生物质基碳气凝胶的制备及电磁屏蔽应用

Preparation and Electromagnetic Interference Shielding Performance of Biomass-Derived Carbon Aerogels

开发高电磁屏蔽效能和高电磁波吸收系数的电磁屏蔽材料是消除电磁波二次污染的重要途径,但二者通常难以兼顾。以天然生物质材料为前驱体,通过冷冻干燥和梯度升温热解过程制备了三种不同电磁屏蔽性能的生物质基碳气凝胶。其中,哈密瓜基碳气凝胶在8.2~12.4 GHz的频率范围内展现出高达71.9 dB的电磁屏蔽效能,同时电磁波吸收系数达到0.85。厚孔壁紧密连接形成的三维网络结构和高C/O比赋予哈密瓜基碳气凝胶优异的导电性和电磁屏蔽效能,而微米级大孔结构有效缓解阻抗不匹配,获得极高的电磁波吸收系数。仿生自然,提出一种有望兼顾高电磁屏蔽效能和高电磁波吸收系数的结构设计,在微电子、航天航空等领域具有较大应用潜力。

Developing an electromagnetic interference(EMI)shielding material with high shielding effectiveness(SE)and high electromagnetic wave absorption coefficient(A)was a promising strategy to eliminate the secondary pollution of reflected electromagnetic wave(EMW).However,it was a daunting challenge to simultaneously achieving high EMI SE with high A.Herein,biomass materials were utilized as precursors to fabricate three kinds of biomass-derived carbon aerogels for shielding EMWs by freeze-drying and specific two-stage pyrolysis.The as-prepared cantaloupe-derived carbon aerogels exhibited a high EMI SE of 71.9 dB in the frequency range of 8.2~12.4 GHz with an A value of 0.85.The three-dimensional network structure with robust pore wall and high C/O ratio were responsible for the high electrical conductivity and EMI SE.Moreover,the micron-size pore structure was efficient to weaken the impedance mismatch for EMW propagation from air to carbon aerogels,achieving extremely high A value.Inspired by nature,the results presented here provided a potential structure design to fabricate an EMI shielding material with high EMI SE and high A,which was exceedingly promising in the application of microelectronics,aircraft and spacecraft.