CAS: Cooperative Site and Electrolyte Design for Optimizing Interfacial Electrokinetics

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With the support of the Chemical Catalysis program in the Division of Chemistry, Drs. Huiyuan Zhu and Hongliang Xin of the Virginia Polytechnic Institute and State University are studying new strategies to improve the performance of catalysts that recycle carbon dioxide (CO2) using renewable electricity. Traditional metal electrodes, including precious metals (Au, Ag) and base metals (Cu, Zn), have shown encouraging performance toward CO2 reduction. However, the process is limited by low energy efficiency and poor product selectivity. These processes are conducted in water, and the competing reduction of water to H2 is largely responsible for this inefficiency. This proposal addresses this challenge using ionic liquids as non-aqueous electrolytes together with electrode materials designed to work with ionic liquids. The educational components of the project include the following: (1) The interdisciplinary training of undergraduate and graduate students in electrochemical techniques, materials characterization, and molecular modeling. (2) The involvement of diverse underrepresented groups including female students in science and engineering. (3) The implementation of STEM outreach programs to K-12 students from diverse groups and low-income families through hands-on demonstrations that illustrate the importance of nanomaterials, modeling, catalysis, and energy in our daily life. Undergraduate summer interns from underrepresented minority groups will be recruited to work on this project through a partnership with Hampton University. With the support of the Chemical Catalysis program in the Division of Chemistry, Drs. Huiyuan Zhu and Hongliang Xin of the Virginia Polytechnic Institute and State University are studying a cooperative site and electrolyte tuning strategy for the rational design of electrocatalytic systems to get beyond energy-scaling limitations, specifically for electrochemical CO2 reduction reactions (eCO2RR) on bismuth-based bimetallic nanocatalysts with non-aqueous ionic liquid electrolytes. The known Sabatier principle, arising from the adsorption-energy scaling relations at geometrically similar sites, generally imposes volcano-shaped constraints on the attainable catalytic performance. The Zhu-Xin team hypothesizes that the crucial charge-transfer intermediates toward CO2 reduction can be stabilized by cooperatively tailoring the p-band of active Bi sites via doping and heterocyclic cations of ionic liquids, while the competing hydrogen evolution reaction (HER) is suppressed. Using a combination of precision synthesis, electrocatalysis, advanced characterization techniques, as well as molecular modeling tools, the team seeks to uncover structure-reactivity relationships at the interface of nanoparticles and ionic liquid electrolytes. Success of this proposed research has the potential to advance fundamental understanding of CO2 reduction chemistry and provide guiding principles for catalyst design to address current challenges in eCO2RR. The atomistic insights into physicochemical properties of solid-electrolyte interfaces from this project may provide guidance for the design of other electrocatalytic transformations. Beyond scientific and technical impact, this project will train students at the interface of materials chemistry, quantum-chemical modeling, and catalysis, and prepare them for career pathways in academia and/or industry.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.