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|Title: ||Reduction-oxidation dynamics of oxidized graphene: Functional group composition dependent path to reduction|
|Authors: ||洪翊哲;Hong, Yi-Zhe|
|Keywords: ||石墨烯;掃描探針微影;graphene;scanning probe lithography;oxidation and reduction;redox|
|Issue Date: ||2018-08-31 13:57:34 (UTC+8)|
;In recent years, graphene becomes a hot research issue rapidly because of its ultrahigh electron mobility and ultrathin two-dimension structure. Unfortunately, a lack of band gap causes its developed limitation on electronic application. While the band gap can be produced through defects creating in graphene lattices such as ion doping or oxygen plasma bombardment. Among them, reduced graphene oxide (rGO) manufactured by Hummers’ method not only overcomes the barrier of band gap-free in pristine graphene, but also can be manufactured effectively with low cost. Thus, these advantages make rGO may be applied in real life. However, there are lots of complex oxygen functional groups bond with graphene during the Hummers’ method. These complex oxygen functional groups will cause that GO can’t reduce back to rGO completely even through the UV light or thermal reduction. In addition, the electronic and optical properties of graphene will also be influenced by the residual oxygen functional groups. Therefore, how to control the oxidation and reduction of graphene precisely becomes a difficult challenge.
In this research, we used the scanning probe lithography (SPL) to tune the extent of graphene oxidation precisely. During the SPL process, a bias was exerted between the tip and graphene to create hydroxide ions bonding with graphene by electrolysis the water in air. Then, the graphene oxidation was identified and reduced at the same time through measurement of x-ray photoelectron spectroscopy (XPS). The graphene reduction dynamics was observed through analyzing the transformation of functional groups. Furthermore, we found that graphene oxidation could be oxidized again during the reduction process. Through XPS spectrum analysis, the phenomenon was found only occurred when the original graphene oxidation conformed two thresholds simultaneously. The thresholds included that total oxygen concentration needed to exceed 70%, and the total concentration of ether and epoxy also need to exceed 22%.
|Appears in Collections:||[物理研究所] 博碩士論文|
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