Large-scale synthesis and growth mechanism of single-crystal Se nanobelts

Single-crystal trigonal (t) Se nanobelts have been synthesized on a large scale by reducing SeO2 with glucose at 160 degrees C. Electron microscopy images show that the nanobelts are similar to 80 nm in diameter, similar to 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 solid-solution-solid growth mechanism. The redox reaction directly produced amorphous (alpha) Se nanoparticles under hydrothermal conditions. t-Se nanobelts were formed by dissolution and recrystallization of the initial alpha-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.