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-alpha (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 degrees C. Proton conduction in the samples was investigated from 300 to 600 degrees 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 degrees C in hydrogen atmosphere The highest protonic conductivity was observed for x = 0.15 at 600 degrees C with the value of 1.4 x 10(-2) Scm(-1). Ammonia was synthesized successfully in an electrolytic cell based on BaCe0.85Gd0.15O3-alpha film (about 90 mu m in thickness). It was found that the rate of NH3 formation was 4.63 x 10(-9) mol s(-1) cm(-2) at 480 degrees C with an imposed direct current of 15 mA. (C) 2009 Elsevier B.V. All rights reserved