(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.