Selective Hydrocarbon Production from Carbon Dioxide Electro-reduction via Electrochemical Potential and Mass Transport Engineering

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The use of renewable electricity to convert water and carbon dioxide into energy-dense fuels and high-valued chemicals can improve the storage and utilization of intermittent solar and wind energy. This technology for "solar fuels" has benefits in utilization of renewable energy sources and in sequestering carbon from carbon dioxide into value added chemicals used to make industrial products such as polymers. This project utilizes an electrochemical conversion with carbon dioxide as a feedstock and an externally applied electrical potential (voltage) to produce higher valued chemicals as a goal. The researchers will investigate how to engineer the application of the electrochemical potential to the device in order to improve the yield of products such as ethylene in an energy efficient manner. The project will involve investigations of the impact of using a series of pulses of electrical potential rather than a steady application on the elementary reactions that occur at the boundary of the electrode and electrolyte of the device. The goal is that application of a series of voltage pulses and varying its frequency and energy magnitude could tune the reactions occurring to favor production of hydrocarbons over competing products such as carbon monoxide. For educational broader impacts, the PIs will continue their commitment to fostering undergraduate researchers through summer and academic year research projects. The PIs will continue to sponsor a research ethics workshop for researchers in energy and materials designed for both students and senior investigators. The research outcomes will be integrated into Cornell chemical engineering capstone course projects that are designed to integrate technological innovation, intellectual property, practical engineering, entrepreneurship, and communication in carbon dioxide processing technologies. These activities are aimed at improving students' interests in chemical and materials engineering at both undergraduate and graduate levels, especially for women and members of underrepresented minorities to build diversity in the future STEM workforce.This research will result in fundamental understanding on how to control the selectivity of the carbon dioxide electroreduction reaction by tailoring the temporal profile of the applied electrochemical potential. A number of variables including surface adsorbates, electrical double layer, and transport, play an important role in the carbon dioxide electroreduction selectivity. The project's driving hypothesis is that key reaction and transport phenomena in this system occur at varying timescales that could be taken advantage of to impact the observed reaction selectivity. This project seeks to control these variables by tuning the temporal profile of the electrochemical potential pulse. The central focus is to identify the principles for designing the temporal profile of the electrochemical potential to promote hydrocarbon production and suppress the hydrogen evolution reaction. In addition to selectivity control, the temporal control of the electrochemical potential represents an opportunity to address open questions concerning competing pathways in the carbon dioxide electroreduction and their rate constants. Spectroscopy and simulations will be done in parallel to reveal the thermodynamics and kinetics during the temporal control of the electrochemical potential.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.