Titanium dioxide/tungsten trioxide nanoarrays film for high electrochromic performance

A novel type of TiO2/WO3 core/shell nanoarrays film as a good electrode material with superior performance has been successfully synthesized by hydrothermal and sol-gel method. The advantage of core/shell structure and the electrochromic behavior of the film have been discussed. The effects of annealing temperature and dipping times on the structure, optical modulation, electrochromic property and cycle stability of the film were also investigated in detail. The results indicate that the TiO2/WO3 core/shell nanoarrays with two dipping times under 250 °C have significant optical modulation (vary between 16–73% in 400–700 nm range) and fast Li1+ diffusion rate (with 1.4 × 10−10 cm2/s Li1+ diffusion coefficients). The improved electrochromic properties are mainly attributed to the core/shell structure and the optimization function of TiO2, which have high surface area, good contact with the electrolyte solution and fewer defects, leading to faster Li1+ diffusion rate and better electrochemical cycling stability. The new structure of TiO2/WO3, producing the best possible advantage of WO3 and TiO2, can be regarded as an ideal electrochromic material with high practical value.