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

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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.