Tailoring Built‐In Electric Field in a Self‐Assembled Zeolitic Imidazolate Framework/MXene Nanocomposites for Microwave Absorption

Heterointerface engineering, which plays a pivotal role in developing advanced microwave‐absorbing materials, is employed to design zeolitic imidazolate framework (ZIF)–MXene nanocomposites. The ZIF–MXene composites are prepared by electrostatic self‐assembly of negatively charged titanium carbide MXene flakes and positively charged Co‐containing ZIF nanomaterials. This approach effectively creates abundant Mott–Schottky heterointerfaces exhibiting a robust built‐in electric field (BIEF) effect, as evidenced by experimental and theoretical analyses, leading to a notable attenuation of electromagnetic energy. Systematic manipulation of the BIEF‐exhibiting heterointerface, achieved through topological modulation of the ZIF, proficiently alters charge separation, facilitates electron migration, and ultimately enhances polarization relaxation loss, resulting in exceptional electromagnetic wave absorption performance (reflection loss RLmin = −47.35 dB and effective absorption bandwidth fE = 6.32 GHz). The present study demonstrates an innovative model system for elucidating the interfacial polarization mechanisms and pioneers a novel approach to developing functional materials with electromagnetic characteristics through spatial charge engineering.