Heterogeneous Fenton Degradation of Organic Pollutants in Water Enhanced by Combining Iron-type Layered Double Hydroxide and Sulfate.

Water pollution derived from organic pollutants is one of the global environmental problems. The Fenton reaction using Fe as a homogeneous catalyst has been known as one of clean methods for oxidative degradation of organic pollutants. Here, a layered double hydroxide (Fe Al -LDH) containing Fe and Al in the structure was used to develop a "heterogeneous" Fenton catalyst capable of mineralizing organic pollutants.

Metamagnetic Behavior in a Quadruple Perovskite Oxide.

A cubic quadruple perovskite oxide CeMnCrO has been synthesized under high-pressure and high-temperature conditions of 8 GPa and 1273 K. The X-ray absorption spectroscopy reveals that the Ce ions are in a trivalent state, as represented by the ionic model of CeMnCrO. The magnetic study demonstrates three independent antiferromagnetic transitions attributed to Ce (∼10 K), Mn (46 K), and Cr (133 K) ions.

TiO superstructures with oriented nanospaces: a strategy for efficient and selective photocatalysis.

Highly ordered superstructures of semiconductor nanocrystals contain abundant nanometer-scale pores between the crystals; however, there have been difficulties in controlling the size and orientation of these nanospaces without the use of a template or a capping reagent. This constraint has affected their development and applications in potential fields including catalysis and optoelectronics adversely. In this study, we synthesized a rod-shaped TiO2 mesocrystal (TMC) having a length of a few hundreds of micrometers and comprising regularly ordered anatase TiO2 nanocrystals that form oriented nanospaces by exposed {001} facets.

Design of Advanced Functional Materials Using Nanoporous Single-Site Photocatalysts.

Nanoporous silica solids can offer opportunities for hosting photocatalytic components such as various tetra-coordinated transition metal ions to form systems referred to as "single-site photocatalysts". Under UV/visible-light irradiation, they form charge transfer excited states, which exhibit a localized charge separation and thus behave differently from those of bulk semiconductor photocatalysts exemplified by TiO . This account presents an overview of the design of advanced functional materials based on the unique photo-excited mechanisms of single-site photocatalysts.

Single-site and nano-confined photocatalysts designed in porous materials for environmental uses and solar fuels.

Silica-based micro-, meso-, macro-porous materials offer attractive routes for designing single-site photocatalysts, supporting semiconducting nanoparticles, anchoring light-responsive metal complexes, and encapsulating metal nanoparticles to drive photochemical reactions by taking advantage of their large surface area, controllable pore channels, remarkable transparency to UV/vis and tailorable physicochemical surface characteristics. This review mainly focuses on the fascinating photocatalytic properties of silica-supported Ti catalysts from single-site catalysts to nanoparticles, their surface-chemistry engineering, such as the hydrophobic modification and synthesis of thin films, and the fabrication of nanocatalysts including morphology controlled plasmonic nanostructures with localized surface plasmon resonance. The hybridization of visible-light responsive metal complexes with porous materials for the construction of functional inorganic-organic supramolecular photocatalysts is also included.

Multifunctional surface designed by nanocomposite coating of polytetrafluoroethylene and TiO photocatalyst: self-cleaning and superhydrophobicity.

Multifunctional surface, having both a superhydrophobic property and a photocatalytic self-cleaning property, was designed through a nanocomposite coating of polytetrafluoroethylene (PTFE) and TiO photocatalyst onto a flat quartz glass with a precise structural controlling by applying a radio frequency magnetron sputtering deposition technique. Systematic water contact angle measurements were carried out in relation to the controlling of the surface structure such as size, height and others. Surface wettability gradually changes from Wenzel state to Cassie-Baxter state by controlling of the surface structure, resulting in a well water repellent behavior.

Complete hydrogen release from aqueous ammonia-borane over a platinum-loaded titanium dioxide photocatalyst.

Complete H2 release from ammonia-borane (NH3BH3, AB) in water was achieved by using platinum-loaded TiO2 (Pt/TiO2) via two consecutive reaction steps, i.e., hydrolysis of AB and photocatalytic decomposition of thus formed NH3 in water, under inert conditions at 298 K.

Photocatalytic performance of TiO2-zeolite templated carbon composites in organic contaminant degradation.

TiO2 composites with zeolite templated carbon (TiO2-ZTC) and activated carbon (TiO2-AC) were prepared and used as the photocatalysts for comparative studies with pure TiO2. TiO2-ZTC exhibited the highest rate of methylene blue degradation with a rate approximately 4 and 400 times higher than those of TiO2-AC and pure TiO2, respectively. Moreover, the highest catalytic performance of TiO2-ZTC in gas-phase degradation of acetone was approximately 1.

