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

二氧化钛(Ti02)是一种用于太阳能捕获和传输以驱动化学过程的模型系统。这种材料能够吸收紫外光，并用它来协助或催化水(H2O)分解为氢(H2)和氧(O2)气体，这些气体可以被储存起来，然后根据需要结合起来产生能量。这种材料还可以催化二氧化碳(CO2)的减少，二氧化碳是燃烧化石燃料的最终产物，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。佩泰克博士从事基础研究，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在材料中传输，并被用来影响化学变化，以实现可持续的太阳能转换。这些反应的快速度是在飞秒(1飞秒等于0.000000000000001秒)内测量的，并用超快激光光谱进行了研究。佩泰克博士和他的合作者赵博士将先进的超快激光光谱学实验与理论计算相结合，以理解这些光催化事件。除了这项研究对开发清洁和高效的太阳能捕获技术有更广泛的影响外，参与该项目的学生还能从教育中获益良多。Petek博士与科技大学的赵博士、武汉大学的中国博士和她的同事冯敏博士建立的合作安排为匹兹堡大学的学生提供了在中国实验室工作的绝佳机会，也为中国学生在Petek博士的实验室担任暑期实习生提供了极好的机会。为了扩大学生参与研究的范围，佩泰克博士利用匹兹堡量子计划招募有才华的本科生加入研究助学金。他是光催化研究的热心推动者，致力于组织关于这一主题的国际研讨会，并担任《表面科学进展》杂志的主编。在化学系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发射(TR-2PP)实验和先进的电子结构理论研究了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到二氧化钛导带中的电子的极化子特征，化学吸附的分子与极化子的相互作用，以及化学吸附的分子如二氧化碳的未占据共振。佩特克博士在贵金属修饰的二氧化钛表面进行了tr-2PP实验，以揭示等离子体增强光催化的机理。在合作中，赵博士进行电子结构计算，以确定吸附在二氧化钛表面的分子的电子和空穴受体状态，这可能涉及光催化。此外，还用非绝热分子动力学计算方法描述了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弛豫速率。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技大学(科大)的实验者和理论家，致力于通过二氧化钛光催化实现可持续太阳能转换的基本方面。除了这项研究的广泛影响外，参与科大与武汉大学与匹兹堡大学建立的合作项目的学生也获得了实质性的教育收益，该项目为本科生和研究生提供了国际交流的机会。为了扩大学生参与研究的范围，佩泰克博士利用匹兹堡量子计划招募有才华的本科生加入研究助学金。他是光催化研究的热心推动者，致力于组织关于这一主题的国际研讨会，并担任《表面科学进展》杂志的主编

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