Gas-Diffusion Type Oxygen Cathode Loaded with Large Surface Area Perovskite-type Oxide

Abstract

LaMnO₃ with a large surface area (45 m²/g) prepared by an amorphous citrate complex precursor (ACP) method was found to be much more active for the direct four-electron reduction of oxygen than a conventional LaMnO₃ sample (4.6 m²/g) prepared by the acetate decomposition (AD) method (Figs.1 and 2, Table 1). This high activity was effectively utilized for fabricating a high performance oxygen cathode. It was revealed that a gasdiffusion type PTFE-bonded carbon electrode loaded with the large surface area LaMnO₃ catalyst of 60 wt% gave a current density as high as 2.0 A/cm² at -125 mV vs. Hg/HgO (0.8 V vs. RHE) in 9 mol/dm³ NaOH at 80°C, which was 2.5 times as large as that of the electrode loaded with the conventinal LaMnO₃ (Fig.3).