C. N. Tharamani

Hydrothermal synthesis of amorphous MoS2nanofiber bundles via acidification of ammonium heptamolybdate tetrahydrate

MoS2nanofiber bundles have been prepared by hydrothermal method using ammonium molybdate with sulfur source in acidic medium and maintained at 180 °C for several hours. The obtained black crystalline products are characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The PXRD pattern of the sample can be readily indexed as hexagonal 2H-MoS2. FTIR spectrum of the MoS2shows the band at 480 cm−1corresponds to the γas(Mo-S). SEM/TEM images of the samples exhibit that the MoS2nanofiber exist in bundles of 120–300 nm in diameter and 20–25 μm in length. The effects of temperature, duration and other experimental parameters on the morphology of the products are investigated.

Combustion-derived CuO nanoparticles: An effective and environmentally benign catalyst in the synthesis of aromatic nitriles from aromatic aldehydes

Abstract CuO nanoparticles were synthesized using an energy–efficient and rapid solution combustion technique with malic acid employed as a fuel. The combustion–derived CuO nanoparticles were used as catalysts in a one–pot synthesis of aromatic nitriles from aromatic aldehydes and hydroxylamine hydrochloride. The catalyst was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, and Brunauer-Emmett-Teller surface area analysis. The catalytic activity of the CuO nanoparticles in the synthesis of aromatic nitriles from aromatic aldehydes was evaluated. The present protocol offers the advantages of a clean reaction, simple methodology, short reaction duration (1–2 min), and high yield (85%–98%). The catalytic activity of the CuO nanoparticles was found to be higher than that of bulk CuO powder under the same conditions. The catalyst can also be recovered and reused up to four times with no significant loss of catalytic activity. The present approach is inexpensive and is a convenient technique suitable for industrial production of CuO nanoparticles and nitriles.

Electrodeposition and characterization of Ni-Cr alloy coating

Simultaneous deposition of both nickel and chromium in the form of alloy is a subject with pronounced practical significance in automobile industries. Electroplating of Ni-Cr alloy has been carried out using suitable plating bath solution and working conditions. The alloys are partially crystalline and new phases appear on heat-treatment of the coating. Surface morphology and microstructure of the coating are closely related to the nature of the bath components, bath composition, alloy composition, and post-treatment of the coating. X-ray photoelectron spectroscopy studies indicated that the alloy contains nickel in +2 and +3 oxidation states, whereas it contains chromium in the +3 oxidation state in the deposited Ni-Cr coating. The sputtering of the coatings up to 20 min changed the nickel and chromium to metallic state. The coated alloys exhibited good corrosion resistance to acidic media, e.g., 0.5 M H2 S O4, 1 M HCl, and 5 NaCl (pH 5), and heat-treatment of the coating enhanced the corrosion resistance. © 2006 The Electrochemical Society. All rights reserved.

Development of new brightener for industrial zinc coating

SUMMARY An acidic sulphate bath solution has been developed by Hull Cell studies to electroplate industrial zinc coatings on mild steel. Histidine in combination with ninhydrin has been evaluated as a brighener for zinc. The brightness of the coating was enhanced in the presence of traces of additives: sodium taurocholate, polyvinyl alcohol, and ascorbic acid. Working conditions and plating bath composition were optimised to obtain a good quality zinc coating with current efficiency and throwing power of 100% and 35% respectively. The functional properties (adhesion, hardness, corrosion resistance and surface morphology) of the coating have been evaluated.