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

Amorphous Mo-doped WO3 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 WO3 in a simple and economic all-solution route. By optimizing the dopant concentration of Mo, the as-prepared 2 at% Mo-doped WO3 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 WO3 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 WO3 films are demonstrated with satisfactory electrochromic and energy-storage properties as well, indicating the practical applications of the Mo-doped WO3 films in both energy-saving and energy-storage fields.