Search results for "Nanomaterial"
showing 10 items of 330 documents
2020 Roadmap on two-dimensional nanomaterials for environmental catalysis
2019
Abstract Environmental catalysis has drawn a great deal of attention due to its clean ways to produce useful chemicals or carry out some chemical processes. Photocatalysis and electrocatalysis play important roles in these fields. They can decompose and remove organic pollutants from the aqueous environment, and prepare some fine chemicals. Moreover, they also can carry out some important reactions, such as O2 reduction reaction (ORR), O2 evolution reaction (OER), H2 evolution reaction (HER), CO2 reduction reaction (CO2RR), and N2 fixation (NRR). For catalytic reactions, it is the key to develop high-performance catalysts to meet the demand for targeted reactions. In recent years, two-dimen…
Chemical modification of carbon nanomaterials (SWCNTs, DWCNTs, MWCNTs and SWCNHs) with diphenyl dichalcogenides
2015
Control over chemical functionalization is a crucial point in the field of nanotechnology. Herein, we present the covalent functionalization of several carbon nanoforms (single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanohorns) by means of diphenyl dichalcogenides. These ones show different reactivity to the nanomaterials and are able to modify their electronic properties depending on the electronegativity of the functionalizing heteroatom. Theoretical calculations were also performed to support the experimental results. All the modified structured nanocarbons were thoroughly characterized by TGA Raman, XPS, UV/Vis/nIR, IR and TEM te…
Determination of association constants towards carbon nanotubes
2015
Single-walled carbon nanotubes (SWNTs) are one of the most promising nanomaterials and their supramolecular chemistry has attracted a lot of attention. However, despite well over a decade of research, there is no standard method for the quantification of their noncovalent chemistry in solution/suspension. Here, we describe a simple procedure for the determination of association constants (Ka) between soluble molecules and insoluble and heterogeneous carbon nanotube samples. To test the scope of the method, we report binding constants between five different hosts and two types of SWNTs in four solvents. We have determined numeric values of Ka in the range of 1–104 M−1. Solvent effects as wel…
Use of Nanomaterials as Alternative for Controlling Enzymatic Browning in Fruit Juices
2020
Abstract Polyphenol oxidase (PPO) enzyme, present in most of fruits and vegetables, frequently induces browning in juices and beverages during postharvest and processing. Many efforts have been done to prevent or avoid this reaction. Nevertheless, the development of new methods is still of interest since many of the current methods present important drawbacks. An overview of the exiting techniques to inhibit enzymatic browning has been compiled in this chapter, including physical (i.e., thermal treatments, high pressures, irradiation, ultrasonication, pulsed electric fields, and ultrafiltration) and chemical techniques (acidification, addition of antibrowning agents) but with particular att…
Synthesis of novel polypyridylcarbonylpyridines from triazolopyridines. Building blocks in supramolecular chemistry
2009
The synthesis from triazolopyridines 1, of novel triazolopyridylcarbonylpyridylcarbonyltriazolopyridines (TPyCOPyCOTPy) (tpcpctp) 7, and polypyridylcarbonylpyridines (pPyCOPy) (ppcp) 14, building blocks in supramolecular chemistry, is described. These compounds are interesting polynitrogenated ligands as potential molecular sensors, new magnetic materials, single molecular magnets, or in the emerging science of nanomaterials. Abarca Gonzalez, Belen, Belen.Abarca@uv.es ; Ballesteros Campos, Rafael, Rafael.Ballesteros@uv.es ; Chadlaoui, Mimoun, michad@alumni.uv.es
Biogenic synthesis of palladium nanoparticles using Pulicaria glutinosa extract and their catalytic activity towards the Suzuki coupling reaction.
2014
Green synthesis of nanomaterials finds the edge over chemical methods due to its environmental compatibility. Herein, we report a facile and eco-friendly method for the synthesis of palladium (Pd) nanoparticles (NPs) using an aqueous solution of Pulicaria glutinosa, a plant widely found in a large region of Saudi Arabia, as a bioreductant. The as-prepared Pd NPs were characterized using ultraviolet-visible (UV-vis) spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform-infrared spectroscopy (FT-IR). The hydroxyl groups of the plant extract (PE) molecules were found mainly responsible for the red…
Localized Surface Plasmon Resonance in Colloidal Copper Sulphide (Cu2-xS, x = 0 ≤ x < 1) Nanocrystals and Its Applications
2021
Colloidally prepared copper sulphide (Cu2-xS) nanocrystals are possessing superior structural and optical properties owing to the presence of copper vacancies. The application of colloidal Cu2-xS nanocrystals are critically analysed for several optoelectronic applications. Furthermore, colloidally prepared Cu2-xS nanocrystals undergo facile process such as cation exchange, additives induced structural modifications etc. Therefore, it is important to evaluate the optical properties of these nanomaterials in order to apply them for future optoelectronic applications. Out of other properties, localized surface plasmon resonance (LSPR) by controlling composition of the Cu2-xS nanocrystals is in…
Challenges in the determination of engineered nanomaterials in foods
2016
Detection, characterization, and quantification of engineering nanomaterials (ENMs) in foods is still a pending issue that needs to be tackle to protect consumers and to fix some related aspects (e.g. labelling or control). The global challenge for the analytical sciences is that ENMs are a new sort of analytes, involving both chemical (composition, mass and number concentration) and physical information (e.g. size, shape, aggregation). In this critical review, we evaluate and compare the procedures involved in the analytical methods and studies developed thus far for the identification and quantification of ENMs in food. We discuss advantages and limitation as well as prospects. We pointed…
Nanomaterial-based molecularly imprinted polymers for pesticides detection: Recent trends and future prospects
2020
Abstract Pesticides have been widely used in agricultural and industrial production to prevent pests. So, sensing pesticides with high selectivity and sensitivity level plays a significant role in food safety management. Molecularly imprinted polymer (MIP) based sensors overcome the current restriction of traditional detection approaches and offer great potential for efficient, low-cost and low detection limit using smart miniaturized equipment. But some drawbacks could come from the lack of electrocatalytic activity and conductivity of MIPs that restrict their utilization in the sensing field. The integration of NPs with MIPs has opened new ways for rapid screening and monitoring of pestic…
Genotoxicity investigations on nanomaterials: methods, preparation and characterization of test material, potential artifacts and limitations--many q…
2008
Nanomaterials display novel properties to which most toxicologists have not consciously been exposed before the advent of their practical use. The same properties, small size and particular shape, large surface area and surface activity, which make nanomaterials attractive in many applications, may contribute to their toxicological profile. This review describes what is known about genotoxicity investigations on nanomaterials published in the openly available scientific literature to-date. The most frequently used test was the Comet assay: 19 studies, 14 with positive outcome. The second most frequently used test was the micronucleus test: 14 studies, 12 of them with positive outcome. The A…