(600bs) Fundamental Insights on the Electrochemical Reduction of Water and Carbon Dioxide Using Solid Oxide Electrolysis Cells

Extensive use of fossil fuels and consequential high levels of CO₂ emissions are major contemporary challenges. Many proposed strategies for managing CO₂ from chemical processes involve the conversion of CO₂ back to hydrocarbons. The co-reduction of CO₂ and H₂O to syngas (CO and H₂) is one such process for which no efficient approach currently exists. Solid oxide electrolysis cells (SOECs) are solid-state electrochemical systems that, in principle, can facilitate the simultaneous co-reduction of CO₂ with H₂O to syngas with potentially very high rates due to the favorable kinetics at their high operating temperatures. While electrochemical co-reduction of CO₂ and H₂O 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 electrolysis of H₂O and CO₂. We find that the conventional Ni-based electrocatalysts are efficient at catalyzing electrolysis of H₂O but exhibit significant overpotential losses toward electrochemical reduction of CO₂. Based on these insights, we have devised ways and screened through a number of electrocatalysts in order to identify the ones that lead to the lowest overpotential losses during the electrochemical reduction of CO₂ and H₂O.