond. Using an enlarged bias of more than 5V, the magnified adsorption energy that arose from the enriched oxygenated groups could be overcome and the observed dominant chemisorption behavior returned to dominant physisorption. Oxygen doped CNTs is thus a valid area of further research and development for gas sensor designers to consider.

關鍵字

Gas sensors ； Carbon nanotubes ； Oxygen-doped CNTs ； Oxygenated groups ； Thermal CVD

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