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

Abstract

A new facile procedure to prepare three-dimensionally ordered macroporous (3DOM) materials of perovskite-type La 1-x Sr x FeO 3 (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-x Sr x FeO 3 (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.

Three-Dimensionally Ordered Macroporous (3DOM) Materials of Spinel-Type Mixed Iron Oxides. Synthesis, Structural Characterization, and Formation Mechanism of Inverse Opals with a Skeleton Structure

“…In our previous work, we have used PS spheres with a diameter of 161 nm as a template for the preparation of 3 DOM perovskite-type LaFeO 3 . 8 Our first attempt to produce 3DOM nickel ferrite using PS sphere with a diameter of 161 nm failed. No porous structure could be observed by SEM (Table 1, Entry 1) after the calcination (873 K for 5 h.).…”

“…A similar small increase of the BET surface area was observed in the case of 3DOM LaFeO 3 . 8 Formation Mechanism of the 3DOM Spinel-Type Mixed Metal Ferrite. The calcination process was first analyzed by TG-DTA.…”

“…Stefanscu et al have reported a similar reaction in aqueous media, 20 and we have reported a similar reaction for the synthesis of 3DOM LaFeO 3 . 8 The small weight loss around 470 K corresponds to the evaporation of the remaining EG (the boiling point of EG is 470 K). The weight loss up to 510 K was ca.…”

“…8 Our strategy is to use an ethylene glycol (EG)-methanol mixed solution of metal nitrate salts, which are converted to a mixed metal glyoxylate salt by in situ nitrate oxidation at low temperature before the template is removed. Calcination removes the polymer template and causes the conversion of the glyoxylate salt into the mixed metal oxide, i.e., 3DOM perovskite-type materials.…”

Synthesis, Characterization and Application of Nanostructured Porous Metal Oxides

“…6 For the preparation of macroporous TMOs, it is well known that the major technique is the "hard template" method; 7 including templating using ordered colloidal crystal, emulsion, polymer with rod-coil structure, ice, water bubbler and even bacteria. [8][9][10][11] So far, the most applied and successful template would be the colloidal particles, typically silica or polymer, such as polystyrene spheres. 2 Depending on the choice of the inorganic sources and template removal method, different single metal oxides can be readily obtained.…”