Enhanced microwave absorption properties of large-sized monolayer two-dimensional Ti₃C₂T_x loaded with Fe₃O₄ nanoparticles

With the rapid updating and development of electronic equipment, electromagnetic interference and electromagnetic radiation pollution have became serious problems, because that excessive electromagnetic interference will not only affect normal operation of electronic equipment but also cause great harm to human health. In general, an ideal material for microwave absorption with the characteristics of high reflection loss (RL) intensity, wide effective absorption band (EAB), thin thickness, and lightweight could effectively consume electromagnetic wave (EMW) energy. Therefore, it is crucial to search for such an ideal microwave absorption material to deal with the electromagnetic radiation pollution. Two-dimensional (2D) carbon/nitride MXene has received more and more attention in recent years, because excellent electrical conductivity and rich surface-functional groups in MXene show positive effects on electromagnetic wave absorption. However, as a non-magnetic material with only dielectric loss, MXene exists obvious impedance mismatch, which greatly limits its practical applications. Combining MXene with magnetic materials becomes a hotspot for exploration of ideal microwave absorption materials. As a typical ferrite, Fe₃O₄ shows excellent soft magnetic properties such as high saturation magnetization, high chemical stability, simple preparation, and so on. In this paper, the 2D Fe₃O₄@Ti₃C₂T_x composite was successfully prepared by hydrothermal method and simple electrostatic adsorption process. Fe₃O₄ nanoparticles were uniformly anchored on the surface of large-sized monolayer Ti₃C₂T_x, which effectively reduced the stacking of MXene. By regulating the proportion of magnetic materials, the microwave absorption performance of 2D Fe₃O₄@Ti₃C₂T_x composite was investigated. With increasing the content of Fe₃O₄ nanoparticles in the 2D Fe₃O₄@Ti₃C₂T_x composite from 4 mg to 8 mg, the microwave absorption performance was enhanced obviously. This is caused by the abundant Fe₃O₄/Ti₃C₂T_x interfaces, scattering channels, point defect, charge density difference in 2D Fe₃O₄@Ti₃C₂T_x composite, and the optimized impedance matching. The minimum reflection loss (RL_min) of 2D Fe₃O₄@Ti₃C₂T_x composite reached -69.31 dB with the frequency of 16.19 GHz, and the effective absorption band (EAB) achieved 3.39 GHz. With further increasing the content of Fe₃O₄ nanoparticles to 10 mg, the microwave absorption performance showed a decreasing trend. Excessive Fe₃O₄ nanoparticles in the 2D Fe₃O₄@Ti₃C₂T_x composite induced the over decreasing of conductivity and thus the impedance dis-matching and decreasing of dielectric loss, which lead to the decrease of microwave absorption performance. Radar scattering cross section (RCS) is a physical quantity that evaluates the intensity of the scattered echo energy in the intercepted electromagnetic wave energy. The results of the RCS simulation can be applied to real objects which have been widely applied in radar wave stealth. Its multi-angle simulation results can be used as an important basis for evaluating the stealth capability of microwave-absorbing materials. The RCS simulations show that the average RCS value of 2D Fe₃O₄@Ti₃C₂T_x composite was over -47.92 dB m² at the incidence angle of 25°, demonstrating its excellent radar wave absorption performance. This study provides new ideas for the improvement and practical application of two-dimensional and magnetic materials in the microwave absorption field and provides a new path for the subsequent development of microwave-absorbing composites.