High-Performance Proton Conductor BaZr0.8Y0.1Yb0.1O3–δ for Hydrogen Separation: Effects of Co-doping Strategy of Y and Yb on Grain Boundary Properties

In this work, BaZr_0.8Y_0.2O_3–δ (BZY), BaZr_0.8Y_0.1Yb_0.1O_3–δ (BZYYb), and BaZr_0.8Yb_0.2O_3–δ (BZYb) proton conductors were prepared via the solid-state reaction method. X-ray diffraction results indicate that BZY, BZYYb, and BZYb were successfully synthesized, and all three samples exhibited a dense appearance. For BZYYb co-doped with Y and Yb, the conductivity in wet air (0.0019 atm H₂O partial pressure) at 800°C reached 5.5 × 10⁻³ S cm⁻¹, demonstrating superior electrochemical performance among the three samples. To further investigate this result, the grain boundary properties of BZY, BZYYb, and BZYb were studied by analyzing relaxation time distribution. The results show that the grain boundary resistance of BZYYb is 461 Ω at 600°C, smaller than those of single-doped BZY and BZYb. At 800°C, the hydrogen flux of BZYYb was 0.0034 mL cm⁻² min⁻¹. Overall, BZYYb, with its high proton conductivity, is a potential material for hydrogen separation applications.