Modification Of Nanomaterials Research Articles

Optical Properties and Antibacterial Bioactivity of ZnO Nanopowder Annealed in Different Ambient

Nanomaterials have attracted much attention for their unique properties and promising performance compared to macroscopic materials. Nanotechnology refer to the cutting-edge approach of synthesis and modification of nanomaterials whose structures exhibit novel and improved physical, chemical, biological properties and functionality due to their nanoscaled size [1-2]. The ongoing revolution of the technology has imposed significant impact into several areas of biomedical research and engineering applications. Among the biomedical application include nanoparticle drug delivery, cell imaging, and cancer therapy.

Tunable bandgap energy of fluorinated nanocrystals for flash memory applications produced by low-damage plasma treatment

A plasma system with a complementary filter to shield samples from damage during tetrafluoromethane (CF4) plasma treatment was proposed in order to incorporate fluorine atoms into gadolinium oxide nanocrystals (Gd2O3-NCs) for flash memory applications. X-ray photoelectron spectroscopy confirmed that fluorine atoms were successfully introduced into the Gd2O3-NCs despite the use of a filter in the plasma-enhanced chemical vapour deposition system to shield against several potentially damaging species. The number of incorporated fluorine atoms can be controlled by varying the treatment time. The optimized memory window of the resulting flash memory devices was twice that of devices treated by a filterless system because more fluorine atoms were incorporated into the Gd2O3-NCs film with very little damage. This enlarged the bandgap energy from 5.48 to 6.83 eV, as observed by ultraviolet absorption measurements. This bandgap expansion can provide a large built-in electric field that allows more charges to be stored in the Gd2O3-NCs. The maximum improvement in the retention characteristic was >60%. Because plasma damage during treatment is minimal, maximum fluorination can be achieved. The concept of simply adding a filter to a plasma system to prevent plasma damage exhibits great promise for functionalization or modification of nanomaterials for advanced nanoelectronics while introducing minimal defects.

Nanomaterials via Laser Ablation/Irradiation in Liquid: A Review

AbstractLaser ablation of solid targets in the liquid medium can be realized to fabricate nanostructures with various compositions (metals, alloys, oxides, carbides, hydroxides, etc.) and morphologies (nanoparticles, nanocubes, nanorods, nanocomposites, etc.). At the same time, the post laser irradiation of suspended nanomaterials can be applied to further modify their size, shape, and composition. Such fabrication and modification of nanomaterials in liquid based on laser irradiation has become a rapidly growing field. Compared to other, typically chemical, methods, laser ablation/irradiation in liquid (LAL) is a simple and “green” technique that normally operates in water or organic liquids under ambient conditions. Recently, the LAL has been elaborately developed to prepare a series of nanomaterials with special morphologies, microstructures and phases, and to achieve one‐step formation of various functionalized nanostructures in the pursuit of novel properties and applications in optics, display, detection, and biological fields. The formation mechanisms and synthetic strategies based on LAL are systematically analyzed and the reported nanostructures derived from the unique characteristics of LAL are highlighted along with a review of their applications and future challenges.

Calculation of layer thickness on nanotube surfaces from XPS intensity data

Surface modification of nanomaterials is the subject of numerous recent investigations. Quantitative characterisation of such modifications is of great theoretical and practical interest. As a first step, our attention is focussed on carbon nanotubes because of their unique morphology and physicochemical properties, having many potential advantages in nanotechnology, electronics, optics and other fields of material science. Surface modification or coating of the nanotubes is essential in several applications, using them as drug carriers, reinforcing component in polymeric matrices or hi‐tech structural ceramics to create reactive surface groups or protection for efficient processing. Applying the simple planar approach to cylindrical‐shaped samples, as known, leading to overestimated layer thickness values because the effective thickness of the layers (seen from the direction of analyser) varies from point to point along the convex surface of the tubes of essentially cylindrical geometry. In case of nanotubes, and any type of nano‐objects, however, a further significant difference is that they have no ‘bulk‐like’ core material because they are usually thin enough to be transparent by the photoelectrons evolving in the XPS measurements. In a step forward for quantitative characterisation, in this article, a special model was developed to calculate the thickness of the modified layer on nanotubes, taking into account that several rows of the tubes are randomly piled on each other. The applicability of the model was tested for quantitative characterisation on multiwall carbon nanotubes (MWCNT), which were treated in d.c.‐biased RF N2 plasma for covalent attachment of nitrogen to their outer shells. This model will be implemented, and thus the calculations would be conveniently performed in the latest versions (from 7.0) of the XPS MultiQuant program. Copyright © 2012 John Wiley & Sons, Ltd.

Os nanomateriais e a descoberta de novos mundos na bancada do químico

In recent years there has been great progress in the field of nanotechnology largely driven by research into nanomaterials. Chemistry appears in this context for its relevant role in the synthesis and surface modification of nanomaterials. This review article discusses fundamental concepts related to the synthesis and properties of inorganic nanoparticles with diverse properties. Aspects related to unique size dependent optical and magnetic properties are discussed and the chemistry involved in the preparation of nanomaterials reviewed. Fundamental aspects of the chemical modification of nanoparticles envisaging potential applications for these materials are also addressed.

