Electrochemical ammonia synthesis from steam and nitrogen using proton conducting yttrium doped barium zirconate electrolyte with silver, platinum, and lanthanum strontium cobalt ferrite electrocatalyst

Electrochemical ammonia synthesis from steam and nitrogen has been systematically investigated using a proton-conducting electrolyte supported cell based on 20 mol% yttrium doped barium zirconate (BaZr0.8Y0.2O3-delta) in a temperature range of 475-600 degrees C at atmospheric pressure. Silver (Ag), platinum (Pt), and lanthanum strontium cobalt ferrite (La0.6Sr0.4CO0.2Fe0.8O3-delta) are used for both anode and cathode electrocatalysts. Maximum ammonia formation rates of 4.9 x 10(-11) mol cm(-2) s(-1) and 8.5 x 10(-11) mol cm(-2) s(-1) are observed for Ag and La0.6Sr0.4C0.2Fe0.8O3-delta electrocatalysts, respectively, when a voltage of 0.8 V is applied. However, Pt electrocatalyst shows a negligible ammonia formation rate lower than 1 x 10(-12) mol cm(-2) s(-1). This is ascribed to the high activity of Pt for the hydrogen evolution reaction rather than the ammonia formation reaction. The conversion efficiency of all electrocatalysts is below 1%, primarily due to the limited nitrogen disassociation activity of the electrocatalysts. (C) 2015 Elsevier B.V. All rights reserved.