Facile synthesis of ultrasmall Fe3O4 nanoparticles on MXenes for high microwave absorption performance

Although two dimensional (2D) materials have already been studied as promising microwave absorption materials due to fascinating layered structure, it is hard to achieve both thin coating and excellent absorbing capability. Herein, 2D hierarchical composites of nano-sized Fe3O4 particles on MXenes (TiO2/Ti3C2Tx/Fe3O4) with different [TiO2/Ti3C2Tx]/[Fe3O4] ratios were synthesized by using a moderate chemical hydrothermal reaction. Scanning electron microscope and transmission electron microscope techniques indicated that the surfaces of MXenes were densely covered with Fe3O4 nanoparticles of ∼4.9 nm in diameter and TiO2 particles. By tuning the ratio of [TiO2/Ti3C2Tx]/[Fe3O4], microwave absorption capabilities in terms of the maximum reflection loss (RL) value and absorber thickness could be readily optimized. Specifically, the sample TiO2/Ti3C2Tx/Fe3O4-5 exhibited a remarkable absorption performance, with a maximum reflectivity of −57.3 dB at 10.1 GHz and a band range below −10 dB to over 9.1–11.1 GHz at a thickness of 1.9 mm. Therefore, our 2D MXene composites are expected to be promising candidates as ultrathin and lightweight absorbing materials.