Supplementary Materials for

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1 advances.sciencemag.org/cgi/content/full/3/6/e /dc1 Supplementary Materials for Ultralight, scalable, and high-temperature resilient ceramic nanofiber sponges Haolun Wang, Xuan Zhang, Ning Wang, Yan Li, Xue Feng, Ya Huang, Chunsong Zhao, Zhenglian Liu, Minghao Fang, Gang Ou, Huajian Gao, Xiaoyan Li, Hui Wu The PDF file includes: Published 2 June 2017, Sci. Adv. 3, e (2017) DOI: /sciadv fig. S1. Photograph of the experimental setup. fig. S2. Diameter of TiO2 fibers at different concentrations of PVP. fig. S3. Structural characterization of ZrO2 nanofiber sponge. fig. S4. Structural characterization of YSZ nanofiber sponge. fig. S5. Structural characterization of BaTiO3 nanofiber sponge. fig. S6. Room temperature compression and recovery of different ceramic nanofiber sponges. fig. S7. An Ashby plot of compressive modulus versus relative density to compare the present ceramic sponge with different foams and aerogels. fig. S8. In situ SEM cyclic compression of TiO2 nanofiber sponge. fig. S9. Compressive testing of TiO2 nanofiber sponge. fig. S10. Compression and recovery of ceramic nanofiber sponges heated with the flame of an alcohol lamp. fig. S11. Temperature distribution in the methane flame used in this work. fig. S12. Compressive stress-strain curves of YSZ nanofiber sponge at 400 and 600 C. fig. S13. XRD data of TiO2 calcined at 450 and 650 C. fig. S14. TEM images of TiO2 nanofibers after calcining at 650 C. fig. S15. Cyclic compressive stress-strain curves for 10 cycles of a TiO2 nanofiber sponge calcined at 650 C. fig. S16. Hydroscopicity of TiO2 nanofiber sponge. fig. S17. A TiO2 nanofiber sponge, which absorbed methylene blue solution was compressed and then recovered after being released.

2 fig. S18. Temperature raising on the top surface of a ZrO2 nanofiber sponge and other materials on a 400 C heating stage. table S1. The densities and thermal conductivities of ZrO2 nanofiber sponge and other thermal insulation materials. References (35 46) Other Supplementary Material for this manuscript includes the following: (available at advances.sciencemag.org/cgi/content/full/3/6/e /dc1) movie S1 (.mp4 format). Room temperature compression and recovery of TiO2, ZrO2, and BaTiO3 nanofiber sponges. movie S2 (.mp4 format). In situ SEM compressive testing of a TiO2 nanofiber sponge. movie S3 (.mp4 format). Compressive testing of macroscopic TiO2 nanofiber sponge for 100 cycles. movie S4 (.mp4 format). Compression of TiO2, ZrO2, and BaTiO3 nanofiber sponges in an alcohol flame. movie S5 (.mp4 format). In situ SEM compressive of a TiO2 nanofiber sponge at 400 C. movie S6 (.mp4 format). Compression and recovery of YSZ nanofiber sponge in a high-temperature methane flame. movie S7 (.mp4 format). YSZ nanofiber sponge maintaining elasticity after cyclic compression in the methane flame.

3 fig. S1. Photograph of the experimental setup. The process of blow-spinning to fabricate nanofiber. fig. S2. Diameter of TiO2 fibers at different concentrations of PVP. Solution: Ti(OBu)4:PVP=2:1 (mass ratio), Spinning parameters: 10 psi gas pressure, 15 cm collecting distance, and 3 ml/h solution injection rate. Annealing condition: heating speed of 2 C/min to 450 C and kept for 200 min.

4 fig. S3. Structural characterization of ZrO2 nanofiber sponge. (A) XRD data of ZrO2 nanofibers. (B) SEM image of ZrO2 nanofibers. (C) TEM image of ZrO2 nanofiber. fig. S4. Structural characterization of YSZ nanofiber sponge. (A) XRD data of YSZ nanofibers. (B) SEM image of YSZ nanofibers. (C) TEM image of a YSZ nanofiber. fig. S5. Structural characterization of BaTiO3 nanofiber sponge. (A) XRD data of BaTiO3 nanofibers. (B) SEM image of BaTiO3 nanofibers. (C) TEM image of BaTiO3 nanofiber.

5 fig. S6. Room temperature compression and recovery of different ceramic nanofiber sponges. (A) ZrO2 nanofiber sponge. (B) BaTiO3 nanofiber sponge. fig. S7. An Ashby plot of compressive modulus versus relative density to compare the present ceramic sponge with different foams and aerogels.

6 fig. S8. In situ SEM cyclic compression of TiO2 nanofiber sponge. (A to C) SEM images of TiO2 nanofiber sponge recovered after compression to 23% strain for 20, 50, and 100 times, respectively. fig. S9. Compressive testing of TiO2 nanofiber sponge. (A) the compression and recovery process of a TiO2 nanofiber sponge (B) Cyclic compressive stress-strain curves of TiO2 nanofiber sponge of 8 mg/cm 3 under 50% strain for 100 cycles.

7 fig. S10. Compression and recovery of ceramic nanofiber sponges heated with the flame of an alcohol lamp. (A) ZrO2 nanofiber sponge. (B) BaTiO3 nanofiber sponge. fig. S11. Temperature distribution in the methane flame used in this work.

8 fig. S12. Compressive stress-strain curves of YSZ nanofiber sponge at 400 and 600 C. fig. S13. XRD data of TiO2 calcined at 450 and 650 C.

9 fig. S14. TEM images of TiO2 nanofibers after calcining at 650 C. A TiO2 nanofiber consisting of large grain nanofibers in a sponge calcined at 650 C for 200 min. fig. S15. Cyclic compressive stress-strain curves for 10 cycles of a TiO2 nanofiber sponge calcined at 650 C.

10 fig. S16. Hydroscopicity of TiO2 nanofiber sponge. fig. S17. A TiO2 nanofiber sponge, which absorbed methylene blue solution was compressed and then recovered after being released. fig. S18. Temperature raising on the top surface of a ZrO2 nanofiber sponge and other materials on a 400 C heating stage. All materials have been engineered with same geometric dimensions.

11 table S1. The densities and thermal conductivities of ZrO2 nanofiber sponge and other thermal insulation materials. Materials Density (mg/cm 3 ) Thermal conductivity Thermal stability Room-temp erature High-temperatur e resilience (mw/m K) resilience ZrO 2 sponge [our results] Cotton [4] Glass foams [4] Polymer foams [4] Carbon aerogels [4] Ceramic foams [4] Cellular aerogels [24] Silica aerogels [40] Silica hybrid aerogels [41] Carbon monoliths [42] Aerogel-PVB [43] ZrO 2 SiO 2 aerogel [44] Fibrous ceramic [45] ZrO 2 aerogel [46]