(621dx) Fundamental Insights on the Electrochemical Reduction of Carbon Dioxide Using Solid Oxide Electrolysis Cells

Extensive use of fossil fuels and consequential high levels of carbon dioxide (CO₂) emissions are major contemporary challenges. A direct way to mitigate this problem is to activate reverse chemical pathways in which CO₂ is reduced into high-energy molecules. The reduction of CO₂ to CO has attracted increasing attention since CO represents a valuable intermediate to the production of synthetic fuels, using established processes, such as Fischer-Tropsch. Solid oxide electrolysis cells (SOECs) are solid-state electrochemical systems that, in principle, can facilitate the electrochemical reduction of CO₂ to CO with potentially very high rates due to the favorable kinetics at their high operating temperatures. While electrochemical reduction of CO₂ using SOECs offers a great deal of promise, these systems are limited by the inability to operate near the thermodynamic reversible potentials due to the activation overpotential losses. In the present work, we combine experimental and theoretical techniques to determine the factors that lead to the overpotential losses in SOEC during CO₂ electrolysis. We have found that alloying Ni with another metal can lower the overpotential losses toward the electrochemical reduction of CO₂. We have developed structure/performance relationships for CO₂ electro-reduction on Ni alloys in order to guide the design of the optimal electrocatalyst for this process.