Investigation into structure and property of W and Ti co-doped SrFeO3 perovskite as electrode of symmetrical solid oxide fuel cell

SrFe0.9-xW0.1TixO3-δ (SFWT, x = 0.1 and 0.2) perovskite oxides are synthesized by combustion process. The experimental and computational analyses are conducted to reveal the effect of dopant W and Ti on the material properties and structure. The crystal structure transform from tetragonal (I4/m) to cubic(pm3¯m) when temperature is higher than 700 °C. Substitution of Fe with Ti can enhance the lattice structure. However, the Ti incorporation causes the increase in thermal expansion coefficient above 700 °C. The XPS and TG analyses show that the Ti incorporation also decreases oxygen activity. Thus, it is important to optimize the Ti content to design the SFWT materials to gain fast kinetics and high stability. The total conductivity (48 S cm−1), polarization resistances of symmetric single cell (0.28 Ω cm2), and durability (150 h, at 750 °C) reveal that the SrFe0.8W0.1Ti0.1O3-δ is a promising electrode materials for symmetric fuel cell. The first-principles calculation suggests that the Fe–O bond in SFWT dominates electric conductivity and can be suitably tailored by the dopant Ti and W.