Surface structure engineering and electromagnetic character regulation synergestically boosts electromagnetic shielding performances of carbon nanotube sponge

Abstract

The negative effects of electromagnetic (EM) pollution on precise electronic devices as well as public health have received serious attention. Although various electromagnetic interference (EMI) shielding materials have emerged, it is still a great challenge to effectively balance the high EMI shielding performance and low secondary emission of EM waves induced by direct reflection. In this study, we designed two type of shielding materials based on 3D carbon nanotube sponge (CNTS) with manufactured surface structure. By combining the 2D MXene layer or magnetic nickel coating with patterned CNTS, we achieve high EMI shielding performance and low reflectivity, as well as adjustable shielding mechanism through the dual adjustment of the structure and electromagnetic properties. The EMI shielding effectiveness of CNTS/MXene up to 90 dB and reflectivity as low as 0.31 (at 18 GHz), a reduction of about 64 % compared to the original CNTS. And the EMI shielding effectiveness of Ni/CNTS up to 67 dB and reflectivity as low as 0.44 (at 12 GHz). Microwave microscope (NFSMM), COMSOL simulation and vector network analyzer consistently confirmed the synergestical surpression effect on the reflectivity from surface structure engineering and electromagnetic regulation. These results not only guide the designing of advanced EMI shielding materials with low reflectivity, but also shed light on the hidden mechanism between interface structures and performances of the composite materials.