Synthesis and characterization of bismuth sulfide and bismuth telluride nanorods and their polyaniline nanocomposites

We present here a simplified approach to the synthesis of bismuth sulfide and bismuth telluride nanorods and their polyaniline(PAN)-coated nanocomposites. The present method gives highly crystalline nanorods of bismuth sulfide of varying aspect ratio depending on the capping ligand employed, and involves reacting bismuth(III) trioleate with thioacetamide in phenyl ether at elevated temperatures in the presence of excess capping ligand. Bismuth telluride was obtained in high yields by reacting bismuth(III) trioleate with trioctylphosphine telluride at relatively low temperature. Oleic acid, sodium dodecylsulfonate and sodium dodecylbenzene sulfonate, used as capping ligands, did not have significant effect on the aspect ratio of Bi2Te3 nanorods. The nanostructured materials obtained this way were then coated with polyaniline (PAN) by heating a specific amount of material with half as much PAN in toluene close to reflux temperature for 6-8 h. It was necessary to keep the mixture thoroughly stirred and intermittently sonicated in order to ensure that the particles remain dispersed at all times. Bismuth chalcogenide nanoparticles as well as their composites were characterized using transmission electron microscopy and X-ray powder diffraction.