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Published January 19, 2016 | Published
Journal Article Open

On the dynamical nature of the active center in a single-site photocatalyst visualized by 4D ultrafast electron microscopy


Understanding the dynamical nature of the catalytic active site embedded in complex systems at the atomic level is critical to developing efficient photocatalytic materials. Here, we report, using 4D ultrafast electron microscopy, the spatiotemporal behaviors of titanium and oxygen in a titanosilicate catalytic material. The observed changes in Bragg diffraction intensity with time at the specific lattice planes, and with a tilted geometry, provide the relaxation pathway: the Ti^(4+)=O^(2−) double bond transformation to a Ti^(3+)−O^(1−) single bond via the individual atomic displacements of the titanium and the apical oxygen. The dilation of the double bond is up to 0.8 Å and occurs on the femtosecond time scale. These findings suggest the direct catalytic involvement of the Ti^(3+)−O^(1−) local structure, the significance of nonthermal processes at the reactive site, and the efficient photo-induced electron transfer that plays a pivotal role in many photocatalytic reactions.

Additional Information

© 2016 National Academy of Sciences. Contributed by Ahmed H. Zewail, November 19, 2015 (sent for review November 4, 2015; reviewed by Oh-Hoon Kwon, Tobin J. Marks, and Hiromi Yamashita). Published online before print January 4, 2016. We are grateful to Drs. Matthew E. Potter and Robert Raja for providing us with the JDF-L1 samples, and Prof. Harry Gray for helpful discussion. This work was supported by the National Science Foundation (DMR-0964886) and the Air Force Office of Scientific Research (FA9550-11-1-0055) in the Gordon and Betty Moore Center for Physical Biology at the California Institute of Technology. J.M.T. is grateful to the Kohn Foundation for financial support. Author contributions: B.-K.Y., Z.S., J.M.T., and A.H.Z. designed research; B.-K.Y. and Z.S. performed experiments; B.-K.Y. and Z.S. analyzed data; and B.-K.Y., Z.S., J.M.T., and A.H.Z. wrote the paper. B.-K.Y. and Z.S. contributed equally to this work. Reviewers: O.-H.K., Ulsan National Institute of Science and Technology; T.J.M., Northwestern University; and H.Y., Osaka University. The authors declare no conflict of interest.

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