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Wataru Ueda - One of the best experts on this subject based on the ideXlab platform.
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preparation of three dimensionally ordered macroporous perovskite type lanthanum iron oxide lafeo3 with tunable pore diameters high porosity and photonic property
Journal of Solid State Chemistry, 2010Co-Authors: Masahiro Sadakane, Keisuke Sasaki, Nobuyasu Kato, Toshitaka Horiuchi, Wataru UedaAbstract:Abstract Three-dimensionally ordered macroporous (3DOM) lanthanum–iron-oxide (LaFeO3) with different pore diameters was prepared using a Colloidal Crystal of polymer spheres with different diameters as templates. Ethylene glycol–methanol mixed solution of metal nitrates was infiltrated into the void of the Colloidal Crystal template of a monodispersed poly(methyl methacrylate) (PMMA) sphere. Heating of this PMMA–metal salt–ethylene glycol composite produced the desired well-ordered 3DOM LaFeO3 with a high pore fraction, which was confirmed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), mercury (Hg) porosimetry, and ultraviolet–visible (UV–vis) diffuse reflectance spectra. 3DOM LaFeO3 with pore diameters of 281 and 321 nm shows opalescent colors because of photonic stop band properties. Catalytic activity of the 3DOM LaFeO3 for combustion of carbon particles was enhanced by a potassium cation, which was involved from K2S2O8 used as a polymerization initiator.
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preparation of 3 d ordered macroporous tungsten oxides and nano Crystalline particulate tungsten oxides using a Colloidal Crystal template method and their structural characterization and application as photocatalysts under visible light irradiation
Journal of Materials Chemistry, 2010Co-Authors: Masahiro Sadakane, Keisuke Sasaki, Hironobu Kunioku, Unsho Ohtani, Ryu Abe, Wataru UedaAbstract:Three-dimensionally ordered macroporous (3DOM) tungsten(VI) oxide (WO3) was prepared using a Colloidal Crystal template method. Well-ordered 3DOM WO3 was prepared with a high pore fraction using ammonium metatungstate ((NH4)6H2W12O40), a Keggin-type dodecatungstate, as a tungsten precursor; WO3 materials prepared by other commercially available W precursors, tungsten chloride (WCl6), tungsten(V) ethoxide (W(OEt)5), and phosphotungstic acid (H3PW12O40), have a low 3DOM pore fraction. These WO3 materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), powder X-ray diffraction (XRD), Brunauer–Emmet–Teller (BET) analysis of nitrogen adsorption isotherm, and Raman spectroscopy. Non-porous WO3 prepared from ammonium metatungstate without a poly(methyl metacrylate) (PMMA) template grew to Crystal sizes of up to several micrometres with a low specific surface area (ca. 1–2 m2 g−1). In the presence of a Colloidal Crystal template of PMMA spheres, WO3 Crystal grew in the nanometre-sized voids between the PMMA spheres, and the specific surface area thus increased up to ca. 30 times compared to non-porous WO3. The surface area is tunable by changing the PMMA sphere diameter. Calcination of the 3DOM WO3 produced WO3 nano-Crystalline particles by sintering-induced disassembly. After Pt-loading, these WO3 materials showed higher photocatalytic activity compared to non-porous WO3 for decomposition of acetic acid in air under visible light irradiation.
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preparation of nano structured Crystalline tungsten vi oxide and enhanced photocatalytic activity for decomposition of organic compounds under visible light irradiation
Chemical Communications, 2008Co-Authors: Masahiro Sadakane, Wataru Ueda, Keisuke Sasaki, Hironobu Kunioku, Bunsho Ohtani, Ryu AbeAbstract:Nano-structured Crystalline tungsten(VI) oxides (WO3) were prepared using a Colloidal Crystal template method; these materials have increased specific surface area compared to Crystalline WO3 prepared without the template, and after platinum loading they show enhanced photocatalytic activity for acetic acid decomposition under visible light.
