A remarkable feature of TiO2 is that band gap excitation with near UV light can induce photocatalytic dissociation of simple molecules such as H2O and CH3OH.  Heterogeneous photocatalysis is usually initiated by electron-hole pair generation in the bulk semiconductor1 followed by charge migration and transfer to the molecular overlayer at the interface.  We study the carrier-induced dynamics by combining ultrafast spectroscopic and UHV surface science techniques.  By time resolved two-photon photoemission and calculations at the DFT and GW-BSE levels we identify the partially solvated or �wet� electron accepter states for H2O and CH3OH overlayers on TiO2(110) surface 2, 3, and their proton-coupled electron transfer (PCET) dynamics 4, 5.  Because holes are through to be the primary reagents for photocatalysis on TiO2, we also explore possible hole driven PCET dynamic pathways by theory.  The coupling of electron and proton motions on the femtosecond time scale is a prerequisite for solar energy conversion to clean H2 fuel.  1 L. Chiodo, J. M. Garc�a-Lastra, A. Iacomino, S. Ossicini, J. Zhao, H. Petek, and A. Rubio, Phys. Rev. B 82 , 045207 (2010).2  K. Onda, B. Li, J. Zhao, K. D. Jordan, J. Yang, and H. Petek, Science 308 , 1154 (2005).3 J. Zhao, B. Li, K. Onda, M. Feng, and H. Petek, Chem. Rev. 106 , 4402 (2006).4 B. Li, J. Zhao, K. Onda, K. D. Jordan, J. Yang, and H. Petek, Science 311 , 1436 (2006).5 H. Petek and J. Zhao, Chem. Rev. 110 , 7082 (2010).

Ultrafast interfacial charge transfer dynamics in TiO<sub>2</sub> photocatalysis

243rd National Meeting (2012)

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Ultrafast interfacial charge transfer dynamics in TiO2 photocatalysis

Ultrafast interfacial charge transfer dynamics in TiO₂ photocatalysis