Synthesis and Electrochromic Properties of WO₃ Nanowires by Using Regulating pH Value Hydrothermal Method

The effects of pH value of hydrothermal system on the microstructure and structure of WO₃were comprehensively studied by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. It is found that WO₃ crystals with hexagonal structure were obtained at various pH values within the inspection range. The increase in pH value was conducive to the formation of nanowires, while the aspect ratio and orientation of the nanowires were also improved. An electrochromic film was further prepared by spraying the dispersion of WO₃ nanowire obtained at pH=1.8. The film exhibited a high optical modulation (71.5%@633 nm) and a high coloring efficiency (32.6 cm²·C⁻¹), which showed great potential for large-area devices, flexible substrates or patterned structure applications.