Hydrogen transport between proton conducting oxide and hydrogen storage metal

Abstract

Abstract We constructed an electrochemical cell consisting of proton conducting oxide as a electrolyte and hydrogen storage metal as a negative electrode. Hydrogen transport between the proton conducting oxide and the hydrogen storage metal, which induced by the gradient of electric potential or the hydrogen concentration, were studied by the measurements of electromotive force (EMF) and proton flux across the electrolyte. The transport of protons from SrCe 0.95 Yb 0.05 O 3− α proton conducting oxide to the hydrogen storage metals of V and Zr induced by the electric potential was investigated from the measurement of proton flux which flow in the negative electrode, where the proton flux was determined from the time evolution of the hydrogen content in the electrode material which could be obtained by the d.c. current and the ERDA measurements. From the relations between the hydrogen flux and the total electric current across the electrolyte, we evaluated the proton transport numbers and the proton diffusivity for SrCe 0.95 Yb 0.05 O 3− α oxide used as the electrolyte. As for the hydrogen transport from the hydrogen storage metal to the proton conducting oxide, we observed the temporal evolution of the voltage between the electrodes. The temperature dependence of the electromotive force revealed that the protons emitted from the hydrogen storage metals such as V, Zr, Nb and LaNi 5 had entered into the proton conducting oxide. This result indicated that the hydrogen storage metals has a possibility to use as the negative hydrogen electrode of the hydrogen–air fuel cell.