Overall water splitting by Ta3N5 nanorod single crystals grown on the edges of KTaO3 particles


Although one-step-excitation overall water splitting on a particulate photocatalyst is a simple means of performing scalable solar-to-hydrogen energy conversion, there is a lack of photocatalysts with significant activity under visible light. Despite its superior visible-light absorption, the Ta3N5 photocatalyst has not accomplished overall water splitting due to strong charge recombination at defects. Here, we show rapid growth of Ta3N5 nanorods on lattice-matched cubic KTaO3 particles through the volatilization of potassium species during a brief nitridation process. The Ta3N5 nanorods generated selectively on the edge of KTaO3 are spatially separated and well-defined single crystals free from grain boundaries. When combined with the Rh/Cr2O3 co-catalyst, the single-crystal Ta3N5 nanorods split water into hydrogen and oxygen very efficiently under visible light and simulated sunlight. Our findings demonstrate the importance of nanostructured single-crystal photocatalysts free from structural defects in solar water splitting.

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Fig. 1: Morphology and UV-Vis DRS analysis of Ta3N5/KTaO3.
Fig. 2: Single-crystal structure of Ta3N5 nanorods grown on KTaO3.
Fig. 3: Selective photodeposition of rhodium metal particles on Ta3N5 nanorods.
Fig. 4: Effect of the nitridation time and co-catalyst loading amount on the overall-water-splitting activity of Rh/Cr2O3-modified Ta3N5/KTaO3.
Fig. 5: Overall-water-splitting performance and AQE of Rh/Cr2O3-modified Ta3N5/KTaO3.


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This work was financially supported by the Artificial Photosynthesis Project of the New Energy and Industrial Technology Development Organization and Grants-in-Aid for Scientific Research (A) (number 16H02417), Scientific Research (C) (number 16K06862) and Young Scientists (A) (number 15H05494) from the Japan Society for the Promotion of Science.

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Z.W., Y.Inoue and K.D. conceived the material growth design. Z.W. fabricated the photocatalyst materials, and conducted the XRD, UV-Vis DRS and SEM characterizations, co-catalyst modifications and overall-water-splitting reactions. R.I., N.S. and Y.Ikuhara carried out the ADF-STEM and STEM-EDS measurements. Q.W. conducted the AQE and STH measurements. Y.Inoue, T.H., T.T. and K.D. supervised the research work. Z.W., Y.Inoue, T.H., Q.W., T.T., S.C. and K.D. contributed to valuable discussion. Z.W., Y.Inoue, T.H. and K.D. wrote and revised the paper. All authors commented on the paper.

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Correspondence to Kazunari Domen.

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Supplementary Tables 1 & 2; Supplementary Figures 1–12; Supplementary References

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Wang, Z., Inoue, Y., Hisatomi, T. et al. Overall water splitting by Ta3N5 nanorod single crystals grown on the edges of KTaO3 particles. Nat Catal 1, 756–763 (2018). https://doi.org/10.1038/s41929-018-0134-1

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