title: Strong photon energy dependence of the photocatalytic dissociation rate of methanol on TiO2(110).
abstract: Photocatalytic dissociation of methanol (CH3OH) on a TiO2(110) surface has been studied by temperature programmed desorption (TPD) at 355 and 266 nm. Primary dissociation products, CH2O and H atoms, have been detected. The dependence of the reactant and product TPD signals on irradiation time has been measured, allowing the photocatalytic reaction rate of CH3OH at both wavelengths to be directly determined. The initial dissociation rate of CH3OH at 266 nm is nearly 2 orders of magnitude faster than that at 355 nm, suggesting that CH3OH photocatalysis is strongly dependent on photon energy. This experimental result raises doubt about the widely accepted photocatalysis model on TiO2, which assumes that the excess potential energy of charge carriers is lost to the lattice via strong coupling with phonon modes by very fast thermalization and the reaction of the adsorbate is thus only dependent on the number of electron-hole pairs created by photoexcitation.
authors.forename: Chenbiao
authors.initials: C
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , 457 Zhongshan Road, Dalian 116023, P. R. China.
authors.forename: Chengbiao
authors.initials: C
authors.lastname: Xu
authors.forename: Wenshao
authors.initials: W
authors.lastname: Yang
authors.forename: Zefeng
authors.initials: Z
authors.lastname: Ren
authors.forename: Dongxu
authors.initials: D
authors.lastname: Dai
authors.forename: Qing
authors.initials: Q
authors.lastname: Guo
authors.forename: Timothy K
authors.initials: TK
authors.lastname: Minton
authors.forename: Xueming
authors.initials: X
authors.lastname: Yang