Thermal conversion of tungsten oxide nanorods to tungsten disulfide nanoflakes

We designed a facile thermal conversion route to synthesize 2H-WS2 nanoflakes using different tungsten oxide nanorods and S powder as starting reaction reagents. Various sizes and dimensions of nanoflakes with very regular hexagonal outer shapes and smooth surfaces were obtained by using different tungsten oxide nanorods such as W18O49 and WO3 as precursors. The structural properties and formation mechanisms of the 2H-WS2 nanoflakes were systematically investigated. It is found that both the size of tungsten oxide nanorods and reaction temperatures play crucial roles in the formation of regular hexagonal WS2 nanoflakes. These results may give a new insight to the syntheses of other layer-structural MX2 nanotructures (M = transition metal, X = S, Se).