Lei Dai

Ambient pressure drying is a promising route to scale up MXene aerogels, but it is limited by severe capillary collapse during solvent evaporation. Here, robust ambient‐pressure‐dried MXene aerogels are fabricated via multiscale structural engineering. At the molecular scale, ethanol acts as both a low‐surface‐tension solvent and a poor solvent inducing MXene phase separation, revealing its role in stabilizing wet gels beyond reducing surface tension. This process increases the contact between oxygen‐containing groups on MXene and hydroxyl groups of TEMPO‐oxidized cellulose nanofiber (TOCNF), leading to a dense hydrogen‐bonding network. More importantly, the phase separation degree serves as a microstructural descriptor linking ethanol‐induced structural evolution to mechanical reinforcement, providing a basis for optimizing capillary‐resistant aerogels. Macroscopically, polydopamine‐modified loofah acts as a reinforcing framework to form a reinforced concrete‐like architecture with the MXene/TOCNF matrix. The molecular hydrogen bonding network and the macroscopic skeleton jointly preserve an intact porous structure after drying. The resulting aerogel exhibits a Young's modulus of 0.57 MPa, an electromagnetic shielding effectiveness of 74.6 dB, excellent infrared stealth performance, and a rapid Joule heating response. This work clarifies the hidden role of ethanol in ambient pressure drying and establishes a microstructure‐guided design principle for robust multifunctional MXene aerogels.