Simple Method to Synthesize NaxWO₃ Nanorods and Nanobelts

A simple method for synthesis of Na x WO 3 nanorods and nanobelts on sputtered tungsten films by using sodium in soda lime substrate as the catalyst was reported for the first time. After thermally post annealing thin films in a temperature range of 600−750 °C in N 2 ambient for 80 min, crystalline Na x WO 3 nanorods and nanobelts with [001] direction were formed depending on the annealing temperature. Experimental results reveal that the annealing temperature at 700 °C is the optimum temperature for the growth of sodium-doped tungsten oxide nanorods with maximum density on the surface. According to scanning electron microscopic observations, the synthesized nanorods are ∼50 nm in width and a few micrometers in length at the optimum temperature. It was also observed that increasing annealing temperature facilitates the growth of the Na x WO 3 nanobelts. A solid−liquid−solid mechanism was proposed for describing the growth process of the sodium-doped tungsten oxide nanorods and nanobelts.