In-situ growth of TiO2 nanoparticles on crumpled Ti3C2Tx with negative permittivity for electromagnetic interference shielding

MXenes have been attracting enormous attention owning to their high electronic conductivity, abundant func-tional groups, and surface modification ability in the application of electromagnetic interference (EMI) shielding. In this work, TiO2 nanoparticles were in-situ grown on the surface of crumpled Ti3C2Tx MXene to generate TiO2/ MXene heterointerfaces and create an extra absorption path. It was found that Ti3C2Tx with less oxidation time generated more TiO2. This intriguing phenomenon was caused by the fact that more functional groups escaped in the pre-oxidation step, creating extra active sites and allowing for more intense oxidation in a shorter period. Besides, the hybrid showed negative permittivity due to the metal-like conduction behavior, contributing to the reflection-dominant shielding mechanism. The TiO2/MXene heterostructure with negative permittivity exhibited an excellent total EMI shielding effectiveness of 73.98 dB at a filler content of 25 wt% in 8.0-12.4 GHz (covering the X band) at 2 mm. This work offers a new insight into exploring the structure-property relationship for MXene-based materials.