(514c) Automated Reaction Model Generation for Electrocatalytic Reduction of Carbon Dioxide

The urgent need for climate change mitigation has spurred intense research into carbon dioxide (CO₂) conversion processes. One of the potential pathways is electrocatalytic CO₂ reduction, converting renewable electrical energy into chemical energy and producing carbon-neutral chemical feedstocks and fuel sources. However, the design and optimization of catalysts and reactor parameters require comprehensive understanding of reaction mechanisms. Enumerating these mechanisms manually is a laborious process because a comprehensive model could involve hundreds of species and thousands of elementary reactions. This work presents an innovative approach to streamline mechanism development for electrocatalytic CO₂ reduction using automated techniques.

The Reaction Mechanism Generator (RMG) is a widely-used open-source software package, utilizing libraries of existing thermodynamic and kinetics data, reaction family templates, parameter estimation methods, and a core-edge model for fully automated model generation. However, currently RMG lacks the necessary components for electrochemical processes. This study aims to bridge this gap with the RMG-Electrocat extension. The first challenge is RMG's inability to incorporate species with net charges; therefore, new atom types and charge transfer actions were implemented to represent proton-electron interactions during the proton-coupled electron transfer (PCET) process while not violating the zero net-charge restriction. Furthermore, new reaction family templates were created to enumerate possible surface PCET reactions. The computational hydrogen electrode model was utilized for estimating reaction free energies and a potential-dependent surface Arrhenius kinetics model was implemented to calculate kinetics parameters. Finally, a new reactor model was developed to simulate the electrode-electrolyte interface, where both liquid- and surface-phase reactions could occur.

By incorporating these developments into RMG, we constructed a reaction mechanism for electrocatalytic CO₂ reduction which produces various value-added C1-C3 species. This advancement not only enhances RMG's utility in the field of sustainable energy, but also lays the foundation for its application in broader electrochemical systems such as battery and fuel-cells.