Mechanistic Studies of Water Electrolysis and Hydrogen Electro-Oxidation on High Temperature Ceria-Based Solid Oxide Electrochemical Cells

Through the use of ambient pressure X-ray photoelectron spectroscopy (APXPS) and a single-sided solid oxide electrochemical cell (SOC), we have studied the mechanism of electrocatalytic splitting of water (H2O + 2e– → H2 + O2–) and electro-oxidation of hydrogen (H2 + O2– → H2O + 2e–) at ∼700 °C in 0.5 Torr of H2/H2O on ceria (CeO2–x) electrodes. The experiments reveal a transient build-up of surface intermediates (OH– and Ce3+) and show the...