Phase Interface Engineering Using Defective 1T/2H-MoSe₂ for Electromagnetic Wave Absorption

In recent years, molybdenum diselenide (MoSe2) nanomaterials have been proven to be promising electromagnetic wave (EMW) absorbers, attributed to the formation of a heterogeneous interface between the 2H semiconductor phase and the 1T metal phase during its preparation. However, the difficulty in precisely controlling the two-phase ratio and the complexity of the process hinder its further development. In this work, we constructed a simple phase engineering strategy based on the regulation of reducing agent concentration, achieving a regulation of the 1T phase proportion in defective 1T/2H-MoSe2 nanomaterials (ranging from 67.91 to 41.45%) by accurately adjusting the amount of NaBH4 added. The findings indicate that the material exhibits excellent microwave absorption performance when the 1T phase proportion reaches 53.55% (1T/2H-MoSe2-2), demonstrating a minimum reflection loss (RLmin) of −40.0 dB, and the effective absorption bandwidth (EAB) covers 6.08 GHz (11.92–18.0 GHz) when the thickness is 2.6 mm. The enhancement in performance results from a synergistic balance mechanism established by the abundant 1T-2H heterogeneous interface, which induces interfacial polarization loss, along with a moderately enhanced conductive loss in the 1T/2H-MoSe2-2 nanomaterial. Furthermore, radar cross-section (RCS) simulation results confirm the dramatic dissipation ability of absorbers for EMW in practical applications. This strategy paves the way for designs of interfaces and the control of the performance of absorbing nanomaterials based on transition-metal dichalcogenides (TMDs).