Tungsten oxide nanostructures based on laser ablation in water and a hydrothermal route

Abstract

A facile and chemically clean method is presented to fabricate the nanostructured tungsten oxide (WO₃) based on laser ablation of a tungsten flake in water and a subsequent hydrothermal route. The typically nanostructured WO₃ objects were well-dispersed and brick-like in shape. The bricks have average dimensions of ca. 200 nm in length, 150 nm in width and 130 nm in thickness, with stepped structures on their planar surfaces. Further experiments revealed that the reaction temperature, pH value and composition of the precursor in the subsequent hydrothermal treatment are crucial to formation of the brick-like WO₃ nanostructures. Correspondingly, a rectangular cuboidal stacking growth model is proposed to describe the formation of such nanobricks. The nanobricks could be good building blocks of complex micro/nanostructures and devices. Also, the combination of laser ablation in liquid with hydrothermal treatment could provide an effective synthetic approach for morphologically tunable WO₃ nanomaterials, which have potential applications in gas sensing, electrochromic devices and photocatalysis.