Nanotechnology
I. Benammar; R. Salhi; J. -L. Deschanvres; R. Maalej
Abstract
This paper describes the systematic preparation of doped and undoped TiO2 with Er and/or Yb nanoparticles by hydrothermal-assisted sol-gel method using supercritical drying of ethanol followed by systematic calcination steps at 500°C, 800°C and 1000°C for 2/h. The structural study of these ...
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This paper describes the systematic preparation of doped and undoped TiO2 with Er and/or Yb nanoparticles by hydrothermal-assisted sol-gel method using supercritical drying of ethanol followed by systematic calcination steps at 500°C, 800°C and 1000°C for 2/h. The structural study of these powders with XRD reveals that our samples are crystalline with a tetragonal structure and anatase phase, which is well crystallized at 500°C. The annealing at 800°C reveals a transformation of the anatase phase to the rutile phase, which is well crystallized at 1000°C. The XRD analysis clearly indicates that the dopants are incorporated into the TiO2 network without any phase segregation-taking place in these nanoparticles. The study of the grain sizes has shown that they are nanometric in size of around 8-12 nm and that their sizes decrease with Er and/or Yb doping. The elemental analyses with micro-EDX using SEM confirmed the presence of chemical elements of TiO2 nanoparticles with expected atomic ratios. The analysis of the SEM images confirmed the XRD observations. In addition, they attest that the nanoparticles are spherical in shape. The optical analysis with excitation at 488 nm shows the presence of three emission bands in the green zone and the red zone. The heat treatment improves the optical, structural and spectroscopic properties and eliminates the contaminations that are due to the preparation conditions.
Zahraa Khedaer; Duha Ahmed; Selma Al-Jawad
Abstract
In this research, raw multiwalled carbon nanotubes (R-MWCNT) was successfully functionalized using sulfuric acid and nitric acid. Then a hybrid (ZnO-MWCNT) synthesized by the sol-gel method where diethylene glycol was used as a solvent and stabilizer that works to prevent the accumulation of nanoparticles ...
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In this research, raw multiwalled carbon nanotubes (R-MWCNT) was successfully functionalized using sulfuric acid and nitric acid. Then a hybrid (ZnO-MWCNT) synthesized by the sol-gel method where diethylene glycol was used as a solvent and stabilizer that works to prevent the accumulation of nanoparticles and reduces the viscosity of the solution. A group of diagnostic techniques, including XRD, UV-Vis, EDX and microscopy has recognized the structural and optical properties of the prepared nanoparticles. High Resolution Electronic Scanner (FE-SEM) was also used in the investigation. FE-SEM images showed the formation of the hybrid (ZnO-MWCNT) by the growth of spherical clusters on the surface of the cross-linked tubes (MWCNT). In addition, FE-SEM images confirmed the success of a ZnO-MWCNT hybrid. The emergence of spherical shapes deposited on cylindrical tubes and associated with a wrinkled surface was recognized. In addition, the particle size ratio increased. The UV-Vis spectra revealed that all the composites had good absorbency with a shift towards short wavelengths. While it was observed from the analysis of X-ray diffraction (XRD) the formation of a hexagonal wurtzite crystal structure due to zinc oxide with a polycrystalline nature. The average crystal size calculated from the Debye-spark equation increased with the increase in the concentration of the streaked material. Antibacterial activity was studied for all prepared samples against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) at different μg/ml concentrations (500, 750, and 1000). It was observed that the highest inhibition Zone for functionalized multiwalled carbon nanotubes (F-MWCNT) and ZnO-MWCNT hybrid was (17.3, 12.3mm), (22.5, 19mm) for Escherichia coli and Staphylococcus aureus, respectively.