Fig. 1. Schematic illustration of fabricating procedure of multi-functional FGSA samples. (a) Illustration of the synthesis route of FGSA. (b, c) SEM images and schematic diagram of the network transformation from SA to FGSA samples. (d-g) Basic physical performance of FGSA-2.0, showing lightweight (～0.135 g/cm3), wide-temperature mechanical reliability, super-hydrophobicity (WCA of ～153°), flame resistance (structure integrity after 30 s flame attack), and excellent thermal insulation (top 35 °C on the hot stage of 100 °C for the sample with 20 mm thickness after 30 min).

Fig. 2. Structural characterizations and analysis. Photographs of preparation process of (a) GSA and (b) FGSA-2.0 sample via a facile sol-gel method, showing different structure integrity. (c) Silane-functionalized FGO sheets: (i) Schematic illustration of different reaction mechanisms of GO sheets with APTES molecules and (ii) FTIR spectra results. (d) Optical microscopy images of FGO/silane mixture, demonstrating good dispersion of FGO. (e) FTIR results and (f, g) high-resolution XPS spectra of silicone aerogel without and with incorporation of FGO sheets.

Fig. 3. Mechanical properties of FGSA samples. Compressive stress-strain curves of (a) pure SA and (b) FGSA-2.0 at different compressive strain values of 10%, 30%, 50%, 70%. (c) Compressive strain-stress curves and (d) cyclic compressive performance of FGSA-2.0 sample at different compressive rates. (e) Comparison of cyclic compressive performance of various silicone aerogels under 200 °C, and (f) compression cyclic performance of FGSA-2.0 sample at different temperature conditions. (g) Schematic diagram of compression recovery process of FGSA-2.0 sample during the cyclic loading-unloading process.

Fig. 4. Thermal stability and flame-retardant properties of various aerogel samples. (a) TGA and (b) DTG curves of FGSA with different FGO content in N2 atmosphere, demonstrating improved thermal stability. Comparison of typical combustion processes of (c) SA, (d) FGSA-1.0, (e) FGSA-2.0 samples, demonstrating improved flame resistance after APTES functionalization.

Fig. 5. Flame-retardant mechanism analysis. (a) FTIR spectra of the FGSA samples before and after different temperature treatments. (b) XPS survey spectrum of pure SA, FGSA and burned FGSA samples. (c) High-resolution XPS spectrum of Si2p of FGSA-2.0 sample after burning. SEM images of (d) pure SA and (e) FGSA-2.0 samples after burning, showing different silica protective layer due to the presence of FGO sheets.

Fig. 6. Thermal insulating performance of FGSA sample and other commercial polymer foam materials. Digital and infrared thermography images of (a) PE foam and PU foam, (b) pure SA and (c) FGSA-2.0 samples (The heater temperature is ～200 °C for 90 s, thickness of samples is ～10 mm).

Fig. 7. Flame attack test and the corresponding thermal insulating images. Optical and infrared images of (a) pure SA, (b) FGSA-1.0 and (c) FGSA-2.0 samples after being exposed in the blowtorch flame for 5 s (The flame temperature is ～1300 °C).

Fig. 8. Wetting properties and oil/water separation of FSGA samples. (a) Photos of water and oil droplets on the surface of FGSA-2.0 and (b) the sample upon immersion in water. (c) Water contact angles of pure SA and FGSA-2.0 samples. (d) Images of n-hexane/water separation stability of the FGSA-2.0 sample; (e) Absorption capacities of FGSA-2.0 for various organic solvents and oils. (f) Comparison of n-hexane absorption stability performance for pure SA and FGSA-2.0 samples.