Simple Method to Synthesize NaxWO3 Nanorods and Nanobelts

Abstract

A simple method for synthesis of NaxWO3 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 N2 ambient for 80 min, crystalline NaxWO3 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 NaxWO3 nanobelts. A solid−liquid−solid mechanism was proposed for describing the growth process of the sodium-doped tungsten oxide nanorods and nanobelts.