(661b) Understanding the Mechanism and Electronic Structure Origin of CO2 Electroreduction on Bi Surfaces with Ionic Liquid Electrolytes

Electrochemical reduction of CO₂ has attracted researchers’ attention as it has the potential to utilize the abundant greenhouse gas in the Earth’s atmosphere and store intermittent energy from solar panels and wind turbines in chemical bonds. CO₂ can be reduced to CO or hydrocarbons and oxygenates depending on the nature of catalysts(Peterson et al. 2010) . However, the high overpotential needed to drive the reactions causes low efficiencies that inhibit its practical applications. Recent experimental studies have shown that the CO₂ reduction overpotential was reduced by using Bismuth (Bi) as catalysts and ionic liquids as electrolytes under electrochemical conditions (Rosen et al. 2011; Zhang et al. 2016). The ionic liquids are believed to act as co-catalysts during the reaction, reducing the overpential, but the underneath mechanisms remain elusive (Papasizza et al. 2020). Here we perform density functional theory (DFT) studies of how ionic liquids interact with key reaction intermediates (e.g. *CO₂^-, *COOH, *OCHO) and help reduce the theoretical overpotential and direct the production toward formate or CO. To unravel the electronic origin of surface reactivity, physics-model of chemisorption will be developed, in analogous to the d-band model for transition-metal metals, by Bayesian learning from ab initio adsorption properties of intermediates on a variety of Bi surfaces. The insights into structure-activity relationships shed light on the strategies to improve Bi catalysts via alloying and nanostructuring toward electrochemical reactions.