Design of composite photocatalyst of TiO2 and Y-zeolite for degradation of 2-propanol in the gas phase under UV and visible light irradiation.

Hydrophobic Y-zeolite (SiO2/Al2O3 = 810) and TiO2 composite photocatalysts were designed by using two different types of TiO2 precursors, i.e., titanium ammonium oxalate and ammonium hexafluorotitanate.

Amine-functionalized MIL-101(Cr) with imbedded platinum nanoparticles as a durable photocatalyst for hydrogen production from water.

The incorporation of Pt nanoparticles into a highly stable and porous amine-functionalized MIL-101(Cr) was performed for construction of a visible light driven H2 evolution system with high activity and strong stability.

Hydrophobic modification of Pd/SiO2 @single-site mesoporous silicas by triethoxyfluorosilane: enhanced catalytic activity and selectivity for one-pot oxidation.

To enhance the catalytic activity in a selective one-pot oxidation using in-situ generated H(2)O(2), a hydrophobically modified core-shell catalyst was synthesized by means of a simple silylation reaction using the fluorine-containing silylation agent triethoxyfluorosilane (TEFS, SiF(OEt)(3)). The catalyst consisted of a Pd-supported silica nanosphere and a mesoporous silica shell containing isolated Ti(IV) and F ions bonded with silicon (SiF bond). Structural analyses using XRD and N(2) adsorption-desorption suggested that the mesoporous structure and large surface area of the mesoporous shells were retained even after the modification.

Design and functionalization of photocatalytic systems within mesoporous silica.

In the past decades, various photocatalysts such as TiO2, transition-metal-oxide moieties within cavities and frameworks, or metal complexes have attracted considerable attention in light-excited catalytic processes. Owing to high surface areas, transparency to UV and visible light as well as easily modified surfaces, mesoporous silica-based materials have been widely used as excellent hosts for designing efficient photocatalytic systems under the background of environmental remediation and solar-energy utilization. This Minireview mainly focuses on the surface-chemistry engineering of TiO2/mesoporous silica photocatalytic systems and fabrication of binary oxides and nanocatalysts in mesoporous single-site-photocatalyst frameworks.

Surfactant-free nonaqueous synthesis of plasmonic molybdenum oxide nanosheets with enhanced catalytic activity for hydrogen generation from ammonia borane under visible light.

Plasmonic materials have drawn emerging interest, especially in nontraditional semiconductor nanostructures with earth-abundant elements and low resistive loss. However, the actualization of highly efficient catalysis in plasmonic semiconductor nanostructures is still a challenge, owing to the presence of surface-capping agents in their synthetic procedures. To fulfill this, a facile non-aqueous procedure was employed to prepare well-defined molybdenum oxide nanosheets in the absence of surfactants.

Preparation of aluminum-containing mesoporous silica with hierarchical macroporous architecture and its enhanced catalytic activities.

Aluminum-containing mesoporous silica with hierarchical macroporous architecture (Al-MMS) was successfully prepared using a solvent evaporation method through the combination of precursor solution for synthesis of Al-containing mesoporous silica (Al-MS) and poly(methyl methacrylate) (PMMA) colloidal crystals as a hard template. The porous structure and the state of aluminum were investigated using various characterization techniques. The construction of combined structure of Al-MMS, i.

The synthesis of size- and color-controlled silver nanoparticles by using microwave heating and their enhanced catalytic activity by localized surface plasmon resonance.

Silver nanoparticles (Ag NPs) of various colors were synthesized within the mesopore structure of SBA-15 by using microwave-assisted alcohol reduction. The charge density is partially localized on the surface of these Ag NPs owing to localized surface plasmon resonance. This charge localization results in them having enhanced catalytic activity under visible light irradiation compared to Ag NPs obtained by thermal processes.

Active skeletal Ni catalysts prepared from an amorphous Ni-Zr alloy in the pre-crystallization state.

Skeletal Ni catalysts were prepared from an amorphous Ni40Zr60 alloy (a-NiZr) by heating at various temperatures under vacuum, followed by the selective extraction of Zr moieties by an HF treatment. Each sample was characterized by various spectroscopic methods, and the catalytic performance was tested in the hydrogenation of 1-octene. The differences in preparation temperatures of a-NiZr strongly affected the catalytic performance of the obtained catalysts, whereby those prepared from heated a-NiZr in the pre-crystallization state exhibited higher catalytic activity.

