Formation of hydrogen by electrochemical reaction of CO gas and H2O vapor using porous Gd-doped ceria electrolyte cell

This paper reports on the composition of outlet gas and phase change of electrodes during the reaction of CO gas with H2O vapor using an electrochemical cell with Co–GDC (Gd-doped ceria: Ce0.8Gd0.2O1.9) cathode/porous GDC electrolyte/Fe–GDC anode. In the cathode, H2O reacts with supplied electrons to form a H2 fuel and O2− ions (H2O+2e−→H2+O2−) at 400–700 °C. After the decomposition of H2O vapor, no oxidation occurred in Co metal of the cathode. The produced O2− ions, H2 fuel and CO gas were transported to the anode through the porous GDC electrolyte. In the anode, CO gas reacts with O2− ions to produce CO2 gas and electrons (CO+O2−→CO2+2e−). Fe metal of the anode was oxidized to form Fe3O4 and GdFeO3 through the reaction with GDC. The valence change of Fe (Fe2+↔Fe3+) in Fe3O4 and GdFeO3 may work as a catalyst to promote the reaction of CO and O2− ions in the anode.