Lightweight, three-dimensional carbon Nanotube@TiO2 sponge with enhanced microwave absorption performance

Porous, spongy absorbers are considered to be the most promising candidates for lightweight and highly efficient microwave absorption material. However, conventional sponges or foams reported previously are difficult to meet the high performance requirements. Here, a lightweight (42 mg/cm3), porous [email protected]2 sponge with core-shell structure CNT/TiO2 was successfully prepared via a simple combination of hydrolysis and heat treatment method. In the sponge, the thickness and crystal structure of the TiO2 shell layer, and the mass fraction of TiO2 and CNTs can be precisely controlled by the growth processes, resulting in adjustable dielectric loss properties of the samples. With the optimized component proportion, it was found that a minimum reflection loss value of −31.8 dB was observed at 10.35 GHz, and reflection loss exceeds −10 dB is up to 2.76 GHz for the absorber with the thickness of 2 mm. Moreover, the effective microwave absorption (<10 dB) can be achieved in the range of 3.43–12.0 GHz by adjusting the thickness of the absorber. These results indicate that the [email protected]2 sponges can serve as attractive candidate materials for lightweight microwave absorption materials.