Selenium nanowires and nanotubes synthesized via a facile template-free solution method

Trigonal selenium (t-Se) nanowires and nanotubes were successfully prepared on a large scale via an environment-friendly synthetic process, in which no templates or surfactants were employed. These t-Se nanowires having a width of 70–100 nm and length up to tens of micrometers were synthesized in absolute ethanol at room temperature, while t-Se nanotubes with outer diameter ranging from 180 to 350 nm were obtained at 85 °C in water system. SEM and TEM analyses of the samples obtained at different stages indicated that the formation of these t-Se 1D nanostructures was governed by a “solid-solution-solid” growth process. The amorphous Se (a-Se) nanoparticles were initially generated and then would transform into crystal seeds for the subsequent growth of nanowires or nanotubes. Detailed experiments found that temperature and solvents as well as concentrations of starting materials were crucial to the formation of final morphology.