Scalable electrochemical CO₂ reduction to oxalate in a continuous flow reactor

The electrochemical reduction of CO₂ to oxalate has emerged as a promising pathway for both carbon utilization and negative-emission strategies, as it couples renewable electricity with the production of a high-value platform chemical. In this work, we investigated the electroreduction of CO₂ in a novel designed-flow reactor employing stainless steel cathode in an acetonitrile medium. The reactor design was evaluated by varying electrode spacing (0.5, 1, and 2 mm) and scaling electrode area (from 10 mm² to 656 mm²), aiming to enhance mass transport and reduce ohmic losses. Faradaic efficiencies up to 72% and current densities above 130 mA cm^-2 were achieved, which surpass previously reported results for flow systems. Notably, scaling up to 656 mm² electrodes maintained competitive efficiency while significantly improving oxalate production rates. These results demonstrate one of the few successful demonstrations of CO₂-to-oxalate conversion in a continuous-flow configuration, highlighting the potential of reactor engineering approaches for advancing scalable and environmentally benign CO₂ electroreduction technologies.