The transition toward a sustainable, circular, and carbon-neutral chemical industry requires the development of efficient pathways for CO₂ utilization. Electrochemical CO₂ reduction offers a promising route to convert CO₂ into value added chemicals using renewable electricity. Among the possible products, formate stands out due to its high selectivity as a two electron product, relatively low overpotential, and versatility as a chemical intermediate. Emerging downstream pathways, such as its use as a hydrogen carrier and its integration with fermentation processes for the production of fatty acids, can significantly expand its value chain, enabling applications in personal care products and sustainable aviation fuel (SAF).

This work presents recent advances in electrochemical CO₂ to formate conversion at TNO using gas diffusion electrode Gas Diffusion Electrode (GDE) based electrolyzer systems. The study focuses on the development, optimization, and upscaling of electrolysis reactors, where key operating parameters, including electrolyte composition, current density, and cell voltage, are systematically tuned to enhance performance while maintaining compatibility with downstream processing. Different electrochemical cell configurations were evaluated, including two- and three-compartment systems, to investigate their impact on product selectivity, energy requirements, and process flexibility. Particular attention was given to GDE composition and operational strategies aimed at improving stability and mitigating performance losses associated with electrode degradation. Extended electrolysis experiments were conducted over 50–100 hours to evaluate operational stability and monitor performance evolution under continuous conditions. These studies provide insight into degradation mechanisms and define operating windows for sustained formate production. Additionally, conditioning strategies were explored to achieve target concentrations and manage impurities, ensuring compatibility with downstream applications such as fermentation.

Building on these results, a scale-up strategy is proposed toward larger cell formats (100 cm²) and subsequent validation in pilot scale platforms. Ongoing efforts aim to translate laboratory scale performance to application-relevant conditions, focusing on improved energy efficiency, stable long-term operation, and integration with downstream conversion processes.

Overall, this work contributes to the development of scalable CO₂ electrolyzer technologies and highlights the role of formate as a key intermediate for integrated carbon utilization pathways.