Preparation of porous graphene nanosheets/carbon nanotube/polyvinylidene fluoride (GNS/CNT/PVDF) composites for high microwave absorption in X-band

With the rapid development of electronic devices, it is urgent to design and fabricate lightweight and effective electromagnetic absorption materials. Here, the graphene nanosheets/carbon nanotube/poly(vinylidene fluoride) (GNS/CNT/PVDF) composites with three-dimensional interconnected hierarchically porous networks have been successfully prepared via a facile solution mixing and followed by phase inversion method. The specific hierarchically porous structure in the composites possesses interconnected pores with various sizes. The open micro-scale pores on the top side give much smaller permittivity, which makes it less resistive to the incident microwave in a wide frequency range and is advantageous for multiple reflection and scattering of electromagnetic waves (EMW). The relatively smooth and dense bottom prevents EMW passing through the composites, which endows the prepared composites with a high EMW absorption. The as-prepared porous composites with 3.5 mm thickness exhibit a maximum absorption value of as high as − 32.7 dB at 11.50 GHz and display an ultra-wide efficient absorption bandwidth (entire X-band). Therefore, our work sheds light on a feasible strategy for designing and fabricating high-efficient EMW absorption materials.