Formation mechanism of yolk-shell LaMnO_3 microspheres prepared by P123-template and oxidation of NO

摘要

The yolk-shell LaMnO3 perovskite microspheres were fabricated by a novel, simple and mild soft template approach. A series of template-P123 concentrations (0-6.12 mmol.L-1) were employed to optimize the most complete spheres. When the concentration of P123 is 3.0 mmol.L-1, the obtained yolk-shell microspheres with a diameter of 200-700 nm were constructed by nanoparticles. The possible formation mechanism of the yolk-shell microspheres was revealed step by step via XRD, SEM, TEM, EDS and HRTEM. Molecules of P123 were suitably mixed with solvents for double shelled vesicles through self-assembly, which interacted with metal complexes to form P123-metal vesicles. After the removal of P123 and citric acid by calcination at 700 degrees C, the yolk-shell LaMnO3 microspheres with through-channels were obtained. Through-channels on the surface were due to citric acid and the solid core was attributed to the shrink of inner vesicles. Prepared yolk-shell microsphere samples possessed a larger surface area and a higher maximum NO conversion value of 78% at 314 degrees C for NO oxidation, compared with samples without the yolk-shell structure.