Electrodeposited Mo-doped WO3 film with large optical modulation and high areal capacitance toward electrochromic energy-storage applications

Amorphous Mo-doped WO 3 films are successfully synthesized via an electrodeposition method. In comparison with the reported time-consuming and costly techniques involving heating or vacuuming steps, the proposed electrodeposition method achieves the preparation of Mo-doped WO 3 in a simple and economic all-solution route. By optimizing the dopant concentration of Mo, the as-prepared 2 at% Mo-doped WO 3 film exhibits excellent electrochromic and energy-storage properties with large optical modulation of 83.3% at 633 nm and high pseudocapacitance of 117.1 mF cm −2 (334.6 mF g −1 ), greatly superior to those of pure WO 3 films. These great electrochemical properties could be attributed to the amorphous state and the proper structure distortion caused by doped atoms. Furthermore, bifunctional devices on various substrates contained the 2 at% Mo-doped WO 3 films are demonstrated with satisfactory electrochromic and energy-storage properties as well, indicating the practical applications of the Mo-doped WO 3 films in both energy-saving and energy-storage fields.