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Photocatalytic Properties (photocatalytic + property)
Selected AbstractsNovel RuII Complexes with Bispidine-Based Bridging Ligands: Luminescence Sensing and Photocatalytic PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2010Christoph Busche Abstract New ligands with a bidentate bipyridyl (bpy) and a tetradentate bispidine (bisp) subunit (bipyridyl = 2,2,-bipyridine derivative, bispidine = 3,7-diazabicyclo[3.3.1]nonane derivative) and their heterodinuclear {[Ru(bpy)3]2+ -[M(bisp)]2+} complexes (M = Cu2+, Fe2+) were prepared and characterized. The luminescence of the mononuclear RuII complexes (metal-free bisp subunit) is efficiently quenched in presence of CuII. An EPR spectroscopic study reveals thatvisible light irradiation does not alter the oxidation states of the two metal ions in {[Ru(bpy)3]2+ -[Cu(bisp)]2+}, i.e. there is energy rather than electron transfer. The heterodinuclear {[Ru(bpy)3]2+ -[Cu(bisp)]2+} complex shows a significantphotocatalytic activity in the aziridination of styrene. [source] Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic PropertiesADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Yongquan Qu Abstract Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here, it is shown that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. The Pt/Si/Ag diodes exhibit highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4-nitrophenol are used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen. [source] Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic PropertiesADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Yongquan Qu Abstract Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here, it is shown that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. The Pt/Si/Ag diodes exhibit highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4-nitrophenol are used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen. [source] Enhanced Light-Harvesting and Photocatalytic Properties in Morph -TiO2 from Green-Leaf BiotemplatesADVANCED FUNCTIONAL MATERIALS, Issue 1 2009Xufan Li Abstract The unique structure of green leaves endows them with an extremely high light-harvesting efficiency. In this work, green leaves are applied as biotemplates to synthesize morph -TiO2. The structural features favorable for light harvesting from the macro- to the nanoscale are replicated in morph -TiO2 through a two-step infiltration process and the N contained in the original leaves is self-doped into the resulting samples. The absorbance intensities within the visible-light range of morph -TiO2 derived from different leaves increase by 103,258% and the band-gap-absorption onsets at the edge of the UV and visible-light range show a red-shift of 25,100,nm compared to those in TiO2 without the template. The photocatalytic activity of morph -TiO2 is also improved, as proven by an electron paramagnetic resonance (EPR) study and degradation of rhodamine dye under irradiation with UV and visible light. The present work, as a new strategy, is of far-reaching significance in learning from nature, driving us to make full use of the most-abundant resources and structure-introduced functions endowed by nature, opening up possibilities for extensive study of the physical and chemical properties of morph -structured oxides and extending their potential for use in applications such as solar cells, photocatalysts, photoelectrical devices, and photoinduced sensors. [source] Monomolecular-Layer Ba5Ta4O15 Nanosheets: Synthesis and Investigation of Photocatalytic Properties,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2006T.-G. Xu Abstract Monomolecular-layer perovskite Ba5Ta4O15 nanosheets with hexagonal structure have been synthesized by a hydrothermal method. The thickness of the nanosheets is about 1.1,nm, which corresponds to a monolayer of Ba5Ta4O15 molecules, with the lateral size ranging from 50,to 200,nm. The optimal conditions for the formation of the nanosheets are maintaining the reactants above 270,°C for 24,h. A dissolution,recrystallization mechanism is suggested based on observations of the factors that influence nanosheet formation, such as reaction time, temperature, and basicity. Formation of Ba5Ta4O15 nanosheets takes precedence over other nanostructures under high concentrations of OH, because the hindering effect of OH, ions on the c -axis growth is strong. Thus, the extended growth rate of polyhedrons on one monolayer is much faster than the superposition rate of the monolayer, and the crystal grows more easily along the a - and b -planes. The Ba5Ta4O15 nanosheets show a high photocatalytic activity in the degradation of Rhodamine B and gaseous formaldehyde. The layered perovskite probably affects the photocatalytic activity by promoting the charge separation and delocalization of photogenerated electrons and holes. [source] Preparation, Characterization, and Photocatalytic Properties of CaNb2O6 NanoparticlesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2009In-Sun Cho CaNb2O6 nanoparticles with a size range of 30,50 nm were synthesized by heat treatment at 600°C after a solvothermal process and their optical and photocatalytic properties were investigated. The prepared powders were characterized by X-ray powder diffractometer, field-emission scanning electron microscope, transmission electron microscope, UV-Vis diffuse reflectance spectroscopy, Fluorescence spectroscopy, and Raman spectroscopy. Compared with a powder of the same material prepared by a solid-state reaction (SS) method, the nanoparticles exhibited a higher Brunauer,Emmett,Teller (BET) surface area, more efficient light absorption, and enhanced photocatalytic activity for producing H2 from pure water under UV irradiation. The photoluminescence spectra revealed that a radiative recombination process is dominant in the powder prepared by the SS method (strong blue emission at 300 K) under UV light irradiation, while no obvious emission was observed in the nanoparticles. This decrease of the radiative recombination as well as the higher optical absorption ability and higher BET surface area resulting from the reduced dimensionality led to enhanced photocatalytic activity of the nanoparticles. [source] ChemInform Abstract: The Synthesis of Bismuth Vanadate Powders and Their Photocatalytic Properties under Visible Light Irradiation.CHEMINFORM, Issue 26 2010Yue Shen Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Structural, Photophysical and Photocatalytic Properties of New Bi2SbVO7 under Visible Light Irradiation.CHEMINFORM, Issue 42 2009Jingfei Luan Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Visible-Light Photocatalytic Properties of Weak Magnetic BiFeO3 Nanoparticles.CHEMINFORM, Issue 49 2007Feng Gao Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] SrSnO3 Nanostructures: Synthesis, Characterization, and Photocatalytic Properties.CHEMINFORM, Issue 46 2007Di Chen Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Preparation and Photocatalytic Property of Potassium Niobate K6Nb10.8O30.CHEMINFORM, Issue 6 2007Gaoke Zhang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Sol-gel Preparation of CNT/ZnO Nanocomposite and Its Photocatalytic PropertyCHINESE JOURNAL OF CHEMISTRY, Issue 7 2009Xuejing WANG Abstract Using carbon nanotubes (CNT) as templete, CNT/ZnO nanocomposite was prepared by a sol-gel method. Its structure was characterized by XRD, IR and TEM. The UV absorbing properties were detected by a UV spectrophotometer. Photo degradation of methyl red in aqueous solution was investigated by using CNT/ZnO nanocomposite as photocatalyst. The results showed that the nanocomposite was composed of carbon nanotubes coated evenly by ZnO particles, with a diameter of 50,60 nm. UV-vis spectra indicated that the as-prepared CNT/ZnO nanocomposite had absorption of visible light as well as ultraviolet light. 60% CNT-added nanocomposite had the highest degradation rate for methyl red under the sunlight irradiation. [source] Highly Reactive Multilayer-Assembled TiO2 Coating on Electrospun Polymer NanofibersADVANCED MATERIALS, Issue 12 2009Jung Ah Lee Highly efficient photocatalytically active TiO2 -coated polymer fibers are prepared using a facile and universal method involving layer-by-layer assembly of TiO2 nanoparticles and POSS molecules on various electrospun fibers. The TiO2 -coated fibers display excellent photocatalytic properties in degradation of allyl alcohol under UV illumination, without degradation of substrates. [source] Preparation, Characterization, and Photocatalytic Properties of CaNb2O6 NanoparticlesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2009In-Sun Cho CaNb2O6 nanoparticles with a size range of 30,50 nm were synthesized by heat treatment at 600°C after a solvothermal process and their optical and photocatalytic properties were investigated. The prepared powders were characterized by X-ray powder diffractometer, field-emission scanning electron microscope, transmission electron microscope, UV-Vis diffuse reflectance spectroscopy, Fluorescence spectroscopy, and Raman spectroscopy. Compared with a powder of the same material prepared by a solid-state reaction (SS) method, the nanoparticles exhibited a higher Brunauer,Emmett,Teller (BET) surface area, more efficient light absorption, and enhanced photocatalytic activity for producing H2 from pure water under UV irradiation. The photoluminescence spectra revealed that a radiative recombination process is dominant in the powder prepared by the SS method (strong blue emission at 300 K) under UV light irradiation, while no obvious emission was observed in the nanoparticles. This decrease of the radiative recombination as well as the higher optical absorption ability and higher BET surface area resulting from the reduced dimensionality led to enhanced photocatalytic activity of the nanoparticles. [source] Enhanced Visible-Light Photocatalytic Degradation