Dual template strategy to prepare ultralight and high-temperature resistant ceramic nanorod aerogels for efficient thermal insulation

Abstract

Ceramic aerogels are considered as promising thermal insulation materials used in extreme environments. However, the combination of ultralight, high heat tolerance and ultra-low high-temperature thermal conductivity is still a great challenge for both brittle granular aerogels and micron-porous fibrous aerogels. Here, a dual-template strategy is proposed for the simple fabrication of high-performance nanoporous ceramic aerogels (SARAs) by adopting one-dimensional high-crystallinity and high-aspect-ratio Al2O3 nanorods as the basic unit. After delicate design of the composition and pore structures, SARAs exhibit excellent comprehensive properties including ultra-low density (8.12–28.43 mg cm−3), low room temperature thermal conductivity (down to 0.0246 W m−1 K−1) and extremely high temperature resistance (up to 1400 °C). In addition, the unique nanoporous structure lapped by nanorods also confer SARAs superior high-temperatures thermal insulation performance (0.0949 W m−1 K−1 at 1000 °C). The successful preparation of nanorod aerogels with fascinating properties not only provides a new vision on the pore structure regulation of aerogels for thermal insulation, but also offers an opportunity to develop new ultralight functional ceramic aerogels.