Nanocellulose assisted preparation of ambient dried, large-scale and mechanically robust carbon nanotube foams for electromagnetic interference shielding

Abstract

Nanofibrillated cellulose is efficiently employed as a green dispersant, cross-linker and structure-directing agent assisting in the preparation of large-area ambient pressure dried carbon nanotube (CNT) foams using a facile, energy-efficient, and scalable freezing–thawing–drying approach. The resultant CNT based foams show unidirectional microhoneycomb pore channels, high mechanical strength, good conductivity, controllable wide-ranging densities, and functional attributes of high-efficiency organic dye absorption and designed hydrophobicity. The significant pore microchannel orientation allows for a facile tuning of the electromagnetic interference (EMI) shielding performances of the CNT foams. This is demonstrated by efficiently controlling the angle of the pore orientation with respect to the electric field direction of the incident electromagnetic waves. Combining the adept controllability of the building blocks and the excellent EMI shielding effectiveness (SE) of more than 70 dB, resulting in a specific SE of up to 6111 dB cm² g⁻¹, our work shows the great potential of these air-dried nanostructured cellular monoliths in EMI shielding applications.