A homogenized model for multi-phase transport and reaction processes in electrochemical CO₂ reduction at gas diffusion electrodes

The limited carbon- and energy-efficiency of electrochemical CO₂ reduction cells has prompted the development of multi-scale gas diffusion electrodes (GDEs) with embedded catalyst structures, which are intended to improve dissolution of gaseous reactants into the aqueous phase and accelerate the rate of favorable Faradaic reactions. Accurate and efficient modeling of the coupled reaction and transport processes in GDEs may substantially contribute to the optimization of CO₂ reduction cells, but considerable challenges arise due to the multi-scale, multi-phase, and morphologically complex nature of GDE and catalyst structures. In this work, we develop and numerically simulate a model that efficiently incorporates a wide range of physical richness in GDEs, enabling the prediction of system-level behavior while capturing pore-scale and embedded interfacial effects via homogenization. This model, coupled with the appropriate numerics, permits exploration of the high-dimensional parameter space associated with CO₂ reduction cells, offering insight into the optimal design of catalysts and GDEs.