Low–Temperature Ammonia Decomposition Catalysts for Direct Ammonia Solid Oxide Fuel Cells

Abstract

Ammonia is regarded as a promising alternative fuel for solid oxide fuel cells (SOFCs) compared with hydrogen due to its low cost and ease for transportation and storage. The conventional anode Ni/yttria-stabilized zirconia (Ni/YSZ) of SOFCs can serve as an efficient catalyst for ammonia decomposition at high temperatures above 700 °C but its catalytic activity decreases rapidly at lower temperatures, leading to an undesirable degradation of cell performance. Here we report a low-temperature ammonia decomposition catalyst Ba-modified Ni/yttria-stabilized zirconia (Ba-Ni/YSZ) prepared by a one-pot solid-liquid (SL) method. Enhanced performance can be obtained for Ba-Ni/YSZ compared with that of Ni/YSZ catalysts, indicating that the addition of Ba promotes the catalytic activity. X-ray photoelectron spectroscopy (XPS) and Temperature-programmed reduction with H 2 (H 2 -TPR) characterizations of Ba-Ni/YSZ catalysts indicate that Ba changes the electronic structure of Ni and facilitates the interaction between Ni and support. The kinetics analysis demonstrates that the modification by a small amount of Ba species alleviated the negative effect of the hydrogen poisoning on the active sites of Ni/YSZ catalysts. Besides, the Ba-Ni/YSZ catalyst is introduced into the flat-tube SOFC with symmetric double-sided cathodes (DSC), and significantly improves the electrochemical performance of directly ammonia-fed DSC cells at low temperatures.