Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas

Nature volume 446, pages 172–175 (2007)Cite this article

Abstract

The carbothermal reduction of silica into silicon requires the use of temperatures well above the silicon melting point (≥2,000 °C)1. Solid silicon has recently been generated directly from silica at much lower temperatures (≤850 °C) via electrochemical reduction in molten salts2,3. However, the silicon products of such electrochemical reduction did not retain the microscale morphology of the starting silica reactants2,3. Here we demonstrate a low-temperature (650 °C) magnesiothermic reduction process for converting three-dimensional nanostructured silica micro-assemblies into microporous nanocrystalline silicon replicas. The intricate nanostructured silica microshells (frustules) of diatoms (unicellular algae) were converted into co-continuous, nanocrystalline mixtures of silicon and magnesia by reaction with magnesium gas. Selective magnesia dissolution then yielded an interconnected network of silicon nanocrystals that retained the starting three-dimensional frustule morphology. The silicon replicas possessed a high specific surface area (>500 m2 g-1), and contained a significant population of micropores (≤20 Å). The silicon replicas were photoluminescent, and exhibited rapid changes in impedance upon exposure to gaseous nitric oxide (suggesting a possible application in microscale gas sensing). This process enables the syntheses of microporous nanocrystalline silicon micro-assemblies with multifarious three-dimensional shapes inherited from biological4,5,6 or synthetic silica templates7,8,9 for sensor, electronic, optical or biomedical applications10,11,12,13.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it

$39.95

Learn more

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Shape-preserving magnesiothermic reduction of silica diatom frustules.
Figure 2: Phase content of diatom frustules after magnesiothermic reduction.
Figure 3: Fine-scale structure of silicon replicas produced by magnesiothermic reduction of Aulacoseira diatom frustules.
Figure 4: Gas sensor based on a silicon frustule replica.

References

  1. Nagamori, M., Malinsky, I. & Claveau, A. Thermodynamics of the silicon-carbon-oxygen system for the production of silicon carbide and metallic silicon. Metall. Trans. B 17, 503–514 (1986)

    Article  CAS  Google Scholar 

  2. Nohira, T., Yasuda, K. & Ito, Y. Pinpoint and bulk electrochemical reduction of insulating silicon dioxide to silicon. Nature Mater. 2, 397–401 (2003)

    Article  ADS  CAS  Google Scholar 

  3. Yasuda, K., Nohira, T., Takahashi, K., Hagiwara, R. & Ogata, Y. H. Electrolytic reduction of a powder-molded SiO2 pellet in molten CaCl2 and acceleration of reduction by Si addition to the pellet. J. Electrochem. Soc. 152, D232–D237 (2005)

    Article  CAS  Google Scholar 

  4. Round, F. E., Crawford, R. M. & Mann, D. G. The Diatoms: Biology and Morphology of the Genera (Cambridge Univ. Press, New York, 2000)

    Google Scholar 

  5. Aizenberg, J. et al. Skeleton of Euplectella sp.: structural hierarchy from the nanoscale to the macroscale. Science 309, 275–278 (2005)

    Article  ADS  CAS  Google Scholar 

  6. Hall, S. R., Bolger, H. & Mann, S. Morphosynthesis of complex inorganic forms using pollen grain templates. Chem. Commun. 2784–2785 (2003)

  7. Blaaderen, A., Ruel, R. & Wiltzius, P. Template-directed colloidal crystallization. Nature 385, 321–324 (1997)

    Article  ADS  Google Scholar 

  8. Cha, J. N., Stucky, G. D., Morse, D. E. & Deming, T. J. Biomimetic synthesis of ordered silica structures mediated by block copolypeptides. Nature 403, 289–292 (2000)

    Article  ADS  CAS  Google Scholar 

  9. Fan, H. et al. Rapid prototyping of patterned functional nanostructures. Nature 405, 56–60 (2000)

    Article  ADS  CAS  Google Scholar 

  10. Cullis, A. G. & Canham, L. T. Visible light emission due to quantum size effects in highly porous crystalline silicon. Nature 353, 335–338 (1991)

    Article  ADS  CAS  Google Scholar 

  11. Baratto, C. et al. Front-side micromachined porous silicon nitrogen dioxide gas sensor. Thin Solid Films 391, 261–264 (2001)

    Article  ADS  CAS  Google Scholar 

  12. Shin, H.-C., Corno, J. A., Gole, J. L. & Liu, M. Porous silicon negative electrodes for rechargeable lithium batteries. J. Power Sources 139, 314–320 (2005)

    Article  ADS  CAS  Google Scholar 

  13. Bengtsson, M. et al. Applications of microstructured porous silicon as a biocatalytic surface. Phys. Status Solidi A 182, 495–504 (2000)

    Article  ADS  CAS  Google Scholar 

  14. Powder Diffraction File Card No. 27–1402 for Si, Card No. 45–946 for MgO, Card No. 35–0773 for Mg2Si (International Center on Diffraction Data, Newtown Square, Pennsylvania); 〈www.icdd.com〉.

