Preparation and characterization of quantum size zinc oxide:  a detailed spectroscopic study

Bahnemann, Detlef W.; Kormann, Claudius; Hoffmann, Michael R.

doi:10.1021/j100298a015

Cited by 757 publications

(679 citation statements)

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“…[2][3][4]15 However, quantum confinement effects in the ZnO nanoparticle array were not observed, presumably because of the relatively large diameter of the nanoparticle. [5][6][7] In conclusion, we successfully demonstrated the synthesis of photoluminescent ZnO nanoparticles in an ordered array on the solid substrate conserving the dimensional order of PS-PVP diblock copolymer micelles. Thus, the array of optically active nanoparticles was directly fabricated on the substrate with a single synthetic step, instead of separated procedures for the synthesis and deposition of nanoparticles.…”

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confidence: 77%

Self-assembled arrays of zinc oxide nanoparticles from monolayer films of diblock copolymer micelles

et al. 2004

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A hexagonal array of optically active ZnO nanoparticles was synthesized in situ on the solid substrate by utilizing a singlelayered film of diblock copolymer micelles as a nanostructured template.During the last decade, research on semiconductor nanoparticles has been a wide and interdisciplinary field of science to elucidate and utilize their novel material properties. 1 Zinc oxide, a wideband-gap semiconductor oxide, is a very fascinating material due to its large exciton binding energy and bond strength, 2,3 which make it applicable for a blue or ultraviolet optical device. [2][3][4] Nanoparticles of zinc oxide can be effectively synthesized in aqueous or organic solutions. Colloidal synthetic routes for ZnO nanoparticles usually involve the reaction of Zn 21 salts in basic solutions. [5][6][7] For their applications, however, controlled deposition of ZnO nanoparticles from solutions to solid substrates is necessary. To place nanoparticles on a substrate in a specific arrangement, templates have been utilized, which can be lithographically fabricated or self-assembled. [8][9][10][11][12][13][14] In the case of self-assembled templates, a periodic nanostructure of diblock copolymers or their micelles was successfully employed to arrange nanoparticles with a considerable stability. [10][11][12][13][14] For example, the nanometre-sized micelles of diblock copolymers in a selective solvent for one of the blocks were transferred onto silicon wafers to form a hexagonally ordered monolayer film, which served as a structured template to direct the spatial location of nanoparticles. [10][11][12][13][14] In addition, an ordered array of metal or oxide nanoparticles was directly synthesized by employing plasma treatments as a successful method of oxidation or reduction of precursors of nanoparticles as well as removal of copolymer templates. Möller and coworkers demonstrated arrays of gold nanoparticles on various substrates with a combination of diblock copolymer micelles and plasma treatments. 11 Similarly, we reported an array of iron oxide nanoparticles surrounded by gold nanoparticles from a monolayer film of diblock copolymer micelles with subsequent exposure to oxygen plasma. 13 The fabricated arrays of nanoparticles from diblock copolymer micelles, however, were applied mostly to passive applications such as an etching resistant mask. As an active nanopattern, an array of cobalt nanoparticles was recently synthesized from diblock copolymer micelles although magnetic properties of the array were not reported. 12 In this communication, we demonstrate instant synthesis of optically active ZnO nanoparticles in a hexagonal order from a single-layered film of diblock copolymer micelles with oxygen plasma treatment. The near-band-edge emission was observed for the array of ZnO nanoparticles.For a monolayer film of diblock copolymer micelles, polystyrene-block-poly(4-vinylpyridine), PS-PVP (M n PS~4 7.6 kg mol 21 , M n PVP~2 0.4 kg mol 21 , polydispersity index~1.14) was dissolved in toluene and stirred for 3 h at room ...

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confidence: 77%

Self-assembled arrays of zinc oxide nanoparticles from monolayer films of diblock copolymer micelles

et al. 2004

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“…Most of the reported photocatalysts possess limitations, e.g., GaAs, PbS, and CdS are not sufficiently stable for catalysis in aqueous media as they readily undergo photocorrosion and are also toxic [53]. ZnO is unstable because it readily dissolves in water [61] to yield Zn(OH) 2 on the ZnO particle surface, which inactivates the catalyst over time. Fe 2 O 3 , SnO 2 , and WO 3 possess a conduction band edge at an energy level below the reversible hydrogen potential, thus systems using these materials require application of an external electrical bias to complete the water splitting reaction and achieve The spacing of the energy levels (i.e., density of states) varies among systems [51].…”

