Facing the Challenges of Industrial Scale-up for CO ₂ Reduction to Formate in a Zero-Gap Electrolyzer

Formate, valued at $700M globally, serves as a critical feedstock in de-icing, corrosion removal, and as a preservative in animal feed. Electrochemical CO 2 conversion to formate delivers three quantifiable advantages over conventional production methods: (1) operation at ambient temperature and pressure, reducing capital equipment costs by 30-40%, (2) potential for direct utilization of intermittent renewable electricity, achieving a 60% lower carbon footprint than the petrochemical process, and (3) compatibility with downstream bioprocessing to high-value compounds like methanol and acetate, increasing potential market value by 2-3 times. 1 This approach enables industrial decarbonization while creating new revenue streams from captured CO 2 . Various systems have demonstrated the ability to electrochemically reduce CO 2 into formate with high selectivity, 2 and recent advancements have enabled industrial-scale electrolysis. However, challenges such as energy efficiency, long-term stability, and cost-effectiveness persist, requiring further improvements in flow electrolyzers. Herein, we address one of the main failure mechanisms for CO 2 electrolysis: flooding. Flooding is caused by inevitable salt formation, which leads to a gradual transition of gas diffusion electrodes from hydrophobic to hydrophilic properties, blocking CO 2 diffusion channels and reducing CO 2 availability. Additionally, in long-term testing, catalyst degradation further hinders performance due to catalyst dissolution and redeposition, nanoparticle agglomeration and sintering, carbonate formation blocking active sites, and membrane poisoning by electrolyte impurities. These issues collectively compromise Faradaic efficiency at low overpotentials, highlighting the need for further advancements in durability and stability. In this study, a zero-gap membrane electrode assembly architecture equipped with a conventional cation exchange membrane and commercial catalyst was used for the direct electrochemical synthesis of formate from CO 2 . Through careful optimization of the ink and deposition process, selection of improved carbon electrode substrates for better water management, and the use of a cost-effective and more efficient anode material in a lab-scale flow electrolyzer, an industrial-scale electrolyzer containing five cells with a total electrode area of 2500 cm 2 were stacked to produce formate continuously. Our system demonstrated unprecedented stability, achieving over 1000 hours of continuous operation through strategic anolyte concentration management, impurity removal protocols, and systematic maintenance. This breakthrough performance yielded 600 L of 0.71 M formate solution, effectively fixing 14.33 kg of CO₂ as value-added product. These results validate the industrial viability of our electrochemical CO₂ conversion technology, overcoming critical barriers in scalability, energy efficiency, and long-term durability that have historically limited commercial deployment for carbon capture and utilization. Reference S. Guo, T. Asset, and P. Atanassov, ACS Catal , 11 , 5172–5188 (2021) https://doi.org/10.1021/acscatal.0c04862. S. Guo et al., Appl Catal B , 316 , 121659 (2022) https://www.sciencedirect.com/science/article/pii/S0926337322006002.