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Ultralight, scalable, and high-temperature–resilient ceramic nanofiber sponges

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Science Advances  02 Jun 2017:
Vol. 3, no. 6, e1603170
DOI: 10.1126/sciadv.1603170
  • Fig. 1 Synthesis and structural characterization of TiO2 nanofiber sponge.

    (A) Schematic of a solution blow-spinning. (B) Photograph of a macro-sized Ti(OBu)4/PVP precursor sponge. (C) Ultralight TiO2 sponge standing on a setaria viridis. (D) Sponge heated by an alcohol lamp without damage, indicicating good heat resistance. (E) SEM image of millimeter-sized TiO2 sponge. (F) Zoomed-in section of TiO2 sponge. The image shows the cellular fibrous structure and the uniform distribution of nanofibers. (G) Transmission electron microscopy (TEM) image of a TiO2 nanofiber.

  • Fig. 2 Compressive test results of TiO2 nanofiber sponge with a density of ~35 mg/cm3 at room temperature.

    (A) Compression and recovery processes of macroscopic TiO2 sponge. (B) SEM image of TiO2 sponge pressed by a nanoindenter. (C) In situ SEM images of compressive process of TiO2 sponge. (D and E) Cyclic compressive stress-strain curves of TiO2 sponge under 10 to 50% strain. Each test was repeated for three cycles, and the inset shows the magnification of initial part of curves in (E). (F) Cyclic compressive stress-strain curves of TiO2 sponge under 23% strain for 100 cycles. (G) Energy loss coefficient of sponge compressed for three cycles by 10 to 50% strain in (D) and (E). (H) Variation of energy loss coefficient and maximum stress with cycle number of TiO2 sponge in (F). (I) Schematic of energy dissipation mechanisms. (J) Zoomed-in SEM images during the compression process, showing the bending and springback of a hank of nanofibers and the friction of neighboring nanofibers, and the fourth picture shows their breakage after some cycles.

  • Fig. 3 Compressive test results of nanofiber sponge at high temperatures.

    (A) Compression and recovery processes of macroscopic TiO2 sponge in the flame of an alcohol lamp. (B) SEM image of TiO2 sponge pressed by a nanoindenter on the loading stage with a MEMS heating system. (C) In situ SEM images of compressive process of TiO2 sponge at 400°C. The insets show the bending and springback of single nanofiber remarked in (C). (D) Stress-strain curves of TiO2 sponge with a density of ~40 mg/cm3 at 400°C for 10 cycles. (E) Variation of energy loss coefficient and maximum stress with cycle number of TiO2 sponge in (D). (F) YSZ sponge heated by a methane flame. (G) Stress-strain curves of YSZ sponge at 800°C for 10 cycles.

  • Fig. 4 Multifunctionality of ceramic nanofiber sponges.

    (A and B) Normalized electrical resistance change of TiO2 sponges repeatedly compressed by 50% strain at room temperature and by 30% strain at 400°C for 10 cycles. (C) TiO2 sponge dyed by rhodamine B and faded after illumination for 15 min. The photocatalysis process was repeated for many cycles. (D) High-temperature insulation capacity of ZrO2 sponge. The ZrO2 sponge effectively protects the fresh petal from withering, whereas petals on other materials were already carbonized on the 400°C heating stage after 10 min. (E) Infrared image of ZrO2 sponge on a 400°C heating stage for 1 hour.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/6/e1603170/DC1

    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.

    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.

    movie S1. Room temperature compression and recovery of TiO2, ZrO2, and BaTiO3 nanofiber sponges.

    movie S2. In situ SEM compressive testing of a TiO2 nanofiber sponge.

    movie S3. Compressive testing of macroscopic TiO2 nanofiber sponge for 100 cycles.

    movie S4. Compression of TiO2, ZrO2, and BaTiO3 nanofiber sponges in an alcohol flame.

    movie S5. In situ SEM compressive of a TiO2 nanofiber sponge at 400°C.

    movie S6. Compression and recovery of YSZ nanofiber sponge in a high-temperature methane flame.

    movie S7. YSZ nanofiber sponge maintaining elasticity after cyclic compression in the methane flame.

    References (3546)

  • Supplementary Materials

    This PDF file includes:

    • 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.
    • 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)

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    Other Supplementary Material for this manuscript includes the following:

    • 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.

    Download Movies S1 to S7

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