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Facet Dependence of Photochemistry of Methanol on Single Crystalline Rutile Titania
Qun-qing Hao1, Zhi-qiang Wang1, Xin-chun Mao2, Chuan-yao Zhou1, Dong-xu Dai1, Xue-ming Yang1
1.State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023, China;2.Center of Interface Dynamics for Sustainability, Institute of Materials, China Academy of Engineering Physics, Chengdu 610200, China
Abstract:
The crystal phase, morphology and facet significantly influence the catalytic and photocatalytic 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 TiO2(011)-(2×1) and TiO2(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.
Key words:  TiO2  Excited state  Two-photon photoemission spectroscopy  Reaction rate of photooxidation
FundProject:
甲醇在二氧化钛上的光化学性质与表面结构的相关性
郝群庆1, 王志强1, 毛新春2, 周传耀1, 戴东旭1, 杨学明1
1.中国科学院大连化学物理研究所分子反应动力学国家重点实验室, 大连 116023;2.中国工程物理研究院材料研究所可持续界面动力学研究中心, 成都 610200
摘要:
通过双光子光电子的方法探测了TiO2(011)-(2×1) 和TiO2(110)-(1×1)表面的光催化氧化甲醇的性质. 在吸附了甲醇的二氧化钛(011)和(110)界面处探测到了一个费米能级以上2.5 eV的电子激发态,该电子激发态可作为测试二氧化钛界面还原性的探针使用. 利用此探针在甲醇/TiO2(011)-(2×1)和甲醇/TiO2(110)-(1×1)界面探测到了一个随光照时间的电子激发态信号变化,这一变化可以归于光催化生成的表面羟基对界面还原性的影响. 由此得出的光催化氧化甲醇的速率TiO2(110)-(1×1)比TiO2(011)-(2×1)快了大约11.4倍. 这可能由于表面原子结构排布的原因不同. 本工作不仅介绍了一个利用双光子光电子能谱探测到的甲醇/TiO2界面电子结构的细节特征,还揭示了表面结构对二氧化钛光反应性质的重要影响.
关键词:  二氧化钛  电子激发态  双光子光电子能谱  光催化氧化速率
DOI:10.1063/1674-0068/29/cjcp1601005
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