N. Krishna Chandar

Bio: N. Krishna Chandar is an academic researcher from VIT University. The author has contributed to research in topics: Materials science & Fourier transform infrared spectroscopy. The author has an hindex of 6, co-authored 12 publications receiving 109 citations. Previous affiliations of N. Krishna Chandar include Anna University.

Synthesis and characterization of C14TAB passivated cerium oxide nanoparticles prepared by co-precipitation route

Abstract: A facile co-precipitation route has been employed to synthesize cerium oxide (CeO 2 ) nanoparticles using cationic surfactant (tetradecyltrimethyl ammonium bromide, C 14 TAB) and cerium nitrate hexahydrate at room temperature. X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM), selected area electron diffraction (SAED), fourier transform infrared spectroscopy (FT-IR), UV–vis spectrophotometer and photoluminescence spectroscopy (PL) were employed to characterize the as-prepared sample. The XRD pattern showed cubic fluorite structure of CeO 2 without any impurity peaks, revealing high purity of the sample. The lattice strain experienced by the sample was analyzed using Williamson-Hall plot. FTIR studies confirmed the presence of C 14 TAB on the CeO 2 nanoparticles. TEM revealed that the as-prepared CeO 2 sample consists of uniform particles with particle size of 10 nm. The red shift phenomenon was observed in UV–vis spectrum, which was further supported by PL studies.

Synthesis and photoluminescence properties of HMT passivated Dy2O3 nanoparticles

Abstract: Dy2O3 nanoparticles were synthesized at room temperature through soft chemical route using dysprosium acetate hexahydrate and hexamethylenetetramine as starting materials. As-synthesized Dy2O3 nanoparticles were calcined up to 600 °C and the samples were subjected to various characterizations. The decomposition course of as-prepared particles and the formation process of Dy2O3 were studied by TG/DTA. The cubic bixbyite phase formation of Dy2O3 nanoparticles was confirmed by XRD results. The particle size and morphology were investigated by TEM. The composition and surface passivation were confirmed by EDS and FTIR studies, respectively. The possible formation mechanism has been discussed based on the experimental results. Bandgap of the material was estimated from the UV–vis absorption spectra. A blue-shift was observed in the absorbance as a result of quantum confinement effect, which was supported by PL spectra.

Nanocrystalline Pr6O11: synthesis, characterization, optical and photocatalytic properties

Abstract: Nanocrystalline praseodymium oxide was prepared by a novel facile precipitation route via reaction of praseodymium nitrate and triethylenetetramine (Trien) as a new precipitating agent in the presence of poly ethylene glycol (PEG). To the best of our knowledge, this work is the first successful attempt for the synthesis of nanocrystalline praseodymium oxide by using PEG via a simple precipitation route in the presence of Trien. To investigate the effect of the amount of Trien on the morphology and particle size of praseodymium oxide, several experiments were carried out. Based on the experimental findings of this research, it was found that this parameter has an important impact on the morphology and particle size of the products. The structural, morphological and optical properties of the as-obtained products were characterized by techniques such as Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence (PL) spectroscopy. To evaluate the catalytic properties of nanocrystalline praseodymium oxide, the photocatalytic degradation of 2-naphthol under ultraviolet light irradiation was carried out.

Praseodymium oxide nanostructures: novel solvent-less preparation, characterization and investigation of their optical and photocatalytic properties

Abstract: Praseodymium oxide (Pr6O11) nanostructures were prepared via a new simple solvent-less route. The nanostructures were synthesized by a heat treatment in air at 600 °C for 5 h, using [Pr L(NO3)2]NO3 (L = bis-(2-hydroxy phenyl methyl ketone)-dipropylene triamin Schiff base ligand), as a precursor, which was obtained by a solvent-free solid–solid reaction from different molar ratios of praseodymium nitrate and a Schiff base ligand. The as-prepared nanostructures were characterized by means of several techniques including X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX), photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), nuclear magnetic resonance spectroscopy (1H NMR) analysis, UV-vis diffuse reflectance spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The obtained results showed that the morphology and particle size of the final Pr6O11 could be dramatically affected via the molar ratio of praseodymium nitrate and the Schiff base ligand. The photocatalytic activity of the as-synthesized nanostructures was also investigated by the degradation of 2-naphthol as an organic contaminant under ultraviolet light irradiation.

Antimicrobial potential of green synthesized CeO 2 nanoparticles from Olea europaea leaf extract.

Abstract: This article reports the green fabrication of cerium oxide nanoparticles (CeO2 NPs) using Olea europaea leaf extract and their applications as effective antimicrobial agents. O. europaea leaf extract functions as a chelating agent for reduction of cerium nitrate. The resulting CeO2 NPs exhibit pure single-face cubic structure, which is examined by X-ray diffraction, with a uniform spherical shape and a mean size 24 nm observed through scanning electron microscopy and transmission electron microscopy. Ultraviolet-visible spectroscopy confirms the characteristic absorption peak of CeO2 NPs at 315 nm. Fourier transform infrared spectroscopy reflects stretching frequencies at 459 cm-1, showing utilization of natural components for the production of NPs. Thermal gravimetric analysis predicts the successful capping of CeO2 NPs by bioactive molecules present in the plant extract. The antimicrobial studies show significant zone of inhibition against bacterial and fungal strains. The higher activities shown by the green synthesized NPs than the plant extract lead to the conclusion that they can be effectively used in biomedical application. Furthermore, reduction of cerium salt by plant extract will reduce environmental impact over chemical synthesis.

Ceria Stabilized by Titanium Carbide as a Sustainable Filler in the Nafion Matrix Improves the Mechanical Integrity, Electrochemical Durability, and Hydrogen Impermeability of Proton-Exchange Membrane Fuel Cells: Effects of the Filler Content

Abstract: Cerium oxide-anchored titanium carbide (CeO2-TiC) is realized as a potential inorganic filler when modifying the Nafion matrix of a proton-exchange membrane fuel cell (PEMFC). A hydrothermal strategy was employed to synthesize CeO2-TiC of high crystallinity as a filler to mitigate the problematic properties of a proton-exchange membrane (PEM). CeO2-TiC with a weight ratio of 0.5, 1, 1.5, or 2% was incorporated into a Nafion matrix to form a hybrid by adopting a solution-casting procedure. Reinforcement owing to the presence of TiC provides increased tensile strength to PEM, and the addition of CeO2 improves the durability of PEM by scavenging free radicals. The microstructural, thermomechanical, physiochemical, and electrochemical properties of PEM, including contact angle, water sorption, water uptake, and proton conductivity, were extensively studied. Random dispersion of CeO2-TiC in the Nafion matrix improves the thermal stability, tensile strength, and water uptake while retaining proton conductivity, as compared with those of pristine Nafion. As a result, optimized Nafion/CeO2-TiC (1 wt %) achieved undiminished PEMFC performance compared to that of pristine Nafion while operating the device at 60 °C and 100% relative humidity. In addition, Nafion/CeO2-TiC (1 wt %) experienced the degradation of merely 0.6 mV h-1 during 200 h operation under identical conditions. Compared to that of Nafion/CeO2-TiC (1 wt %), pristine Nafion and Nafion-212 displayed accelerated and comparable degradation (for pristine Nafion, 1.3 mV h-1; for Nafion-212, 0.4 mV h-1). PEMFC power output, hydrogen permeability, and morphology of samples were examined after the durability test; the results indicate that Nafion/CeO2-TiC (1 wt %) is extremely stable. Since various Nafion hybrids have been reported as highly durable PEMs, this study is expected to open up new perspectives to expanding their applications, especially in sustainable PEMFC technology.