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GREENER SYNTHESIS OF NOBLE METAL NANOSTRUCTURES AND NANOCOMPOSITES
Citation:
VARMA, R. S. AND M. N. Nadagouda. GREENER SYNTHESIS OF NOBLE METAL NANOSTRUCTURES AND NANOCOMPOSITES. Presented at 235th American Chemical Society National Meeting, New Orleans, LA, April 02 - 10, 2008.
Impact/Purpose:
To inform the public.
Description:
A brief account of a greener preparation of nanoparticles which reduces or eliminates the use and generation of hazardous substances is presented. The utility of vitamins B1 and B2, which can function both as reducing and capping agents, provides an extremely simple, one-pot, greener method to synthesize bulk quantities of nanospheres, nanorods, nanowires, and nanoballs of aligned nanobelts and nanoplates of the metals in water without the need for large amounts of insoluble templates. A bulk and shape-controlled synthesis of noble nanostructures with various shapes occurs via microwave (MW)-assisted spontaneous reduction of noble metal salts using an aqueous solution of -D-glucose, sucrose, and maltose. A general MW method has been developed that accomplishes the cross-linking reaction of poly (vinyl alcohol) (PVA) with metallic systems such as Pt, Cu, and In; bimetallic systems, namely Pt-In, Ag-Pt, Pt-Fe, Cu-Pd, Pt-Pd and Pd-Fe; and single-wall carbon nanotubes (SWNT), multi-wall carbon nanotubes (MWNT), and Buckminsterfullerene (C-60) in various shape forms such as spheres, dendrites, and cubes. The strategy is extended to the formation of biodegradable carboxymethyl cellulose (CMC) composite films with noble nanometals; such metal decoration and alignment of carbon nanotubes in carboxymethyl cellulose is possible using MW approach which also enables the shape-controlled bulk synthesis of Ag and Fe nanorods in poly (ethylene glycol). A clean synthesis of core (Fe, Cu)-shell (Au, Pt, Pd and Ag) nanocrystals has been achieved using aqueous vitamin C. Newer form of carbon-doped titania has also been prepared using a benign natural polymer dextrose that helps generate a spongy porous structure and the general method is applicable to other transition metal oxides such as ZrO2, Al2O3, and SiO2.