Temperature effect on electrochemical promotion of bulk lattice-oxygen extraction for hydrogen oxidation over SOFC anodes

A solid oxide fuel cell unit was constructed with yttria-stabilized zirconia (YSZ) as the solid electrolyte, Ni-YSZ as the anode and Pt as the cathode. Hydrogen oxidation was performed from 680 to 800 °C under either an open or closed circuit. The phenomena of electrochemical promotion of bulk lattice-oxygen extraction and fuel-free current were observed. The rate enhancement ratio of water formation, the Faradaic efficiency and the promotion factor all decrease with increasing temperature. The novel phenomenon of electrochemical promotion of bulk lattice-oxygen extraction, observed over the SOFC anodes without anode-side oxygen feed under generated voltage, follows the rules for conventional electrochemical promotion of catalysis, observed over electrodes with gas-phase oxygen feed under applied voltage.