Engineered core-shell SiO2@Ti3C2Tx composites: Towards ultra-thin electromagnetic wave absorption materials

Ti3C2Tx nanosheets are attractive for electromagnetic wave absorption (EMA) materials requiring ultra-thin and high-performance due to their high conductivity and polarizability. However, the self-restacking of Ti3C2Tx nanosheets unavoidably decreases the number of active sites, specific surface area, and conductivity. Herein, a simple strategy is developed to prepare a core–shell structure of SiO2@Ti3C2Tx by electrostatic assembly and hydrogen bonding. SiO2 spheres as templates cannot only prevent Ti3C2Tx nanosheets from further stacking, but also modulate the surface impedance and significantly increase interfacial polarization loss. The resulted SiO2@Ti3C2Tx composite can deliver superior absorption capacity with minimum reflection coefficient (RL) of −58.01 dB at an ultra-thin thickness of only 1.3 mm. The absorption efficiency is calculated over 99.999 % with an effective absorption bandwidth (EAB) of 3.44 GHz. Furthermore, with increasing amounts of SiO2 templates, the EAB can be broadened up to 15.04 GHz (2.96–18 GHz) in the thickness range of 1–3 mm. The absorption mechanisms are described based on multiple reflection, polarization behaviors, tunable impedance matching, and conduction loss. The present work could pave a way for obtaining ultra-thin, high-performance MXene-based EMA materials.