(650e) Continuous Gas-to-Liquid Conversion for Carbon-Efficient Electroreduction of CO2

Electrochemical reduction of CO₂ is promising way to take advantage of renewable energy to produce value added chemicals and fuels as well as mitigating the increasing CO₂ emission. Most studies of CO₂ reduction so far have focused on single-pass measurements, with carbon-conversion efficiencies (CCEs) being limited to <10%. Here we report on the continuous gas-to-liquid conversion for carbon-efficient electroreduction of CO₂. A GDE-based CO₂ electrolyzer with the integration of gas and liquid circulation system is designed to utilize the unreacted reactants in single pass and thus enhance the CCE and enrich products in the flowing electrolyte. In this study we prove this recirculation design by conducting continuous electroreduction of CO₂ to formate. Formate (or the derived formic acid) is one of the products that can make the CO₂ electroreduction process economic. It’s widely used in textile, leather and pharmaceutical industries. When applied a commercial tin oxide catalyst in our novel recirculation system, we can achieve a 95% faradaic efficiency towards sodium formate with over 100 mA/cm² at a voltage of 2.65 V. Meanwhile a two-week-long continuously production of sodium formate solution with over 90% carbon conversion efficiency is demonstrated to highlight the robustness of both the catalytic material and the reported electrochemical system. The as-produced solution with > 100 mmol/L sodium formate is an ideal C-1 feedstock for biosynthesis utilizing formate metabolic pathway such as poly(hydroxyalkanoates) production.