of Humic Acid by Palladium-Modified Nitrogen-Doped Titanium OxideJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2007Qi Li Palladium-modified nitrogen-doped titanium oxide (TiON/PdO) nanoparticles were synthesized by a sol,gel process, for visible-light-induced photocatalysis using humic acid (HA) as a target. Our work shows that palladium modification has strong effects on the optical and photocatalytic properties of nitrogen-doped titanium oxide (TiON) photocatalysts. TiON/PdO nanoparticles demonstrated an enhanced photocatalytic activity over TiON within a narrow range of palladium concentration. Beyond this range, the adverse effect of palladium modification was observed in the visible-light-induced degradation of HA. The effects of palladium modification are discussed in terms of its role in controlling electron,hole recombination. [source] Correlation of anatase particle size with photocatalytic propertiesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2010Sangwook Lee Abstract The influence of the anatase TiO2 particle size on the photocatalytic properties was systematically investigated on the nanometer-size scale. The anatase TiO2 crystallite size estimated using the Scherrer equation was varied from 8.0 to 16.4,nm, and the photocatalytic properties were significantly deteriorated with decreasing crystallites size. The photocurrent measurements showed that the charge generation diminished with decreasing TiO2 particle size. The bandgap energies were measured as a function of the particle size using UV,Vis spectroscopy in order to investigate the origin of the lowered charge-generation characteristics. The absorption band edge shift was found in the anatase nanocrystallites, which was attributed to the quantum size effect. Therefore, the increased bandgap energy induced the low light absorption capability, which was responsible for the low photoactivity of the very tiny anatase nanoparticles. These findings demonstrated that the particle-size reduction was not the best way to maximize the photocatalytic properties of TiO2 because of the diminished light absorption. [source] A novel characteristic of porous titanium oxide implantsCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2007Takashi Sawase Abstract Objective: The anatase form of titanium dioxide (TiO2) is one of the most common crystalline forms of TiO2 and is normally produced by oxidation of titanium via thermal oxidation or anodizing. This crystalline form exhibits photocatalytic activity when it is irradiated with ultraviolet A (UVA) light. The aim of the current study was to analyze the crystal structure of anodic-oxidized TiUniteŽ implants and to confirm the photocatalytic properties in vitro and in vivo. Material and methods: Cross-sectional observations by transmission electron microscopy were used to determine the surface crystal structure on the TiUnite implant. Subsequently, photocatalytic activity was confirmed by degradation of methylene blue, and hydrophilicity was measured based on the water contact angle. Furthermore, the in vivo effects of the photocatalytic activity of this compound were investigated. Results: An amorphous layer that was about 10 ,m thick was observed on the TiUnite implant surface. In the amorphous layer, the anatase form of the crystalline TiO2 was identified. Photocatalytic activity was clearly demonstrated by the bleaching effect of methylene blue under UVA illumination. The contact angle decreased from 44° to 11° after UVA illumination. Although these data suggest increased hydrophilicity for the TiUnite implant, the bone-to-metal contact at 4 weeks was not influenced. Conclusion: The anodic-oxidized TiUnite implant has inherent photocatalytic activity. UVA illumination increases the surface hydrophilicity of the implant. However, this increase in hydrophilicity does not improve bone apposition to the implant surface at 4 weeks. [source] Environmentally friendly coloured materials: cellulose/titanium dioxide/inorganic pigment composite spherical microbeads prepared by viscose phase-separation methodCOLORATION TECHNOLOGY, Issue 6 2007Shoji Nagaoka In order to develop environmentally friendly coloured materials, cellulose composite spherical microbeads hybridised with titanium dioxide (TiO2) particles and inorganic pigment were prepared by a phase-separation method using viscose and an aqueous solution containing sodium polyacrylate. Findings regarding the relationships between cellulose xanthate and the electronic characteristics of TiO2 particles used in the cellulose/inorganic material composite sphering process are also reported. These findings suggest that the location of TiO2 particles in cellulose microbeads is related to electrical repulsion between the xanthate (CSS,) group and TiO2. The use of TiO2 powder as colour pigment is limited, as its colour is white. The cellulose composite spherical microbeads covered with TiO2 and Fe2O3 particles were developed by addition of iron