SusChEM: Mechanistic Studies of Photocatalytic Water-Splitting and CO2Reduction: The control of surface chemical reactivity and its effect on product distribution

光催化水分解和二氧化碳还原的机理研究：表面化学反应性的控制及其对产品分布的影响开发廉价的催化材料，有效地利用太阳能将简单、易得的物质转化为可持续生产的燃料和化学品是21世纪的重大挑战之一。这种光催化过程被称为“人工光合作用”，因为它有望从二氧化碳（CO2）和水（H2O）中提供廉价、清洁的能源和化学品。目前，科学家们还不能完全理解如何控制光催化反应，从大量潜在的产物中生产出最理想的化学物质。在这个项目中，Laursen博士正在研究如何精确地控制人工光合作用的表面化学反应性。如果我们要以对环境负责的方式有选择地生产燃料或基本化学物质，这是我们社会所需要的，那么高度的控制是至关重要的。他积极参与建立在他的研究基础上的外展活动，以促进学生对科学、技术、工程和数学（STEM）学科的参与。这些活动，包括在Laursen博士实验室的暑期研究实习，旨在改善有前途的高中毕业生和女学生的教育，并鼓励她们对STEM职业的兴趣。在化学部门化学催化项目的资助下，田纳西大学诺克斯维尔分校的Siris Laursen博士正在对Bi2S3、GaP和CdS半导体光催化剂的表面性质如何决定它们在将CO2和H2O还原为氢气、甲烷和简单含氧碳氢化合物时的催化活性和产物选择性进行基本的了解。表面结合的中间体在决定催化剂效能的机制中起重要作用，随后使用原位漫反射红外傅立叶变换光谱（DRIFTS）将各种中间体的热化学稳定性与反应速率和产物选择性联系起来。目前正在研究的是，如何控制表面结合的氢的化学性质，使其优先产生还原的有机分子，而不是氢分子或一氧化碳分子。密度泛函理论（DFT）计算与实验工作并行进行，并用于支持结构-活性和组成-活性性质的确定。Laursen博士积极参与STEM外展计划，专注于女性学生招募进入STEM领域和高中生研究实习，以支持该项目的更广泛影响。

SusChEM: Mechanistic Studies of Photocatalytic Water-Splitting and CO2 Reduction: The control of surface chemical reactivity and its effect on product distributionDeveloping inexpensive catalytic materials that efficiently use solar energy to transform simple, readily-available substances into sustainably-produced fuels and chemicals is one of the grand challenges of the 21st century. This photocatalytic process is called "Artificial Photosynthesis" and is pursued for its promise of supplying cheap, clean energy and chemicals from carbon dioxide (CO2) and water (H2O). Currently, scientists do not completely understand how photocatalytic reactions can be controlled to produce the most desirable chemicals out of a large number of potential products. In this project, Dr. Laursen is developing an understanding of exactly how to control the surface chemical reactivity of Artificial Photosynthesis. A high level of control is critical if we are to produce the fuel or building-block chemicals selectively in an environmentally responsible fashion, as needed by our society. Dr. Laursen is actively engaged in outreach activities that build upon his research to promote engagement of students in science, technology, engineering and mathematics (STEM) disciplines. These activities, which include summer research internships in Dr. Laursen's laboratory, are directed at improving the education of promising high school seniors and women students and encouraging their interest in STEM careers. With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Siris Laursen of the University of Tennessee - Knoxville is developing a fundamental understanding of how the surface properties of Bi2S3, GaP, and CdS semiconductor photocatalysts dictate their catalytic activity and product selectivity in the reduction of CO2 and H2O to hydrogen, methane and simple oxygenated hydrocarbons. The surface-bound intermediates important in the mechanisms that determine catalyst efficacy are followed with in situ Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFTS) to correlate the thermochemical stability of the various intermediate species with reaction rate and product selectivity. Also under investigation is how the chemical nature of surface bound hydrogen can be controlled to produce reduced organic molecules preferentially over molecular hydrogen or carbon monoxide. Density functional theory (DFT) calculations are carried out in parallel to the experimental work, and are used in support of structure-activity and composition-activity property determination. Dr. Laursen is actively engaged in STEM outreach programs focused on female student recruitment into the STEM fields and in high school student research internships, in support of the broader impacts of the project.