Phosphomolybdic acid-modified highly organized TiO2 nanotube arrays with rapid photochromic performance

TiO2 nanotube arrays were prepared by means of an electrochemical anodization technique in an organic electrolyte solution doped with polyvinyl pyrrolidone (PVP) and were subsequently modified with phosphomolybdic acid (PMoA) to obtain PMoA/TiO2 nanotube arrays. The microstructure and photochromic properties were investigated via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM). transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The results indicated that the Keggin structure of PMoA and the nanotube structure of TiO2 were not destroyed, and there was a strong degree of interaction between PMoA and TiO2 at the biphasic interface with lattice interlacing during the compositing process. The XPS results further indicated that there was a change in the chemical microenvironment during the formation process of the composite, and a new charge transfer bridge was formed through the Mo-O-Ti bond. Under visible light irradiation, the colorless PMoA/TiO2 nanotube array quickly turned blue and exhibited a photochromic response together with reversible photochromism in the presence of H2O2. After visible light irradiation for 60 s, the appearance of Mo5+ species in the XPS spectra indicated a photoreduction process in accordance with a photoinduced electron transfer mechanism. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.