A Two-Step Route to SiO₂ Nanofiber-Reinforced Aerogel Composites with Lightweight and High Temperature Resistance for Thermal Insulation

Fiber reinforcement is an effective method to improve the inherent brittleness of conventional aerogels. However, high-density and complex preparation processes plague fiber-reinforced aerogel composites (FACs). For example, they are usually prepared using costly supercritical drying, freeze-drying, and time-consuming atmospheric drying, limiting the further development in applications and technologies of the material. Herein, a straightforward route to FACs is proposed. Namely, electrostatically spun nanofibers are used as reinforcement materials for aerogels. The nanofiber composite silica gel precursors are produced using chemical swelling and sol–gel techniques. Direct calcination is then used to prepare FACs with distinct nanoporous structures. As a result, FACs have a thermal conductivity as low as 0.029 W m –1 K –1 at room temperature, a high porosity of up to 99.55%, and excellent temperature resistance, maintaining a stable porous structure even at 1400 °C. Therefore, FACs have greater potential for thermal insulation applications. The route described in this study will contribute to the opening of a pathway for the simple preparation of FACs with ultralow density and high temperature resistance, thereby promoting the application and development of nanofiber-reinforced aerogel materials.