Composite oxygen electrode LSM-BCZYZ impregnated with Co_3O_4 nanopartides for steam electrolysis in a proton-conducting solid oxide electrolyzer

摘要

A composite oxygen electrode based on Co_3O_4-loaded La_(0.8)Sr_(0.2)MnO_3 (LSM)-BaCe_(0.5)Zr_(0.3)Y_(0.16)6Zn_(0.04)O_(3-δ) (BCZYZ) is investigated for steam electrolysis in a proton-conducting solid oxide electrolyzer. The conductivity of LSM is studied with respect to temperature and oxygen partial pressure and correlated to the electrochemical properties of the composite oxygen electrodes in symmetric cells and solid oxide electrolyzers at 800 ℃. The optimal Co_3O_4 loading in the composite oxygen electrode is systematically investigated in symmetric cells; loading catalytically active Co_3O_4 significantly enhances the electrode performance, unlike the bare LSM-BCZYZ electrode. Steam electrolysis was then performed using LSM-BCZYZ and 6 wt.% Co_3O_4-loaded LSM-BCZYZ oxygen electrodes, respectively. The Co_3O_4-loaded catalyst significantly improves the electrode process and enhances the current density below a certain applied voltage. The current efficiencies reach approximately 46% with a 10% H_2O/air feed for the oxygen electrode.