TiO2 Photocatalysis: The coupling of electrons, plasmons, polarons, and molecules by ultrafast photoemission spectroscopy and theory

TiO2 光催化：通过超快光电子能谱和理论耦合电子、等离激元、极化子和分子

• 批准号: 1565842
• 负责人: Hrvoje Petek
• 金额: $ 67.5万
• 依托单位: University of Pittsburgh
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-15 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1565842&HistoricalAwards=false
• 关键词: TiO2; Photocatalysis; coupling; electrons; plasmons

Titanium dioxide (Ti02) is a model system for solar energy capture and transfer to drive chemical processes. The material has the ability to absorb ultraviolet (UV) light and use it to assist in, or catalyze, the decomposition of water (H2O) to hydrogen (H2) and oxygen (O2) gases, which can be stored and later combined to produce energy on demand. The material can also catalyze the reduction of carbon dioxide (CO2), a greenhouse gas that is the final product of burning fossil fuels, and transform this environmentally harmful gas into useful hydrocarbons for the chemical industry. Dr. Petek is engaged in fundamental studies of how this material absorbs UV light to create electron-hole pairs and how these electrons and holes are transported through the material and used to effect chemical change for sustainable solar energy conversion. The fast speeds of these reactions are measured in femtoseconds (1 femtosecond equals 0.000000000000001 second), and are studied by ultrafast laser spectroscopy. Dr. Petek and his collaborator, Dr. Zhao, combine advanced ultrafast laser spectroscopy experiments with theoretical calculations to understand these photo-catalytic events. In addition to the broader impacts of the research to contribute to the development of clean and efficient solar energy capture, there are substantial educational benefits for the students involved in the project. The collaborative arrangement that Dr. Petek has established with Dr. Zhao at the University of Science and Technology China and her co-worker Dr. Min Feng at Wuhan University provides excellent opportunities for students from the University of Pittsburgh to work in the Chinese laboratories, as well as for Chinese students to serve as summer interns in Dr. Petek's laboratory. To broaden student participation in research, Dr. Petek uses the Pittsburgh Quantum Initiative to recruit talented undergraduate students into research assistantships. He is an ardent promotor of photocatalytic research, working to organize of international symposia on the topic as well as serving in the role of Editor-in-Chief of the journal Progress in Surface Science. With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Petek and Dr. Zhao study the electron spectroscopy and dynamics related to photocatalytic processes by means of time-resolved two-photon photoemission (TR-2PP) experiments and advanced electronic structure theory. The 2PP spectra and time resolved measurements reveal the polaronic character of electrons introduced into the conduction band of TiO2, the interaction of chemisorbed molecules with the polarons, and the unoccupied resonances of chemisorbed molecules such as CO2. Dr. Petek conducts TR-2PP experiments on noble metal decorated TiO2 surfaces to reveal the mechanisms of plasmonically enhanced photocatalysis. In collaboration, Dr. Zhao performs electronic structure calculations to identify the electron and hole acceptor states, potentially involved in photocatalysis, for molecules adsorbed on TiO2 surface. In addition, nonadiabatic molecular dynamics calculations are used to describe the interfacial charge transfer dynamics and carrier energy relaxation rates for chemisorbed molecular overlayers at finite temperatures. The research has broader impacts as it brings together experimentalists and theorists from the University of Pittsburgh and University of Science and Technology of China (USTC) to work on the fundamental aspects of sustainable solar energy conversion via TiO2 photocatalysis. In addition to the broader impacts of the research, there are substantial educational benefits for students involved in the established collaborative project between the USTC and Wuhan University with the University of Pittsburgh, which provides opportunities for undergraduate and graduate student international exchange. To broaden student participation in research, Dr. Petek uses the Pittsburgh Quantum Initiative to recruit talented undergraduate students into research assistantships. He is an ardent promotor of photocatalytic research, working to organize of international symposia on the topic as well as serving in the role of Editor-in-Chief of the journal Progress in Surface Science

二氧化钛 (Ti02) 是太阳能捕获和传输以驱动化学过程的模型系统。 该材料具有吸收紫外线 (UV) 的能力，并用它来协助或催化水 (H2O) 分解为氢气 (H2) 和氧气 (O2)，这些气体可以被储存起来，然后根据需要结合产生能量。 该材料还可以催化二氧化碳（CO2）（一种燃烧化石燃料的最终产物温室气体）的还原，并将这种对环境有害的气体转化为化学工业有用的碳氢化合物。 Petek 博士从事基础研究，研究这种材料如何吸收紫外线以产生电子空穴对，以及这些电子和空穴如何通过材料传输并用于影响化学变化以实现可持续的太阳能转换。这些反应的快速速度以飞秒为单位（1飞秒等于0.000000000000001秒），并通过超快激光光谱进行研究。 Petek 博士和他的合作者赵博士将先进的超快激光光谱实验与理论计算相结合，以了解这些光催化事件。 该研究除了对清洁高效太阳能捕获的发展做出贡献之外，还为参与该项目的学生带来了巨大的教育效益。 Petek博士与中国科学技术大学的赵博士以及她的同事武汉大学的冯敏博士建立的合作安排为匹兹堡大学的学生在中国实验室工作以及中国学生在Petek博士的实验室担任暑期实习生提供了极好的机会。 为了扩大学生对研究的参与，Petek 博士利用匹兹堡量子计划招募有才华的本科生担任研究助理。 他是光催化研究的热心推动者，致力于组织该主题的国际研讨会，并担任《表面科学进展》杂志的主编。在化学部化学催化项目的资助下，Petek博士和赵博士通过时间分辨双光子光电子发射（TR-2PP）实验和先进的电子结构理论研究与光催化过程相关的电子光谱和动力学。 2PP 光谱和时间分辨测量揭示了引入 TiO2 导带的电子的极化特性、化学吸附分子与极化子的相互作用以及化学吸附分子（如 CO2）的未占据共振。 Petek 博士在贵金属修饰的 TiO2 表面上进行了 TR-2PP 实验，以揭示等离子体增强光催化的机制。在合作中，赵博士进行了电子结构计算，以确定二氧化钛表面吸附分子的电子和空穴受体状态，这些状态可能参与光催化。此外，非绝热分子动力学计算用于描述有限温度下化学吸附分子覆盖层的界面电荷转移动力学和载流子能量弛豫率。这项研究具有更广泛的影响，因为它汇集了匹兹堡大学和中国科学技术大学 (USTC) 的实验家和理论家，致力于通过 TiO2 光催化实现可持续太阳能转换的基本方面。除了该研究的更广泛影响之外，参与中国科大、武汉大学与匹兹堡大学合作项目的学生也能获得巨大的教育效益，该项目为本科生和研究生的国际交流提供了机会。为了扩大学生对研究的参与，Petek 博士利用匹兹堡量子计划招募有才华的本科生担任研究助理。 他是光催化研究的热心推动者，致力于组织该主题的国际研讨会，并担任《表面科学进展》杂志的主编