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:

A silicon-based photocathode for water reduction with an epitaxial SrTiO3 protection layer and a nanostructured catalyst

Nature Nanotechnology volume 10, pages 84–90 (2015)Cite this article

Subjects

Abstract

The rapidly increasing global demand for energy combined with the environmental impact of fossil fuels has spurred the search for alternative sources of clean energy. One promising approach is to convert solar energy into hydrogen fuel using photoelectrochemical cells. However, the semiconducting photoelectrodes used in these cells typically have low efficiencies and/or stabilities. Here we show that a silicon-based photocathode with a capping epitaxial oxide layer can provide efficient and stable hydrogen production from water. In particular, a thin epitaxial layer of strontium titanate (SrTiO3) was grown directly on Si(001) by molecular beam epitaxy. Photogenerated electrons can be transported easily through this layer because of the conduction-band alignment and lattice match between single-crystalline SrTiO3 and silicon. The approach was used to create a metal–insulator–semiconductor photocathode that, under a broad-spectrum illumination at 100 mW cm−2, exhibits a maximum photocurrent density of 35 mA cm−2 and an open circuit potential of 450 mV; there was no observable decrease in performance after 35 hours of operation in 0.5 M H2SO4. The performance of the photocathode was also found to be highly dependent on the size and spacing of the structured metal catalyst. Therefore, mesh-like Ti/Pt nanostructured catalysts were created using a nanosphere lithography lift-off process and an applied-bias photon-to-current efficiency of 4.9% was achieved.

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

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

Figure 1: RHEED and XPS results.
Figure 2: Schematic structure, band alignment and STO-thickness-dependent performance.
Figure 3: PEC characterization and performance.
Figure 4: Nanostructured metal-catalyst fabrication and performance.

Similar content being viewed by others

References

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

    Article  CAS  Google Scholar 

  2. Lewis, N. S. et al. Solar water splitting cells. Chem. Rev. 110, 6446–6473 (2010).

    Article  Google Scholar 

  3. Esposito, D. V., Levin, I., Moffat, T. P. & Talin, A. A. H2 evolution at Si-based metal–insulator–semiconductor photoelectrodes enhanced by inversion channel charge collection and H spillover. Nature Mater. 12, 562–568 (2013).

    Article  CAS  Google Scholar 

  4. Kye, J. et al. Platinum monolayer electrocatalyst on gold nanostructures on silicon for photoelectrochemical hydrogen evolution. ACS Nano 7, 6017–6023 (2013).

    Article  CAS  Google Scholar 

  5. Sun, K. et al. Nickel oxide functionalized silicon for efficient photo-oxidation of water. Energy Environ. Sci. 5, 7872–7877 (2012).

    Article  CAS  Google Scholar 

  6. Chen, Y. W. et al. Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation. Nature Mater. 10, 539–544 (2011).

    Article  CAS  Google Scholar 

  7. Seger, B. et al. Hydrogen production using a molybdenum sulfide catalyst on a titanium-protected n plus p-silicon photocathode. Angew. Chem. Int. Ed. 51, 9128–9131 (2012).

    Article  CAS  Google Scholar 

  8. Seger, B. et al. Using TiO2 as a conductive protective layer for photocathodic H2 evolution. J. Am. Chem. Soc. 135, 1057–1064 (2013).

    Article  CAS  Google Scholar 

  9. Kenney, M. J. et al. High-performance silicon photoanodes passivated with ultrathin nickel films for water oxidation. Science 342, 836–840 (2013).

    Article  CAS  Google Scholar 

  10. Reece, S. Y. et al. Wireless solar water splitting using silicon-based semiconductors and earth-abundant catalysts. Science 334, 645–648 (2011).

    Article  CAS  Google Scholar 

  11. Pijpers, J. J. H. et al. Light-induced water oxidation at silicon electrodes functionalized with a cobalt oxygen-evolving catalyst. Proc. Natl Acad. Sci. USA 108, 10056–10061 (2011).

    Article  CAS  Google Scholar 

  12. Sun, K. et al. Metal oxide composite enabled nanotextured Si photoanode for efficient solar driven water oxidation. Nano Lett. 13, 2064–2072 (2013).

    Article  CAS  Google Scholar 

  13. Dasgupta, N. P. et al. Atomic layer deposition of platinum catalysts on nanowire surfaces for photoelectrochemical water reduction. J. Am. Chem. Soc. 135, 12932–12935 (2013).

    Article  CAS  Google Scholar 

  14. Paracchino, A. et al. Highly active oxide photocathode for photoelectrochemical water reduction. Nature Mater. 10, 456–461 (2011).

    Article  CAS  Google Scholar 

  15. Khan, S. U. M., Al-Shahry, M. & Ingler, W. B. Efficient photochemical water splitting by a chemically modified n-TiO2 . Science 297, 2243–2245 (2002).

