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.

  • Article
  • Published:

Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation

Abstract

A leading approach for large-scale electrochemical energy production with minimal global-warming gas emission is to use a renewable source of electricity, such as solar energy, to oxidize water, providing the abundant source of electrons needed in fuel synthesis. We report corrosion-resistant, nanocomposite anodes for the oxidation of water required to produce renewable fuels. Silicon, an earth-abundant element and an efficient photovoltaic material, is protected by atomic layer deposition (ALD) of a highly uniform, 2 nm thick layer of titanium dioxide (TiO2) and then coated with an optically transmitting layer of a known catalyst (3 nm iridium). Photoelectrochemical water oxidation was observed to occur below the reversible potential whereas dark electrochemical water oxidation was found to have low-to-moderate overpotentials at all pH values, resulting in an inferred photovoltage of ~550 mV. Water oxidation is sustained at these anodes for many hours in harsh pH and oxidative environments whereas comparable silicon anodes without the TiO2 coating quickly fail. The desirable electrochemical efficiency and corrosion resistance of these anodes is made possible by the low electron-tunnelling resistance (<0.006 Ω cm2 for p+-Si) and uniform thickness of atomic-layer deposited TiO2.

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

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

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

Figure 1: Ir/TiO2/Si nanocomposite water oxidation anode.
Figure 2: Anode stability under illumination during water splitting.
Figure 3: Anode stability in the dark during water splitting.
Figure 4: Representative XPS depth profiles of samples after stability testing.
Figure 5: Electronic transport characterization.

Similar content being viewed by others

References

  1. Lewis, N. S. & Nocera, D. G. Powering the planet: Chemical challenges in solar energy utilization. Proc. Natl Acad. Sci. USA 103, 15729–15735 (2006).

    Article  CAS  Google Scholar 

  2. Lewis, N. S. Toward cost-effective solar energy use. Science 315, 798–801 (2007).

    Article  CAS  Google Scholar 

  3. Pourbaix, M. J. N. Atlas of Electrochemical Equilibria in Aqueous Solutions 1st edn (Pergamon Press, 1966).

    Google Scholar 

  4. Hwang, Y. J., Boukai, A. & Yang, P. D. High density n-Si/n-TiO2core/shell nanowire arrays with enhanced photoactivity. Nano Lett. 9, 410–415 (2009).

    Article  CAS  Google Scholar 

  5. Walter, M. G. et al. Solar water splitting cells. Chem. Rev. 110, 6446–6473 (2010).

    Article  CAS  Google Scholar 

  6. Kay, A., Cesar, I. & Gratzel, M. New benchmark for water photooxidation by nanostructured alpha-Fe2O3 films. J. Am. Chem. Soc. 128, 15714–15721 (2006).

    Article  CAS  Google Scholar 

  7. Sivula, K., Le Formal, F. & Gratzel, M. WO3–Fe2O3 photoanodes for water splitting: A host scaffold, guest absorber approach. Chem. Mater. 21, 2862–2867 (2009).

    Article  CAS  Google Scholar 

  8. Matsumura, M. & Morrison, S. R. Anodic properties of n-Si and n-Ge electrodes in HF solution under illumination and in the dark. J. Electroanal. Chem. 147, 157–166 (1983).

    Article  CAS  Google Scholar 

  9. Fan, F. R. F., Keil, R. G. & Bard, A. J. Semiconductor electrodes.48. Photo-oxidation of halides and water on N-silicon protected with silicide layers. J. Am. Chem. Soc. 105, 220–224 (1983).

    Article  CAS  Google Scholar 

  10. Howe, A. T., Hawkins, R. T. & Fleisch, T. H. Photoelectrochemical cells of the electrolyte–metal–insulator–semiconductor (Emis) configuration.1. Metal thickness and coverage effects in the Pt–Silicon Oxide–N–Si system. J. Electrochem. Soc. 133, 1369–1375 (1986).

    Article  CAS  Google Scholar 

  11. Contractor, A. Q. & Bockris, J. O. M. Investigation of a protective conducting silica film on N -Silicon. Electrochim. Acta 29, 1427–1434 (1984).

    Article  CAS  Google Scholar 

  12. Kohl, P. A., Frank, S. N. & Bard, A. J. Semiconductor electrodes.11. Behavior of N-type and P-type single-crystal semiconductors covered with thin normal-TiO2 films. J. Electrochem. Soc. 124, 225–229 (1977).

    Article  CAS  Google Scholar 

  13. Suleymanov, A. S. On the possibility of the transformation of solar energy to chemical energy in the electrochemical cell with photoanode CdSe/TiO2 . Int. J. Hydrogen Energy 16, 741–743 (1991).

    Article  CAS  Google Scholar 

  14. Siripala, W., Ivanovskaya, A., Jaramillo, T. F., Baeck, S. H. & McFarland, E. W. A CU2O/TiO2 heterojunction thin film cathode for photoelectrocatalysis. Sol. Energ. Mater. Sol. C 77, 229–237 (2003).

    Article  CAS  Google Scholar 

  15. Rajeshwar, K., Kaneko, M., Yamada, A. & Noufi, R. N. Photoelectrochemical oxidation of halide-ions at naked, catalytically modified, and polymer-coated N-Cds electrodes in aqueous-media. J. Phys. Chem. 89, 806–811 (1985).

