High-speed and scalable combustion fabrication of ultralight carbon nanotube aerogels below air density

Abstract

In this study, we introduce a fast, scalable method to fabricate ultralight carbon nanotube (CNT) aerogels with a bulk density (ρ) lower than air, using a combustion process. Typical fabrication methods for ultralight nanocarbon aerogels (ρ ≤ 1.0 mg cm−3) often involve intricate steps, such as high-temperature annealing and thermal reduction. These processes are time-consuming and pose scalability challenges. Here, we propose a high-speed fabrication process for ultralight CNT aerogels by combusting cellulose nanofibers (CNF) as a sacrificial template. The combustion process for CNT/CNF composite aerogels in an open environment takes only a few seconds, and the fabricated CNT aerogels with a lower-than-air density (ρ ≥ 0.48 mg cm−3) have high light absorption and good thermal and mechanical stability. We further illustrate the capability of these ultralight CNT aerogels to achieve levitation upon heating like a hot air balloon. Ultralight CNT aerogels capable of levitation by heating, fabricated by our fast and scalable method, hold the potential to replace traditional motor-driven unmanned aerial vehicles and conventional stratospheric platforms, such as high-altitude balloons, with sunlight-driven materials.