Controllable Assembly of WO₃ Nanorods/Nanowires into Hierarchical Nanostructures

Abstract

The controlled synthesis of two novel h-WO3 hierarchical structures made of nanorods/nanowires has been successfully realized in a large scale via a simple hydrothermal method. It is demonstrated that the morphology of the final products is significantly influenced by adding different sulfates. The urchinlike and ribbonlike structures of WO3 can be selectively prepared by adding Rb2SO4 and K2SO4, respectively. The morphology evolvement and the growth mechanism were studied carefully. The sulfate-induced oriented attachment growth mechanism has been proposed for the possible formation mechanism of the ribbonlike sample. For urchinlike products, two growing stages are believed to be involved in the growth process. The current understanding of the growth mechanism of these nanostructures may be potentially applied for designing other oriented or hierarchical nanostructures based on 1D nanoscale building blocks through the direct solution-growth.

Site‐Selective Deposition of Metal Nanoparticles on Aligned WO3 Nanotrees for Super‐Hydrophilic Thin Films

“…In addition, Gu et al synthesized WO 3 nanostructure by adding metal salts in a hydrothermal solution, and Rb 2 SO 4 led to nanorod and nanoplate structures, whereas K 2 SO 4 led to ribbonlike structures. [17] In the present hydrothermal conditions, Rb 2þ ions played an important role in the 1D growth of WO 3 nanotrees. We have synthesized WO 3 films by adding various metal salts, but we could not successfully synthesize the treelike structures except for the case of Rb 2 SO 4 .…”

“…Although several types of unique WO 3 nanostructures have been produced by wet chemical synthesis, [16,17] aligned thin films of these nanostructures have yet to be reported. Herein, aligned WO 3 nanotree films were directly grown on a metal tungsten substrate in a one-step hydrothermal synthesis.…”

“…Yao and coworkers have reported that a rodlike hexagonal WO 3 powder is produced by hydrothermal reaction on sodium tungstate in an aqueous solution containing H 2 C 2 O 4 , Rb 2 SO 4 , and hydrochloric acid (HCl). [17] Although we treated a metal tungsten plate with the same aqueous solution, very few aligned WO 3 nanotrees were produced. At the beginning of our hydrothermal reaction on metal tungsten, a dense oxidative layer was formed on the W substrate, but further hydrothermal treatment resulted in the dissolution of this oxidative layer as well as of the nuclei for subsequent growth of the single crystalline WO 3 nanotrees.…”

Electrochromic properties of nanostructured tungsten trioxide (hydrate) films and their applications in a complementary electrochromic device

“…To date, a number of hydrothermal methods have been developed for preparing 1D WO 3 nanostructures, including nanorods [19] and nanoribbons [26] by adding different inorganic salts as capping agents. However, previous reports of directly grown WO 3 thin films on substrate using a template-free hydrothermal process and their corresponding electrochromic characteristics have been quite limited.…”

Hierachical Self-Assembly of an Anthracene Derivative in Aqueous Solution

“…[4][5][6][7] Recently, some investigations on assembling nanorods/nanowires building blocks into 2D or 3D complex superstructures have been reported. [7][8][9][10] As a powerful tool for creating designed nanomaterials, molecular self-assembly is showing ever increasing importance in chemistry, material science, life science, and nanotechnology.…”