Perovskite oxide LaCr0.25Fe0.25Co0.5O3-δ as an efficient non-noble cathode for direct ammonia fuel cells
Georgina Jeerh, Peimiao Zou, Mengfei Zhang, Shanwen Tao
Abstract
LaCoO3-δ (LCO) based perovskites including LaCr0.5Co0.5O3-δ (LCCO), LaFe0.5Co0.5O3-δ (LFCO) and LaCr0.25Fe0.25Co0.5O3-δ (LCFCO) were prepared and their oxygen reduction reaction (ORR) activity was studied. The presence of both Cr and Fe played vital roles in enhancing activity, affecting structural and electronic properties respectively. Cr doping was associated with surface oxygen vacancy formation whilst Fe doping enhanced the onset and half-wave potential. Furthermore, the effects of calcinating temperatures were explored and LCFCO fired at 700 oC (LCFCO-700) gave superior activity. Remarkably, when LCFCO-700 was employed in a direct ammonia fuel cell (DAFC), an OCV of 0.72 V and a maximum current density of ∼320 mAcm-2 was achieved when using air as the oxidant. Under similar conditions, DAFCs with LaCr0.25Fe0.25Co0.5O3-δ/C cathode, show comparable performance to the DAFC using Pt/C cathode, indicating that perovskite oxides, such as LaCr0.25Fe0.25Co0.5O3-δ, are promising non-noble cathodes for DAFCs.