Temasek Laboratories, Nanyang Technological University, 50 Nanyang Drive, 637553, Singapore.
School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore.
J Colloid Interface Sci. 2017 Apr 15;492:112-118. doi: 10.1016/j.jcis.2016.12.060. Epub 2016 Dec 28.
Electromagnetic interference (EMI) shielding performance of chemically and thermally reduced graphene aerogels (GAs) was systematically studied. The EMI shielding mechanisms were extensively analyzed in terms of the distinct surface characteristics resulted from the different reduction methods for the first time. EMI shielding effectiveness (SE) of chemically and thermally reduced GAs reached 27.6 (GAC) and 40.2dB (GAT) at the thickness of 2.5mm, respectively. It was found that the introduction of nitrogen atoms through chemical reduction induced localized charges on the carbon backbone leading to strong polarization effects of GAC. The relatively incomplete reduction caused a large number of side polar groups which prevented the graphene sheets from π-π stacking. In contrast, the higher extent of reduction of graphene sheets in GAT left a smaller amount of side polar groups and formed more sp graphitic lattice, both factors favored π-π stacking between the adjacent graphene sheets, resulting in higher electrical conductivity and enhanced EMI SE. The EMI shielding performance of the GAs prepared outperformed the recent reported porous carbon materials with respect to the absolute SE value at the similar thickness and/or density.
化学和热还原氧化石墨烯气凝胶（GAs）的电磁干扰（EMI）屏蔽性能得到了系统研究。首次从不同还原方法导致的不同表面特性的角度，广泛分析了 EMI 屏蔽机制。化学还原和热还原 GAs 的 EMI 屏蔽效能（SE）在 2.5mm 厚度时分别达到 27.6（GAC）和 40.2dB（GAT）。研究发现，化学还原过程中氮原子的引入导致碳主链上产生局部电荷，从而产生 GAC 的强烈极化效应。相对不完全的还原导致大量的侧极性基团，阻止了石墨烯片层的π-π堆积。相比之下，GAT 中石墨烯片层还原程度较高，留下较少的侧极性基团，并形成更多的 sp 石墨晶格，这两个因素都有利于相邻石墨烯片层之间的π-π堆积，从而导致更高的电导率和增强的 EMI SE。与相似厚度和/或密度的最近报道的多孔碳材料相比，所制备的 GAs 的 EMI 屏蔽性能在绝对 SE 值方面表现优异。