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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
Bulletin of the Chemical Society of Japan, 2007Co-Authors: Masahiro Sadakane, Chigusa Takahashi, Nobuyasu Kato, Hitoshi Ogihara, Yoshinobu Nodasaka, Yoshihiro Doi, Yukio Hinatsu, Wataru UedaAbstract:Three-dimensionally ordered macroporous (3DOM) materials of spinel-type MFe 2 Ο 4 (M = Zn, Ni, Zn x Ni i1-x (x = 0.2-0.8), and Co) mixed iron oxides were prepared in excellent yields by using a Colloidal Crystal templating method. Mixed metal nitrates were dissolved in an ethylene glycol (EG)-methanol mixed solvent and penetrated into the void of the Colloidal Crystal template of poly(methyl methacrylate) (PMMA) spheres. During the calcination process, the mixed metal nitrates reacted with ethylene glycol and converted into mixed metal glyoxylate derivatives in the voids of the Colloidal Crystals before the polymer sphere was removed. After removing the sphere template and converting the mixed metal glyoxylates into the mixed metal oxides, the well-ordered 3DOM materials of the desired spinel-type mixed metal oxides with a skeleton structure were obtained. The preparation procedure was analyzed on the basis of TG-DTA, XRD, SEM, TEM, elemental analysis, and BET surface area determination, and the formation mechanism was clarified. After the PMMA templates were removed, an amorphous 3DOM material with a shell structure was obtained. Crystallization of the amorphous material to the spinel-type mixed metal oxides by further calcination changed the morphology of the 3DOM material from the shell structure to a skeleton structure.
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three dimensionally ordered macroporous mixed iron oxide preparation and structural characterization of inverse opals with skeleton structure
Chemistry Letters, 2006Co-Authors: Masahiro Sadakane, Takahito Asanuma, Chigusa Takahashi, Nobuyasu Kato, Hitoshi Ogihara, Wataru UedaAbstract:Three-dimensionally ordered macroporous (3DOM) materials of polyCrystalline spinel- and perovskite-type mixed metal oxide (ZnFe 2 O 4 , NiFe 2 O 4 , and LaFeO 3 ) could be successfully fabricated using Colloidal Crystal template method in excellent yield. More than 90% of the obtained materials had the 3DOM structure. The Crystallites of the spinel- or perovskite-type mixed iron oxide construct struts, tetrahedral and square prism vertexes. The struts connect the tetrahedral and square prism vertexes to produce inverse opals with skeleton structure in three dimensions.
Masahiro Sadakane - One of the best experts on this subject based on the ideXlab platform.
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preparation of three dimensionally ordered macroporous perovskite type lanthanum iron oxide lafeo3 with tunable pore diameters high porosity and photonic property
Journal of Solid State Chemistry, 2010Co-Authors: Masahiro Sadakane, Keisuke Sasaki, Nobuyasu Kato, Toshitaka Horiuchi, Wataru UedaAbstract:Abstract Three-dimensionally ordered macroporous (3DOM) lanthanum–iron-oxide (LaFeO3) with different pore diameters was prepared using a Colloidal Crystal of polymer spheres with different diameters as templates. Ethylene glycol–methanol mixed solution of metal nitrates was infiltrated into the void of the Colloidal Crystal template of a monodispersed poly(methyl methacrylate) (PMMA) sphere. Heating of this PMMA–metal salt–ethylene glycol composite produced the desired well-ordered 3DOM LaFeO3 with a high pore fraction, which was confirmed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), mercury (Hg) porosimetry, and ultraviolet–visible (UV–vis) diffuse reflectance spectra. 3DOM LaFeO3 with pore diameters of 281 and 321 nm shows opalescent colors because of photonic stop band properties. Catalytic activity of the 3DOM LaFeO3 for combustion of carbon particles was enhanced by a potassium cation, which was involved from K2S2O8 used as a polymerization initiator.
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preparation of 3 d ordered macroporous tungsten oxides and nano Crystalline particulate tungsten oxides using a Colloidal Crystal template method and their structural characterization and application as photocatalysts under visible light irradiation
Journal of Materials Chemistry, 2010Co-Authors: Masahiro Sadakane, Keisuke Sasaki, Hironobu Kunioku, Unsho Ohtani, Ryu Abe, Wataru UedaAbstract:Three-dimensionally ordered macroporous (3DOM) tungsten(VI) oxide (WO3) was prepared using a Colloidal Crystal template method. Well-ordered 3DOM WO3 was prepared with a high pore fraction using ammonium metatungstate ((NH4)6H2W12O40), a Keggin-type dodecatungstate, as a tungsten precursor; WO3 materials prepared by other commercially available W precursors, tungsten chloride (WCl6), tungsten(V) ethoxide (W(OEt)5), and phosphotungstic acid (H3PW12O40), have a low 3DOM pore fraction. These WO3 materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), powder X-ray diffraction (XRD), Brunauer–Emmet–Teller (BET) analysis of nitrogen adsorption isotherm, and Raman spectroscopy. Non-porous WO3 prepared from ammonium metatungstate without a poly(methyl metacrylate) (PMMA) template grew to Crystal sizes of up to several micrometres with a low specific surface area (ca. 1–2 m2 g−1). In the presence of a Colloidal Crystal template of PMMA spheres, WO3 Crystal grew in the nanometre-sized voids between the PMMA spheres, and the specific surface area thus increased up to ca. 30 times compared to non-porous WO3. The surface area is tunable by changing the PMMA sphere diameter. Calcination of the 3DOM WO3 produced WO3 nano-Crystalline particles by sintering-induced disassembly. After Pt-loading, these WO3 materials showed higher photocatalytic activity compared to non-porous WO3 for decomposition of acetic acid in air under visible light irradiation.
