Yang Wei, Zhang Huairuo, Sun Chunwen, Liu Lilu, Alonso J A, Fernández-Díaz M T, Chen Liquan
†Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
‡Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, U.K.
Inorg Chem. 2015 Apr 6;54(7):3477-84. doi: 10.1021/acs.inorgchem.5b00051. Epub 2015 Mar 10.
A new perovskite cathode, Sr0.95Ce0.05CoO3-δ, performs well for oxygen-reduction reactions in solid oxide fuel cells (SOFCs). We gain insight into the crystal structure of Sr1-xCexCoO3-δ (x = 0.05, 0.1) and temperature-dependent structural evolution of Sr0.95Ce0.05CoO3-δ by X-ray diffraction, neutron powder diffraction, and scanning transmission electron microscopy experiments. Sr0.9Ce0.1CoO3-δ shows a perfectly cubic structure (a = a0), with a large oxygen deficiency in a single oxygen site; however, Sr0.95Ce0.05CoO3-δ exhibits a tetragonal perovskite superstructure with a double c axis, defined in the P4/mmm space group, that contains two crystallographically different cobalt positions, with distinct oxygen environments. The structural evolution of Sr0.95Ce0.05CoO3-δ at high temperatures was further studied by in situ temperature-dependent NPD experiments. At 1100 K, the oxygen atoms in Sr0.95Ce0.05CoO3-δ show large and highly anisotropic displacement factors, suggesting a significant ionic mobility. The test cell with a La0.8Sr0.2Ga0.83Mg0.17O3-δ-electrolyte-supported (∼300 μm thickness) configuration yields peak power densities of 0.25 and 0.48 W cm(-2) at temperatures of 1023 and 1073 K, respectively, with pure H2 as the fuel and ambient air as the oxidant. The electrochemical impedance spectra evolution with time of the symmetric cathode fuel cell measured at 1073 K shows that the Sr0.95Ce0.05CoO3-δ cathode possesses superior ORR catalytic activity and long-term stability. Mixed ionic-electronic conduction properties of Sr0.95Ce0.05CoO3-δ account for its good performance as an oxygen-reduction catalyst.
一种新型钙钛矿阴极材料Sr0.95Ce0.05CoO3-δ在固体氧化物燃料电池（SOFC）的氧还原反应中表现良好。我们通过X射线衍射、中子粉末衍射和扫描透射电子显微镜实验，深入了解了Sr1-xCexCoO3-δ（x = 0.05, 0.1）的晶体结构以及Sr0.95Ce0.05CoO3-δ随温度变化的结构演变。Sr0.9Ce0.1CoO3-δ呈现出完美的立方结构（a = a0），在单个氧位点存在大量氧缺陷；然而，Sr0.95Ce0.05CoO3-δ表现出具有双c轴的四方钙钛矿超结构，属于P4/mmm空间群，其中包含两个晶体学上不同的钴位置，具有不同的氧环境。通过原位变温中子粉末衍射实验进一步研究了Sr0.95Ce0.05CoO3-δ在高温下的结构演变。在1100 K时，Sr0.95Ce0.05CoO3-δ中的氧原子显示出大且高度各向异性的位移因子，表明具有显著的离子迁移率。具有La0.8Sr0.2Ga0.83Mg0.17O3-δ电解质支撑（厚度约300μm）结构的测试电池，以纯H2为燃料、环境空气为氧化剂，在1023 K和1073 K温度下分别产生0.25和0.48 W cm(-2)的峰值功率密度。在1073 K下测量的对称阴极燃料电池的电化学阻抗谱随时间的演变表明，Sr0.95Ce0.05CoO3-δ阴极具有优异的氧还原反应催化活性和长期稳定性。Sr0.95Ce0.05CoO3-δ的混合离子-电子传导特性解释了其作为氧还原催化剂的良好性能。
