Nanocellulose-MXene Biomimetic Aerogels with Orientation-Tunable Electromagnetic Interference Shielding Performance

Area of Science:

• Materials Science
• Nanotechnology
• Electromagnetism

Background:

• Designing lightweight, high-performance electromagnetic interference (EMI) shielding materials is a significant challenge.
• Aerogels offer low density but often lack mechanical robustness and high conductivity for effective EMI shielding.
• Cellulose nanofibrils (CNFs) and transition metal carbides/nitrides (MXenes) are promising nanomaterials for advanced applications.

Purpose of the Study:

• To develop ultralow-density, robust, and flexible MXene/CNF aerogels for high-performance EMI shielding.
• To investigate the influence of microstructure, specifically the orientation of cell walls, on EMI shielding effectiveness.
• To achieve superior EMI shielding performance exceeding existing materials.

Main Methods:

• Fabrication of ultrathin CNF-assisted MXene aerogels with oriented biomimetic cell walls.
• Characterization of the aerogels' microstructure, mechanical properties, and electrical conductivity.
• Measurement of EMI shielding effectiveness (SE) at different aerogel densities and orientations.

Main Results:

• The developed MXene/CNF aerogels exhibit ultralow densities (1.5-8.0 mg cm⁻³), high mechanical strength, and electrical conductivity.
• An ultrahigh EMI shielding effectiveness (SE) of up to 74.6 dB was achieved at 8.0 mg cm⁻³.
• The normalized surface specific SE reached 189,400 dB cm² g⁻¹, significantly outperforming current EMI shielding materials.
• A strong correlation was found between cell wall orientation and EMI shielding performance.

Conclusions:

• The nacre-like structure of MXene/CNF aerogels, with CNF acting as a binder, enhances mechanical strength, conductivity, and interfacial polarization for superior EMI shielding.
• The oriented cell wall design presents a novel strategy for optimizing EMI shielding performance.
• These aerogels represent a breakthrough in lightweight, high-performance EMI shielding materials.