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preparation of nano structured Crystalline tungsten vi oxide and enhanced photocatalytic activity for decomposition of organic compounds under visible light irradiation
Chemical Communications, 2008Co-Authors: Masahiro Sadakane, Wataru Ueda, Keisuke Sasaki, Hironobu Kunioku, Bunsho Ohtani, Ryu AbeAbstract:Nano-structured Crystalline tungsten(VI) oxides (WO3) were prepared using a Colloidal Crystal template method; these materials have increased specific surface area compared to Crystalline WO3 prepared without the template, and after platinum loading they show enhanced photocatalytic activity for acetic acid decomposition under visible light.
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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
Bulletin of the Chemical Society of Japan, 2007Co-Authors: Masahiro Sadakane, Chigusa Takahashi, Nobuyasu Kato, Hitoshi Ogihara, Yoshinobu Nodasaka, Yoshihiro Doi, Yukio Hinatsu, Wataru UedaAbstract:Three-dimensionally ordered macroporous (3DOM) materials of spinel-type MFe 2 Ο 4 (M = Zn, Ni, Zn x Ni i1-x (x = 0.2-0.8), and Co) mixed iron oxides were prepared in excellent yields by using a Colloidal Crystal templating method. Mixed metal nitrates were dissolved in an ethylene glycol (EG)-methanol mixed solvent and penetrated into the void of the Colloidal Crystal template of poly(methyl methacrylate) (PMMA) spheres. During the calcination process, the mixed metal nitrates reacted with ethylene glycol and converted into mixed metal glyoxylate derivatives in the voids of the Colloidal Crystals before the polymer sphere was removed. After removing the sphere template and converting the mixed metal glyoxylates into the mixed metal oxides, the well-ordered 3DOM materials of the desired spinel-type mixed metal oxides with a skeleton structure were obtained. The preparation procedure was analyzed on the basis of TG-DTA, XRD, SEM, TEM, elemental analysis, and BET surface area determination, and the formation mechanism was clarified. After the PMMA templates were removed, an amorphous 3DOM material with a shell structure was obtained. Crystallization of the amorphous material to the spinel-type mixed metal oxides by further calcination changed the morphology of the 3DOM material from the shell structure to a skeleton structure.
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three dimensionally ordered macroporous mixed iron oxide preparation and structural characterization of inverse opals with skeleton structure
Chemistry Letters, 2006Co-Authors: Masahiro Sadakane, Takahito Asanuma, Chigusa Takahashi, Nobuyasu Kato, Hitoshi Ogihara, Wataru UedaAbstract:Three-dimensionally ordered macroporous (3DOM) materials of polyCrystalline spinel- and perovskite-type mixed metal oxide (ZnFe 2 O 4 , NiFe 2 O 4 , and LaFeO 3 ) could be successfully fabricated using Colloidal Crystal template method in excellent yield. More than 90% of the obtained materials had the 3DOM structure. The Crystallites of the spinel- or perovskite-type mixed iron oxide construct struts, tetrahedral and square prism vertexes. The struts connect the tetrahedral and square prism vertexes to produce inverse opals with skeleton structure in three dimensions.
Joanna Aizenberg - One of the best experts on this subject based on the ideXlab platform.
