Additive‐Free Aerogel 3D Printing Using Ultra‐Low Storage Modulus Inks

Abstract State‐of‐the‐art aerogels, when crafted through 3D printing, exhibit remarkable properties and innovative functionalities. Yet, printing additive‐free aerogels with excellent intrinsic properties remains a challenge. Here a rheology matching strategy is introduced that effectively resolves this issue. Importantly, this strategy not only mitigates the negative effects of rapidly evolving resorcinol (R)‐formaldehyde (F) sol‐gel rheology, but also prevents the gravitational and capillary slumping. This breakthrough enables the 3D printing of additive‐free RF aerogels using an ink with ultra‐low storage modulus (≈2 Pa, the lowest record for aerogel‐based inks) and a fluid‐like loss factor (tan α >1). These additive‐free prints perfectly retain intrinsic properties of aerogels, showing uniform nanostructure and high specific surface area of up to 836.1 m 2 g −1 , which is significantly superior to conventional prints that incorporate additives. Moreover, the flexibility in 3D design extends the application range for advanced aerogels. Consequently, well‐designed aerogel‐based solar steam generation devices demonstrate competitive evaporation rates of 1.85–2.30 kg m −2 h −1 . This protocol broadens the scope of printable rheology for aerogel 3D printing and enables the fabrication of aerogel objects with intrinsic properties and large‐span overhanging features, which opens up new possibilities for the 3D construction of various aerogels across diverse applications.