Template-free self-assembly of MXene and CoNi-bimetal MOF into intertwined one-dimensional heterostructure and its microwave absorbing properties

Transition metal carbide (MXene) has attracted much attention due to its special structure and surface chemical properties. However, like other two-dimensional (2D) materials, its application is severely affected by stacking and agglomeration. Herein, we construct intertwined one-dimensional (1D) heterostructure via the assembly of MXene and metal–organic frameworks (MOFs) without any assistance of template and rigid framework. The results have shown that by manipulating the loading of MOFs on 1D MXene fibers, the growth of CNTs can be effectively controlled, thereby realizing the regulation of electromagnetic parameters. The 3D cross-linked network constructed by intertwined 1D heterogeneous components (MXene fibers/CoNi/C and CNTs/CoNi) features extensive heterogeneous interfaces, hierarchical pore structure and desirable conductivity, exhibiting superior microwave absorbing properties. Notably, under a matching thickness of 1.6 mm, the minimum reflection loss (RL_min) of the absorber (MMC) exceeds −51.6 dB, and the effective absorption bandwidth (EAB, RL < −10 dB) covers 4.5 GHz (13.2–17.7 GHz). The results might shed light on the preparation of efficient microwave absorbers.