Effect of tungsten doping on strontium ferrite electrode for symmetrical solid oxide electrochemical cell. (3rd September 2020)

• Record Type: Journal Article
• Authors: Su, Taolong; Li, Yihang; Yang, Yi; Xu, Zheqiang; Shi, Nai; Wan, Yanhong; Xie, Yun; Huan, Daoming; Xue, Shuangshuang; Xia, Changrong
• Is Part Of: International journal of hydrogen energy. Volume 45:Number 43(2020)
• Page Start: 23401
• Page End: 23410
• Publication Date: 2020-09-03
• Subjects: Strontium ferrite -- Tungsten -- Solid oxide electrochemical cell -- Symmetrical cell -- Ceramic electrode; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2020.06.111
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Tungsten-doped strontium ferrite (SrFe1-x Wx O3-δ, SFW) is prepared and characterized as the electrode materials for symmetrical solid oxide electrochemical cell. X-ray diffraction refinement reveals the symmetrical structure transform from cubic ( p m 3 ¯ m ) for x = 0.1 to tetragonal ( I 4/ m ) when x = 0.2. According to the analysis including electrical conductivity, Hydrogen temperature-programmed reduction (H2 -TPR), thermal expansion and X-ray photoelectron spectra (XPS), it suggests that the decrease in conductivity, content of Fe 2+ and oxygen vacancy concentration with the increase of W content is attributed to the stronger lattice framework. The oxygen vacancy can be dramatically activated around 600 °C. Using SrFe0.8 W0.2 O3-δ as the electrodes, symmetrical single cells supported on doped ceria electrolytes can achieve acceptable power density (0.19 W cm −2 at 750 °C) and considerable stability. Meanwhile symmetrical cells with La0.9 Sr0.1 Ga0.8 Mg0.2 O3-δ (LSGM) electrolyte substrates can achieve 0.75 A cm −2 at 800 °C under the voltage of OCV (open circuit voltage) +0.5 V when it is operated in electrolysis mode. SrFe0.8 W0.2 O3-δ can gain a considerable stability and electrochemical activity under both oxide and reductive atmospheres. Oxygen vacancy formation energy ( E vac ) and electron density distribution are computed to verify the enhancement on crystal structure stability by doping W. The E vac critically depends on the distance from the W atom. Highlights: Symmetrical solid oxide cells with tungsten-doped strontium ferrite electrode. Improvement in the stability maintaining considerable electrochemical activity. Lattice framework enhancement by W incorporation was interpreted. Oxygen vacancy formation energy critically depends on the distance from the W atom. Oxygen vacancy can be dramatically activated around 600 °C.