Facile Solution Synthesis of Tungsten Trioxide Doped with Nanocrystalline Molybdenum Trioxide for Electrochromic Devices

摘要

A facile, highly efficient approach to obtain molybdenum trioxide (MoO3)-doped tungsten trioxide (WO3) is reported. An annealing process was used to transform ammonium tetrathiotungstate [(NH4)2WS4] to WO3 in the presence of oxygen. Ammonium tetrathiomolybdate [(NH4)2MoS4] was used as a dopant to improve the film for use in an electrochromic (EC) cell. (NH4)2MoS4 at different concentrations (10, 20, 30, and 40 mM) was added to the (NH4)2WS4 precursor by sonication and the samples were annealed at 500 °C in air. Raman, X-ray diffraction, and X-ray photoelectron spectroscopy measurements confirmed that the (NH4)₂WS₄ precursor decomposed to WO₃ and the (NH₄)₂MoS₄–(NH₄)₂WS₄ precursor was transformed to MoO₃-doped WO₃ after annealing at 500 °C. It is shown that the MoO₃-doped WO₃ film is more uniform and porous than pure WO₃, confirming the doping quality and the privileges of the proposed method. The optimal MoO₃-doped WO₃ used as an EC layer exhibited a high coloration efficiency of 128.1 cm²/C, which is larger than that of pure WO₃ (74.5 cm²/C). Therefore, MoO₃-doped WO₃ synthesized by the reported method is a promising candidate for high-efficiency and low-cost smart windows.