(173aa) Cooperative Site and Electrolyte Design for Optimizing Interfacial Electrokinetics of CO2 Reduction
AIChE Annual Meeting
Wednesday, November 16, 2022 - 3:30pm to 5:00pm
In heterogeneous catalysis, the interaction of key reaction intermediates with active sites should be neither too strong nor too weak for fast turnovers. This Sabatier principle provides the conceptual basis for designing optimized catalysts but also imposes constraints on the attainable catalytic performance. In this regard, developing design strategies and ultimately predictive models of catalytic systems that overcome such constraints represents one of the greatest challenges faced by the catalysis community today. In this presentation, we focus on electrochemical CO2 reduction reactions (eCO2RR) at the metal-electrolyte interface, as it has the potential to utilize the abundant greenhouse gas and provide a strategy to store the intermittent energy from solar panels and wind turbines in the form of chemical bonds. However, the practical applications suffer from two key challenges: poor selectivity with the competition of hydrogen evolution reaction (HER); high overpotential (~ 0.8 V) needed to drive the reaction. Researchers found that by substituting the aqueous solution with an aprotic solvent and supporting electrolytes, such as ionic liquids (ILs), eCO2RR can occur on non-precious p-block metals, e.g., bismuth (Bi), with an unprecedented selectivity toward CO, presumably attributed to the stabilization of the *CO-2 radical anion intermediate by the cations of ILs. Supported by in situ experimental measurements, we performed theoretical studies of a surface-electrolyte interface model to understand the reaction mechanisms of CO2 reduction on Bi surfaces with ILs as electrolytes. Meanwhile, a cooperative site doping and cation tethering design principle is developed to guide the optimization of catalytic Bi-IL systems beyond the adsorption-energy scaling limitations.