Hollow spherical La0.8Sr0.2MnO3 perovskite oxide with enhanced catalytic activities for the oxygen reduction reaction

A hollow spherical La0.8Sr0.2MnO3 (HS-LSM) perovskite oxide has been prepared using a new carbonate-template route, and characterized by XRD, SEM and TEM. SEM and TEM results show that the pre-prepared oxides consist of porous microspheres composed of submicrometer-sized subunits with a secondary particle diameter of ∼20-50 nm. The catalytic activity of the oxide for the oxygen reduction reaction (ORR) in 0.1 M KOH solution has been studied using a rotating ring-disk electrode (RRDE). In the ORR tests, a maximum cathodic current density of 6.4 mA cm−2 at −0.9 V (vs. Ag/AgCl) with 2500 rpm has been obtained, and the ORR mainly favors a direct four-electron pathway. The chronoamperometric test shows that the HS-LSM exhibits excellent stability for the ORR.