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

Microwave absorption materials can effectively eliminate harmful electromagnetic radiation to protect hu-manity, 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 mor-phologies 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.

Automated summary

In this study, MoO3-x@MWCNT with tunable morphologies were prepared by a facile one-step hydrothermal route. The microwave absorption properties and multifunctionality of the materials were systematically investigated. By changing the hybrid ratios of MoO3-x and defective MWCNT, absorbers with quad-band and tri-band absorption characteristics were achieved, along with significant effective absorption bandwidth. The synthesized absorbing coating also exhibited remarkable fire-retardancy, photothermal de-icing, and antibacterial performance.