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

二氧化钛（Ti 〇 2）是用于太阳能捕获和转移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，并利用它来帮助或催化水（H2O）分解为氢气（H2）和氧气（O2），这些气体可以储存并随后结合以根据需要产生能量。 该材料还可以催化减少二氧化碳（CO2），这是一种温室气体，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对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实现可持续太阳能转换的化学变化。这些反应的快速速度以飞秒（1飞秒等于0.000000000001秒）为单位测量，并通过超快激光光谱学进行研究。 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。 除了研究的广泛影响，以促进清洁和高效的太阳能捕获的发展，有参与该项目的学生的实质性教育效益。Petek博士与中国科技大学的赵博士以及她在武汉大学的同事闵峰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，也为中国学生提供了在Petek博士实验室进行暑期实习的绝佳机会。 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进入研究助理。 他是光催化研究的热心推动者，致力于组织关于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Zhao博士通过时间分辨双光子光电发射（TR-2 PP）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。 2 PP光谱和时间分辨测量揭示了引入到TiO 2的导带中的电子的极化子特性，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的未占共振。 Petek博士在贵金属修饰的TiO 2表面上进行TR-2 PP实验，以揭示等离子体增强的光催化机制。在合作中，赵博士进行电子结构计算，以确定电子和空穴受体状态，可能涉及的电子，吸附在二氧化钛表面的分子。此外，非绝热分子动力学计算用于描述在有限温度下的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（USTC）的实验学家和理论家，致力于通过TiO 2纳米粒子进行可持续太阳能转换的基本方面。除了研究的广泛影响外，对于参与中国科学技术大学和武汉大学与匹兹堡大学之间建立的合作项目的学生来说，也有实质性的教育利益，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进入研究助理。 他是光催化研究的热心推动者，致力于组织关于该主题的国际研讨会，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