Enhancing microwave absorbing properties of C/TiO2/NiNW composites through built-in electric field effect

Microwave-absorbing materials (MAMs) play an important role in reducing electromagnetic pollution. However, achieving a balance between low filler loading, low minimum reflection loss (RL min ) and wide effective absorption bandwidth (EAB) for efficient absorption of microwaves remains challenging. In this work, an innovative method of using CO 2 atmosphere annealed Ti 3 C 2 T x MXene (C/TiO 2 ) combined with nickel nanowires (NiNW) via ultrasonic treatment was performed to yield C/TiO 2 /NiNW (CTN) composites with abundant NiNW/TiO 2 contacts. The electromagnetic (EM) parameters of the as-synthesized composites were closely studied through a series of experiments and computed theoretical calculations. Through the establishment of built-in electric fields (BIEFs) at the NiNW/TiO 2 interface, the derived CTN composite demonstrated improved dielectric properties and impedance matching characteristics that are clearly reflected on the microwave absorption performance of our as-synthesized MAMs, with RL min improving by 127.9% from −31.93 dB to −72.77 dB, and widest EAB increasing by 25.9% from 4.25 GHz to 5.35 GHz, at a low filler loading of 10 wt.%. This work investigates the mechanisms by which BIEFs influence EM parameters, providing critical insights into improving microwave absorption performance via BIEF structural design.