ATR-FTIR Spectroscopy of Electrochemical Catalytic Reactions in Aqueous Systems at Doped Diamond Film Electrodes

0931749施雷德的学术价值：这项研究的目标是开发一种新的方法，以了解水相系统中高官能化有机化合物的电催化转化机理。为此，一种强大的原位技术--衰减全反射傅里叶变换红外光谱(ATR-FTIR)将被集成到创新的“光谱-电化学池”的设计中。该装置将用于系统地研究溶液/电极界面(例如，作为电极电位、溶液pH和表面功能的函数)。具有关键化学官能团的模型有机化合物将被用作主要在还原(阴极)条件下阐明催化电荷转移机理的探针。此外，还将并行进行一系列间歇反应实验，以确定这些还原转化的动力学，包括作为温度函数的测量，以确定活化能。实验数据将与密度泛函理论(DFT)计算相补充，以增强和验证力学见解。将原位ATR-FTIR光谱、动力学测量和密度泛函计算相结合，将为深入理解水溶液中的电化学反应机理提供一种新的方法。这一新方法将使用导电的掺硼金刚石(BDD)薄膜电极进行演示。与传统的玻碳、贵金属和金属氧化物电极相比，BDD电极的主要优点是：1)阳极极化下的高稳定性，2)抑制水电解反应，3)化学惰性，4)低本底电流和双层充电。这些性质也使BDD薄膜成为研究金属纳米颗粒催化和电化学性质的理想载体。虽然近年来对BDD电极的研究有所增加，但对原位条件下BDD表面和负载型金属纳米颗粒的表面化学机理的了解还没有发展。BDD表面的表面化学成分可以根据施加的电极电位和溶液条件而改变，是溶液/电极界面电荷转移的控制因素。这些因素决定了BDD电极在大量应用中的用途。更广泛的影响：BDD电极已被成功地证明具有各种技术应用：1)水消毒和处理；2)电化学传感；以及3)有机化合物的电合成。它们作为催化剂载体的潜在用途在很大程度上仍未开发，尽管它们的应用对于可能涉及水环境的系统非常有吸引力，例如用于燃料的生物原料加工或用于特种化学品生产的“绿色化学”。该项目还将增加来自代表性不足群体的研究生和本科生对工程研究的参与。这些研究生将参加阿尔弗雷德·P·斯隆基金会：美国印第安人研究生伙伴关系奖学金和亚利桑那州学者计划。这项计划旨在满足全国对有学术准备的美洲原住民的需求，这些原住民能够帮助刺激他们所在社区和保留地的经济发展，并在学院和大学、政府和企业界担任领导职位。该项目还将通过UA高中高年级专业实习计划、NASA太空助学金本科生实习计划、UA水可持续本科生奖学金计划和UA暑期研究所(SRI)提供新的更多机会，让高中生和本科生参与研究。化学和环境工程部目前是美国国家科学基金会“可持续发展的系统方法：制造、水和能源”(美国国家科学基金会#0649202)REU和RET网站的东道主。这项拟议的研究将在每一年的拨款期间涉及这些项目的几名本科生和高中教师。

0931749 Schrader Intellectual Merit: The objective of this research is to develop a new methodology for understanding the mechanisms of electro-catalytic conversions of highly functionalized organic compounds in aqueous phase systems. To that end, a powerful in situ technique, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, will be integrated into the design of an innovative "spectro-electrochemical cell". This device will be used to study solution/electrode interfaces systematically (e.g., as a function of electrode potential, solution pH, and surface functionality). Model organic compounds with key chemical functional groups will be used as probes for elucidating catalytic charge transfer mechanisms, primarily under reductive (cathodic) conditions. Additionally, a series of batch-reaction experiments will be performed in parallel to determine the kinetics of these reductive conversions, including measurements as a function of temperature for determination of activation energies. The experimental data will be complemented with density functional theory (DFT) calculations to augment and validate the mechanistic insights. The combination of in situ ATR-FTIR spectroscopy, kinetic measurements, and DFT calculations will constitute a new methodology for developing a deeper understanding of the mechanisms of electrochemical reactions in aqueous solutions. This new methodology will be demonstrated using conductive boron-doped diamond (BDD) film electrodes. The main advantages of BDD electrodes over traditional glassy carbon, noble metal, and metal oxide electrodes are: 1) high stability under anodic polarization, 2) suppression of water electrolysis reactions, 3) chemical inertness, and 4) low background current and double layer charging. These properties also make BDD films an ideal support for studying the catalytic and electrochemical properties of metal nanoparticles. Although research on BDD electrodes has increased in recent years, a mechanistic understanding of the surface chemistry of the BDD surface and supported metal nanoparticles under in situ conditions has not been developed. The surface chemistry of the BDD surface can change depending on the applied electrode potential and solution conditions and is the governing factor for charge transfer at the solution/electrode interface. These factors dictate the utility of BDD electrodes for a vast number of applications. Broader Impact: BDD electrodes have been successfully shown to have a variety of technological applications: 1) water disinfection and treatment; 2) electrochemical sensing; and 3) electro-synthesis of organic compounds. Their potential use as catalyst supports remains largely untapped, although their application is highly attractive for systems that may involve aqueous environments such as bio-feedstock processing for fuels or "green chemistry" for specialty chemicals production. This project will also increase participation of graduate and undergraduate students from underrepresented groups in engineering research. The graduate students will participate in the Alfred P. Sloan Foundation: American Indian Graduate Partnership Fellowships and Arizona Scholars Program. This program is designed to address the national need for academically - prepared Native Americans who can help spur economic development in their communities and reservations and occupy leadership positions in colleges and universities, government and the corporate world. The project will also provide new expanded opportunities to involve high school and undergraduates in research through the UA Professional Internship Program for High School Seniors, the NASA Space Grant Undergraduate Internship Program, the UA Water Sustainability Undergraduate Fellowship Program, and the UA Summer Research Institute (SRI). The Chemical and Environmental Engineering Department is currently the host for an NSF REU and RET site on "Systems Approach to Sustainability: Manufacturing, Water and Energy" (NSF# 0649202). The proposed research will involve several undergraduates and high school teachers from these programs during each year of the grant.