H. S. Bhatti

Photo-catalytic activity of Zn1-xMnxS nanocrystals synthesized by wet chemical technique

Polyvinyl pyrrolidone capped Zn1-xMnxS (0 ≤ x ≤ 0.1) nanocrystals have been synthesized using wet chemical co-precipitation method. Crystallographic and morphological characterization of the synthesized materials have been done using X-ray diffraction and transmission electron microscope. Crystallographic studies show the zinc blende crystals having average crystallite size approx. 3 nm, which is almost similar to the average particle size calculated from electron micrographs. Atomic absorption spectrometer has been used for qualitative and quantitative analysis of synthesized nanomaterials. Photo-catalytic activity has been studied using methylene blue dye as a test contaminant. Energy resolved luminescence spectra have been recorded for the detailed description of radiative and non-radiative recombination mechanisms. Photo-catalytic activity dependence on dopant concentration and luminescence quantum yield has been studied in detail.

Structural and optical characterization of hydroxy-propyl methyl cellulose-capped ZnO nanorods

Zinc oxide nanostructures have been synthesized using an eco-friendly bottom-up synthesis technique. Effect of hydroxy-propyl methyl cellulose-capping concentration is observed for the effectiveness in limiting the particle growth. It is observed that the structural and optical characteristics have strong dependence on capping concentration. Detailed structural characterizations confirmed that the as-prepared products possess a wurtzite hexagonal phase and the preferred direction of growth is along the c-direction. UV–Visible absorption investigation reveal variation in optical band gap. Room temperature energy resolved photoluminescence spectra of the obtained nanostructures show band edge emission as well as blue-green emission.

Investigation of optical properties of pristine and functionalized single-walled carbon nanotubes

Single-walled carbon nanotubes have been synthesized by chemical vapor deposition technique followed by hydroxyl addent functionalization. Crystallographic, topographic and morphological analyses of pristine and functionalized single walled carbon nanotubes (SWCNTs) have been studied via powder X-ray diffraction, field emission scanning electron microscope, high resolution transmission electron microscope and atomic force microscope respectively. UV–Vis absorption, Raman spectroscopy, thermogravemetric analysis, X-ray photo electron spectroscopy and Fourier transform infra-red spectroscopic studies have been carried out for confirmation of functionalization. Optical, quantitative and qualitative analysis of the pristine and functionalized SWCNTs have been completed via energy resolved and time resolved photoluminescence and energy dispersive X-ray spectroscopic studies respectively. Spectroscopic studies confirm the formation of good quality pristine and functionalized SWCNTs with hydroxyl addent. Recorded electron micrographs reveal the formation of fragmented functionalized SWCNTs with high aspect ratio whereas recorded diffraction patterns show the good crystallinity of synthesized nanostructures. Structural analyses of pristine and functionalized SWCNTs have been studied using Brunauer–Emmett–Teller surface area analysis, Barrett–Joyner–Halenda pore size and volume analysis technique. Improved CVD method used in present studies is an eco-friendly method, which gives good yield of high quality SWCNTs.

Microwave-assisted synthesis and characterization of silver nanowires by polyol process

Silver nanowires have been synthesized by the polyol process with ethylene glycol as a reducing agent and polyvinylpyrrolidone as a stabilizer, using microwave technique. Crystallographic, topographic, and morphological characterizations of the synthesized nanostructures have been studied via powder X-ray diffraction and electron microscopy (Field Emission Scanning Electron Microscope) and Transmission Electron Microscope, respectively. Fourier Transform-Infrared Spectroscopy, UV–Vis absorption spectroscopy, Raman spectroscopy, Thermogravometric analysis, and X-ray photoelectron spectroscopy have been carried out for the detailed quantitative and qualitative analyses. Optical characterizations of the synthesized silver nanowires have been concluded via energy-resolved and time-resolved photoluminescence and energy dispersive X-ray spectroscopic studies, respectively. Spectroscopic studies confirm the formation of good-quality silver nanowires. The X-ray photoelectron spectroscopy investigation and Raman spectra further show that the PVP molecules are adsorbed on the surface of Ag nanowires through Ag: O coordination. A possible growth mechanism of the Ag nanowires has been proposed. It is implied that the PVP molecules are used as both a protecting agent and a structure-directing agent for the growth of Ag nanowires. These studies confirm the formation of high-quality silver nanowires. Topographic and morphological studies confirm that average grain size of silver nanowires is in the nanometer range.