    Article  CAS  Google Scholar 

  16. Chen, X. B., Liu, L., Yu, P. Y. & Mao, S. S. Increasing solar absorption for photocatalysis with black hydrogenated titanium dioxide nanocrystals. Science 331, 746–750 (2011).

    Article  CAS  Google Scholar 

  17. Warren, S. C. et al. Identifying champion nanostructures for solar water-splitting. Nature Mater. 12, 842–849 (2013).

    Article  CAS  Google Scholar 

  18. Shi, J. et al. Interface engineering by piezoelectric potential in ZnO–based photoelectrochemical anode. Nano Lett. 11, 5587–5593 (2011).

    Article  CAS  Google Scholar 

  19. McKone, J. R., Pieterick, A. P., Gray, H. B. & Lewis, N. S. Hydrogen evolution from Pt/Ru-coated p-type WSe2 photocathodes. J. Am. Chem. Soc. 135, 223–231 (2012).

    Article  Google Scholar 

  20. Liao, L. et al. Efficient solar water-splitting using a nanocrystalline CoO photocatalyst. Nature Nanotech. 9, 69–73 (2013).

    Article  Google Scholar 

  21. Khaselev, O. & Turner, J. A. A monolithic photovoltaic–photoelectrochemical device for hydrogen production via water splitting. Science 280, 425–427 (1998).

    Article  CAS  Google Scholar 

  22. Li, Y. et al. Cobalt phosphate-modified barium-doped tantalum nitride nanorod photoanode with 1.5% solar energy conversion efficiency. Nature Commun. 4, 2566 (2013).

    Article  Google Scholar 

  23. Higashi, M., Domen, K. & Abe, R. Highly stable water splitting on oxynitride TaON photoanode system under visible light irradiation. J. Am. Chem. Soc. 134, 6968–6971 (2012).

    Article  CAS  Google Scholar 

  24. Li, Y. et al. Vertically aligned Ta3N5 nanorod arrays for solar-driven photoelectrochemical water splitting. Adv. Mater. 25, 125–131 (2013).

    Article  CAS  Google Scholar 

  25. Powell, D. M. et al. Crystalline silicon photovoltaics: a cost analysis framework for determining technology pathways to reach baseload electricity costs. Energy Environ. Sci. 5, 5874–5883 (2012).

    Article  Google Scholar 

  26. Swanson, R. M. A vision for crystalline silicon photovoltaics. Prog. Photovoltaics Res. Appl. 14, 443–453 (2006).

    Article  Google Scholar 

  27. Sim, U. et al. N-doped monolayer graphene catalyst on silicon photocathode for hydrogen production. Energy Environ. Sci. 6, 3658–3664 (2013).

    Article  CAS  Google Scholar 

  28. Wang, X. et al. High-performance silicon nanowire array photoelectrochemical solar cells through surface passivation and modification. Angew. Chem. Int. Ed. 50, 9861–9865 (2011).

    Article  CAS  Google Scholar 

  29. Munoz, E. C., Schrebler, R. S., Orellana, M. A. & Cordova, R. Rhenium electrodeposition process onto p-Si(100) and electrochemical behaviour of the hydrogen evolution reaction onto p-Si/Re/0.1 M H2SO4 interface. J. Electroanal. Chem. 611, 35–42 (2007).

    Article  CAS  Google Scholar 

  30. Strandwitz, N. C. et al. Photoelectrochemical behavior of n-type Si(100) electrodes coated with thin films of manganese oxide grown by atomic layer deposition. J. Phys. Chem. C 117, 4931–4936 (2013).

    Article  CAS  Google Scholar 

  31. Lana-Villarreal, T., Straboni, A., Pichon, L. & Alonso-Vante, N. Photoelectrochemical characterization of p-type silicon electrodes covered with tunnelling nitride dielectric films. Thin Solid Films 515, 7376–7381 (2007).

    Article  CAS  Google Scholar 

  32. McKee, R. A., Walker, F. J. & Chisholm, M. F. Crystalline oxides on silicon: the first five monolayers. Phys. Rev. Lett. 81, 3014–3017 (1998).

    Article  CAS  Google Scholar 

  33. Yu, Z. et al. Advances in heteroepitaxy of oxides on silicon. Thin Solid Films 462–463, 51–56 (2004).

    Article  Google Scholar 

  34. Warusawithana, M. P. et al. A ferroelectric oxide made directly on silicon. Science 324, 367–370 (2009).

    Article  CAS  Google Scholar 

  35. Demkov, A. A. et al. Monolithic integration of oxides on semiconductors. ECS Transactions 54, 255–269 (2013).

    Article  Google Scholar 

  36. McKee, R. A., Walker, F. J. & Chisholm, M. F. Physical structure and inversion charge at a semiconductor interface with a crystalline oxide. Science 293, 468–471 (2001).

