Three-dimensional network-like structure formed by silicon coated carbon nanotubes for enhanced microwave absorption

The rapid development of electronic technology generates a great deal of electromagnetic wave (EMW) that is tremendously hazardous to environment and human health. Correspondingly, the high efficient EMW absorption materials with lightweight, high capacity and broad bandwidth are highly required. Herein, a series of three-dimensional (3D) network-like structure formed by silicon coated carbon nanotubes (NW-CNT@SiO₂) are massively prepared through an improved sol-gel process. The as-obtained 3D NW-CNT@SiO₂ exhibit low densities of about 1.6 ± 0.2 g/cm³. The formation of this special 3D structure can provide high dielectric loss and good impedance matching for EMW absorption. As expected, a minimum reflection loss (RL) of -54.076 dB is obtained when uses the sample prepared by 0.1 g of CNTs and 0.2 mL of tetraethoxysilane as absorbent with a low loading rate of 10 wt% and thin absorber thickness of 1.08 mm. This specific minimum RL value exceeds many other CNT based EMW absorbers reported in previous literature. These findings featured with a green and scalable preparation process provides a facile strategy to design and fabricate high-performance EMW absorption materials, which can be applied to other materials such as carbon fibers and graphene.