Effect of pore sizes on catalytic activities of arenetricarbonyl metal complexes constructed within Zr-based MOFs.

Arenetricarbonyl metal complexes ([-phM(CO)3-] and [-biphM(CO)3-]; ph = phenylene, biph = biphenylene, M = Mo, Cr) constructed within Zr-based MOFs act as highly active and selective catalysts for epoxidation of cyclooctene. Catalytic activities of these complexes are enhanced with increasing the pore sizes of Zr-based MOFs.

Preparation of hydroxynaphthalene-modified TiO2 via formation of surface complexes and their applications in the photocatalytic reduction of nitrobenzene under visible-light irradiation.

Visible light-sensitive photocatalysts were designed by the surface modification of TiO(2) using hydroxynaphthalenes, i.e., mono- and dihydroxy derivatives of naphthalene, via formation of surface complexes.

Enhanced CO2 adsorption over polymeric amines supported on heteroatom-incorporated SBA-15 silica: impact of heteroatom type and loading on sorbent structure and adsorption performance.

Silica supported amine materials are promising compositions that can be used to effectively remove CO(2) from large stationary sources, such as flue gas generated from coal-fired power plants (ca. 10 % CO(2)) and potentially from ambient air (ca. 400 ppm CO(2)).

Waste-slag hydrocalumite and derivatives as heterogeneous base catalysts.

Blast furnace slag (BFS), a high-volume byproduct resulting from iron-making processes, can be considered as a low-cost and abundant precursor for preparing layered double hydroxide (LDH) compounds. Here we demonstrate that a Ca-based LDH compound (hydrocalumite) synthesized from waste BFS through facile two-step procedures and its derivatives work as useful heterogeneous base catalysts for multiple chemical reactions including the Knoevenagel condensation, oxidation of alkylaromatics with O(2), transesterification, and cycloaddition reaction of epoxides with atmospheric CO(2). Structures were verified by using XRD and thermogravimetric analysis.

Dramatic enhancement of CO2 uptake by poly(ethyleneimine) using zirconosilicate supports.

The CO(2) adsorption characteristics of prototypical poly(ethyleneimine)/silica composite adsorbents can be drastically enhanced by altering the acid/base properties of the oxide support via incorporation of Zr into the silica support. Introduction of an optimal amount of Zr resulted in a significant improvement in the CO(2) capacity and amine efficiency under dilute (simulated flue gas) and ultradilute (simulated ambient air) conditions. Adsorption experiments combined with detailed characterization by thermogravimetric analysis, temperature-programmed desorption, and in situ FT-IR spectroscopy clearly demonstrate a stabilizing effect of amphoteric Zr sites that enhances the adsorbent capacity, regenerability, and stability over continued recycling.

Superhydrophobic surfaces with photocatalytic self-cleaning properties by nanocomposite coating of TiO(2) and polytetrafluoroethylene.

Superhydrophobic surfaces with photocatalytic self-cleaning properties are designed through coating a nanocomposite TiO(2) photocatalyst and hydrophobic polytetrafluoroethylene onto a structured substrate by applying a co-deposition technique. This coating realizes adequate photocatalytic activity for self-cleaning and inducing unique surface wettability changes. The nanocomposite can contain multiple functions, enabling energy-saving and maintenance-free characteristics.

Highly dispersed platinum nanoparticles on TiO2 prepared by using the microwave-assisted deposition method: an efficient photocatalyst for the formation of H2 and N2 from aqueous NH3.

A simple and practical technique to synthesize nanosized platinum particles loaded on TiO(2) (Pt-TiO(2)) by using a microwave (Mw)-assisted deposition method has been exploited in the development of a highly efficient photocatalyst for the formation of H(2) and N(2) gases from harmful nitrogen-containing chemical wastes, for example, aqueous ammonia (NH(3)). Upon Mw irradiation, a platinum precursor can be deposited quickly on the TiO(2) surface from an aqueous solution of platinum and subsequent reduction with H(2) affords the nanosized platinum metal particles with a narrow size distribution (Mw-Pt-TiO(2)). Characterization by CO adsorption, platinum L(III)-edge X-ray absorption fine structure analysis, and TEM analysis revealed that the size of the metal nanoparticles strongly depended on the preparation methods.

Lipase-embedded silica nanoparticles with oil-filled core-shell structure: stable and recyclable platforms for biocatalysts.

Lipase enzyme was embedded within silica nanoparticles with oil-filled core-shell structure. The enzyme embedded within such architecture retained all of its activity and showed high catalytic performance both in water and in organic media with optimal stability and recyclability.