Photocatalytic degradation of methyl-red by immobilised nanoparticles of TiO2 and ZnO

none6noIn this work, we report on the degradation of methyl-red (2-(4-Dimethylamino-phenylazo)-benzoic acid - C.I. 13020) under UV irradiation in the presence of nanosized ZnO and TiO2. Oxide nanocrystals with controlled size were synthesised by using non-hydrolytic approaches and tested for the photocatalysed degradation. The performances of the immobilised nanoparticles were compared with their commercial counterparts after immobilization onto a solid support. The influence of some experimental conditions, namely pH and dye concentration, were investigated by monitoring the dye decoloration spectrophotometrically. Several intermediate by-products were identified by HPLC-MS, showing that two different mechanisms were operative during the photocatalytic oxidationsee at: http://www.iwaponline.com/wst/04904/wst049040183.htmopenR. COMPARELLI; P. D. COZZOLI; M. L. CURRI; A. AGOSTIANO; G. MASCOLO; G. LOVECCHIOR., Comparelli; Cozzoli, Pantaleo Davide; M. L., Curri; A., Agostiano; G., Mascolo; G., Lovecchi

"Nanohybrids" based on pH-responsive hydrogels and inorganic nanoparticles for drug delivery and sensor applications.

Allyl-PEG capped inorganic NPs, including magnetic iron oxide (IONPs), fluorescent CdSe/ZnS quantum dots (QDs), and metallic gold (AuNPs of 5 and 10 nm) both individually and in combination, were covalently attached to pH-responsive poly(2-vinylpyridine-co-divinylbenzene) nanogels via a facile and robust one-step surfactant-free emulsion polymerization procedure. Control of the NPs associated to the nanogels was achieved by the late injection of the NPs to the polymerization solution at a stage when just polymeric radicals were present. Remarkably, by varying the total amount of NPs injected, the swelling behavior could be affected. Furthermore, the magnetic response as well as the optical features of the nanogels containing either IONPs or QDs could be modified. In addition, a radical quenching in case of gold nanoparticles was observed, thus affecting the final nanogel geometry

In quest of a systematic framework for unifying and defining nanoscience

This article proposes a systematic framework for unifying and defining nanoscience based on historic first principles and step logic that led to a “central paradigm” (i.e., unifying framework) for traditional elemental/small-molecule chemistry. As such, a Nanomaterials classification roadmap is proposed, which divides all nanomatter into Category I: discrete, well-defined and Category II: statistical, undefined nanoparticles. We consider only Category I, well-defined nanoparticles which are >90% monodisperse as a function of Critical Nanoscale Design Parameters (CNDPs) defined according to: (a) size, (b) shape, (c) surface chemistry, (d) flexibility, and (e) elemental composition. Classified as either hard (H) (i.e., inorganic-based) or soft (S) (i.e., organic-based) categories, these nanoparticles were found to manifest pervasive atom mimicry features that included: (1) a dominance of zero-dimensional (0D) core–shell nanoarchitectures, (2) the ability to self-assemble or chemically bond as discrete, quantized nanounits, and (3) exhibited well-defined nanoscale valencies and stoichiometries reminiscent of atom-based elements. These discrete nanoparticle categories are referred to as hard or soft particle nanoelements. Many examples describing chemical bonding/assembly of these nanoelements have been reported in the literature. We refer to these hard:hard (H-n:H-n), soft:soft (S-n:S-n), or hard:soft (H-n:S-n) nanoelement combinations as nanocompounds. Due to their quantized features, many nanoelement and nanocompound categories are reported to exhibit well-defined nanoperiodic property patterns. These periodic property patterns are dependent on their quantized nanofeatures (CNDPs) and dramatically influence intrinsic physicochemical properties (i.e., melting points, reactivity/self-assembly, sterics, and nanoencapsulation), as well as important functional/performance properties (i.e., magnetic, photonic, electronic, and toxicologic properties). We propose this perspective as a modest first step toward more clearly defining synthetic nanochemistry as well as providing a systematic framework for unifying nanoscience. With further progress, one should anticipate the evolution of future nanoperiodic table(s) suitable for predicting important risk/benefit boundaries in the field of nanoscience

