Nickel sulfide nanotubes formed by a directional infiltration self-assembly route in AAO templates

Nickel sulfide nanotube was successfully synthesized by a directional infiltration self-assembly route in AAO templates. The self-assembly process mainly involves infiltration, decomposition and crystal growth in nanochannels, in which dimethyl sulfoxide (DMSO) first acts as both sulfur source and unique infiltrator. For increasing S atom content in nickel sulfides thiourea was also used as additional sulfur source. Scanning electron microscope images (SEM) revealed that the nanotubes have uniform length distributions, several tens micrometers lengths and ultrathin tube-walls of 20 nm thickness. The nanotubes were confirmed by X-ray diffraction (XRD) and Raman spectroscopy, showing hexagonal Ni3S2, α-NiS and cubic NiS2, respectively. The magnetic hysteresis scan of NiS2 NTs showed weak ferromagnetism at room temperature. Its growth mechanism was discussed and proposed as well.