Lightweight TiO 2 @C/Carbon Fiber Aerogels Prepared from Ti 3 C 2 T x /Cotton for High-Efficiency Microwave Absorption.

Carbon fiber aerogel (CFA) derived from cotton wool as a potential microwave absorbing material has received intensive attention owing to the low density, high conductivity, large surface area, and low cost, but its applications are limited by the relatively high complex permittivity. To solve this problem, TiO 2 @C (derived from Ti 3 C 2 T x ) is introduced into CFA to prepare lightweight TiO 2 @C/CFA composites based on electromagnetic (EM) parameter optimization and enhanced EM wave attenuation performance. The microwave absorption capacity of TiO 2 @C/CFA-2 composite is obviously better than that of CFA. It is confirmed that good impedance matching derived from the combination of TiO 2 @C and CFA is the main factor to achieve excellent microwave absorption. Moreover, the improved microwave absorption capabilities are closely related to multiple EM wave absorbing mechanisms including multiple reflections and scattering, dipolar and interfacial polarization, and conductivity loss. TiO 2 @C/CFA-2 possesses a maximum reflection loss (RL) of -43.18 dB at a low response frequency of 6.0 GHz. As the matching thickness is less than 2.0 mm, the maximum RL values can still exceed -20 dB, and at the same time, the wide effective absorption bandwidth (EAB) below -10 dB achieves 4.36 GHz at only 1.9 mm thickness. Our work confirms that the lightweight and high-performance TiO 2 @C/CFA composites are promising choices and offer a new approach to design and construct carbon-based microwave absorbents derived from biomass.