Rapid foaming of dense MXene films induced by acid-base neutralization reaction

Transforming dense MXene (Ti₃C₂T_x) films into lightweight 3D porous frameworks is crucial for practical applications of 2D MXene materials. However, traditional foaming technologies may compromise the intrinsic properties of MXene films, such as foldability, which is essential for future applications. Here, we report an approach using a common acid-base neutralization reaction to rapidly foam MXene films. The acid solution triggers the generation of porous structures in alkalized MXene films, resulting in a 3D porous MXene film with good foldability, excellent absolute shielding efficiency (25,445 dB cm² g⁻¹), electrochemical capacitance, and infrared stealth properties. Furthermore, the acid-base neutralization reaction strategy can be applied to foam other 2D material films, such as graphene oxide, broadening the potential for developing innovative foaming modes of 2D materials. This work enhances our understanding of MXene film foaming and lays the foundation for further applications of MXenes.