Browsing by Author "Zhang, Yongxin"

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Cu-Ce0.8Sm0.2O2-δ anode for electrochemical oxidation of methanol in solid oxide fuel cell: Improved activity by La and Nd doping
(2021-10-15) Zhang, Yongxin; Huang, Zhiyong; Gan, Tian; Hou, Nianjun; Fan, Lijun; Zhou, Xin; Gao, Ge; Li, Jingyu; Zhao, Yicheng; Li, Yongdan
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Cu–Ce0.8La0.1Sm0.1O2-δ and Cu–Ce0.8Nd0.1Sm0.1O2-δ are studied as anode materials for solid oxide fuel cells with methanol as fuel. The oxygen surface exchange and bulk diffusion coefficients of Ce0.8Sm0.2O2-δ both increase with La and Nd doping. The CH3OH temperature-programmed surface reaction results show that the addition of La and Nd accelerates the chemical oxidation of CH3OH. Furthermore, compared with Cu–Ce0.8Sm0.2O2-δ, the anodes with La and Nd show higher resistance to coking in CH3OH atmosphere. The Cu-based cermet anode exhibits a low catalytic activity for the electrochemical oxidation of H2, and a single cell supported by a Ce0.8Sm0.2O2-δ‑carbonate composite electrolyte with Cu–Ce0.8Sm0.2O2-δ anode exhibits a maximum power density of 160 mW cm−2 at 650 °C using dry hydrogen as fuel. However, the maximum power density reaches 550 mW cm−2 when CH3OH is used as fuel, and further increases to 730 and 830 mW cm−2 with the addition of La and Nd in the anode, respectively. The results indicate that with the promotion of the oxygen activity, the Cu-based cermet is a promising anode material for solid oxide fuel cells using CH3OH as fuel.
Enhanced oxygen reduction reaction activity of BaCe0.2Fe0.8O3-δ cathode for proton-conducting solid oxide fuel cells via Pr-doping
(2021-05-31) Zhou, Xin; Hou, Nianjun; Gan, Tian; Fan, Lijun; Zhang, Yongxin; Li, Jingyu; Gao, Ge; Zhao, Yicheng; Li, Yongdan
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
BaCe0.2Fe0.8-xPrxO3-δ (x = 0–0.3) is studied as a cobalt-free cathode material for proton-conducting solid oxide fuel cells. The cathode is composed of a cubic BaFeO3-δ phase and an orthorhombic BaCeO3-δ phase, and Pr is doped in both phases. The partial substitution of Pr for Fe decreases the content of the BaFeO3-δ phase, leading to a lower electrical conductivity. BaCe0.2Fe0.6Pr0.2O3-δ has the most adsorbed oxygen and Fe3+ on the surface, resulting in the fastest oxygen surface exchange kinetics and the highest activity. The partial pressure of H2O shows a negligible effect on the polarization resistance of the cathode. In contrast, the polarization resistance increases remarkably with the decrease of oxygen partial pressure, indicating that the rate of the cathode process is controlled by the surface exchange of oxygen. At 700 °C, BaCe0.2Fe0.6Pr0.2O3-δ shows the lowest polarization resistance of 0.057 Ω cm2, and a single cell with that cathode exhibits the highest maximum power density of 562 mW cm−2. The results demonstrate that Pr doped BaCe0.2Fe0.8O3-δ is a promising cobalt-free cathode material for proton-conducting solid oxide fuel cells.