The crystal phase, morphology and facet significantly influence the catalytic and photocat- alytic activity of TiO2. In view of optimizing the performance of catalysts, extensive efforts have been devoted to designing...The crystal phase, morphology and facet significantly influence the catalytic and photocat- alytic activity of TiO2. In view of optimizing the performance of catalysts, extensive efforts have been devoted to designing new sophisticate TiO2 structures with desired facet exposure, necessitating the understanding of chemical properties of individual surface. In this work, we have examined the photooxidation of methanol on TiO 2 （011）- （ 2 × 1 ） and TiO 2 （110） - （1 ×1） by two-photon photoemission spectroscopy （2PPE）. An excited state at 2.5 eV above the Fermi level （EF） on methanol covered （011） and （110） interface has been detected. The excited state is an indicator of reduction of TiO2 interface. Irradiation dependence of the excited resonance signal during the photochemistry of methanol on TiO2（011）-（2×1） and TiO2（110）-（1× 1） is ascribed to the interface reduction by producing surface hydroxyls. The reaction rate of photooxidation of methanol on TiO2（110）-（1× 1） is about 11.4 times faster than that on TiO2（011）-（2×1）, which is tentatively explained by the difference in the surface atomic configuration. This work not only provides a detailed characterization of the electronic structure of methanol/TiO2 interface by 2PPE, but also shows the importance of the surface structure in the photoreactivity on TiO2.展开更多
基金This work was supported the Natural Science Foundation of Liaoning Province （No.2015020242）, the National Natural Science Foundation of China （No.21203189 and No.21573225）, and the State Key Laboratory of Molecular Reaction Dynamics （No.ZZ- 2014-02）.
文摘The crystal phase, morphology and facet significantly influence the catalytic and photocat- alytic activity of TiO2. In view of optimizing the performance of catalysts, extensive efforts have been devoted to designing new sophisticate TiO2 structures with desired facet exposure, necessitating the understanding of chemical properties of individual surface. In this work, we have examined the photooxidation of methanol on TiO 2 （011）- （ 2 × 1 ） and TiO 2 （110） - （1 ×1） by two-photon photoemission spectroscopy （2PPE）. An excited state at 2.5 eV above the Fermi level （EF） on methanol covered （011） and （110） interface has been detected. The excited state is an indicator of reduction of TiO2 interface. Irradiation dependence of the excited resonance signal during the photochemistry of methanol on TiO2（011）-（2×1） and TiO2（110）-（1× 1） is ascribed to the interface reduction by producing surface hydroxyls. The reaction rate of photooxidation of methanol on TiO2（110）-（1× 1） is about 11.4 times faster than that on TiO2（011）-（2×1）, which is tentatively explained by the difference in the surface atomic configuration. This work not only provides a detailed characterization of the electronic structure of methanol/TiO2 interface by 2PPE, but also shows the importance of the surface structure in the photoreactivity on TiO2.
