Building architecture of TiO2 nanocrystals embedded in amorphous WO3 films with improved electrochromic properties

TiO 2 nanocrystals embedded amorphous WO 3 electrochromic films have been successfully fabricated with a facile one-step solution process. The structure and electrochromic properties of composite films were studied by transmission electron microscope, scanning electron microscope, X-ray diffraction, Raman spectroscopy, and electrochemical methods. The results show that anatase TiO 2 nanocrystals with a size of about 5–10 nm were homogeneously embedded in the amorphous WO 3 matrix (TiO 2 @WO 3 ). Compared with pure WO 3 film, the electrochromic performances of TiO 2 @WO 3 are evidently enhanced. The further electrochemical analysis indicates that the enhancement may be mainly ascribed to the reconstruction of amorphous WO 3 matrix with the emerging interfaces between nanocrystals and amorphous matrix. And the extremely high value of the coloration/bleaching reversibility is associated with the suppressing effect of TiO 2 nanocrystals upon the Li + trapping in WO 3 matrix.