Balancing MoS₂ Growth and MXene In Situ Oxidation to Construct Dual Schottky Contacts for Enhanced Dielectric Loss and Broadband Electromagnetic Wave Absorption

The emerging 2D material MXene is regarded as a promising electromagnetic wave absorbing (EMWA) material. By compounding MXene with other dielectric materials and constructing heterointerfaces, its inherently poor impedance matching can be ameliorated. However, the poor oxidative stability of MXene makes it challenging to precisely control its oxidation during thermal treatment, which is crucial for composite and interfacial engineering strategies. In this work, we proposed a balancing strategy to control the in situ oxidation of MXene and the growth of MoS₂ nanosheets during a hydrothermal synthesis. Through ex situ monitoring of the composite structure, it was observed that moderate oxidation of MXene at a suitable temperature enhanced the dielectric properties while preserving its 2D morphology. Based on this, we designed a MoS₂/MXene/TiO₂ composite system with dual Schottky contacts and optimized the proportion of each component. The nanohybrid achieves an efficient minimum reflection loss (RL_min) of −48.44 dB at a low thickness of 2.0 mm, and a broadened effective absorption bandwidth (EAB) of 6.8 GHz. Remarkably, the distinctive dual Schottky contacts contribute to enhanced polarization relaxation, optimal electron migration, and appropriate impedance matching. This study provides profound insight into the MXene-based 2D composites and the development of high-performance dielectric EMWA materials.