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Detecting the oxyl radical of photocatalytic water oxidation at an n-SrTiO3/aqueous interface through its subsurface vibration

Nature Chemistry volume 8, pages 549–555 (2016)Cite this article

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Abstract

Although the water oxidation cycle involves the critical step of O–O bond formation, the transition metal oxide radical thought to be the catalytic intermediate for this step has eluded direct observation. The radical represents the transformation of charge into a nascent catalytic intermediate, which lacks a newly formed bond and is therefore inherently difficult to detect. Here, using theoretical calculations and ultrafast in situ infrared spectroscopy of photocatalysis at an n-SrTiO3/aqueous interface, we reveal a subsurface vibration of the oxygen directly below, and uniquely generated by, the oxyl radical (Ti–O•). Intriguingly, this interfacial Ti–O stretch vibration, once decoupled from the lattice, couples to reactant dynamics (water librations). These experiments demonstrate subsurface vibrations and their coupling to solvent and electron dynamics to detect nascent catalytic intermediates at the solid–liquid interface at the molecular level. One can envision using the subsurface vibrations and their coupling across the interface to track and control catalysis dynamically.

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Figure 1: Infrared activity of the oxyl radical.
Figure 2: Investigating the Ti–O• oxyl signature of n-SrTiO3.
Figure 3: Fano lineshapes tuned by doping, electrolyte, H/D exchange and pH.
Figure 4: Theory of surface-related modes.

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Change history

  • 18 May 2016

    The original version of this Article contained an incorrectly labelled y axis in Fig. 2c. The chart is showing normalized data and so the y axis should have been labelled 'ΔA (a.u.)'. This has been corrected in all versions of the Article.

References

  1. Licht, S. et al. Efficient solar water splitting, exemplified by RuO2-catalyzed AlGaAs/Si photoelectrolysis. J. Phys. Chem. B 104, 8920–8924 (2000).

    Article  CAS  Google Scholar 

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

    Article  CAS  PubMed  Google Scholar 

  3. Eisenberg, R. & Gray, H. B. Preface on making oxygen. Inorg. Chem. 47, 1697–1699 (2008).

    Article  CAS  PubMed  Google Scholar 

  4. Zhang, M., de Respinis, M. & Frei, H. Time-resolved observations of water oxidation intermediates on a cobalt oxide nanoparticle catalyst. Nature Chem. 6, 362–367 (2014).

    Article  CAS  Google Scholar 

  5. Ramasesha, K., De Marco, L., Mandal, A. & Tokmakoff, A. Water vibrations have strongly mixed intra- and intermolecular character. Nature Chem. 5, 935–940 (2013).

    Article  CAS  Google Scholar 

  6. Renger, G. Light induced oxidative water splitting in photosynthesis: energetics, kinetics and mechanism. J. Photochem. Photobiol. B 104, 35–43 (2011).

    Article  CAS  PubMed  Google Scholar 

  7. Yano, J. & Yachandra, V. K. Where water is oxidized to dioxygen: structure of the photosynthetic Mn4Ca cluster from X-ray spectroscopy. Inorg. Chem. 47, 1711–1726 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Tagore, R., Crabtree, R. H. & Brudvig, G. W. Oxygen evolution catalysis by a dimanganese complex and its relation to photosynthetic water oxidation. Inorg. Chem. 47, 1815–1823 (2008).

    Article  CAS  PubMed  Google Scholar 

  9. Siegbahn, P. E. M. Theoretical studies of O–O bond formation in photosystem II. Inorg. Chem. 47, 1779–1786 (2008).

    Article  CAS  PubMed  Google Scholar 

  10. Groot, M. L. et al. Initial electron donor and acceptor in isolated photosystem II reaction centers identified with femtosecond mid-IR spectroscopy. Proc. Natl Acad. Sci. USA. 102, 13087–13092 (2005).

    Article  CAS  PubMed  Google Scholar 

  11. Britt, R. D. et al. Recent pulsed EPR studies of the photosystem II oxygen-evolving complex: implications as to water oxidation mechanisms. Biochim. Biophys. Acta 1655, 158–171 (2004).

    Article  CAS  PubMed  Google Scholar 

  12. Kern, J. et al. Taking snapshots of photosynthetic water oxidation using femtosecond X-ray diffraction and spectroscopy. Nature Commun. 5, 4371 (2014).

    Article  CAS  Google Scholar 

  13. Cummings, C. Y., Marken, F., Peter, L. M., Wijayantha, K. G. U. & Tahir, A. A. New insights into water splitting at mesoporous α-Fe2O3 films: a study by modulated transmittance and impedance spectroscopies. J. Am. Chem. Soc. 134, 1228–1234 (2012).

    Article  CAS  PubMed  Google Scholar 

  14. Klahr, B. & Hamann, T. Water oxidation on hematite photoelectrodes: insight into the nature of surface states through in situ spectroelectrochemistry. J. Phys. Chem. C 118, 10393–10399 (2014).

    Article  CAS  Google Scholar 

  15. Norton, A. P., Bernasek, S. L. & Bocarsly, A. B. Mechanistic aspects of the photooxidation of water at the n-titania/aqueous interface: optically induced transients as a kinetic probe. J. Phys. Chem. 92, 6009–6016 (1988).

    Article  CAS  Google Scholar 

  16. Nakamura, R. & Nakato, Y. Primary intermediates of oxygen photoevolution reaction on TiO2 (rutile) particles, revealed by in situ FTIR absorption and photoluminescence measurements. J. Am. Chem. Soc. 126, 1290–1298 (2004).

    Article  CAS  PubMed  Google Scholar 

  17. Imanishi, A., Okamura, T., Ohashi, N., Nakamura, R. & Nakato, Y. Mechanism of water photooxidation reaction at atomically flat TiO2 (rutile) (110) and (100) surfaces: dependence on solution pH. J. Am. Chem. Soc. 129, 11569–11578 (2007).

    Article  CAS  PubMed  Google Scholar 

  18. Micic, O. I., Zhang, Y., Cromack, K. R., Trifunac, A. D. & Thurnauer, M. C. Trapped holes on titania colloids studied by electron paramagnetic resonance. J. Phys. Chem. 97, 7277–7283 (1993).

    Article  CAS  Google Scholar 

  19. Kanan, M. W. et al. Structure and valency of a cobalt-phosphate water oxidation catalyst determined by in situ X-ray spectroscopy. J. Am. Chem. Soc. 132, 13692–13701 (2010).

    Article  CAS  PubMed  Google Scholar 

  20. McAlpin, J. G. et al. Electronic structure description of a [Co(III)3Co(IV)O4] cluster: a model for the paramagnetic intermediate in cobalt-catalyzed water oxidation. J. Am. Chem. Soc. 133, 15444–15452 (2011).

    Article  CAS  PubMed  Google Scholar 

  21. Surendranath, Y., Kanan, M. W. & Nocera, D. G. Mechanistic studies of the oxygen evolution reaction by a cobalt-phosphate catalyst at neutral pH. J. Am. Chem. Soc. 132, 16501–16509 (2010).

    Article  CAS  PubMed  Google Scholar 

  22. Bediako, D. K., Costentin, C., Jones, E. C., Nocera, D. G. & Savéant, J. Proton–electron transport and transfer in electrocatalytic films. application to a cobalt-based O2-evolution catalyst. J. Am. Chem. Soc. 135, 10492–10502 (2013).

    Article  CAS  PubMed  Google Scholar 

  23. Bediako, D. K., Surendranath, Y. & Nocera, D. G. Mechanistic studies of the oxygen evolution reaction mediated by a nickel-borate thin film electrocatalyst. J. Am. Chem. Soc. 135, 3662–3674 (2013).

    Article  CAS  PubMed  Google Scholar 

  24. Huynh, M., Bediako, D. K. & Nocera, D. G. A functionally stable manganese oxide oxygen evolution catalyst in acid. J. Am. Chem. Soc. 136, 6002–6010 (2014).

    Article  CAS  PubMed  Google Scholar 

  25. Sivasankar, N., Weare, W. W. & Frei, H. Direct observation of a hydroperoxide surface intermediate upon visible light-driven water oxidation at an Ir oxide nanocluster catalyst by rapid-scan FT-IR spectroscopy. J. Am. Chem. Soc. 133, 12976–12979 (2011).

    Article  CAS  PubMed  Google Scholar 

  26. Sezen, H. et al. Evidence for photogenerated intermediate hole polarons in ZnO. Nature Commun. 6, 6901 (2015).

  27. Sezen, H. et al. Probing electrons in TiO2 polaronic trap states by IR-absorption: evidence for the existence of hydrogenic states. Sci. Rep. 4, 3808 (2014).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  28. Waegele, M. M., Chen, X., Herlihy, D. M. & Cuk, T. How surface potential determines the kinetics of the first hole transfer of photocatalytic water oxidation. J. Am. Chem. Soc. 136, 10632–10639 (2014).

    Article  CAS  PubMed  Google Scholar 

  29. Kasinski, J. J., Gomez-Jahn, L. A., Faran, K. J., Gracewski, S. M. & Miller, R. J. D. Picosecond dynamics of surface electron transfer processes: surface restricted transient grating studies of the n-TiO2/H2O interface. J. Chem. Phys. 90, 1253–1269 (1989).

    Article  CAS  Google Scholar 

  30. Lane, I. M., King, D. A., Liu, Z. & Arnolds, H. Real-time observation of nonadiabatic surface dynamics: the first picosecond in the dissociation of NO on iridium. Phys. Rev. Lett. 97, 186105 (2006).

    Article  CAS  PubMed  Google Scholar 

  31. Haran, G., Sun, W. D., Wynne, K. & Hochstrasser, R. M. Femtosecond far-infrared pump-probe spectroscopy: a new tool for studying low-frequency vibrational dynamics in molecular condensed phases. Chem. Phys. Lett. 274, 365–371 (1997).

    Article  CAS  Google Scholar 

  32. Roberts, S. T., Ramasesha, K., Petersen, P. B., Mandal, A. & Tokmakoff, A. Proton transfer in concentrated aqueous hydroxide visualized using ultrafast infrared spectroscopy. J. Phys. Chem. A 115, 3957–3972 (2011).

    Article  CAS  PubMed  Google Scholar 

  33. Bakker, H., Bonn, M. & Fayer, M. Femtosecond Vibrational Spectroscopy of Aqueous Systems (CRC, 2013).

    Book  Google Scholar 

  34. Hussain, H. et al. A quantitative structural investigation of the 0.1 wt % Nb-SrTiO3(001)/H2O interface. J. Phys. Chem. C 118, 10980–10988 (2014).

    Article  CAS  Google Scholar 

  35. Ketteler, G. et al. The nature of water nucleation sites on TiO2(110) surfaces revealed by ambient pressure X-ray photoelectron spectroscopy. J. Phys. Chem. C 111, 8278–8282 (2007).

    Article  CAS  Google Scholar 

  36. Barker, A. S. Temperature dependence of the transverse and longitudinal optic mode frequencies and charges in SrTiO3 and BaTiO3 . Phys. Rev. 145, 391–399 (1966).

    Article  CAS  Google Scholar 

  37. Fischer, B., Bäuerle, D. & Buckel, W. J. Surface polaritons in KTaO3 and SrTiO3 . Solid. State. Commun. 14, 291–294 (1974).

    Article  CAS  Google Scholar 

  38. Wrighton, M. S. et al. Strontium titanate photoelectrodes. Efficient photoassisted electrolysis of water at zero applied potential. J. Am. Chem. Soc. 98, 2774–2779 (1976).

    Article  CAS  Google Scholar 

  39. Zhu, Y., Uchida, H. & Watanabe, M. Oxidation of carbon monoxide at a platinum film electrode studied by Fourier transform infrared spectroscopy with attenuated total reflection technique. Langmuir 15, 8757–8764 (1999).

    Article  CAS  Google Scholar 

  40. Zhu, Y., Uchida, H., Yajima, T. & Watanabe, M. Attenuated total reflection-Fourier transform infrared study of methanol oxidation on sputtered Pt film electrode. Langmuir 17, 146–154 (2001).

    Article  CAS  Google Scholar 

  41. Fano, U. Effects of configuration interaction on intensities and phase shifts. Phys. Rev. 124, 1866–1878 (1961).

    Article  CAS  Google Scholar 

  42. Gervais, F., Servoin, J., Baratoff, A., Bednorz, J. G. & Binnig, G. Temperature dependence of plasmons in Nb-doped SrTiO3 . Phys. Rev. B 47, 8187–8194 (1993).

    Article  CAS  Google Scholar 

  43. Giguère, P. A. & Harvey, K. B. On the infrared absorption of water and heavy water in condensed states. Can. J. Chem. 34, 798–808 (1956).

    Article  Google Scholar 

  44. Giustino, F. & Pasquarello, A. Infrared spectra at surfaces and interfaces from first principles: evolution of the spectra across the Si(100)–SiO2 interface. Phys. Rev. Lett. 95, 187402 (2005).

    Article  CAS  PubMed  Google Scholar 

  45. Milosevic, M. Internal Reflection and ATR Spectroscopy 264 (Wiley, 2012).

    Book  Google Scholar 

Download references

Acknowledgements

This research is based on work supported by the Air Force Office of Scientific Research (AFOSR, award no. FA9550-12-1-0337), which supplied the 64-element infrared array detector and partially supported a postdoctoral fellow, and by the Department of Energy (DOE) Office of Basic Energy Sciences (CPIMS program no. KC030102, FWP no. CH12CUK1), which supported two graduate students. The theory work of C.D.P. and D.P. was supported by a User Project at The Molecular Foundry (TMF), LBNL, with calculations performed on its computing resources, Nano and Vulcan, managed by the High Performance Computing Services Group of LBNL, and on the Cray XE6 Hopper computer at the National Energy Research Scientific Computing Center (NERSC), LBNL. Both TMF and NERSC are DOE Office of Science User Facilities supported by the Office of Science of the US Department of Energy (contract no. DE-AC02-05CH11231).

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Authors and Affiliations

  1. Department of Chemistry, University of California, Berkeley, 94720, California, USA

    David M. Herlihy, Matthias M. Waegele, Xihan Chen & Tanja Cuk

  2. Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, 94720, California, USA

    C. D. Pemmaraju & Tanja Cuk

  3. The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, 94720, California, USA

    C. D. Pemmaraju & David Prendergast

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  1. David M. Herlihy
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Contributions

T.C. conceived the project and wrote the manuscript with input from all authors. D.M.H. and M.M.W. constructed the transient set-up, collected transient data and prepared samples. X.C. collected and analysed the static reflectance measurements and characterized sample quantum efficiency. T.C. and D.M.H. analysed the transient data. C.D.P. and D.P. were responsible for the theoretical calculations.

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Correspondence to Tanja Cuk.

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Herlihy, D., Waegele, M., Chen, X. et al. Detecting the oxyl radical of photocatalytic water oxidation at an n-SrTiO3/aqueous interface through its subsurface vibration. Nature Chem 8, 549–555 (2016). https://doi.org/10.1038/nchem.2497

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