This oral presentation was presented at the ESYMS 2025 – European School of Young Materials Scientists. The work presents integrated modeling approaches for the design and optimization of porous cathodes used in electrochemical CO₂ reduction systems. By combining multiscale simulations and transport-reaction modeling, the study investigates the interplay between electrode structure, mass transport, and electrochemical performance. The results provide insights into the development of efficient solar fuels technologies, supporting the design of advanced materials and reactor configurations for sustainable CO₂ conversion and renewable energy storage.