Hydrophobic, Flexible, and Lightweight MXene Foams for High‐Performance Electromagnetic‐Interference Shielding

TLDR

Ultrathin, lightweight, flexible EMI shielding materials are urgently needed; MXenes offer excellent conductivity but their hydrophilicity limits stability in moist environments. The study reports a facile method to fabricate freestanding, flexible, hydrophobic MXene foam by assembling sheets into films and inducing foaming with hydrazine. The authors assemble MXene sheets into films and trigger foaming with hydrazine to create a lightweight, flexible foam. The resulting foam is hydrophobic, water‑resistant, and durable, and achieves ≈70 dB EMI shielding—about 17 dB higher than the unfoamed film—making it promising for aerospace and wearable electronics.

Abstract

Ultrathin, lightweight, and flexible electromagnetic‐interference (EMI) shielding materials are urgently required to manage increasingly serious radiation pollution. 2D transition‐metal carbides (MXenes) are considered promising alternatives to graphene for providing excellent EMI‐shielding performance due to their outstanding metallic electrical conductivity. However, the hydrophilicity of MXene films may affect their stability and reliability when applied in moist or wet environments. Herein, for the first time, an efficient and facile approach is reported to fabricate freestanding, flexible, and hydrophobic MXene foam with reasonable strength by assembling MXene sheets into films followed by a hydrazine‐induced foaming process. In striking contrast to well‐known hydrophilic MXene materials, the MXene foams surprisingly exhibit hydrophobic surfaces and outstanding water resistance and durability. More interestingly, a much enhanced EMI‐shielding effectiveness of ≈70 dB is achieved for the lightweight MXene foam as compared to its unfoamed film counterpart (53 dB) due to the highly efficient wave attenuation in the favorable porous structure. Therefore, the hydrophobic, flexible, and lightweight MXene foam with an excellent EMI‐shielding performance is highly promising for applications in aerospace and portable and wearable smart electronics.