Hydrothermal preparation of WO3 nanorod arrays and their photocatalytic properties

WO3 nanorod arrays were prepared on indium tin oxide (ITO) substrates by hydrothermal synthesis with Na2WO4·2H2O as a raw material and NaCl as an additive. The nanorods were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The effects of pH values on the morphology, size, and orientation of products were studied. The results show that the single crystalline WO3 nanorod is hexagonal. When the pH value of the precursor solution increases, WO3 nanorod bundles parallel to the substrate turn into nanorod arrays vertical to the substrate. In addition, two different orientation WO3 nanorod structures were investigated by photocatalytic degradation of methyl blue solutions. It is found that the photocatalytic property of WO3 nanorod arrays is better than that of WO3 nanorod bundles.