CYO–BZCYO composites with enhanced proton conductivity: Candidate electrolytes for low-temperature solid oxide fuel cells

Novel composite oxide ion conductors were developed based on a fluorite-type Ce0.8Y0.2O1.9 (CYO) and a perovskite-type BaZr0.1Ce0.7Y0.2O2.9 (BZCYO) synthesized by the carbonate co-precipitation route at 700 °C and the sol–gel process at 1000 °C, respectively. When sintered at 1400 °C, CYO and BZCYO showed an ac conductivity of 1.60 × 10−2 S cm−1 and 1.21 × 10−2 S cm−1 at 600 °C, respectively, in dry air and wet hydrogen. CYO–BZCYO composites sintered at 1400 °C showed much lower conductivity than CYO and BZCYO in dry air, but they showed enhanced conductivity in wet hydrogen. The highest conductivities of 3.27 × 10−2 S cm−1 at 500 °C and 9.40 × 10−3 S cm−1 at 400 °C were achieved in wet hydrogen by the composite containing 30wt.% BZCYO, which are 3–5 times higher than those of CYO and BZCYO, making this composite material a promising candidate as an electrolyte for low-temperature solid oxide fuel cells (LT-SOFCs).