Synthesis and photochromic properties of EDTA-induced MoO3 powder

Graphical abstract: The MoO3 powder, which exhibits highly dispersed floral aggregated-like structure built up by superimposed and staggered nanoflakes with a diameter of 1-1.5 μm and a thickness of 0.1-0.2 μm, has been successfully obtained when the molar ratio of EDTA/Mo6+ is 0.05:1. The EDTA inducer obviously enlarges the surface area and apparently enhances the reactivity of MoO3 powders, making it show greater absorptive capacity to the excitation light and better photochromic properties than the pure MoO3 powder. Highlights: → EDTA as organic inducing agent. → EDTA inducer at EDTA/Mo6+ molar ratio of 0.05:1 enables growth of flower-like microspheres. → The formation of flower-like MoO3 makes its photochromic properties strongly enhanced. -- Abstract: In this study, the photochromic MoO3 powder with novel morphology has been synthesized via hydrothermal method, using ethylene diamine tetraacetice acid (EDTA) as organic inducing agent. The influence of EDTA on the morphology, structure and photochromic properties of MoO3 powder has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), as well as ultraviolet and visible spectroscopy (UV-vis) and color difference meter. When the molar ratio of EDTA/Mo6+ is 0.05:1, the EDTA-induced MoO3 powder is found to have 3D flower-like morphologies and excellent photochromic properties. Furthermore, the possible growth mechanism of the flower-like structure and the photochromic mechanism of MoO3 powder are also discussed in detail.