(79g) 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.¹ The most direct way to mitigate this process is to activate the reverse chemical pathways in which CO₂ is reduced into high-energy molecules.² The electrochemical 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.^3-6 One approach to electrochemically reduce CO₂ to CO is using solid oxide electrolysis cells (SOECs). 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 high operating temperatures.⁷ 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.¹ In the present work, we combine experimental and theoretical techniques to determine the factors that lower the overpotential losses in SOECs during electrolysis of CO₂. We find that the conventional Ni-yttria stabilized zirconia (Ni-YSZ) composite cathodes exhibit significant overpotential losses toward electrochemical reduction of CO₂. Incorporation of gadolinium-doped ceria (GDC) improves the SOEC performance. We have conducted controlled electrochemical studies to investigate the influence of gadolinium-doped ceria in the electrochemical reduction of CO_2.

 

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