  15. Bouvard, D. & Lange, F. F. Relation between percolation and particle coordination in binary powder mixtures. Acta Metall. Mater. 39, 3083–3090 (1991)

    Article  CAS  Google Scholar 

  16. Barrett, E. P., Joyner, L. G. & Halenda, P. P. The determination of pore volume and area distributions in porous substances. I. Computations from nitrogen isotherms. J. Am. Chem. Soc. 73, 373–380 (1951)

    Article  CAS  Google Scholar 

  17. Barin, I. Thermochemical Data of Pure Substances 3rd edn, pages 994, 1012, 1014, 1481, 1504, 1505 (VCH, Weinheim, 1995)

    Book  Google Scholar 

  18. Wynnyckyj, J. R. & Rao, D. B. The mechanism of reduction of silica by magnesium vapor. High Temp. Sci. 8, 203–217 (1976)

    CAS  Google Scholar 

  19. Banerjee, H. D., Sen, S. & Acharya, H. N. Investigations on the production of silicon from rice husks by the magnesium method. Mater. Sci. Eng. 52, 173–179 (1982)

    Article  CAS  Google Scholar 

  20. Sandhage, K. H. et al. Novel, bioclastic route to self-assembled, 3D, chemically tailored meso/nanostructures: shape-preserving reactive conversion of biosilica (diatom) microshells. Adv. Mater. 14, 429–433 (2002)

    Article  CAS  Google Scholar 

  21. Cullity, B. D. Elements of X-ray Diffraction 101–102 (Addison-Wesley, Reading, Massachusetts, 1978)

    Google Scholar 

  22. Watanabe, K., Okada, T., Choe, I. & Sato, Y. Organic vapor sensitivity in a porous silicon device. Sensors Actuators B 33, 194–197 (1996)

    Article  CAS  Google Scholar 

  23. Boarino, L. et al. NO2 monitoring at room temperature by a porous silicon gas sensor. Mater. Sci. Eng. B 69–70, 210–214 (2000)

    Article  Google Scholar 

  24. Seals, L., Gole, J. L., Tse, L. A. & Hesketh, P. J. Rapid, reversible, sensitive porous silicon gas sensor. J. Appl. Phys. 91, 2519–2523 (2002)

    Article  ADS  CAS  Google Scholar 

  25. Balagurov, L. A., Leiferov, B. M., Petrova, E. A., Orlov, A. F. & Panasenko, E. M. Influence of water and alcohols on photoluminescence of porous silicon. J. Appl. Phys. 79, 7143–7147 (1996)

    Article  ADS  CAS  Google Scholar 

  26. Gelloz, B., Kojima, A. & Koshida, N. Highly efficient and stable luminescence of nanocrystalline porous silicon treated by high-pressure water vapour annealing. Appl. Phys. Lett. 87, 031107 (2005)

    Article  ADS  Google Scholar 

  27. Miron, A. S., Gomez, A. C., Camacho, F. G., Grima, E. M. & Chisti, Y. Comparative evaluation of compact photobioreactors for large-scale monoculture of microalgae. J. Biotechnol. 70, 249–270 (1999)

    Article  Google Scholar 

  28. Schmid, A.-M. M., Borowitzka, M. A. & Volcani, B. E. in Cytomorphogenesis in Plants (ed. Kiermayer, O.) Cell Biology Monographs 8 63–97 (Springer, Vienna, 1981)

    Book  Google Scholar 

  29. Li, X., He, Y., Talukdar, S. S. & Swihart, M. T. Process for preparing macroscopic quantities of brightly photoluminescent silicon nanoparticles with emission spanning the visible spectrum. Langmuir 19, 8490–8496 (2003)

    Article  CAS  Google Scholar 

Download references

Acknowledgements

This work was supported by the US Air Force Office of Scientific Research (H. C. DeLong and J. Fuller) and the US Office of Naval Research (M. Spector). We thank M. Bestor for assistance with XPS analysis and S. Yoo for help with focused ion beam milling.

Author Contributions Z.B., M.R.W., S.M.A., P.D.G., M.B.D. and K.H.S. conceived, developed and demonstrated the low-temperature magnesiothermic reduction and selective dissolution process. S.S. prepared and tested silicon replica gas sensors. G.A. cultured diatoms for conversion. Transmission electron microscope and BET analyses were conducted by Y.C. and B.C.C., respectively. H.W.A. and M.L. conducted and analysed FTIR measurements. Z.K. and C.J.S. conducted and analysed photoluminescence measurements. M.B.D. conducted fluorescence microscopy. Overall data analyses, project planning and paper preparation were largely conducted by Z.B. and K.H.S.

Author information

Authors and Affiliations

  1. School of Materials Science & Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA,

    Zhihao Bao, Michael R. Weatherspoon, Samuel Shian, Ye Cai, Phillip D. Graham, Shawn M. Allan, Gul Ahmad, Matthew B. Dickerson, Benjamin C. Church, Zhitao Kang, Harry W. Abernathy III, Christopher J. Summers, Meilin Liu & Kenneth H. Sandhage

Authors
  1. Zhihao Bao
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Michael R. Weatherspoon
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Samuel Shian
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Ye Cai
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Phillip D. Graham
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Shawn M. Allan
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Gul Ahmad
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Matthew B. Dickerson
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Benjamin C. Church
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Zhitao Kang
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Harry W. Abernathy III
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Christopher J. Summers
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Meilin Liu
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. Kenneth H. Sandhage
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Kenneth H. Sandhage.

Ethics declarations

Competing interests

Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

Supplementary information

Supplementary Figures and Methods

This file contains Supplementary Figures S1-S5 with Legends and Supplementary Methods. Figure S1 reveals silicon-converted Melosira nummoloides frustule replicas. Figures S2 and S3 provide XPS and FTIR confirmation of silicon in Aulacoseira frustule replicas. Figure S4 reveals the significant micropore population in silicon replicas of Aulacoseira frustules. Figure S5 demonstrates the photoluminescence of silicon Aulacoseira frustule replicas after immersion in water. The equipment and conditions used to obtain the secondary electron, transmission electron, and fluorescence microscope images of silica and silicon-converted diatom frustules are described in Supplementary Methods. (PDF 1127 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Bao, Z., Weatherspoon, M., Shian, S. et al. Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas. Nature 446, 172–175 (2007). https://doi.org/10.1038/nature05570

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature05570

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing