Photocatalytic water splitting with a quantum efficiency of almost unity



Overall water splitting, evolving hydrogen and oxygen in a 2:1 stoichiometric ratio,  using particulate photocatalysts is a potential means of achieving scalable and economically viable solar hydrogen production. To obtain high solar energy conversion efficiency, the quantum efficiency of the photocatalytic reaction must be increased over a wide range of wavelengths and semiconductors with narrow bandgaps need to be designed. However, the quantum efficiency associated with overall water splitting using existing photocatalysts is typically lower than ten per cent1,2. Thus, whether a particulate photocatalyst can enable a quantum efficiency of 100 per cent for the greatly endergonic water-splitting reaction remains an open question. Here we demonstrate overall water splitting at an external quantum efficiency of up to 96 per cent at wavelengths between 350 and 360 nanometres, which is equivalent to an internal quantum efficiency of almost unity, using a modified aluminium-doped strontium titanate (SrTiO3:Al) photocatalyst3,4. By selectively photodepositing the cocatalysts Rh/Cr2O3 (ref. 5) and CoOOH (refs. 3,6) for the hydrogen and oxygen evolution reactions, respectively, on different crystal facets of the semiconductor particles using anisotropic charge transport, the hydrogen and oxygen evolution reactions could be promoted separately. This enabled multiple consecutive forward charge transfers without backward charge transfer, reaching the upper limit of quantum efficiency for overall water splitting. Our work demonstrates the feasibility of overall water splitting free from charge recombination losses and introduces an ideal cocatalyst/photocatalyst structure for efficient water splitting.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Photocatalytic water-splitting activities.
Fig. 2: Location of cocatalysts.
Fig. 3: Transmission electron microscopy.
Fig. 4: Simulations of photocarrier distributions in SrTiO3:Al particles.

Data availability

Supporting data are available at the Shinshu University Institutional Repository at


  1. 1.

    Kudo, A. & Miseki, Y. Heterogeneous photocatalyst materials for water splitting. Chem. Soc. Rev. 38, 253–278 (2009).

    CAS  Article  Google Scholar 

  2. 2.

    Chen, S., Takata, T. & Domen, K. Particulate photocatalysts for overall water splitting. Nat. Rev. Mater. 2, 17050 (2017).

    ADS  CAS  Article  Google Scholar 

  3. 3.

    Goto, Y. et al. A particulate photocatalyst water-splitting panel for large-scale solar hydrogen production. Joule 2, 509–520 (2018).

    CAS  Article  Google Scholar 

  4. 4.

    Ham, Y. et al. Flux-mediated doping of SrTiO3 photocatalysts for efficient overall water splitting. J. Mater. Chem. A 4, 3027–3033 (2016).

    CAS  Article  Google Scholar 

  5. 5.

    Maeda, K. & Domen, K. Photocatalytic overall water splitting: recent progress and future challenges. J. Phys. Chem. Lett. 1, 2655–2661 (2010).

    CAS  Article  Google Scholar 

  6. 6.

    Lyu, H. et al. An Al-doped SrTiO3 photocatalyst maintaining sunlight-driven overall water splitting activity over 1,000 h of constant illumination. Chem. Sci. 10, 3196–3201 (2019).

    CAS  Article  Google Scholar 

  7. 7.

    Sakata, Y., Hayashi, T., Yasunaga, R., Yanaga, N. & Imamura, H. Remarkably high apparent quantum yield of the overall photocatalytic H2O splitting achieved by utilizing Zn ion added Ga2O3 prepared using dilute CaCl2. Chem. Commun. 51, 12935–12938 (2015).

    CAS  Article  Google Scholar 

  8. 8.

    Kato, H., Asakura, K. & Kudo, A. Highly efficient water splitting into H2 and O2 over lanthanum-doped NaTaO3 photocatalysts with high crystallinity and surface nanostructure. J. Am. Chem. Soc. 125, 3082–3089 (2003).

    CAS  Article  Google Scholar 

  9. 9.

    Chiang, T. H. et al. Efficient photocatalytic water splitting using Al-doped SrTiO3 coloaded with molybdenum oxide and rhodium-chromium oxide. ACS Catal. 8, 2782–2788 (2018).

    CAS  Article  Google Scholar 

  10. 10.

    Li, Y. et al. Photocatalytic water splitting by N-TiO2 on MgO(111) with exceptional quantum efficiency at elevated temperatures. Nat. Commun. 10, 4421 (2019).

    ADS  Article  Google Scholar 

  11. 11.

    Wagner, F. T. & Somorojai, G. A. Photocatalytic and photoelectrochemical hydrogen production on strontium titanate single crystals. J. Am. Chem. Soc. 102, 5494–5502 (1980).

    CAS  Article  Google Scholar 

  12. 12.

    Domen, K. et al. Photocatalytic decomposition of water vapour on an NiO-SrTiO3 catalyst. J. Chem. Soc. Chem. Commun. 543–544 (1980).

  13. 13.

    Lehn, J. M., Sauvage, J. P., Zlessel, R. & Hilaire, L. Water photolysis by UV irradiation of rhodium loaded strontium titanate catalysts. Relation between catalytic activity and nature of the deposit from combined photolysis and ESCA studies. Isr. J. Chem. 22, 168–172 (1982).

    CAS  Article  Google Scholar 

  14. 14.

    Takata, T. & Domen, K. Defect engineering of photocatalyst by doping of aliovalent metal cations for efficient water splitting. J. Phys. Chem. C 113, 19386–19388 (2009).

    CAS  Article  Google Scholar 

  15. 15.

    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).

    ADS  CAS  Article  Google Scholar 

  16. 16.

    Ohno, T., Sarukawa, K. & Matsumura, M. Crystal faces of rutile and anatase TiO2 particles and their roles in photocatalytic reactions. New J. Chem. 26, 1167–1170 (2002).

    CAS  Article  Google Scholar 

  17. 17.

    Liu, G., Yu, J. C., Lu, G. Q. & Cheng, H. M. Crystal facet engineering of semiconductor photocatalysts: motivations, advances and unique properties. Chem. Commun. 47, 6763–6783 (2011).

    CAS  Article  Google Scholar 

  18. 18.

    Xie, Y. P., Liu, G., Yina, L. & Cheng, H. M. Crystal facet-dependent photocatalytic oxidation and reduction reactivity of monoclinic WO3 for solar energy conversion. J. Mater. Chem. 22, 6746–6751 (2012).

    CAS  Article  Google Scholar 

  19. 19.

    Zhen, C., Yu, J. C., Liu, G. & Cheng, H. M. Selective deposition of redox co-catalyst(s) to improve the photocatalytic activity of single-domain ferroelectric PbTiO3 nanoplates. Chem. Commun. 50, 10416–10419 (2014).

    CAS  Article  Google Scholar 

  20. 20.

    Li, R. et al. Spatial separation of photogenerated electrons and holes among {010} and {110} crystal facets of BiVO4. Nat. Commun. 4, 1432 (2013).

    ADS  Article  Google Scholar 

  21. 21.

    Mu, L. et al. Enhancing charge separation on high symmetry SrTiO3 exposed with anisotropic facets for photocatalytic water splitting. Energy Environ. Sci. 9, 2463–2469 (2016).

    CAS  Article  Google Scholar 

  22. 22.

    Luo, Y. et al. Construction of spatial charge separation facets on BaTaO2N crystals by flux growth approach for visible-light-driven H2 production. ACS Appl. Mater. Interfaces 11, 22264–22271 (2019).

    CAS  Article  Google Scholar 

  23. 23.

    Wang, Z. et al. Overall water splitting by Ta3N5 nanorod single crystals grown on the edges of KTaO3 particles. Nat. Catal. 1, 756–763 (2018).

    CAS  Article  Google Scholar 

  24. 24.

    Wang, Q. et al. Oxysulfide photocatalyst for visible-light-driven overall water splitting. Nat. Mater. 18, 827–832 (2019).

    ADS  CAS  Article  Google Scholar 

  25. 25.

    Frederikse, H., Thurber, W. & Hosler, W. Electronic transport in SrTiO3. Phys. Rev. 134, A442–A445 (1964).

    ADS  Article  Google Scholar 

  26. 26.

    Weaver, H. Dielectric properties of single crystals of SrTiO3 at room temperatures. J. Phys. Chem. Solids 11, 275–277 (1959).

    ADS  Article  Google Scholar 

  27. 27.

    Zhao, Z. et al. Electronic structure basis for enhanced overall water splitting photocatalysis with aluminum doped SrTiO3 in natural sunlight. Energy Environ. Sci. 12, 1385–1395 (2019).

    CAS  Article  Google Scholar 

  28. 28.

    Konta, R., Ishii, T., Kato, H. & Kudo, A. Photocatalytic activities of noble metal ion doped SrTiO3 under visible light irradiation. J. Phys. Chem. B 108, 8992–8995 (2004).

    CAS  Article  Google Scholar 

  29. 29.

    Cohen, M. I. & Blunt, R. F. Optical properties of SrTiO3 in the region of absorption edge. Phys. Rev. 168, 929–933 (1968).

    ADS  CAS  Article  Google Scholar 

  30. 30.

    Zollner, S. et al. Optical properties of bulk and thin film SrTiO3 on Si and Pt. J. Vac. Sci. Technol. B 18, 2242–2254 (2000).

    CAS  Article  Google Scholar 

  31. 31.

    Sze, S. M. Physics of Semiconductor Devices (John Wiley & Sons, 1981).

Download references


This work was primarily supported by the Artificial Photosynthesis Project of the New Energy and Industrial Technology Development Organization (NEDO) and partly supported by JSPS KAKENHI grant number JP19K05669, JP16K06862. A part of this work was conducted at the Advanced Characterization Nanotechnology Platform of the University of Tokyo, supported by “Nanotechnology Platform” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (grant number JPMXP09A-19-UT-0023). We are grateful to M. Yamaguchi and Y. Kuromiya at the University of Tokyo for the preparation and evaluation of photocatalysts.

Author information




T.T. conceived the photocatalyst design and performed the photocatalytic reactions. T.H. synthesized Al-doped SrTiO3. J.J. and Y.S. performed quantum efficiency measurements. M.N. and N.S. performed electron microscopy measurements. V.N. and K.S. performed electrical simulations. K.D. supervised the project. T.T., T.H. and K.D. wrote the manuscript with input from all authors.

Corresponding author

Correspondence to Kazunari Domen.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks David Tilley, Martijn Zwijnenburg and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Extended data figures and tables

Extended Data Fig. 1 Dependence of water-splitting activities on the amounts and components of cocatalysts.

a, b, Dependence of water-splitting activity on the amount of Cr2O3 added to Rh (0.1 wt%)-loaded SrTiO3:Al (a) and CoOOH added to Rh (0.1 wt%)/Cr2O3(0.05 wt%)-loaded SrTiO3:Al (b). c, Time course of H2 and O2 evolution over SrTiO3:Al unloaded (i) and loaded with Rh (0.1 wt%) (ii), Rh (0.1 wt%)/CoOOH (0.05 wt%) (iii), CoOOH (0.05 wt%) (iv) and CoOOH (0.05 wt%)/Cr2O3 (0.05 wt%) (v).

Extended Data Fig. 2 Reproducibility and stability of water-splitting activity of SrTiO3:Al loaded with Rh (0.1 wt%)/Cr2O3 (0.05 wt%)/CoOOH (0.05 wt%).

a, Variation of water-splitting activity of SrTiO3:Al loaded with Rh (0.1 wt%)/Cr2O3 (0.05 wt%)/CoOOH (0.05 wt%) (25 samples) from different batches (B) and lots (L). Batches and lots represent SrTiO3:Al samples and the cocatalysts synthesized and loaded at different timings, respectively. The averages (μ) of the H2 and O2 evolution rates were 3.54 mmol h−1 and 1.78 mmol h−1 and their standard deviations (σ) were 0.26 mmol h−1 and 0.12 mmol h−1, respectively. All the gas evolution rates were within μ ± 2σ. b, Stability test of SrTiO3:Al loaded with Rh (0.1 wt%)/Cr2O3 (0.05 wt%)/CoOOH (0.05 wt%) during photocatalytic water splitting. The produced H2 and O2 accumulated in the reaction system were evacuated every 2.5 h. The inner wall of the reactor window was cleaned before every evacuation.

Extended Data Fig. 3

Time course of H2 and O2 evolution over SrTiO3:Al photodeposited with Rh (0.1 wt%)/Cr2O3 (0.05 wt%)/CoOOH (0.05 wt%) under simulated sunlight irradiation.

Extended Data Fig. 4

Effect of initial background pressure on the photocatalytic water-splitting activity of SrTiO3:Al photodeposited with Rh (0.1 wt%)/Cr2O3 (0.05 wt%)/CoOOH (0.05 wt%).

Extended Data Fig. 5 Simulations of graded band energy values and resulting anisotropic charge separation based on various differences in work function between the {110} and {100} facets.

a, Maps of conduction band energy and logarithms of the electron and hole densities (n and p, respectively). b, c, Energy band diagrams (b) and electron and hole densities (c) as functions of position. See Methods for further discussion.

Extended Data Fig. 6

Power spectrum of the Xe lamp used in the study.

Extended Data Fig. 7

XRD pattern of the synthesized SrTiO3:Al.

Extended Data Fig. 8 EQE measurement.

a, Photographs of the devices used in the measurement. Left, side view of the measurement system. Middle left, top view of the measurement system. Middle right, arrangement of the lamp and reactor. Right, arrangement of the Si photodiode. b, c, Illustrations of water-splitting reactor and photon-counting system (b) and illumination unit (c). d, Example of light intensity distribution (365-nm bandpass filter and 0.1-optical-density neutral density filter; left) and model used to calculate the number of incident photons (right).

Extended Data Table 1 Results of EQE measurements
Extended Data Table 2 Parameters used in the calculations of the energy band diagrams and electron and hole densities for the SrTiO3:Al particulate system

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Takata, T., Jiang, J., Sakata, Y. et al. Photocatalytic water splitting with a quantum efficiency of almost unity. Nature 581, 411–414 (2020).

Download citation

Further reading


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.