Abstract:

Heterostructure design serves as a critical approach for synergistically enhancing the performance of electromagnetic wave absorption (EMWA) materials. Nevertheless, creating composite materials, derived from covalent/metal-organic frameworks (COFs/MOFs) that possess both excellent absorption intensity and broadband response remains a substantial challenge. In this work, the Fe₃C/NC/TiO₂ composites were successfully prepared via a solvothermal route coupled with subsequent high-temperature carbonization. Built-in electric field within the heterostructure enables synergy of multiple loss mechanisms. The EMWA performance of the samples initially ascended and subsequently declined with variations in composition. In particular, the sample achieved a minimum reflection loss value of −55.79 dB at a matching thickness of 2.57 mm, with an effective absorption bandwidth value of 5.44 GHz (10.40–15.84 GHz). The outstanding performance can be ascribed to the synergistic effects of multiple loss mechanisms, including interfacial polarization, magnetic loss, and dielectric loss, which jointly enhance the impedance matching characteristics and dissipation properties. Density functional theory indicates that both materials are intrinsically conductive. Upon forming a heterostructure, charge density difference analysis reveals charge transfer, suggesting that the built-in electric field between them facilitates electron transport. This study outlines a synthetic strategy centered on MOFs/COFs derivatives, providing valuable avenue for the designing of high-performance EMWA materials with remarkable absorption and broadband coverage.

Key words: Metal organic frameworks, Covalent organic frameworks, Electromagnetic wave absorption, Broadband, Density functional theory