Design of Experiments Guided Identification of Coupled Component Interactions in Cu Gas Diffusion Electrodes for Electrochemical CO ₂ Reduction to Multi‐Carbon Products

ABSTRACT A Design of Experiments (DoE) approach is used in the design and development of gas diffusion electrodes (GDEs) for electrochemical CO 2 reduction (CO 2 R). Rational GDE design remains challenging due to the presence of multiple components and their complex effects on performance. Here, five electrode components, Cu, carbon, polytetrafluoroethylene, Nafion, and Sustainion, are evaluated for electrochemical CO 2 R using the DoE approach by evaluating 17 distinct single‐active‐layer (SAL)‐GDEs. Experimental results are analyzed using a definitive screen design (DSD) framework to identify component‐performance relationships, including first‐ and second‐order effects. Nafion is found to strongly affect overall product distribution, while carbon is most influential for improving C 2 H 4 selectivity. The DSD models are validated with experiments, enabling formulation predictions beyond the original design space. Following model predictions, increasing carbon loading was experimentally shown to improve C 2 H 4 selectivity, achieving a peak faradaic efficiency of 36.1%. The improvement is rationalized by structural characterization, which reveals that increased carbon loading leads to electrode porosity and Cu dispersion favorable for CO 2 transport and interfacial surface area. This work demonstrates the strength of statistical methods for rationally designing complex, multi‐component GDE architectures and understanding interacting component effects, highlighting potential impact across a wide range of electrochemical conversion systems.