Surface modification and shape adjustment of polymer semiconductor nanowires

Low-dimensional nanomaterials have brilliant potential applications in a lot of fields. The surface of nanomaterials plays an important role in their applications. Under many circumstances, surface modification of nanomaterials is needed to endow them with novel or improved properties. Although the surface modification of inorganic one-dimensional nanomaterials by organic molecules can be easily achieved, decoration on the surface of organic semiconductor one-dimensional nanomaterials by organic molecules has not been reported yet. The harsh reaction conditions such as high temperature, acid or alkaline catalysis for the surface modification of inorganic materials will do harm to organic semiconductors and are not suitable. So the surface modification of organic semiconductor one-dimensional nanomaterials is still a big challenge. We report here the surface treatment of polymer semiconductor nanowires by alkylsilanes with different end groups. By selection of the appropriate alkylsilane, we can either modify the surface of polymer semiconductor nanowires with a self-assembled monolayer or adjust the shape of the nanowires to nanoparticles. The surface-modified polymer semiconductor nanowires show improved device performance when used in organic optoelectronic devices. Consequently, our results will open a way for the surface modification and shape adjustment of organic semiconductor one-dimensional nanomaterials, which is highly desired for their future applications in catalysis or nanodevices.

Wettability Modification of Nanomaterials by Low-Energy Electron Flux

Controllable modification of surface free energy and related properties (wettability, hygroscopicity, agglomeration, etc.) of powders allows both understanding of fine physical mechanism acting on nanoparticle surfaces and improvement of their key characteristics in a number of nanotechnology applications. In this work, we report on the method we developed for electron-induced surface energy and modification of basic, related properties of powders of quite different physical origins such as diamond and ZnO. The applied technique has afforded gradual tuning of the surface free energy, resulting in a wide range of wettability modulation. In ZnO nanomaterial, the wettability has been strongly modified, while for the diamond particles identical electron treatment leads to a weak variation of the same property. Detailed investigation into electron-modified wettability properties has been performed by the use of capillary rise method using a few probing liquids. Basic thermodynamic approaches have been applied to calculations of components of solid–liquid interaction energy. We show that defect-free, low-energy electron treatment technique strongly varies elementary interface interactions and may be used for the development of new technology in the field of nanomaterials.

Preparation and characterization of ZnS nanocrystal from Zn(II) coordination polymer and ionic liquid

We report a facile synthesis of spherical ZnS nanocrystals modified with dianion of 3-ferrocenyl-2-crotonic acid (FCA) from one-dimensional (1-D) coordination polymer. Zn(II) coordination polymer has been demonstrated as both precursor and template in the preparation and surface modifications of nanomaterials. Moreover, an ionic liquid 1-butyl-3-methylimidaz-olium tetrafluoroborate ([BMIM]BF 4) solution system has been designed as an assisting template in this experiment. We demonstrate that the 1-D polymeric chain structure is an excellent template for synthesizing organized assemblies of ZnS nanocrystals at low temperatures and ambient atmosphere. From a combination of X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM), the morphology of the synthesized nanocrystals is spherical and with diameters ranging from 40 to 60 nm. The nanocrystals were further examined by FT-IR and UV–visible absorption spectra. In all, we represent a general strategy which is not only environment friendly but also fast and seedless for the preparation of functional nanomaterials.

TiO2 Surface State Control for Dye Sensitized Solar Cells with High Efficiency and the Solidification -Fabrication of Charge Carrier Path

AbstractImprovement of photovoltaic performance for dye sensitized solar cells (DSC) is discussed in terms of electron-path and ion-path. In order to make electron path, we focused on passivation of TiO2 surface states which are observed by thermally stimulated current (TSC). The TiO2 surface was well-passivated with dye molecules under pressurized CO2 atmosphere. It was found that DSC cells prepared by a CO2 process (Cell-CO2) had higher efficiency than those prepared by a conventional dipping process (Cell-DIP) and the higher efficiency was associated with low TiO2-surface state, high electron diffusion coefficient and long electron life time in TiO2 for the Cell-CO2. In addition, dye-staining under pressurized CO2 atmosphere had advantages over a conventional dipping process on rapid dye-uptake and less dye aggregation. In order to fabricate ion-path in solidified electrolyte, we focused on surface modification of nano-materials. Surface of nano-materials such as TiO2-nanoparticles and porous alumina films were modified with imidazolium iodide moieties consisting of long alkyl chains which render surface-molecules self-organized. Redox-species are concentrated on the self-organized molecules and make ion-path. We propose quasi-solid electrolyte system consisting of two layers having different charge carrier concentration to keep high photoconversion efficiencies even after solidification.