Gradient-structured MXene/ZIF/CNT hybrid films for largely enhanced electromagnetic absorption in EMI shielding

Abstract

• MXene/MOF hybrid nanosheets composed of ZIF-8 and ZIF-67 were synthesized in solvents. • Gradient-structured MXene/MOF/CNT hybrid films with inversely varied concentrations of MXene/MOF and CNT were fabricated. • Gradient-structured films showed good EMI shielding properties (40 dB) and EM wave absorption (42 %) at the Ka-band. • EMI shielding and absorption was achieved through dielectric loss, interfacial polarization, and multiple scattering. Increasing reliance on wireless electronic devices and future mobility has driven demand for EMI shielding solutions that can both shield and absorb electromagnetic (EM) waves, especially at higher frequencies. However, conventional shielding materials, though effective, rely on reflection mechanisms that may generate secondary interference. In this study, we present an advanced MXene/MOF/carbon nanotube (CNT) hybrid film that simultaneously allows electromagnetic interference (EMI) shielding and EM wave absorption. We developed a gradient-structured MXene/MOF/CNT film, where the concentrations of MXene/MOF nanosheets and CNT are varied with inverse proportion through the film thickness. In this configuration, the MOF-rich top surface of the film allows better EM wave absorption, while the CNT-rich bottom regions of the film and the MXene nanosheets provide high EMI shielding properties. In an optimized sample, gradient-structured hybrid films assembled from ZIF-8, ZIF-67, Ti 3 C 2 T x MXene, and CNT demonstrated good EMI shielding properties at the Ka-band with SE T values around 40 dB. At the same time, the film showed a total EM wave absorption efficiency of 42 % in terms of power coefficient, which is a 40-fold increase compared to conventional MXene and MXene/CNT EMI shielding films. This highlights its potential for next-generation EMI shielding applications in highly integrated electronic devices.

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