Elastic moduli of boron nitride, aluminium nitride and gallium nitride nanotubes using second generation reactive empirical bond order potential

Purpose – The purpose of this paper is to study elastic properties of III-V nitride nanotubes (NNTs) using second generation (REBO) potential. Design/methodology/approach – In the present research paper elastic properties of BN, AlN and GaN nanotubes have been investigated, using the second generation REBO potential by Brenner and co-workers, which is a bond order potential earlier used for carbon nanostructures successfully. In the present calculation, the same form of potential is used with adjusted parameters for h-BN, h-AlN and h-GaN. In all these cases the authors have considered graphite like network and strongly polar nature of these atoms so electrostatic forces are expected to play an important role in determining elastic properties of these nanotubes. The authors generate the coordinates of nanotubes of different chirality’s and size. Each and every structure thus generated is allowed to relax till the authors obtain minima of energy. The authors then apply the requisite compressions, elongation...

Some Mechanical Properties of Carbon NanotubesHeterojunctions

Some Mechanical Properties of Carbon Nanotubes Heterojunctions In the present research work, the structure of linear heterojunctions between two CNTs of different chirality’s, but similar radii, joined together through an interface that require more than one pentagon-heptagon defects have been studied. The elastic properties of carbon nanotube heterojunctions are investigated using secondgeneration improved reactive empirical bond order potential by Brenner and co-workers. In this study, the coordinates of carbon nanotube heterojunctions are generated. Each and every structure thus generated is allowed to relax till a minimum of energy is obtained. The requisite compressions, elongations and twists to the structures are applied and thus computed elastic moduli. Young’s Modulus increases with radius for small radii and attains a constant value of the order 1TPa. Poisson’s ratio and shear modulus have also been computed.

Effect of reaction conditions on the morphology and optical properties of ZnO nanocrystals

We report a simple hydrothermal method at low temperature for synthesis of zinc oxide (ZnO) nanorods followed by ultrasonication. The samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), UV–Vis absorption spectrophotometer and photoluminescence (PL) spectroscopy. The XRD results shows the prepared ZnO nanocrystals are in wurtzite structure. TEM results indicate the growth of ZnO nanorods with increasing reaction stirring time and morphology also get affected after ultrasonication. PL studies also reveal the presence of defects considered as the main reason for the green emission in PL with increasing reaction time and blue shift in UV emission corresponds to reduction of tensile strain.

Structure and Strength of Carbon Nanohorns

Research into Carbon Nano Horns or Cones (CNCs) started almost at the same time as the discovery of CNTs in 1991. The official report of the discovery of isolated Nano Cones was made in 1993, when Ge and Sattler from the University of Hawaii reported their observations of Carbon Cones mixed together with tubules on a flat graphite surface. The products were generated by quenching hot carbon vapor on th e substrate. Ge and Sattler also predicted that five apex angles, 19.2°, 38.9°, 60°, 86.6°, and 123.6°, could be used to distinguish CNCs. However, only the angle of 19.2° was found in the opening angles of their samples. The observed cones were up to 24 nm in length and 8 nm in base diameter. At that time, most of researchers focused on the investigation of CNTs, and the exploration of horns attracted little attention. Present paper converse about the structure and elastic moduli of these less explored nanostructures. The second‐generation reactive bond order potential by Brenner and coworkers has been use...

Photo-physical studies of pyridine capped ZnO nanostructures

Pyridine capped ZnO nanocrystals with different sizes were synthesized at room temperature by wet chemical synthesis. Pyridine provides the control over the morphology of final product. X-ray study confirms the crystalline hexagonal structure of the capped and uncapped ZnO nanocrystals. The particle size was found to decrease with increase in capping concentration. Electron microscopy investigation reveals the uniform morphology of the product. Optical absorption studies indicate the blue shift effect for pyridine capped ZnO as compare to uncapped ZnO.

Photo-Catalytic Activity of Quencher Impurity Doped ZnS Nanocrystals

Intrinsic and extrinsic semiconductor nanocrystals seem to be good candidates for modern era optoelectronic and photo-catalytic applications due to their size tunable photo-physical and photo-chemical properties. In the present investigation, polyvinyl pyrrolidone (PVP) capped quencher impurity (Ni) doped ZnS nanocrystals have been synthesized using facile bottom-up synthesis technique; colloidal chemical co-precipitation method. Crystallographic and morphological characterization of synthesized nanomaterials have been carried out using X-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. Photo-catalytic activity of the synthesized nanomaterials has been studied using methylene blue (MB) dye as a test contaminant. Photo-catalytic behavior dependence on dopant concentration, UV radiation curing and annealing of synthesized semiconductor nanomaterials have been studied in detail under sun light exposure.