title: Ultrafast Dynamics of Photongenerated Holes at a CH3OH/TiO2Rutile Interface.
abstract: Photogenerated charge carrier dynamics near molecule/TiO2interfaces are important for the photocatalytic and photovoltaic processes. To understand this fundamental aspect, we performed a time-domain ab initio nonadiabatic molecular dynamics study of the photogenerated hole dynamics at the CH3OH/rutile TiO2(110) interface. We studied the forward and reverse hole transfer between TiO2and CH3OH as well as the hole energy relaxation to the valence band maximum. First, we show that the hole-trapping ability of CH3OH depends strongly on the adsorption structure. Only when the CH3OH is deprotonated to form chemisorbed CH3O will ∼15% of the hole be trapped by the molecule. Second, we find that strong fluctuations of the HOMO energies of the adsorbed molecules induced by electron-phonon coupling provide additional channels, which accelerate the hole energy relaxation. Third, we demonstrate that the charge transfer and energy relaxation processes depend significantly on temperature. When the temperature decreases from 100 to 30 K, the forward hole transfer and energy relaxation processes are strongly suppressed because of the reduction of phonon occupation. These results indicate that the molecule/TiO2energy level alignment, thermal excitation of a phonon, and electron-phonon coupling are the key factors that determine the photogenerated hole dynamics. Our studies provide valuable insights into the photogenerated charge and energy transfer dynamics at molecule/semiconductor interfaces.
authors.forename: Weibin
authors.initials: W
authors.lastname: Chu
authors.affiliation: Department of Mechanical Engineering and Materials Science, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States.
authors.forename: Wissam A
authors.initials: WA
authors.lastname: Saidi
authors.forename: Qijing
authors.initials: Q
authors.lastname: Zheng
authors.affiliation: Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao, Shandong 266101, China.|University of Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao, Shandong 266101, China.|University of Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Zhenggang
authors.initials: Z
authors.lastname: Lan
authors.affiliation: Departments of Chemistry and Physics and Astronomy, University of Southern California , Los Angeles, California 90089, United States.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Prezhdo
authors.affiliation: Department of Physics and Astronomy, University of Pittsburgh , Pittsburgh Pennsylvania 15260, United States.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Petek
authors.affiliation: Department of Physics and Astronomy, University of Pittsburgh , Pittsburgh Pennsylvania 15260, United States.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhao