N. Ponpandian

Enhanced photocatalytic activity of cobalt-doped CeO2 nanorods

In this paper, CeO2 and cobalt-doped CeO2 nanorods synthesized by surfactant free co-precipitation method. The microstructures of the synthesized products were characterized by XRD, FESEM and TEM. The structural properties of the grown nanorods have been investigated using electron diffraction and X-ray diffraction. High resolution transmission electron microscopy studies show the polycrystalline nature of the Co-doped cerium oxide nanorods with a length of about 300xa0nm and a diameter of about 10xa0nm were produced. The X-ray Photoelectron spectrum confirms the presence of cobalt in cerium oxide nanorods. From BET, the specific surface area of the CeO2 (Co-doped) nanostructures (131 m2xa0g−1) is found to be significantly higher than that of pure CeO2 (52 m2xa0g−1). The Co-doped cerium nanorods exhibit an excellent photocatalytic performance in rapidly degrading azodyes acid orange 7 (AO7) in aqueous solution under UV illumination.

Synthesis of CeO 2 nanorods with improved photocatalytic activity: comparison between precipitation and hydrothermal process

The main purpose of this article is to examine the surface free cerium oxide (CeO2) nanostructures prepared by different methods. CeO2 nanoparticles and nanorods were prepared by two different methods including precipitation and hydrothermal process. In precipitation process the nanoparticles were prepared at room temperature, while in hydrothermal process nanorods were prepared at high temperature. X-ray and electron diffraction analysis show the presence of CeO2. X-ray photoelectron spectroscopy (XPS) confirms the presence of CeO2 in both nanostructures. From BET, the specific surface area of nanorods (110 m2g−1) is found to be higher than nanoparticles (52 m2g−1). Also, the effect of morphology on their photodegradation of azo dye acid orange 7 (AO7) under UV–Visible light has been successfully investigated. The results show that the CeO2 nanorods synthesized by hydrothermal method have high surface area and exhibit improved performance in the photocatalytic activity.

Iron oxide nanoparticles induced alterations in haematological, biochemical and ionoregulatory responses of an Indian major carp Labeo rohita

The wide use of iron oxide nanoparticles (Fe2O3 NPs) in various applications has raised great concerns worldwide. In this work, we measured the potential harmful effects of Fe2O3 NP (<50xa0nm) at concentrations of 1 and 25xa0mg/L on haematological, biochemical, and ionoregulatory responses in an Indian major carp, Labeo rohita for a short-term period of 96xa0h. The results revealed significant (Pxa0<xa00.05) decreases in haemoglobin, haematocrit, mean cellular volume, mean cellular haemoglobin, protein, sodium (Na+), potassium (K+), chloride (Cl−) and gill Na+/K+-ATPase levels in both the concentrations. White blood cell, mean cellular haemoglobin concentration and glucose levels were significantly (Pxa0<xa00.05) increased in response to both concentrations during the study period. However, no significant changes in red blood cell count and gill Na+/K+-ATPase (25xa0mg/L) activity were noticed compared to those of the respective control groups. Based on this study, it was found that the Fe2O3 NPs do have prominent effects on freshwater fish L. rohita. Our data suggest that the alterations of these parameters can be used as nonspecific biomarkers to monitor the environmental risks arising from nanoparticles in aquatic ecosystem and also regulate the use, production and release of nanoparticles.

Gas Sensing Properties of Chemically Synthesized V2O5 Thin Films

Nanostructured vanadium pentoxide films have been synthesized by using a sol–gel technology from V2O5 powder and hydrogen peroxide. The V2O5 powder was dissolved in hydrogen peroxide solution, agitated and heated up to 65oC to form gel by the dissociation of the peroxide complexes. The obtained gel was deposited by dip coating technique and dried in air at room temperature. Structural, morphological and compositional analyses were carried out on the prepared samples using X-Ray Diffractometer (XRD), Raman spectrometer and scanning electron microscopy (SEM). The as-prepared films show an amorphous nature, while those annealed at 400oC exhibit orthorhombic structures. The films seem to have grain like structures on annealing which are expected to help the gas sensing properties of the V2O5 films. The annealed films were connected with copper electrodes and used as sensing element. The change in the resistance of the sensing element with respect to the test gas concentration was measured by noting down the resistance at each concentration. Sensitivity of the material linearly increased with different concentrations of ethanol and ammonia. It is clearly seen that the material has more sensing response for ethanol when compared to that of ammonia.

Room Temperature Growth of Cerium-Iron Oxide Nanorods

Cerium-iron oxide composite nanorods were synthesized by a surfactant free precipitation method. The synthesized products were characterized by XRD, FESEM, BET and TEM. Increase in the mole concentration causes the morphology of the cerium oxide to change from nanorods into nanocubes. X-ray diffraction pattern shows a diffraction peak at 28.5° corresponding to (111) reflection plane normal to c axis of a cubic fluorite structure of CeO2 and also hexagonal phase of Fe2O3 and orthorhombic phase of FeO (OH). EDAX analysis on individual nanorod conform the presences of Iron, which supports the XRD spectra. From transmission electron microscopy (TEM), the length and width of the nanorods were estimated in the range of ~100-350 nm and ~20-40 nm respectively. The Brunauer Emmett Teller (BET) analysis showed the increase in surface area for the obtained nanorods with respect to the increase in Fe concentration which in turn enhanced the formation and growth of nanorods.