Ultrathin Self-Assembly MXene@flake Carbonyl Iron Composites with Efficient Microwave Absorption at Elevated Temperatures

The exploration for the potential lightweight and high efficiency microwave absorbers with thermal stability is a great challenge for researchers. More importantly, the electromagnetic parameters of absorbers at elevated temperatures are seldom studied. In this work, sandwich MXene-Ti3C2Tx@flake carbonyl iron (MF) composites with tunable and efficient microwave absorption at elevated temperatures are successfully fabricated by an electrostatic self-assembly method. Both the complex permittivity and permeability of the MF are strongly temperature dependent in the temperature range of 298-473 K and X band (8.2-12.4 GHz). The efficient microwave absorption of MF at different temperatures can be achieved by changing the ratio of raw materials. Specifically, at room temperature, reflection loss (RL) <=-10 dB of MF composite covers the whole X band at 2.12 mm, while the optimum RL value is -26.3 dB at 11.81 GHz. At 373 K, the optimum microwave absorption value of the MF composite reaches up to -63 dB at 10.27 GHz and RL <=-10 dB can cover a whole X band with a thickness of 1.52 mm. Therefore, MF composites are expected to be promising candidates as ultrathin, highly efficient, and broadband absorbing materials at elevated temperatures.