International Journal of Hydrogen Energy, Vol.45, No.15, 8041-8051, 2020
Highly conductive proton-conducting electrolyte with a low sintering temperature for electrochemical ammonia synthesis
BaCe0.7Zr0.1Gd0.2O3-delta (BCZG) powder is synthesized by a citrate sol-gel method, and different amounts of Li2CO3 are introduced to lower the sintering temperature. The densification temperature of BCZG ceramic is decreased drastically to 1250 degrees C by using Li2CO3 as sintering aid. BCZG with 2.5 wt% of Li2CO3 (BCZG-2.5L) can not only remarkably promote the sintering process of BCZG but also enhance its electrical conductivity. The total ionic conductivity of BCZG-2.5L attains to 1.9 x 10(-2) S cm(-1) at 600 degrees C in a wet H-2 atmosphere. Ammonia synthesis at atmospheric pressure is conducted on (2K, 10Fe)/Ni-BCZG vertical bar BCZG-2.5L vertical bar Ni-BCZG electrolytic cell with an applied voltage of 0.2-1.6 V at a temperature of 450-600 degrees C. The highest NH3 formation rate of 1.87 x 10(-10) mol s(-1) cm(-2) and the highest current efficiency of 0.53% is achieved at 500 degrees C with an applied voltage of 0.8 V. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.