Quad-band microwave absorbers based on MoO3-x@MWCNT with tunable morphologies for multifunctional multiband absorption

Abstract

Microwave absorption materials can effectively eliminate harmful electromagnetic radiation to protect humanity, but it still remains challenging to attain absorbers with quad-band compatible strong absorption to date. Herein, MoO3-x@MWCNT with tunable morphologies was fabricated via a facile one-step hydrothermal route and their microwave absorption properties in different frequency bands were systematically investigated, along with the multifunctional properties. The absorbers with a hollow hexagonal prism and cauliflower-like morphologies can be tailored by changing the hybrid ratios of MoO3-x rich in vacancy defects and defective MWCNT from 5:1 (S1), 6:1 (S2) to 7:1 (S3), contributing to quad-band absorption (S-, C-, X- and Ku-bands) with maximum effective absorption bandwidth of 3.68 GHz for S2 and tri-band absorption (S-, X- and Ku-bands) with maximum effective absorption bandwidth of 4.67 GHz for S3, and optimal reflection loss can reach −62.23 dB when a compound ratio of 30% is satisfied in S3/paraffin. The conspicuous quad-band absorption and reflection loss are manipulated by the synergetic effects of multiple factors including porous structures, numerous defects and heterogeneous interfaces, etc. Additionally, remarkable fire-retardancy, photothermal de-icing and antibacterial performance of synthesized MoO3-x@MWCNT-based absorbing coating are expected to deliver solutions for complex communication and detection in the military and civil fields.