A surfactant-assisted photochemical route to single crystalline HgS nanotubes

A surfactant-assisted photochemical method has been developed to prepare tube structural single crystalline mercury sulfide (α-HgS). The HgS nanotubes have well-defined structure with the wall thickness of 20-30 nm. The as-prepared HgS nanotubes were characterized by employing techniques including X-ray powder diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, selected area electron diffraction, high-resolution transmission electron microscopy. The characterizations of the products in various stages exhibited the probable reaction process could be divided into three steps in sequence: the formation of the nascent poly(vinylpyrrolidone) (PVP)-coated HgS particles, their assembly and crystal growth. It was found that PVP served as dispersant and stabilizer in the formation of the homogeneous nascent HgS particles and more importantly, the direct UV photocrosslinking of PVP was exploited to induce the assembly of the PVP-coated particles and the growth to tube structure.