Modulating H2O Activity Promotes CO2 Reduction to Multi-Carbon Products

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Electrochemistry – driven by sustainable or renewable electrical energy generated by wind or solar energy – offers a path toward a sustainable, circular carbon economy, thereby reducing our reliance on fossil fuels and mitigating the impacts of climate change. To that end, the project focuses on transforming carbon dioxide (CO2), a major greenhouse gas, into value-added chemicals and fuels. The novelty of the project lies in understanding the role of water in the electrochemical reactions that convert CO2 efficiently and selectively to multi-carbon hydrocarbon chemicals for use as building-blocks for a broad range of products including fuels, plastics, coatings, and construction products. By varying the concentration of salt in a solution, the chemical activity of water (H2O) can be altered, potentially enabling greater control over the reaction of CO2 with H2O to produce the desired multi-carbon products. Beyond the technical aspects, the project offers educational and training opportunities in STEM areas, especially focused on socioeconomically disadvantaged students. The project investigates the role of H2O in modulating the electrocatalytic CO2 reduction reaction (CO2RR) to favor efficient and selective formation of C2+ products. Preliminary data from the investigator’s laboratory has shown that lowering the water activity favors the generation of multi-carbon products. By adjusting the salt concentrations within a range of 0.1 to 10 molal in the water the investigators have successfully altered the activity of water in the solution, which, in turn, enhances the production of C2 products over their C1 counterparts. Three specific project thrusts will be pursued to understand the origin of improved electrochemical reduction of CO2 to C2 or C2+ products with decreased water activity, namely: 1) optimize solution composition by simultaneously varying the cation, anion, and water activity for improved CO2-to-multicarbon fuels on Cu electrodes, 2) interrogate the role of the electrolyte structure in modulating catalysis with surface-enhanced in-situ infrared absorption spectroscopy (SEIRAS); and 3) explore electrolyte engineering to boost CO2 reduction to multi-carbon alcohols on Cu-alloy catalysts. Broader educational and outreach aspects of the project will introduce socioeconomically disadvantaged students to concepts of renewable energy research. Specifically, the investigator, along with a post-doctoral associate and undergraduate student, will participate in the Engineering Innovation Program (EIP) at Johns Hopkins University. Students will conduct straightforward hands-on experiments to acquaint them with fundamental renewable energy concepts, with the goal of piquing their interest in STEM areas as related to educational and career paths supporting greenhouse gas reduction and mitigation of environmental impacts.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.