Advancements in Electrocatalysts for Low-Temperature CO2 Electrolysis: Progress and Insights from the ECO2Fuel Project

The Electrochemical CO 2 Reduction Reaction (CO2RR) represents a cutting-edge approach for converting CO 2 into valuable chemicals and fuels, marking a significant stride in energy storage through chemical bonds. This innovative method ingeniously merges the well-established water splitting reaction with Fischer-Tropsch synthesis, traditionally dependent on high temperatures and pressures. However, uniquely, CO2RR facilitates this process under ambient conditions, combining hydrogenation with water splitting at room temperature and normal atmospheric pressure. In this context, the ECO2Fuel project, an initiative under the European Green Deal, aims to develop, implement, and validate the first-ever 1MW low-temperature direct electrochemical CO 2 conversion system, poised to produce economically viable and sustainable e-fuels and chemicals. Despite its transformative potential, the ECO2Fuel project acknowledges and addresses several pivotal challenges, including enhancing catalyst performance and selectivity, electrode longevity, mass transport optimization, averting electrolyte flooding, and mitigating the hydrogen evolution reaction. This presentation will predominantly concentrate on refining the gas diffusion electrode at the cathode, for large-scale fuel and alcohol production via CO2RR. This electrode is composed of a gas diffusion layer, ensuring efficient CO 2 transport; a catalyst layer where the reduction transpires; and a top adhesion layer to prevent catalyst delamination. These components collectively influence the electrode’s selectivity, durability, and stability. Our discourse will delve into the intricate aspects of the catalyst layer and porous transport layer design, along with electrode manufacturing techniques, demonstrating their critical roles in achieving high faradaic efficiencies for carbonaceous fuel production. Furthermore, we will explore the nuanced operational modalities of the CO 2 electrolyzer cell, focusing on strategies to curtail the parasitic side reaction of hydrogen evolution, thereby enhancing the system's overall efficiency and productivity. This project has received funding from the European Union’s Horizon 2020 research and Innovation program under grant agreement no. 202037389.