Single-crystal trigonal (t) Se nanobelts have been synthesized on a large scale by reducing SeO 2 with glucose at 160 °C. Electron microscopy images show that the nanobelts are ∼80 nm in diameter, ∼25 nm in thickness, and up to several hundreds of micrometers in length. HRTEM images prove that the nanobelts are single crystals and preferentially grow along the [001] direction. The time-dependent TEM images revealed that the formation and growth of t-Se nanobelts were governed by a solidsolution-solid growth mechanism. The redox reaction directly produced amorphous (R) Se nanoparticles under hydrothermal conditions. t-Se nanobelts were formed by dissolution and recrystallization of the initial R-Se nanoparticles under the functional capping of poly(vinylpyrrolidone) (PVP). The nanobelts obtained exhibit a quantum size effect in optical properties, showing a blue shift of the band gap and direct transitions relative to the values of bulk t-Se.

Nanobelts of hexagonal close-packed cobalt have been synthesized by a hydrothermal reduction process at 160 °C. The as-synthesized nanobelts, with a rectangular cross section, are 200–500 nm in diameter, 50–80 nm in thickness and a few hundreds of micrometres in length. The Co nanobelts are single crystalline and grow preferentially along the [001] direction. Furthermore, the coexisting nanosheets with zigzag edges are 2–4 µm in diameter and several tens of nanometres in thickness. The hysteresis loop at room temperature of the as-obtained product shows a ferromagnetic behaviour. In addition, some influential factors as regards the morphologies of the final products were also discussed.