Synthesis and Characterization of Sodium Tungsten Bronze Nanorods for Electrochromic Smart Window Applications

Single-crystalline sodium tungsten bronze (Na-WO3) nanorods with typical diameters of 10–200 nm and lengths of several of microns were prepared via hydrothermal synthesis. X-ray diffraction data showed that the as-prepared Na-WO3 nanorods crystallize in a hexagonal structure (space group P6 / mmm) with unit cell parameters a = 7.3166(8) Å and c = 3.8990(8) Å, and elongate along the direction. The Na-WO3 nanorods had a mean chemical composition of Na0.18WO3.09•0.5H2O. The Na-WO3 nanorods exhibited a typical cathodic coloration related to proton-electron insertion, indicating their potentials in electrochromic smart window applications.