Abstract:One-dimensional (1D) WO2 nanorods were synthesized by hot-filament metal vapor deposition at high-pressure Ar flow without using any catalyst. The 1D WO2 nanorods grew on the roots and were a few micrometers long and 50–100 nm wide. The x-ray diffraction pattern shows that the as-synthesized 1D WO2 nanorods are the monoclinic structure in space group P21/c, and the roots are the β tungsten crystal of the cubic structure in space group Im3m. Field-emission-gun transmission electron microscopy images and selected-area electron diffraction patterns further confirm that the monoclinic 1D WO2 nanorods consist of the (011) planes and preferentially grow along the 〈01〉 direction. According to these results, an uncatalyzed vapor-solid process is suggested to be the mechanism of growth of the as-synthesized 1D WO2 nanorods. In comparison with the Raman scattering of three-dimensional WO2 bulk powders, the Raman bands of the 1D WO2 nanorod are blueshifted and narrower, indicating phonon confinement associated with the 1D WO2 nanorod.