Oxygen Reduction Electrode Properties of the Ba(Ce,Gd,Ru)O{sub}(3-δ) Oxides in Alkaline Aqueous Solution

摘要

Two series of compositions, BaCe{sub}(0.8-x)Gd{sub}0.2Ru{sub}xO{sub}(3-δ)(BCGR{sub}x, x=0-0.8) and BaGd{sub}(1-y)Ru{sub}yO{sub}(3-δ)(BGR{sub}y, y=0.5-1.0), were synthesized and their crystal phases were examined. The BCGR{sub}0.15 and BGR{sub}0.5 oxides were a single phase of perovskite solid solution, while BCGR{sub}0.67 and BGR{sub}0.67 were a perovskite-related superstructure phase. The onset voltage (V{sub}o) of the reduction current and the efficiency (E{sub}4) of the 4-electron reduction of oxygen were evaluated by semi-steady state voltammetry with rotating ring-disk electrodes. In the BCGR{sub}x series, the activities for electrochemical oxygen reduction (EOR) increased with increasing Ru content. In the BGR{sub}y series, the BGR{sub}0.67 superstructure phase showed a higher EOR activity than the perovskite BGR{sub}0.5 and the hexagonal (4H) BaRuO{sub}3. This indicates that the EOR activity depends on the crystal phase. The BGR{sub}0.67 exhibited the best EOR activity of all the samples. The V{sub}o value was 0.80 V vs. reversible hydrogen electrode and the E{sub}4 value was almost 100%.