Section: Tio 2 Vs Other Materials As a Photocatalystmentioning

confidence: 99%

A review of TiO2 nanoparticles

2011

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Climate change and the consumption of non-renewable resources are considered as the greatest problems facing humankind. Because of this, photocatalysis research has been rapidly expanding. TiO 2 nanoparticles have been extensively investigated for photocatalytic applications including the decomposition of organic compounds and production of H 2 as a fuel using solar energy. This article reviews the structure and electronic properties of TiO 2 , compares TiO 2 with other common semiconductors used for photocatalytic applications and clarifies the advantages of using TiO 2 nanoparticles. TiO 2 is considered close to an ideal semiconductor for photocatalysis but possesses certain limitations such as poor absorption of visible radiation and rapid recombination of photogenerated electron/hole pairs. In this review article, various methods used to enhance the photocatalytic characteristics of TiO 2 including dye sensitization, doping, coupling and capping are discussed. Environmental and energy applications of TiO 2 , including photocatalytic treatment of wastewater, pesticide degradation and water splitting to produce hydrogen have been summarized. Historical backgroundThe growth of industry worldwide has tremendously increased the generation and accumulation of waste byproducts. In general, the production of useful products has been focused on and the generation of waste byproducts has been largely ignored. This has caused severe environmental problems that have become a major concern. Researchers all over the world have been working on various approaches to address this issue. Photoinduced processes have been studied and various applications have been developed. One important technique for removing industrial waste is the use of light energy (electromagnetic radiation) and particles sensitive to this energy to mineralize waste which aids in its removal from solution. Titanium dioxide (TiO 2 ) is considered very close to an ideal semiconductor for photocatalysis because of its high stability, low cost and safety toward both humans and the environment.*Corresponding author (email: shipra.mital@gmail.com)In 1964, Kato et al.[1] published their work on the photocatalytic oxidation of tetralin (1,2,3,4-tetrahydronaphthalene) by a TiO 2 suspension, which was followed by McLintock et al. [2] investigating the photocatalytic oxidation of ethylene and propylene in the presence of oxygen adsorbed on TiO 2 . However, the most important discovery that extensively promoted the field of photocatalysis was the "Honda-Fujishima Effect" first described by Fujishima and Honda in 1972 [3]. This well-known chemical phenomenon involves electrolysis of water, which is related to photocatalysis. Photoirradiation of a TiO 2 (rutile) single crystal electrode immersed in an aqueous electrolyte solution induced the evolution of oxygen from the TiO 2 electrode and the evolution of hydrogen from a platinum counterelectrode when an anodic bias was applied to the TiO 2 working electrode. In 1977, Frank and Bard [4] examined the reduction of ...

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“…The synthesis of ZnO nanoparticles was carried out in an alcoholic medium following the procedure reported by Bahnemann et al [31]. A 1 mM zinc acetate (Zn(CH 3 COO) 2 , Merck, 99% purity) solution was prepared in 20 ml of 2-propanol ((CH 3 ) 2 CHOH, Carlo Erba, 99.7% purity) under vigorous stirring at 50 • C. The solution was then diluted to 230 ml with 2-propanol and cooled.…”

Section: Synthesis Of Zno Nanoparticlesmentioning

confidence: 99%

Growth of ZnO nanowires on nonwoven polyethylene fibers

Baruah

Thanachayanont

Dutta

2008

Science and Technology of Advanced Materials

121

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We report the growth of ZnO nanowires on nonwoven polyethylene fibers using a simple hydrothermal method at a temperature below the boiling point of water. The ZnO nanowires were grown from seed ZnO nanoparticles affixed onto the fibers. The seed ZnO nanoparticles, with diameters of about 6-7 nm, were synthesized in isopropanol by reducing zinc acetate hydrate with sodium hydroxide. The growth process was carried out in a sealed chemical bath containing an equimolar solution of zinc nitrate hexahydrate and hexamethylene tetramine at a temperature of 95 • C over a period of up to 20 h. The thickness and length of the nanowires can be controlled by using different concentrations of the starting reactants and growth durations. A 0.5 mM chemical bath yielded nanowires with an average diameter of around 50 nm, while a 25 mM bath resulted in wires with a thickness of up to about 1 µm. The length of the wires depends both on the concentration of the precursor solution as well as the growth duration, and in 20 h, nanowires as long as 10 µm can be grown. The nonwoven mesh of polyethylene fibers covered with ZnO nanowires can be used for novel applications such as water treatment by degrading pollutants by photocatalysis. Photocatalysis tests carried out on standard test contaminants revealed that the polyethylene fibers with ZnO nanowires grown on them could accelerate the photocatalytic degradation process by a factor of 3.

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Preparation and characterization of quantum size zinc oxide: a detailed spectroscopic study

Cited by 757 publications

References 7 publications

Self-assembled arrays of zinc oxide nanoparticles from monolayer films of diblock copolymer micelles

Self-assembled arrays of zinc oxide nanoparticles from monolayer films of diblock copolymer micelles

A review of TiO2 nanoparticles

Growth of ZnO nanowires on nonwoven polyethylene fibers

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