High temperature electrochemical reduction of the water molecule at cerium dioxide electrodes

The high temperature cathodic reduction of the water molecule at the interface PtCeO_2?x Double Layer Electrode/Yttria Stabilized Zirconia has been investigated. Two different rate determining processes are involved depending on the current density. In the low current density range a Tafel's type kinetic behaviour was found, with an activation free enthalpy around 22 kcal/mole. The rate determining process has been identified in the transport of the oxygen atoms through the CeO_2?x layer. At higher currents a lack of any apparent additional, nonohmic contribution to the overvoltage was put into evidence.At any rate, such DLE resulted in a worsening of the energetic yield of the cathodic process with respect to the porous platinum/YSZ as well as Pt/cerium doped YSZ.