Polyoxometalate-immobilized carbon nanotube constructs triggered by host–guest assembly result in excellent electromagnetic interference shielding

Abstract

In the era of fifth-generation networks and the Internet of Things, new classes of lightweight, ultrathin, and multifunctional electromagnetic interference (EMI) shielding materials have become inevitable prerequisites for the protection of electronics from stray electromagnetic signals. In the present study, for the first time, we have designed a unique nanohybrid composed of a copper-based polyoxometalate (Cu-POM)-immobilized carbon nanotube construct, having a micron (∼100 μm)-level thickness, through a facile vacuum-assisted filtration technique. In this course of study, a total of four Cu-POMs, two from each category of Keggin and Anderson bearing opposite charges, i.e., positive and negative, have been rationally selected to investigate the effects of the host–guest electrostatic interaction between CNT and POMs in the EMI shielding performance. This approach of the host–guest electrostatic assembly between Cu-based polyanionic oxo clusters and counter-charged CNTs in the construct synergistically enhances the EMI shielding performance compared to the individual components dominated by 90% absorption in the X-band (8.2–12.4 GHz) frequency regime. Further, mutable EMI SE can be achieved by tuning the concentration of POMs and CNTs with different weight ratios. Such Cu-POM-immobilized CNT constructs demonstrating excellent shielding (∼45 dB) are not amenable via any other conventional routes, including flakes and dispersion.