Sc掺杂的Sr_(2)Fe_(1.5)Mo_(0.5)O_(6-δ)作为质子导体固体氧化物燃料电池的新型单相阴极

Tailoring Sr_(2)Fe_(1.5)Mo_(0.5)O_(6-δ)with Sc as a new single-phase cathode for proton-conducting solid oxide fuel cells

本文利用Sc元素部分取代Sr_(2)Fe_(1.5)Mo_(0.5)O_(6−δ)(SFM)中的Mo,成功制备了具有高质子扩散速率的新型Sc掺杂SFM(SFMSc)材料.理论计算表明,将Sc掺杂到SFM中可以降低材料的氧空位形成能,降低氧化物中质子迁移的能垒,并提高材料氧还原反应的催化活性.使用单相SFMSc阴极的质子导体固体氧化物燃料电池(H-SOFC)比使用不含Sc的SFM单相阴极电池具有更高的电池性能,其在700℃时的性能达到1258 mW cm^(−2).该性能也超过了许多其他使用单相无钴阴极的HSOFC.此外,材料良好的电化学性能并没有以牺牲其稳定性为代价.SFMSc材料在含CO_(2)的气氛中以及在燃料电池工作条件下都表现出良好的稳定性.高输出性能和良好的稳定性,使SFMSc成为一种有潜力的高效的H-SOFC阴极材料.

Sc-doped Sr_(2)Fe_(1.5)Mo_(0.5)O_(6-δ)(SFMSc)was successfully synthesized by partially substituting Mo in Sr_(2)Fe_(1.5)Mo_(0.5)O_(6-δ)(SFM)with Sc,resulting in a higher proton diffusion rate in the resultant SFMSc sample.Theoretical calculations showed that doping Sc into SFM lowered the oxygen vacancy formation energy,reduced the energy barrier for proton migration in the oxide,and increased the catalytic activity for oxygen reduction reaction.Next,a proton-conducting solid oxide fuel cell(H-SOFC)with a single-phase SFMSc cathode demonstrated significantly higher cell performance than that of cell based on an Sc-free SFM cathode,achieving 1258 mW cm^(−2)at 700℃.The performance also outperformed that of many other H-SOFCs based on single-phase cobalt-free cathodes.Furthermore,no trade-off between fuel cell performance and material stability was observed.The SFMSc material demonstrated good stability in both the CO_(2)-containing atmosphere and the fuel cell application.The combination of high performance and outstanding stability suggests that SFMSc is an excellent cathode material for H-SOFCs.