Proton conduction in BaCe1−xGdxO3−α at intermediate temperature and its application to synthesis of ammonia at atmospheric pressure

The ceramic powders of BaCe1−xGdxO3−α (0.05 ≤ x ≤ 0.20) were prepared by a microemulsion method. A single phase of BaCeO3 orthorhombic perovskite structure was obtained by sintering the ceramic samples at the lower temperature of 1500 °C. Proton conduction in the samples was investigated from 300 to 600 °C in hydrogen atmosphere by electrochemical hydrogen pumping and AC impedance spectroscopy method. It was verified that the ceramic samples were almost pure protonic conductors at 300–600 °C in hydrogen atmosphere. The highest protonic conductivity was observed for x = 0.15 at 600 °C with the value of 1.4 × 10−2 S cm−1. Ammonia was synthesized successfully in an electrolytic cell based on BaCe0.85Gd0.15O3−α film (about 90 μm in thickness). It was found that the rate of NH3 formation was 4.63 × 10−9 mol s−1 cm−2 at 480 °C with an imposed direct current of 1.5 mA.