Modeling the local reaction environment in CO2 electrolysis

The pressing need to address climate change and resource sustainability has catalyzed interest in technologies that can effectively mitigate CO2 emissions. Electrochemical reduction of CO2 is one such technology, offering a pathway to convert CO2 into valuable chemicals and fuels using renewable electricity. Despite its promise, the industrial application of CO2 electrolysis faces significant challenges, including limited mass transport, inefficient reaction kinetics, and poor control over the local reaction environment at the catalyst interface. This dissertation tackles these challenges through advanced numerical modeling. The research identifies key bottlenecks, such as CO2 solubility limits and local pH shifts, and explores strategies to overcome them using innovative electrode designs and operation modes. By extending the Poisson–Nernst–Planck framework to include finite size effects and the Frumkin-corrected Tafel relation, this work provides a detailed understanding of the electric double layer, steric effects, and solvent dynamics near the catalyst surface for H-cell configurations. These models are validated against experimental data, ensuring their robustness and applicability. Gas diffusion electrodes offer significant advantages over traditional H-cell systems by enabling direct CO2 delivery to the reaction site. However, these systems introduce new complexities, such as the interplay between pore structure, ion transport, and local reaction conditions. By simulating the behavior of these gas diffusion electrodes under various operating conditions, the research identifies optimal configurations for an ideal local reaction environment, thus paving the way for more efficient CO2 conversion. A novel aspect of this dissertation is the exploration of dynamic pulsed potential systems. These modes allow better control over product selectivity by leveraging transient reaction environments. The insights gained from these studies not only improve our understanding of CO2 electrolysis mechanisms but also provide practical guidelines for scaling up the technology. The work concludes by presenting a roadmap for the development of scalable, sustainable CO2 electroreduction systems. It emphasizes the importance of integrating experimental and computational approaches to tackle the multiscale challenges inherent in CO2 electrolysis. The models developed here serve as powerful tools for predicting system performance, designing next-generation reactors, and accelerating the transition to industrial-scale applications. The findings contribute to the broader effort of developing technologies that enable a circular carbon economy, thereby addressing global energy and environmental challenges.