Controlled Generation of Uniform Spherical LaMnO3, LaCoO3, Mn2O3, and Co3O4 Nanoparticles and Their High Catalytic Performance for Carbon Monoxide and Toluene Oxidation

Uniform hollow spherical rhombohedral LaMO3 and solid spherical cubic MOx (M = Mn and Co) NPs were fabricated using the PMMA-templating strategy. Hollow spherical LaMO3 and solid spherical MOx NPs possessed surface areas of 21-33 and 21-24 m(2)/g, respectively. There were larger amounts of surface-adsorbed oxygen species and better low temperature reducibility on/of the hollow spherical LaMO3 samples than on/of the solid spherical MOx samples. Hollow spherical LaMO3 and solid spherical MOx samples outperformed their nanosized counterparts for oxidation of CO and toluene, with the best catalytic activity being achieved over the solid spherical Co3O4 sample for CO oxidation (T-50% = 81 degrees C and T-90% = 109 degrees C) at space velocity = 10 000 mL/(g h) and the hollow spherical LaCoO3 sample for toluene oxidation (T-50% = 220 degrees C and T-90% = 237 degrees C) at space velocity. = 20 000 mL/(g h). It is concluded that the higher surface areas and oxygen adspecies concentrations and better low temperature reducibility are responsible for the excellent catalytic performance of the hollow spherical LaCoO3 and solid spherical Co3O4 NPs. We believe that the PMMA-templating strategy provides an effective route to prepare uniform perovskite-type oxide and transition metal oxide NPs.