Symmetrical six-horn nickel diselenide nanostars growth from oriented attachment mechanism

Nickel diselenide nanocrystals in well-defined star shape have been successfully synthesized via an improved solvothermal route with oleic acid as a capping ligand. The obtained products were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and energy-dispersive X-ray analysis (EDS). Results revealed that cubic NiSe2 nanocrystals were in a star-like shape and each nanostar consisted of a central core and six symmetrical horns in which the length of each horn was about 85 nm, the diameter of central core was about 90 nm, and the overall length between two most distance vertices was about 260 nm. Based on the HR-TEM analysis and the reaction process, an oriented attachment growth mechanism was suggested for the formation of six-horn star-like NiSe2, which resulted from the attachment growth of primary building particles along six (100) directions. Controlled experiments further demonstrated that the star-like shape of NiSe2 nanocrystals was controlled by the cooperative effects of precursor, solvent, and capping regents.