    Article  CAS  Google Scholar 

  16. Ritala, M. & Leskela, M. Atomic layer epitaxy—a valuable tool for nanotechnology? Nanotechnology 10, 19–24 (1999).

    Article  CAS  Google Scholar 

  17. Liu, F. et al. Mechanisms of water oxidation from the blue dimer to photosystem II. Inorg. Chem. 47, 1727–1752 (2008).

    Article  CAS  Google Scholar 

  18. Kanan, M. W. & Nocera, D. G. In situ formation of an oxygen-evolving catalyst in neutral water containing phosphate and Co2+. Science 321, 1072–1075 (2008).

    Article  CAS  Google Scholar 

  19. Yagi, M., Tomita, E., Sakita, S., Kuwabara, T. & Nagai, K. Self-assembly of active IrO2 colloid catalyst on an ITO electrode for efficient electrochemical water oxidation. J. Phys. Chem. B 109, 21489–21491 (2005).

    Article  CAS  Google Scholar 

  20. Comninellis, C. & Vercesi, G. P. Characterization of DSA-type oxygen evolving electrodes—choice of a coating. J. Appl. Electrochem. 21, 335–345 (1991).

    Article  CAS  Google Scholar 

  21. Nakagawa, T., Bjorge, N. S. & Murray, R. W. Electrogenerated IrOx nanoparticles as dissolved redox catalysts for water oxidation. J. Am. Chem. Soc. 131, 15578–15579 (2009).

    Article  CAS  Google Scholar 

  22. ASTM International ASTM Standard G173–03 doi:10.150/G0173-03R08 (ASTM, 2008); available via www.astm.org.

  23. Fujishima, A. & Honda, K. Electrochemical photolysis of water at a semiconductor electrode. Nature 238, 37–38 (1972).

    Article  CAS  Google Scholar 

  24. Howe, A. T. & Fleisch, T. H. Photoelectrochemical cells of the electrolyte–metal–insulator–semiconductor (Emis) configuration.2. Use of nonnative oxides in Pt/oxide/N–Si systems. J. Electrochem. Soc. 134, 72–76 (1987).

    Article  CAS  Google Scholar 

  25. http://www.itrs.net/links/2008ITRS/Update/2008Tables_FOCUS_A.xls.

  26. Ouattara, L. et al. Dimensionally stable anode-type anode based on conductive p-silicon substrate. J. Electrochem. Soc. 150, D41–D45 (2003).

    Article  CAS  Google Scholar 

  27. Switzer, J. A. The N-silicon thallium(III) oxide heterojunction photoelectrochemical solar-cell. J. Electrochem. Soc. 133, 722–728 (1986).

    Article  CAS  Google Scholar 

  28. Green, M. A., Emery, K., Hishikawa, Y. & Warta, W. Solar cell efficiency tables (version 35). Prog. Photovolt. 18, 144–150 (2010).

    Article  CAS  Google Scholar 

  29. Nozik, A. J. p–n photoelectrolysis cells. Appl. Phys. Lett. 29, 150–153 (1976).

    Article  CAS  Google Scholar 

  30. Nelson, J. The Physics of Solar Cells (Imperial College Press, 2003).

    Book  Google Scholar 

  31. Sharpe, A. G. The Chemistry of Cyano Complexes of the Transition Metals (Academic, 1976).

    Google Scholar 

  32. Schuegraf, K. F. & Hu, C. M. Hole injection SiO2 breakdown model for very-low voltage lifetime extrapolation. IEEE Trans. Electron Devices 41, 761–767 (1994).

    Article  CAS  Google Scholar 

  33. Nelson, J. & Chandler, R. E. Random walk models of charge transfer and transport in dye sensitized systems. Coord. Chem. Rev. 248, 1181–1194 (2004).

    Article  CAS  Google Scholar 

  34. Doering, R. & Nishi, Y. Handbook of Semiconductor Manufacturing Technology 14-11–14-37 (CRC, 2008).

    Google Scholar 

  35. Raaijmakers, I., Soininen, P. T., Granneman, E. H. A. & Haukka, S. P. Protective layers prior to alternating layer deposition. US patent 2001/0054769A1 (2001).

Download references

Acknowledgements

We thank J-Y. Lee, R. Dinyari and P. Peumans for providing access to the solar simulation setup. We also thank T. Jaramillo, S-J. Choi, K. Kuhl and B. Pinaud for impedence spectroscopy and real hydrogen electrode measurements, as well as their helpful discussions. We thank B. Shin and M. Shandalov for their help in TiO2 deposition and characterization. This work was partially supported by the Stanford Global Climate and Energy Project. We acknowledge support from the Center for Integrated Systems and Precourt Institute for Energy seed grants. Y.W.C. acknowledges financial support from a Stanford Graduate Fellowship.

Author information

Authors and Affiliations

Authors

Contributions

Y.W.C. and Y.P. prepared the samples and performed solid state tunnelling measurements. Y.W.C., J.D.P. and S.D. performed the electrochemical measurements. M.G. performed the TEM measurement. Y.W.C. and J.D.P performed the XPS measurements. Y.W.C., J.D.P, C.E.D.C. and P.C.M. designed the experiments and prepared the manuscript.

Corresponding author

Correspondence to Paul C. McIntyre.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1545 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Chen, Y., Prange, J., Dühnen, S. et al. Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation. Nature Mater 10, 539–544 (2011). https://doi.org/10.1038/nmat3047

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat3047

This article is cited by

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