Study of Electromagnetic Wave Absorption Using activated Holey Graphene

• Main Authors: Yu, Jeng-Shian, 游政憲
• Other Authors: Liu, Yih-Ming
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/9f97sm

碩士 === 國防大學理工學院 === 材料科學與工程碩士班 === 106 === Graphene is used in electromagnetic wave absorbing materials to exhibit excellent performance, and the rapid temperature reduction method is used to prepare porous graphene, which is rich in pores and defects. These defects can promote multiple reflection/scattering and generate interfaces on electromagnetic wave absorption. The polarization phenomenon greatly improves the electromagnetic wave absorption efficiency of graphene. This study is divided into two parts. First, change the oxidation time, and explore the effect of oxidation time on the properties and absorbing properties of porous graphene materials. The porous graphene (4DHGNS) with four days of oxidation time, when the addition amount is 1 wt.%, the simulated thickness is 2 mm. The maximum reflection loss (at 15.44 GHz) can reach -13.94 dB; at 1.5 wt.%, the simulated thickness is 2 mm, the maximum reflection loss (at 14.69 GHz) can reach -19.70 dB; at 2 wt.%, the simulated thickness is 2 mm The maximum reflection loss (at 12.29 GHz) can reach -23.08 dB. The experimental results show that as the amount of graphene added increases, the maximum reflection loss of the same simulated thickness will shift to the low frequency and the absorbing efficiency will increase at the same time. Secondly, the holey graphene is activated by KOH aqueous solution and CO2 gas respectively to increase the pore size and uniformity, thereby establishing the influence of the size of the graphene pores on electromagnetic wave absorption. The surface morphology of KOH-activated holey graphene (KHGNS) produces a special honeycomb-like pore structure, which changes the original characteristics of graphene material. Therefore, the absorbing property has extremely wide frequency performance at a special simulated thickness, and the added amount is 1 wt.% The simulated thickness is 2.5 mm, the RL< -10 dB frequency spans 13.04 ~ 18 GHz ; the added amount is 3 wt.%, the simulated thickness is 2.5 mm, and the RL < -10 dB frequency spans 12.44 ~ 18 GHz. CO2-activated holey graphene (CHGNS) with a surface pore size of 5 nm ~ 400 nm, activation time of one hour, addition amount of 1 wt.%, simulated thickness of 1.5 mm, maximum reflection loss (16.34 GHz) of -20.41 dB; activation At two hours, the addition amount is 1 wt.%, the simulated thickness is 1.5 mm, and the maximum reflection loss (14.39 GHz) can reach -24.28 dB. The porous graphene can produce excellent absorbing efficiency when the thickness is thinner after CO2 activation.