Facile Procedure To Prepare Three-Dimensionally Ordered Macroporous (3DOM) Perovskite-type Mixed Metal Oxides by Colloidal Crystal Templating Method

A new facile procedure to prepare three-dimensionally ordered macroporous (3DOM) materials of perovskite-type La_1-xSr_xFeO₃ (x = 0−0.4) mixed metal oxides by using colloidal crystal templating method is presented. This method can ensure the desired metal ratio throughout the preparation procedure, and the desired single-phase materials can successfully be prepared. Mixed metal nitrates were dissolved in ethylene glycol−methanol mixed solvent and penetrated into the colloidal crystal template of polystyrene spheres. During the calcination process, the mixed metal nitrates react with ethylene glycol and converted to mixed metal glyoxylates in voids of colloidal crystals before the polymer sphere bursts. After removing the sphere template and converting the mixed metal glyoxylates to the mixed metal oxides, the 3DOM materials of the perovskite-type La_1-xSr_xFeO₃ (x = 0−0.4) mixed metal oxides were obtained, which was characterized on the basis of thermogravimetric−differential thermal analysis, X-ray diffraction, chemical analysis, scanning electron microscopy, and nitrogen adsorption−desorption technique. Furthermore, the advantage of the 3DOM perovskite-type materials for combustion of nanosize carbon, which is a model of particulate matter exhausted from diesel engines, was demonstrated.