From Molecules to Modules: Pathways toward Scalable Electrochemical CO₂ Reduction

ConspectusAchieving carbon neutrality requires the development of robust carbon capture, utilization, and storage (CCUS) technologies. Among the various carbon utilization pathways, the electrochemical carbon dioxide (CO₂) reduction reaction (CO₂R) presents a compelling approach, enabling the direct conversion of CO₂ and water into valuable fuels and chemical feedstocks using renewable electricity. While recent breakthroughs in mechanistic insights, catalyst materials, and reactor designs have been achieved, significant challenges remain in translating promising lab-scale results into techno-economically viable technologies. Key challenges hindering this transition include (1) a lack of rational screening and scalable fabrication methods for high-performance electrocatalysts and corresponding electrode assemblies; (2) a shortage of understanding how the transport phenomena within the electrodes and electrolyzers affect the microenvironment of reactions; and (3) a deficiency in designing principles for electrolyzers and stacks capable of large-scale production. All these points originate from the knowledge mismatch of the CO₂R between the microscopic perspective and the systematic point of view. Therefore, bridging the gap between fundamental knowledge of the reaction at the molecular level and process engineering for scale-up at the module level is crucial to accelerating the application of CO₂R.This Account describes chemistry and engineering methodologies, highlighting progress from our group and the broader field, aimed at inspiring a pathway toward large-scale CO₂R. Addressing the need for screening highly active catalysts, we leverage descriptor-based neural networks to rationally construct alloys and single-atom active sites to exhibit tailored reactivity. We then focus on translating these molecular concepts into durable, high-performance catalyst layers integrated into gas diffusion electrodes (GDEs) through advanced coating and fabrication techniques. These approaches are crucial for managing interfacial contact resistances and distributed Ohmic losses. Moreover, they enable precise control over interfacial gas-liquid equilibria within the porous electrode architecture. To tackle challenges of gas-flow pressure drop and Joule heating during scale-up, we have proposed device design requirements for conducting CO₂ electrolysis at elevated pressure and temperature. Additionally, an outlook for a CO₂R technology roadmap is discussed. Ultimately, this Account underscores how integrating fundamental molecular insights with rigorous process design provides a powerful roadmap toward industrial CO₂R technology.