The traits of carbon-nanotubes affect generation of negative air ions by electric discharging
Date Issued
2008
Date
2008
Author(s)
Hsu, Meng-Tsung
Abstract
This study investigated the traits of carbon-nanotubes (CNTs) affect generation of negative air ions (NAIs) by negative electric discharging, and investigated the feasibility of developing a microscale air cleaner. The research investigated the effect of the discharging voltage about CNTs on the one and two dimension metal substrate, the aspect ratio of CNTs, aligned CNTs, single-walled and multi-walled CNTs, metal material, metal aspect ratio, metal needle-point curvature, the stability and the effective distance of NAIs which were generated by negative electric discharging, dectecting ozone concentration. Because electrons can gather on need-point of one dimension substrate to make electrons excite easilier, the discharging voltage of CNTs on the one dimension metal substrate gets lower than other on the two dimension metal substrate. The enhanced field emission gets bigger and the discharging voltage gets lower when the aspect ratio of CNTs gets bigger. Beacause CNTs array align regularly, it can reduce screening effect and the discharging voltage effectively. Because of bigger aspect ratio and better conductivity the discharging voltage of Single-walled CNTs gets lower than the one of multi-walled CNTs. At the same discharging voltage, the stability of NAIs which were generated by negative electric discharging gets better when the aspect ratio of CNTs gets bigger. The NAIs concentration decreased when the distance increased, and The NAIs concentration and the distance indicated logarithmic linear relationship. The NAIs concentration of CNTs on copper and silver electrode which was used as the negative electrode to generate NAIs can reach detecting limit range when the discharging voltage was about 1.6 kV and 1.4 kV, and there was no generation of ozone. When the discharging voltage was about 3.0 kV, ozone concentration which was generated by CNTs on copper and silver electrode was about 0.5 ppb and 0.6 ppb, and ozone concentration increased fast when the discharging voltage increased.
Subjects
negative air ions (NAIs)
carbon-nanotubes (CNTs) array
aspect ratio
enhanced field emission
screening effect
Type
thesis
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