Abstract: Multicomponent core-shell microspheres have garnered significant attention as microwave absorption (MA) materials, owing to their distinctive synergistic effects arising from interfacial polarization and magnetic/dielectric loss. An effective method for optimizing the MA properties of materials is to construct heterogeneous interfacial engineering through component tuning and structural design. Here, a hollow flower-like CoNi@NC@SnS₂ composite was successfully synthesized through high-temperature pyrolysis and vertical growth of SnS₂. The surface of the CoNi@NC microsphere was uniformly coated with SnS₂ nanosheets, resulting in the formation of a core-shell structure. The construction of Schottky barriers through the contact between semiconductors and conductors optimizes polarization relaxation processes and enhances impedance-matching properties. The Schottky interfaces generate a built-in electric field (BIEF) that enhances charge separation and inversion of charge distribution, thereby improving interfacial polarization. Additionally, the Schottky heterogeneous interfaces of composites can be activated through the controllable introduction of defects, resulting in a more robust interfacial polarization. Consequently, the core-shell CoNi@NC@SnS₂ composite demonstrates outstanding MA performance, achieving a minimum reflection loss (RL_min) of -72.6 dB at 1.9 mm and an effective absorption bandwidth (EAB) of 13.2 GHz (ranging from 4.8 to 18.0 GHz) across a thickness range of 1.5-4.0 mm. This research offers novel insights into the mechanisms that underlie polarization loss and facilitates the development of high-performance MA materials.

Key words: Mott-Schottky barrier, Heterointerface engineering, Microwave absorption, Defect engineering