Advanced Wet-Chemical Synthetic Approaches to Inorganic Nanostructures

Inorganic nanomaterials represent one of the most fertile grounds on which the current scientific revolution of nanoscience is being founded. The unique size and shape dependent chemical-physical properties of nanostructures bring them into a key position as constituent elements for realizing a large spectrum of unprecedented self-assembled functional materials, smart devices, and processes. Among the various "bottom-up" fabrication approaches, wet-chemical routes have universally distinguished for their ability to provide high-quality nanocrystals with a number of desirable prerequisites, such as controlled composition and crystal phase, tailored geometric parameters, programmed surface functionalities, chemical robustness, and ease of processability. Disparate applications in fields as diverse as optoelectronics, photovoltaics, sensing, environmental remediation, catalysis, fuel cells, fabrication of novel materials, and biomedicine, are already on the way toward commercialization. Efforts of nanochemistry research toward effective synthetic methods to purpose-built nanomaterials have incredibly proliferated over the past 30 years, and have now reached a high level of advancement. In this book, we venture through this exciting field, addressing the most relevant technical and mechanistic aspects involved in solution-phase synthesis of nanostructures made of inorganic semiconductor, metal and oxide materials. Chapters 1 to 3 provide fundamental concepts for the understanding of wet-chemical processing of inorganic nanomaterials in liquid media. General organic chemistry pathways of transformation of molecular precursors into inorganic frameworks, mechanistic aspects underlying nucleation and growth of nanoparticles, as well the influence of crystal symmetry, surfactants, ligands, solvents, interfaces, and catalysts, on the formation of nanostructures, are described and discussed. Subsequent chapters are individually dedicated to address specific synthetic issues related to the preparation of principal classes of technologically relevant nanoscale materials, with particular emphasis on rationalization of criteria leading to compositional, size and shape control of nanostructures. Chapter 4 provides the basics of sonochemistry and its application to the synthesis of metallic nanoparticles. Chapter 5 focuses on methods for the preparation of functional magnetic nanostructures and nanocomposite systems, addressing their impact on the relevant chemical-physical behaviour of the as-derived nanomaterials. Chapters 6 to 8 describe routes to both free-standing and carbon-supported plasmonic and alloyed metallic nanoparticles, that are relevant to a number of magneto-optical and catalytic uses. Chapters 9 and 10 offer an overview of synthetic approaches to valuable transition metal oxide materials (with special focus on titania) and to nanocomposite systems based thereof, which are desired in photoelectrocatalytic applications. Chapters 11 to 13 deal with synthetic design of various categories of luminescent materials, including core/shell semiconductor and doped oxide nanocrystals on one side, and hybrid organic/inorganic lamellar nanostructures, on the other side. Finally, Chapter 14 illustrates advanced synthetic strategies to multimaterial hybrid nanocrystals with a spatially controlled distribution of their chemical composition, which represent last-generation breeds of colloidal nanostructures with multiple functional capabilities. The book provides a variety of examples of current developments and supports the text descriptions with appropriate characterization data, reaction schemes and explanatorysketches. The result is an up-to-date monographic compendium on wet-chemistrymethods to inorganic nanomaterials, which can appeal to a broad readership of bothpracticing students and more specialized scientists. Enjoy reading

Colloidal TiO2-based nanocrystal heterostructures

Nanoscale TiO2 represents an exclusive encounter platform on which diverse physical-chemical properties coexist with the potential for environmentally safe energy applications [1]. One strategy to diversify and expand the technological opportunities of this oxide is to create TiO2-based heterostructured nanocrystals (HNCs) with a spatially controlled distribution of their composition, which ncorporate epitaxially interconnected domains of TiO2 and distinct metal magnetic materials [2]. In this lecture, we will illustrate progress made by our research group in the development of novel colloidal HNCs based on different TiO2 polymorphs and foreign metallic and magnetic materials (γ-Fe2O3/Fe3O4, Co, Ag, Pt, Cu/Cu2O), discussing their formation mechanism, and peculiar structural, magnetic, optical and photocatalytic properties. Useful criteria for the rational design of future prototypes of TiO2-based heterostructures with higher structural complexity and increased functionality will be suggested

Colloidal Heterostructured Nanocrystals: Synthesis and Growth Mechanisms

One frontier approach of colloidal chemistry to nanoscale entities capable to exhibit enhanced or even unconventional physical–chemical properties as well as diversified capabilities for multitask applications envisages fabrication of breed-new hybrid nanocrystals (HNCs) with a spatially controlled distribution of their chemical composition. These are all-inorganic multicomponent nanoheterostructures in which domains of distinct materials are arranged via permanent bonding interfaces in elaborate concentric/eccentric onion-like or oligomer-type architectures. This review covers recent progress achieved in the wet-chemical development of HNCs based on functional associations of semiconductors, metals and magnetic compounds. Within the frame of seeded-growth techniques to heteroepitaxial deposition in solution media, relevant synthetic strategies are illustrated, along with systematic examination of the mechanisms by which heterostructures can be selectively accessed in nonequivalent topological configurations. The peculiar properties and technological perspectives offered by such novel generations of complex nanomaterials are also succinctly highlighted

Tips on growing nanocrystals

The complexity of the size, shape and composition of nanocrystals is evolving. Equipping them with a single gold tip that can serve as a preferential anchoring point for molecular linkers holds promise for new strategies in self-assembly