Electrochromic Smart Windows Based on Nanometer-Thick Films of WO3 Nanowire/Cu and TiO2/NiO as Composite Electrodes

The application of electrochromic devices (ECDs) in smartwindowsprovides a solution for energy savings and environmental protection.Here, a WO3 nanowire/Cu composite electrode was synthesizedas an electrochromic cathode via hydrothermal and electrodeposition.Meanwhile, a TiO2 nanorod/NiO composite electrode was alsoprepared as an electrochromic anode via hydrothermal and electrodeposition.The Schottky junction structure formed between the Cu and WO3 film interface increases the rate of Li+ injection andextraction. In addition, the TiO2/NiO heterostructure canenhance the separation of the electrons and protons. The designedECD exhibited properties of large optical modulation (74.5% at 633nm), high coloration efficiency (94.1 cm(2) C-1), and fast switching speed (3.1/1.6 s for coloration/bleaching).These characteristics make the WO3/Cu-TiO2/NiOelectrochromic device a very promising smart window candidate forlighting control and energy-saving applications.