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patterning hierarchy in direct and inverse opal Crystals
Small, 2012Co-Authors: Lidiya Mishchenko, Benjamin Hatton, Joanna Aizenberg, Mathias KolleAbstract:B iological strategies for bottom-up synthesis of inorganic Crystalline and amorphous materials within topographic templates have recently become an attractive approach for fabricating complex synthetic structures. Inspired by these strategies, herein the synthesis of multi-layered, hierarchical inverse Colloidal Crystal fi lms formed directly on topographically patterned substrates via evaporative deposition, or “co-assembly”, of polymeric spheres with a silicate sol‐gel precursor solution and subsequent removal of the Colloidal template, is described. The response of this growing composite colloid‐silica system to artifi cially imposed 3D spatial constraints of various geometries is systematically studied, and compared with that of direct Colloidal Crystal assembly on the same template. Substrates designed with arrays of rectangular, triangular, and hexagonal prisms and cylinders are shown to control Crystallographic domain nucleation and orientation of the direct and inverse opals. With this bottom-up topographical approach, it is demonstrated that the system can be manipulated to either form large patterned single Crystals, or Crystals with a fi netuned extent of disorder, and to nucleate distinct Colloidal domains of a defi ned size, location, and orientation in a wide range of length-scales. The resulting ordered, quasi-ordered, and disordered Colloidal Crystal fi lms show distinct optical properties. Therefore, this method provides a means of controlling bottom-up synthesis of complex, hierarchical direct and inverse opal structures designed for altering optical properties and increased functionality.
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assembly of large area highly ordered crack free inverse opal films
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Benjamin Hatton, Lidiya Mishchenko, Stan Davis, Kenneth H Sandhage, Joanna AizenbergAbstract:Abstract Whereas considerable interest exists in self-assembly of well-ordered, porous “inverse opal” structures for optical, electronic, and (bio)chemical applications, uncontrolled defect formation has limited the scale-up and practicality of such approaches. Here we demonstrate a new method for assembling highly ordered, crack-free inverse opal films over a centimeter scale. Multilayered composite Colloidal Crystal films have been generated via evaporative deposition of polymeric Colloidal spheres suspended within a hydrolyzed silicate sol-gel precursor solution. The coassembly of a sacrificial Colloidal template with a matrix material avoids the need for liquid infiltration into the preassembled Colloidal Crystal and minimizes the associated cracking and inhomogeneities of the resulting inverse opal films. We discuss the underlying mechanisms that may account for the formation of large-area defect-free films, their unique preferential growth along the 〈110〉 direction and unusual fracture behavior. We demonstrate that this coassembly approach allows the fabrication of hierarchical structures not achievable by conventional methods, such as multilayered films and deposition onto patterned or curved surfaces. These robust SiO2 inverse opals can be transformed into various materials that retain the morphology and order of the original films, as exemplified by the reactive conversion into Si or TiO2 replicas. We show that Colloidal coassembly is available for a range of organometallic sol-gel and polymer matrix precursors, and represents a simple, low-cost, scalable method for generating high-quality, chemically tailorable inverse opal films for a variety of applications.
Andreas Stei - One of the best experts on this subject based on the ideXlab platform.
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design and functionality of Colloidal Crystal templated materials chemical applications of inverse opals
Chemical Society Reviews, 2013Co-Authors: Andreas Stei, Enjami E Wilso, Stephen G. RudisillAbstract:Templating with Colloidal Crystals composed of monodisperse spheres is a convenient chemical method to obtain porous materials with well-ordered periodicity and interconnected pore systems. The three-dimensionally ordered macroporous (3DOM) products or inverse opals are of interest for numerous applications, both for the optical properties related to structural color of these photonic Crystal materials and because of their bicontinuous nanostructure, i.e., a continuous nanostructured skeleton with large interfacial area and a three-dimensionally interconnected pore system with low tortuosity. This review outlines various synthetic methods used to control the morphology of 3DOM materials with different compositions. It highlights aspects of the choice of Colloidal particles, assembly of the Colloidal Crystal template, infiltration and processing, template removal, and other necessary modifications to enhance the functionality of the materials. It also considers syntheses within the confinement of 3DOM materials and summarizes characterization methods that are particularly useful in the analysis of 3DOM materials. The review then discusses chemical applications of 3DOM materials, namely sorption and controlled release, optical and electrochemical sensors, solar cells, lithium ion batteries, supercapacitors, fuel cells, and environmental and chemical fuel catalysis. A focus is on structural features and materials properties that enable these applications.
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Colloidal Crystal templated synthesis of ordered macroporous electrode materials for lithium secondary batteries
Journal of The Electrochemical Society, 2003Co-Authors: Sergey Sokolov, Justin C Lytle, Andreas Stei, Fa Zhang, William H SmyrlAbstract:This paper presents a general method of preparing three-dimensionally ordered macroporous (3DOM) electrode materials, including both cathode materials (V 2 O 5 and LiNiO 2 ) and an anode material (SnO 2 ). The method is based on templated precipitation of inorganic precursors within a Colloidal Crystal of poly(methyl methacrylate) spheres and subsequent chemical conversion. 3DOM electrodes possess several features of interest in the design of novel battery materials, such as high accessible surface areas, continuous networks, and structural features on the nanometer scale. Optimal synthesis conditions and structural features of 3DOM electrode materials are described on the basis of X-ray diffraction, scanning electron microscopy, nitrogen adsorption, and chemical analysis.
