ABSTRACT
MXene aerogels with a porous microstructure are a promising electromagnetic interference (EMI) shielding material due to its low density and excellent electrical conductivity, which has attracted widespread attention. Compared with traditional EMI shielding materials that rely on reflection as the primary mechanism, MXene aerogels with absorption as the dominant mechanism have greater potential for development as a novel EMI shielding material because of its ability to reduce environmental contamination from reflected electromagnetic (EM) waves from materials. In this study, a novel Ti3C2Tx MXene/PEDOT:PSS hybrid aerogel was presented by freeze-drying and thermal annealing using few-layered Ti3C2Tx MXene and the conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). PEDOT:PSS not only improved the gelling ability of Ti3C2Tx but also successfully established a conductive bridge between MXene nanosheets. The experimental results demonstrated that the hybrid aerogel exhibited an obvious porous microstructure, which was beneficial for the multiple scattering of EM waves within the materials. The EMI shielding effectiveness and specific shielding effectiveness reached up to 59 dB and 10,841 dB·cm2·g-1, respectively, while the SER/SET ratio value was only 0.05, indicating superior wave absorption performance. Furthermore, the good impedance matching, due to the electrical conductance loss and polarization loss effect of the composites, plays a critical role in their excellent wave absorption and EMI shielding performance. Therefore, this work provides a practical approach for designing and fabricating lightweight absorption-dominated EMI shielding materials.
ABSTRACT
Graphene aerogel is a promising electromagnetic interference (EMI) shielding material because of its light weight, excellent electrical conductivity, uniform three-dimensional (3D) microporous structure, and good mechanical strength. The graphene aerogel with high EMI shielding performance is attracting considerable critical attention. In this study, a novel procedure to fabricate high EMI shielding graphene aerogel was presented, inspired by the irreversible deformation of hydrogels under mechanical pressure. The procedure involved a mechanical compression step on graphene hydrogels for the purpose of altering microstructures followed by freeze-drying and thermal annealing at 900 °C to generate the final products. Because of the flow of internal liquid caused by mechanical compression, the microstructures of hydrogels changed from a cellular configuration to a layered configuration. After a high degree of compression, GAs can be endowed with homogeneous layered structure and high density, which plays a leading role in electromagnetic wave dissipation. Consequently, the aerogels with excellent electrical conductivity (181.8 S/m) and EMI shielding properties (43.29 dB) could be obtained. Besides, the compression process enabled us to form complex hydrogel shapes via different molds. This method enhances the formability of graphene aerogels and provides a robust way to control the microstructure.
