Oxalic acid induced Hydrothermal Synthesis of Single Crystalline Hexagonal Tungsten Oxide Nanorods

Abstract

One-dimensional (1D) single-crystalline tungsten trioxide (h-WO3) nanorods have been synthesized by using sodium tungstate and oxalic acid (organic inducer) precursors through a hydrothermal method. Reaction was carried out at 170°C for 24, 48 and 72 hours. The obtained tungsten oxide powder was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. We observed the systematic emergence of nanorod-like structure with increment of reaction time. The 72 hours reaction generates self-assemble 20–30 diameter and 4–5µm length h-WO3 bundles of nanorods. XRD studies show hexagonal structure while SAED reveals single crystalline nature of tungsten trioxide. The photoluminescence (PL) emission spectrum shows a characteristic blue emission peak at 3eV (410nm). Raman spectra provide the evidence of hexagonal structure with stretching vibrations (830cm−1).