Constructing TCNFs/MXene/TiO₂ microspheres with wrinkled surface for excellent electromagnetic wave absorption

Constructing a wrinkled surface can increase the external surface area and provide a multi-directional reflective surface, so as to increase the interface polarization sites and produce multiple reflection scattering. It is considered to be one of the feasible means to improve the microwave absorption performance of materials. In this paper, the TPNFs/MXene composite microspheres with 3D wrinkled structure have been obtained by combining the two elementary materials of 1D TPNFs and 2D MXene nanosheets with the help of ultrasonic spray drying self-assembly technology. After calcination at high temperature, TPNFs/MXene microspheres are transformed into TCNFs/MXene/TiO₂ composite microspheres. TCNFs/MXene/TiO₂ composite microspheres also have a wrinkled surface, providing interfacial polarization sites and reflective surfaces. TCNFs are interspersed in the MXene nanosheets to play the role of structural reinforcement and charge conduction. TiO₂ nanoparticles are uniformly distributed on the surface of MXene, forming multiple heterogeneous interfaces with TCNFs and MXene. Under the synergistic effect of composition and structure, TCNFs/MXene/TiO₂ composite microspheres exhibit excellent microwave absorption performance. At the matching thickness of 3.5 mm, the minimum reflection loss is − 57.01 dB @ 7.2 GHz with an effective bandwidth of 2.5 GHz, covering the low-frequency region of 6.1–8.6 GHz. Adjusting the thickness to 1.8 mm, the effective bandwidth reaches the maximum of 4.7 GHz (13.3–18 GHz). This research provides an effective way for the assembly of low-dimensional nanomaterials to prepare 3D microwave absorbers with wrinkled surface.