In a recent paper, published in Nanotechnology, researchers at Peking University describe a facile and effective method to realize the transformation from trigonal selenium (t-Se) nanotubes to PbSe nanotubes. As shown in the figure, PbSe nanotubes with pseudo-hexagonal cross-sections were prepared by solvothermal transformation of well-faceted t-Se nanotubes in the presence of Pb(Ac)2 and ascorbic acid in ethylene glycol (EG) at 200 ºC. It was revealed that a relatively high reaction temperature, adequate ascorbic acid, and proper lead source were crucial for preparing PbSe nanotubes via shape-preserved transformation of t-Se nanotubes. Preliminary electrochemical measurements showed that the prepared PbSe nanotubes exhibited a good electrochemical activity.
Moreover, novel Se@PbSe composite nanotubes consisting of Se nanotubes covered with a PbSe sheath were obtained by shortening the reaction time. Subsequent removal of the inner Se nanotubes resulted in the formation of thin-walled PbSe nanotubes (less than 20 nm in wall thickness). On the basis of the experimental observations, a plausible mechanism for the formation of PbSe nanotubes as well as Se@PbSe composite nanotubes was proposed.
This solvothermal transformation method provides a simple and effective route to fabricate PbSe nanotubes with adjustable wall thicknesses and Se@PbSe composite nanotubes with tunable compositions, which would find potential applications including nanodevice fabrication. Such a reactive template-based approach is potentially extendable to the controlled synthesis of various 1D nanostructures if suitable reactive templates are employed.