Endowing
composites with defects such as oxygen vacancies is an
easy and effective strategy to determine the physical and chemical
properties of nanomaterials. The influence of defects on microwave
absorption remains a very open question. Herein, MnO2/Ti3C2T
x
MXene composites
are self-assembled, demonstrating the boosting of microwave absorption
through Ni doping in MnO2 to modulate the oxygen vacancies.
The Ni-doped MnO2 (Ni–MnO2) nanorods
with diameters of about 40 nm are dispersed on the surface and interlay
of MXene. As expected, the reflection loss (RL) value and effective
absorption bandwidth (EAB) of Ni–MnO2/MXene composites
are −55.9 dB and 6.32 GHz, which are greatly enhanced over
pure MnO2/MXene with −18.8 dB and 4.56 GHz. This
excellent microwave absorption is mainly attributed to the optimized
impedance matching in Ni–MnO2/MXene composites.
In addition, the random distribution of MnO2 nanorods and
MXene layers will form a conductive network, leading to the inducing
microcurrent to form conduction losses. Moreover, interfacial polarization
between layered MXene and Ni–MnO2 and dipole polarization
induced by oxygen defects yield a strongly dielectric loss. Thus,
our work provides a novel principle of modulation in oxygen vacancies
to develop efficient MXene-based multicomponent composites for electromagnetic
wave absorption.