LaFe-MOFs derivatives with different compositions for boosting low-frequency and broadband electromagnetic wave absorption

Abstract

To achieve low-frequency and broadband electromagnetic wave absorption (EMWA), building excellent metal-organic frameworks (MOFs)-derived EMWA materials is critical but remains challenging. In this research, La₂O₃/La₂O₂CN₂/Fe/N-doped carbon (LFC) composites with different compositions were synthesized by adjusting the La³⁺ content to tune the electromagnetic parameters. As the La³⁺ content increased, the EMWA performance showed a trend of first increasing and then decreasing. As a result, LFC-2 achieved a minimum reflection loss (RL_min) value of −60.82 dB at a thickness of 2.60 mm when the molar ratio of La³⁺ to Fe³⁺ was 1: 1, along with an effective absorption bandwidth value of 5.76 GHz (9.84–15.60 GHz) at 2.29 mm. Moreover, the EMWA performance of LFC-3 at low-frequency (4.08 GHz) was enhanced when the La³⁺ to Fe³⁺ molar ratio was 2: 1, with an RL_min value of −47.47 dB. Comprehensive characterizations suggested that the formation of the La₂O₂CN₂ phase played an indispensable role in optimizing impedance matching and enhancing magnetic loss and dielectric loss. In addition, La³⁺ had a high coordination number, which effectively regulated the electromagnetic parameters. Concurrently, radar cross-section simulation results confirmed the outstanding EMWA capability of the LFC coating. This work proposed a strategy for LaFe-MOFs derivatives, shedding light on the foundation for designing more efficient low-frequency and broadband absorbent materials.