oxide (Fe2O3). Their surfaces were viewed by laser microscope and using SEM images. These composite microbeads retained the photocatalytic property of TiO2. Cellulose/TiO2/Fe2O3 composite spherical microbeads with both colour function and photocatalytic properties were successfully prepared. [source] ZnO Hierarchical Micro/Nanoarchitectures: Solvothermal Synthesis and Structurally Enhanced Photocatalytic Performance,ADVANCED FUNCTIONAL MATERIALS, Issue 7 2008Fang Lu Abstract A novel ZnO hierarchical micro/nanoarchitecture is fabricated by a facile solvothermal approach in an aqueous solution of ethylenediamine (EDA). This complex architecture is of a core/shell structure, composed of dense nanosheet-built networks that stand on a hexagonal-pyramid-like microcrystal (core part). The ZnO hexagonal micropyramid has external surfaces that consist of a basal plane (000) and lateral planes {011}. The nanosheets are a uniform thickness of about 10,nm and have a single-crystal structure with sheet-planar surfaces as {20} planes. These nanosheets interlace and overlap each other with an angle of 60° or 120°, and assemble into a discernible net- or grid-like morphology (about 100,nm in grid-size) on the micropyramid, which shows a high specific surface area (185.6,m2,g,1). Such a ZnO micro/nanoarchitecture is new in the family of ZnO nanostructures. Its formation depends on the concentration of the EDA solution as well as on the type of zinc source. A two-step sequential growth model is proposed based on observations from a time-dependent morphology evolution process. Importantly, such structured ZnO has shown a strong structure-induced enhancement of photocatalytic performance and has exhibited a much better photocatalytic property and durability for the photodegradation of methyl orange than that of other nanostructured ZnO, such as the powders of nanoparticles, nanosheets, and nanoneedles. This is mainly attributed to its higher surface-to-volume ratio and stability against aggregation. This work not only gives insight into understanding the hierarchical growth behaviour of complex ZnO micro/nanoarchitectures in a solution-phase synthetic system, but also provides an efficient route to enhance the photocatalytic performance of ZnO, which could also be extended to other catalysts, such as the inherently excellent TiO2, if they are of the same hierarchical micro/nanoarchitecture with an open and porous nanostructured surface layer. [source] Thinnest Two-Dimensional Nanomaterial,Graphene for Solar EnergyCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 7 2010Yun Hang Hu Prof. Abstract Graphene is a rapidly rising star in materials science. This two-dimensional material exhibits unique properties, such as low resistance, excellent optical transmittance, and high mechanical and chemical stabilities. These exceptional advantages possess great promise for its potential applications in photovoltaic devices. In this Review, we present the status of graphene research for solar energy with emphasis on solar cells. Firstly, the preparation and properties of graphene are described. Secondly, applications of graphene as transparent conductive electrodes and counter electrodes are presented. Thirdly, graphene-based electron- (or hole) accepting materials for solar energy conversion are evaluated. Fourthly, the promoting effect of graphene on photovoltaic devices and the photocatalytic property of graphene,semiconductor composites are discussed. Finally, the challenges to increase the power conversion efficiency of graphene-based solar cells are explored. [source] Environmentally friendly coloured materials: cellulose/titanium dioxide/inorganic pigment composite spherical microbeads prepared by viscose phase-separation methodCOLORATION TECHNOLOGY, Issue 6 2007Shoji Nagaoka In order to develop environmentally friendly coloured materials, cellulose composite spherical microbeads hybridised with titanium dioxide (TiO2) particles and inorganic pigment were prepared by a phase-separation method using viscose and an aqueous solution containing sodium polyacrylate. Findings regarding the relationships between cellulose xanthate and the electronic characteristics of TiO2 particles used in the cellulose/inorganic material composite sphering process are also reported. These findings suggest that the location of TiO2 particles in cellulose microbeads is related to electrical repulsion between the xanthate (CSS,) group and TiO2. The use of TiO2 powder as colour pigment is limited, as its colour is white. The cellulose composite spherical microbeads covered with TiO2 and Fe2O3 particles were developed by addition of iron oxide (Fe2O3). Their surfaces were viewed by laser microscope and using SEM images. These composite microbeads retained the photocatalytic property of TiO2. Cellulose/TiO2/Fe2O3 composite spherical microbeads with both colour function and photocatalytic properties were successfully prepared. [source] | |||||||||||||