Synergistic effects for improving electromagnetic wave absorption in high-entropy MXene heterostructures

Two-dimensional (2D) MXenes possess advantages for electromagnetic wave absorption owing to high electrical conductivity, abundant surface functional groups, and defects, but their excessive conductivity often causes impedance mismatch. High-entropy (HE) engineering can reduce the conductivity of MXenes and thereby improve impedance matching, while the conductivity loss will also decrease. Here, NiCo2S4 (NCS) with relatively high electrical conductivity was coupled with HE MXene (Ti1/4V1/4Cr1/4Mo1/4)3C2Tx (HEM) to balance dielectric attenuation and impedance matching. The NCS/HEM achieves an optimal minimum reflection loss of −57.2 dB (thickness of 1.31 mm) and an optimal effective absorption bandwidth of 4.2 GHz (13.6–17.8 GHz, thickness of 1.4 mm). The enhanced electromagnetic wave absorption performance originates from the synergistic effects of optimized impedance matching, improved dielectric attenuation, and facilitated multiple reflections and scattering from heterostructures. This work provides a feasible strategy for designing high-performance MXene-based absorbers through synergistic effects by constructing heterostructures.