Surface science studies of the photo physics of copper oxides: toward sustainable CO2 recycling

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Solar conversion of CO2 and water to useful chemicals and fuels can provide a pathway to a sustainable carbon cycle, while maintaining existing infrastructure in the chemical and transport industries. Efficient use of solar energy to break the stable CO2 bonds is the first step in this process and requires tailoring the photophysical properties of the catalysts used for that reaction. In this project, Profs. Gupta and Asthagiri of Ohio State University are working to understand the relationship between catalyst surface structure and solar energy transfer into the CO2 molecule. The goal is to understand the factors that promote this energy transfer and promote CO2 conversion. As part of this project, the PIs are training graduate students to combine experiment and theory to tackle important energy generation and conversion problems. In addition, the PIs are engaging students from the K-12 and undergraduate level as part of an outreach effort to diversify student participation in STEM careers. Graduate students, as part of Ohio State's TEK8 program, are developing modules to engage K-12 students interest in STEM careers. In addition, underrepresented undergraduate students are being recruited for summer research as part of Ohio State's Summer Research Opportunities Program. With funding from the NSF Chemical Catalysis program of the Chemistry Division, Dr. Gupta and Asthagiri from The Ohio State University are developing a program that combines experiment and theory aimed to gain a fundamental understanding of the relationship between local surface structure of Cu oxides and the photoexcitation of CO2 molecules. Cu oxide thin films are grown in a controlled fashion in ultrahigh vacuum (UHV) that allows for the introduction of various defects (e.g. vacancies, variation in Cu oxide film stoichiometry, and dopants). Scanning tunneling microscopy (STM) with local photoillumination provide direct images of the surface before and after illumination. Density functional theory (DFT) calculations are assisting in interpreting both the images and spectroscopy from STM to link the relationship between the electronic states of the local Cu oxide site and the resulting CO2 photochemistry. In addition, DFT is being used to explore modifications to the Cu oxide films that enhance CO2 photoactivation; these predictions are being tested experimentally with the goal to establish a predictive model for optimal Cu oxide nanostructures for CO2 photoreduction. As part of this project, the PIs are actively engaged in the recruitment of underrepresented groups in graduate and undergraduate research and developing modules to foster the interest in STEM careers of K-12 students through Ohio State's TEK8 program.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.