A highly efficient electrocatalyst for oxygen reduction reaction: Three-dimensionally ordered macroporous perovskite LaMnO3

Perovskite LaMnO 3 is reported to be a superior electrocatalyst for oxygen reduction reaction in terms of the onset potential and intrinsic activity. However, traditionally prepared LaMnO 3 is characterized to exhibit a low specific surface area and a limited pore volume . Herein, we synthesize a three-dimensional ordered macroporous LaMnO 3 that features ordered and interconnected porous structure , in order to increase catalytic sites. The obtained three-dimensional ordered macroporous LaMnO 3 exhibits an increased specific surface area of 20.328 m 2  g −1 and pore volume of 0.126 cm 3  g −1 . Rotating-ring-disk electrode measurement reveals a more positive onset potential (0.827 V) and half-wave potential (0.686 V), and a much higher current-limited density (5.90 mA cm −2 ) of the three-dimensional ordered macroporous LaMnO 3 compared to counterparts, as well as a high electron transfer number (∼4) and a better stability. Furthermore, a Li O 2 battery employing the three-dimensional ordered macroporous LaMnO 3 as air electrode exhibits excellent electrochemical performance with a higher initial discharge capacity (5592 mAh g −1 ), a smaller discharge-charge voltage gap (1.56 V), and a higher coulombic efficiency (∼100%) in comparison with the carbon electrode. Our results suggest that traditional perovskite oxides could be effectively optimized for efficient electrocatalytic reactions .