SusChEM: Time Resolved In Situ Infrared Spectroscopy of Intermediates in the Electrochemical Reduction of Carbon Dioxide

波士顿学院的Matthias Waegele教授得到了化学系化学催化项目的支持，该项目旨在更好地了解二氧化碳是如何利用现成的铜作为催化剂转化为碳氢化合物的。激发这项研究的主要考虑因素是：二氧化碳的减少可能成为碳氢化合物基燃料的可持续来源，并且该过程还可能为乙烯和其他必需化学品提供可持续的化学途径。开发了一种新颖的、时间分辨的红外光谱方法来检测这一复杂的多步化学转化过程的中间产物。从进行研究中获得的新见解可以更好地理解控制铜的催化活性和选择性的分子起源。对分子水平的更好理解有助于设计和开发工业上可行的催化剂，将二氧化碳转化为燃料和基本化学品。除了该项目在技术上的广泛影响外，在培养研究生和本科生先进化学研究方法方面也实现了社会效益。这项研究是在SusChEM倡议下进行的，因为它使用了一种非贵金属铜作为催化剂。本研究的主要目的是揭示铜在水电化学环境中将二氧化碳还原为甲烷和乙烯的独特催化能力的潜在分子机制。具体来说，本研究旨在描述驱动还原所需的高过电位的机制起源，以及控制一种碳氢化合物产品对另一种碳氢化合物产品选择性的基本步骤。虽然电化学减少二氧化碳的研究已经活跃了三十多年，但该项目开发并采用了一种完全不同的技术，独特地适合于解决这些关键目标。具体来说，电化学电池与时间分辨红外光谱仪耦合。电化学电池的电位在亚微秒的时间尺度上迅速跳跃，为电还原反应提供了快速的电触发。触发反应的瞬态中间体由时间分辨红外光谱仪监测。该方法为指导设计更有效的催化剂提供了新的热力学、动力学和结构信息。

Professor Matthias Waegele of Boston College is supported by the Chemical Catalysis program in the Division of Chemistry to develop a better understanding of how carbon dioxide is converted to hydrocarbons using readily-available copper as a catalyst. The primary considerations that motivate this research are: the reduction of carbon dioxide could potentially serve as a sustainable source of hydrocarbon-based fuels, and the process may additionally provide a sustainable chemical route to ethylene and other essential chemicals. A novel, time-resolved, infrared spectroscopic method is developed to detect intermediates of this complex multi-step chemical conversion process. The new insight gained from conducting the research leads to a better understanding of the molecular origins that control the catalytic activity and selectivity of copper. A better understanding on the molecular level informs the design and development of industrially-viable catalysts for the conversion of carbon dioxide to fuel and building block chemicals. In addition to the technical broader impacts of the project, societal benefits are realized in the training of graduate and undergraduate students in advanced chemical research methods. This research is under the SusChEM initiative as it uses a non-precious metal, copper, as the catalyst. The principal goal of this research is to reveal the underlying molecular mechanism responsible for the unique catalytic ability of copper to reduce carbon dioxide to methane and ethylene in an aqueous electrochemical environment. Specifically, this research aims to delineate the mechanistic origins of the high over-potentials necessary to drive the reduction and the elementary steps which control the selectivity for one hydrocarbon product over the other. While the electrochemical reduction of carbon dioxide has been an active area of research for over three decades, this project develops and employs a fundamentally different technique uniquely suited to address these key aims. Specifically, an electrochemical cell is coupled to a time-resolved infrared spectrometer. The potential of the electrochemical cell is rapidly jumped on a sub-microsecond timescale, providing a fast electrical trigger for the electro-reduction reaction. The transient intermediates of the triggered reaction are monitored by the time-resolved infrared spectrometer. The approach provides new thermodynamic, kinetic, and structural information essential for guiding the design of more efficient catalysts for this reaction.