High specific surface area LaMO3 (M = Co, Mn) hollow spheres: synthesis, characterization and catalytic properties in methane combustion

Abstract

Perovskite-type metal oxides have been regarded as promising materials for solar cells and catalysts. However, they suffer from a major challenge due to their low specific surface area. In this work, high specific surface area LaMO₃ (M = Co, Mn) hollow spheres were synthesized by a hard template method. The influence of the reactant ratios on the properties of the products was investigated. The formation of La₂O₃, Co₃O₄ or MnO₂ prevented the growth of LaMO₃, which resulted in variations in the composition, morphology, specific surface area, surface chemistry and catalytic activity of the products. An acid washing process could remove La₂O₃ and Co₃O₄, which led to the enhancement of the specific surface area of LaCoO₃. Due to the high reactant concentration and the slow heating rate, multishelled LaMnO₃ hollow spheres with a high specific surface area of 42.6 m² g⁻¹ were formed, which showed the best catalytic activity in methane combustion.