    Article  CAS  Google Scholar 

  37. Chambers, S. A. et al. Band discontinuities at epitaxial SrTiO3/Si(001) heterojunctions. Appl. Phys. Lett. 77, 1662–1664 (2000).

    Article  CAS  Google Scholar 

  38. Chambers, S. et al. Band offset and structure of SrTiO3/Si(001) heterojunctions. J. Vac. Sci. Technol. A 19, 934–939 (2001).

    Article  CAS  Google Scholar 

  39. Zhang, X. et al. Atomic and electronic structure of the Si/SrTiO3 interface. Phys. Rev. B 68, 125323 (2003).

    Article  Google Scholar 

  40. Amy, F. et al. Band offsets at heterojunctions between SrTiO3 and BaTiO3 and Si(100). J. Appl. Phys. 96, 1635–1639 (2004).

    Article  CAS  Google Scholar 

  41. Robertson, J. Band offsets of wide-band-gap oxides and implications for future electronic devices. J. Vac. Sci. Technol. B 18, 1785–1791 (2000).

    Article  CAS  Google Scholar 

  42. Yu, Z. et al. Epitaxial perovskite thin films grown on silicon by molecular beam epitaxy. J. Vac. Sci. Technol. B 18, 1653–1657 (2000).

    Article  CAS  Google Scholar 

  43. Chang, T. C., Jian, F. Y., Chen, S. C. & Tsai, Y. T. Developments in nanocrystal memory. Mater. Today 14, 608–615 (2011).

    Article  CAS  Google Scholar 

  44. Haynes, C. L. & Van Duyne, R. P. Nanosphere lithography: a versatile nanofabrication tool for studies of size-dependent nanoparticle optics. J. Phys. Chem. B 105, 5599–5611 (2001).

    Article  CAS  Google Scholar 

  45. Hsu, C. M., Connor, S. T., Tang, M. X. & Cui, Y. Wafer-scale silicon nanopillars and nanocones by Langmuir–Blodgett assembly and etching. Appl. Phys. Lett. 93, 133109 (2008).

    Article  Google Scholar 

  46. Sze, S. M. & Ng, K. K. Physics of Semiconductor Devices (Wiley, 2006).

    Book  Google Scholar 

  47. Wei, Y. et al. Mechanism of cleaning Si(100) surface using Sr or SrO for the growth of crystalline SrTiO3 films. J. Vac. Sci. Technol. B 20, 1402–1405 (2002).

    Article  CAS  Google Scholar 

  48. Wagner, C. D. Sensitivity factors for XPS analysis of surface atoms. J. Electron Spectrosc. 32, 99–102 (1983).

    Article  CAS  Google Scholar 

  49. Wagner, C. D., Davis, L. E. & Riggs, W. M. The energy dependence of the electron mean free path. Surf. Interface Anal. 2, 53–55 (1980).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

The authors acknowledge research support from the National Science Foundation (ECCS-1120823 and Award DMR-1207342), the Office of Naval Research (Grant N00014-10-10489) and the Judson S. Swearingen Regents Chair in Engineering at the University of Texas at Austin.

Author information

Authors and Affiliations

  1. Department of Electrical and Computer Engineering, Microelectronics Research Center, University of Texas at Austin, 78712, Texas, USA

    Li Ji, Xiaohan Li, Haiyu Huang, Jack C. Lee & Edward T. Yu

  2. Department of Chemistry and Biochemistry, Center for Electrochemistry, University of Texas at Austin, 78712, Texas, USA

    Li Ji, Shijun Wang & Allen J. Bard

  3. Department of Chemical Engineering, University of Texas at Austin, 78712, Texas, USA

    Martin D. McDaniel & John G. Ekerdt

  4. Department of Physics, University of Texas at Austin, 78712, Texas, USA

    Agham B. Posadas & Alexander A. Demkov

Authors
  1. Li Ji
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Martin D. McDaniel
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Shijun Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Agham B. Posadas
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Xiaohan Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Haiyu Huang
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Jack C. Lee
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Alexander A. Demkov
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Allen J. Bard
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. John G. Ekerdt
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Edward T. Yu
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

L.J., M.D.M., J.G.E. and E.T.Y. contributed to the design concept. L.J., X.L., S.W. and H.H. performed the fabrication process and measurements. M.D.M., A.B.P., A.A.D. and J.G.E. performed the MBE growth. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Li Ji.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary Information (PDF 642 kb)

Supplementary Movie 1

Supplementary Movie 1 (AVI 1459 kb)

Supplementary Movie 2

Supplementary Movie 2 (AVI 1008 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Ji, L., McDaniel, M., Wang, S. et al. A silicon-based photocathode for water reduction with an epitaxial SrTiO3 protection layer and a nanostructured catalyst. Nature Nanotech 10, 84–90 (2015). https://doi.org/10.1038/nnano.2014.277

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nnano.2014.277

This article is cited by

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