Glycine acid-assisted green hydrothermal synthesis and controlled growth of WO3 nanowires

Abstract

The controlled synthesis of highly uniform hexagonal tungsten oxide (h-WO3) nanowires has been successfully realized for the first time in the presence of glycine by a green hydrothermal process. In the absence of glycine, only aggregated irregular nanosheets were obtained. While increasing the amount of glycine, morphology of the products changed from nanosheets to drum-like nanorod bundles, and then broke into halves. Finally, uniform nanowires growing along [001] direction came into being, which had a length of more than 5μm and a diameter of about 15nm, with a high average aspect ratio of >333. Morphology and preferential orientation of the products are significantly controlled by adjusting the amount of glycine. The combined effects of carboxyl-group and amino-group in glycine might be responsible for the formation of h-WO3 nanowires.