Constructing holey γ-Fe2O3 nanosheets with enhanced capability for microwave absorption

Iron-based nanostructured materials are desirable for various applications owing to their high magne-tization. Herein, we presented a facile fabrication of free-standing gamma-Fe2O3 nanosheets by a molten salt method for microwave absorption. Furthermore, Al component was incorporated to serve as the tem-plate for hole production. The designed holey gamma-Fe2O3 nanosheets were effective to maximize the usage of nanomaterials, thereby providing larger surface area, richer defects, and more polarization centers. Both experimental measurements and electric field simulation showed an enhanced capability for mi-crowave absorption using holey gamma-Fe2O3 when compared with its intact counterpart. Oxygen vacancy was generated during the hole evolution, which significantly improved the electrical conductivity and thus promoted the conductive loss mechanism. In addition, the holey configuration may extend the transmission path of microwave and confer it with multiple refiection and scattering within the absorbent matrix. Meantime, the polarization loss was strengthened owing to Al modulation associated with the induced defect sites. With the improvement in conductive loss, polarization, impedance matching, and attenuation constant, the as-synthesized holey gamma-Fe2O3 exhibited promising microwave absorbability, with a maximum refiection loss of 52.4 dB and an effective bandwidth of 5.12 GHz at a thickness of 2.2 mm, overperforming most pure Fe-based materials. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The holey gamma-Fe2O3 nanosheets prepared by molten salt method exhibit excellent microwave absorption performance, with improved electrical conductivity and enhanced reflection and scattering effects within the absorbent matrix. The holey structure extends the microwave transmission path and strengthens polarization loss through modulation with alumina.