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Colloidal Crystal templating of three dimensionally ordered macroporous solids materials for photonics and beyond
Current Opinion in Solid State & Materials Science, 2001Co-Authors: Andreas Stei, Rick C SchrodeAbstract:Abstract This review discusses strategies for the synthesis of three-dimensionally ordered macroporous (3DOM) solids (inverse opals) by Colloidal Crystal templating. Compositions of 3DOM structures include simple and ternary oxides, chalcogenides, non-metallic and metallic elements, hybrid organo-silicates, and polymers. A wide range of 3DOM synthesis techniques, including sol–gel chemistry, polymerization, salt-precipitation and chemical conversion, chemical vapor deposition, spray pyrolysis, ion spraying, laser spraying, nanoCrystal deposition and sintering, oxide and salt reduction, electrodeposition, electroless deposition, fabrication from core-shell spheres, and patterning methods, as well as templating using inverse opal molds to produce new opal compositions are reviewed. Potential uses of 3DOM solids, including photonic Crystal, optical, catalytic, and bioglass applications are briefly discussed.
Nicholas A Kotov - One of the best experts on this subject based on the ideXlab platform.
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engineering liver tissue spheroids with inverted Colloidal Crystal scaffolds
Biomaterials, 2009Co-Authors: Jungwoo Lee, Meghan J Cuddihy, George Cate, Nicholas A KotovAbstract:Abstract Multicellular spheroids provide a new three-dimensional (3D) level of control over morphology and function of ex vivo cultured tissues. They also represent a valuable experimental technique for drug discovery and cell biology. Nevertheless, the dependence of many cellular processes on the cluster diameter remains unclear. To provide a tool for the systematic evaluation of such dependences, we introduce here inverted Colloidal Crystal (ICC) scaffolds. Uniformly sized pores in ICC cell matrixes afford a high yield production of controlled size spheroids in standard 96 well-plates. Transparent hydrogel matrix and ship-in-bottle effect also allows for convenient monitoring of cell processes by traditional optical techniques. Different developmental stages of 46.5–151.6 μm spheroids from HepG2 hepatocytes with vivid morphological similarities to liver tissue (bile canaliculi) were observed. The liver-specific functions of HepG2 cells were systematically investigated and compared for spheroids of different diameters as well as 2D cultures. Clear trends of albumin production and CYP450 activity were observed; diffusion processes and effect of cellular aggregation on metabolic activity were identified to be the primary contributors to the size dependence of the liver functions in HepG2 spheroids in ICC scaffolds. Since the aggregation of cells into clusters is a universal biological process, these findings and scaffolds can be applied to many other relevant cell types.
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inverted Colloidal Crystal hydrogel matrices as three dimensional cell scaffolds
Advanced Functional Materials, 2005Co-Authors: Yongju Zhang, Shaopeng Wang, Mohammad Eghtedari, Massoud Motamedi, Nicholas A KotovAbstract:Successful engineering of functional tissues requires the development of three-dimensional (3D) scaffolds that can provide an optimum microenvironment for tissue growth and regeneration. A new class of 3D scaffolds with a high degree of organization and unique topography is fabricated from polyacrylamide hydrogel. The hydrogel matrix is molded by inverted Colloidal Crystals made from 104 μm poly(methyl methacrylate) spheres. The topography of the scaffold can be described as hexagonally packed 97 μm spherical cavities interconnected by a network of channels. The scale of the long-range ordering of the cavities exceeds several millimeters. In contrast to analogous material in the bulk, hydrogel shaped as an inverted opal exhibits much higher swelling ratios; its swelling kinetics is an order of magnitude faster as well. The engineered scaffold possesses desirable mechanical and optical properties that can facilitate tissue regeneration while allowing for continuous high-resolution optical monitoring of cell proliferation and cell–cell interaction within the scaffold. The scaffold biocompatibility as well as cellular growth and infiltration within the scaffold were observed for two distinct human cell lines which were seeded on the scaffold and were tracked microscopically up to a depth of 250 μm within the scaffold for a duration of up to five weeks. Ease of production, a unique 3D structure, biocompatibility, and optical transparency make this new type of hydrogel scaffold suitable for most challenging tasks in tissue engineering.