Titanium Dioxide Photocatalysis: Interactions of band edge carriers with molecules by ultrafast photoemission spectroscopy and theory

二氧化钛光催化：超快光电子能谱和理论的带边载流子与分子的相互作用

• 批准号: 1213189
• 负责人: Hrvoje Petek
• 金额: $ 45万
• 依托单位: University of Pittsburgh
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1213189&HistoricalAwards=false
• 关键词: Titanium; Dioxide; Photocatalysis; Interactions; band

With this award from the Chemical Catalysis Program of the Chemistry Division of the National Science Foundation, Prof. Hrvoje Petek, his collaborator Dr. Jin Zhao and their students at the University of Pittsburgh will study by experiment and theory the electron driven processes in photocatalytic chemistry on rutile titanium dioxide surfaces. Excitation of carriers across the band gap of titanium dioxide with near-ultraviolet light is known to initiate a variety of photocatalytic processes involving interaction of adsorbed molecules with energetic electrons and holes. The timescales of photophysical and photochemical processes span femtoseconds to seconds. The interaction of photoexcited electrons with adsorbed molecules and defects will be studied for molecule covered single crystal titanium dioxide surfaces under ultrahigh vacuum conditions by time-resolved two-photon photoemission spectroscopy. The extension of the two-photon photoemission technique to 4.6 eV will enable the study of dynamics of the most chemically significant conduction band edge electrons with chemisorbed molecules. In parallel, advanced theoretical methods will be used to study how photoexcited carriers initiate chemical reactions of chemisorbed molecules.Titanium dioxide is a model photocatalyst of significant fundamental interest for the conversion of solar to chemical energy starting with abundant chemical feedstocks such as water and carbon dioxide. A central issue in photocatalysis is how photoexcited carriers (electrons and holes) interact with adsorbed molecules to initiate chemical reactions. Such knowledge can be used to design more efficient photocatalyst materials and practical solar energy conversion processes. The potential advances in harnessing solar energy can conceivably reduce our reliance on fossil fuels and convert potentially harmful byproducts of combustion into valuable chemical fuels. This research will be used to train the next generation of scientists since students will be exposed to high-level experimental and theoretical methods for investigation of ultrafast interfacial dynamics. They will explore research areas that can have major impacts on society, and will be exposed to international collaboration with colleagues at the University of Science and Technology of China.

在国家科学基金会化学部化学催化计划的这一奖项下，Hrvoje Petek教授和他的合作者金照博士以及他们在匹兹堡大学的学生将通过实验和理论研究金红石型二氧化钛表面光催化化学中的电子驱动过程。利用近紫外光激发跨越二氧化钛带隙的载流子，可以启动各种光催化过程，包括吸附分子与高能电子和空穴的相互作用。光物理和光化学过程的时间跨度从飞秒到秒。在超高真空条件下，利用时间分辨双光子光电子能谱研究了分子覆盖的二氧化钛单晶表面光激发电子与吸附分子和缺陷的相互作用。将双光子光电发射技术扩展到4.6 eV，将使研究最具化学意义的传导带边电子与化学吸附分子的动力学成为可能。同时，还将使用先进的理论方法来研究光激发载体如何引发化学吸附分子的化学反应。二氧化钛是一种模型光催化剂，从水和二氧化碳等丰富的化学原料开始，将太阳能转化为化学能，具有重要的基础意义。光催化中的一个中心问题是光激发的载体(电子和空穴)如何与被吸附的分子相互作用来启动化学反应。这些知识可以用来设计更高效的光催化材料和实用的太阳能转换工艺。可以想象，在利用太阳能方面的潜在进展可以减少我们对化石燃料的依赖，并将燃烧的潜在有害副产品转化为有价值的化学燃料。这项研究将用于培养下一代科学家，因为学生将接触到研究超快界面动力学的高水平实验和理论方法。他们将探索可能对社会产生重大影响的研究领域，并将与中国科技大学的同事开展国际合作。