title: P123-PMMA dual-templating generation and unique physicochemical properties of three-dimensionally ordered macroporous iron oxides with nanovoids in the crystalline walls.
abstract: Three-dimensionally (3D) ordered macroporous (3DOM) iron oxides with nanovoids in the rhombohedrally crystallized macroporous walls were fabricated by adopting the dual-templating [Pluronic P123 and poly(methyl methacrylate) (PMMA) colloidal microspheres] strategy with ferric nitrate as the metal precursor in an ethanol or ethylene glycol and methanol mixed solution and after calcination at 550 °C. The possible formation mechanisms of such architectured materials were discussed. The physicochemical properties of the materials were characterized by means of techniques such as XRD, TGA/DSC, FT-IR, BET, HRSEM, HRTEM/SAED, UV-vis, XPS, and H(2)-TPR. The catalytic properties of the materials were also examined using toluene oxidation as a probe reaction. It is shown that 3DOM-structured α-Fe(2)O(3) without nanovoids in the macroporous walls was formed in the absence of P123 during the fabrication process, whereas the dual-templating strategy gave rise to α-Fe(2)O(3) materials that possessed high-quality 3DOM structures with the presence of nanovoids in the polycrystalline macropore walls and higher surface areas (32-46 m(2)/g). The surfactant P123 played a key role in the generation of nanovoids within the walls of the 3DOM-architectured iron oxides. There was the presence of multivalent iron ions and adsorbed oxygen species on the surface of each sample, with the trivalent iron ion and oxygen adspecies concentrations being different from sample to sample. The dual-templating fabricated iron oxide samples exhibited much better low-temperature reducibility than the bulk counterpart. The copresence of a 3DOM-structured skeleton and nanovoids in the macropore walls gave rise to a drop in the band-gap energy of iron oxide. The higher oxygen adspecies amounts, larger surface areas, better low-temperature reducibility, and unique nanovoid-containing 3DOM structures of the iron oxide materials accounted for their excellent catalytic performance in the oxidation of toluene.
authors.affiliation: Laboratory of Catalysis Chemistry and Nanoscience, Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China.
authors.forename: Ruzhen
authors.initials: R
authors.lastname: Zhang
authors.forename: Hongxing
authors.initials: H
authors.lastname: Dai
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Du
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Jiguang
authors.initials: J
authors.lastname: Deng
authors.forename: Yunsheng
authors.initials: Y
authors.lastname: Xia
authors.forename: Zhenxuan
authors.initials: Z
authors.lastname: Zhao
authors.forename: Xue
authors.initials: X
authors.lastname: Meng
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Liu
mesh_terms: D002627:Chemistry, Physical; D005290:Ferric Compounds / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D011060:Poloxalene / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D016062:Porosity; D013499:Surface Properties
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide; C464484:pluronic block copolymer P123; D011060:Poloxalene; D019904:Polymethyl Methacrylate