Surfactant (PEG 400) effects on crystallinity of ZnO nanoparticles

AbstractThe surfactant effects on the size and crystallinity of ZnO powders prepared by Solid-state mechanochemical method. The present method is a simple and efficient method for the preparation of nanoparticles with high yield at low cost. The size and crystallinity of the nanoparticles were analyzed by X-ray diffraction, scanning electron microscopy and energy-dispersive spectrometer (SEM/EDAX). Optical properties and band gap were studied by UV–Vis spectroscopy. XRD shown that the lattice constants have been changed to some extent. These results showed that the band gap energy decreases with increase in lattice constants, which can be attributed to the improvement in crystallinity of the samples. The band gap of the ZnO can be tuned in the range of 3.37–3.33eV respectively, by the use of PEG 400 surfactant

Development of multi-walled carbon nanotubes modified pencil graphite electrode for the electrochemical investigation of aceclofenac present in pharmaceutical and biological samples

A sensitive and novel chemically modified multi-walled carbon nanotubes modified pencil graphite electrode (MCPGE) has been developed for the electrochemical investigation of aceclofenac (ACF). MCPGE was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Phosphate buffer solution (PBS) of pH7.0 was used as a suitable electrolytic medium, in which aceclofenac (ACF) exhibited a sensitive adsorption controlled oxidation peaks at +0.12, +0.32 and +0.51V and a reduction peak at −0.26V (vs Ag/AgCl). The experimental conditions were optimised by means of investigating the dependence of peak current on solution pH, concentration and scan rate etc. The electrochemical parameters such as surface concentration (Γ), electron transfer coefficient (α) and the standard rate constant (ks) were investigated at MCPGE. The oxidative peak currents were varied linearly with concentration in the range between 1×10−6 to 60×10−6M with a detection limit of 2.6×10−9M. The UV–Vis absorption spectrum of ACF gave the λmax at 272–273nm and is attributed to the presence of ACF. The applicability of the MCPGE was illustrated by the determination of ACF present in pharmaceutical and human urine samples. Keywords: Aceclofenac, Multi-walled carbon nanotubes, Pencil graphite electrode, Cyclic voltammetry, Differential pulse voltammetr

Efficient photocatalytic degradation of crystal violet dye and electrochemical performance of modified MWCNTs/Cd-ZnO nanoparticles with quantum chemical calculations

Several literature studies have defined the doping technique of ZnO with a Cd (transition metal) for photocatalysis applications. Despite this, the properties and the mechanism behind it have never been completely explained. The present work outlines the effect of Cadmium ion doping on structural, optical, electrochemical impedance and photocatalytic properties of ZnO and Cd-ZnO nanoparticles prepared via simple precipitation method. The prepared Cd-ZnO was characterized using advanced techniques such as powder X-ray diffraction, field-emission scanning electron microscope fitted with energy dispersive X-ray diffraction, UV-visible absorbance spectroscopy and electrochemical impedance were performed on modification of glassy carbon electrode (GCE) with multiwalled carbon nanotubes decorated with ZnO and Cd-ZnO. Moreover, Cd-ZnO NPs displayed superior electrochemical performance than undoped ZnO NPs. Experiments revealed that, as compared to ZnO and higher dopant concentration, the photodegradation of crystal violet was enhanced by the use of 0.5 mol% Cd-ZnO catalyst. The implantation of Cd is assisted by faster carrier separation and transfer efficiency. Tauc’s plots illustrate that the incorporation of Cd ion has decreased the optical band-gap of ZnO samples. After Cd doping, the valence and conduction band of ZnO were modified, contributing to the development of O2 ‐ , resulting in a significant improvement in photodegradation. Mulliken atomic charges and molecular properties computed at B3LYP/6-31G level of theory. The HOMO-LUMO band gap of alleged photocatalysts was calculated using density function theory (DFT). Further to support our hypothesis on degradation of the dye using Cd-ZnO was confirmed by the IR and Mass spectral studies. Computational prediction of toxicity of degraded organic molecules was estimated by Toxicity Estimation Software Tool (TEST) by United States Environmental Protection Agency. FTIR and Mass spectroscopy confirm the 100% degradation of CV-dye under UV chamber (6 W) after 30 min at basic medium. The enhanced electrochemical and photocatalytic efficiency of Cd doped ZnO nanoparticles suggest that they have dual activity in energy and water treatment application

Le dispositif anti-abus de l'article 155 A du CGI au coeur de l'actualité

Note sous CAA Paris, 2ème ch., 28 avril 2010, n° 08PA00415. Joueur professionnel de tennis ; fiscalité internationale ; commissions versées à une société implantée à l'étranger ; assujettissement à l'impôt sur le revenu en France