Improved oxygen reduction reaction response of novel spinel structured LaFe2O4 and its heterostructure with Gd-doped-ceria-oxide by Ni foam support for PCFCs cathode

Abstract

Low-temperature operation of ceramic fuel cells (LT-CFCs; 350° to 550 °C) holds grand promise for abundant large and small scaled applications; if suitable, oxygen reduction electrocatalysts can be developed to hinder sluggish redox reaction at low operating temperature. Herein, we have developed a novel spinal structured cobalt-free LaFe2O4-Gd-doped-CeO2 (LFO-GDC) heterostructure composite as an efficient electrocatalyst for solid oxide fuel cells. The designed LaFe2O4-GDC heterostructure composite exhibits low-area-specific resistance and high oxygen reduction reaction (ORR) activity at low operating temperatures. We have demonstrated high-power densities of 835 mW-cm-2 and a current density of 2216 mA-cm2 at 550 °C for button-sized SOFC with H2 and atmospheric air fuels, and even possible operation at 400 °C. Moreover, the LaFe2O4-GDC heterostructure composite shows minimal proton migration energy and activation energy compared to individual LaFe2O4 and GDC, which help promote ORR activity. Various transmission and spectroscopic measurements such as X-ray diffraction and photoelectron spectroscopy, U-visible, Raman, and density functional theory (DFT) calculations were employed to understand the improved ORR electrocatalytic activity of LaFe2O4-GDC heterostructure composite. The results can further help to develop functional cobalt-free electro-catalysts for LT-SOFCs.