The influence of SiO2 doping on the microstructure and photochromic behavior of phosphomolybdic acid/polyvinyl pyrrolidone hybrid films

New hybrid films were synthesized by SiO2 doping into phosphomolybdic acid (PMoA)/polyvinyl pyrrolidone (PVPd) composite system, and the effect of SiO2 doping on microstructure and photochromic properties was studied via atomic force microscope (AFM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectra (UV–vis) and X-ray photoelectron spectroscopy (XPS). The hybrid film surface with dome projection changed rough from smooth after SiO2 doping. The vibrational spectra of FT-IR verified that component of the heteropolyacids and the polymer did not changed, the vibration bands were expanded and had shifted by a few cm−1, and changed interaction between the acid and the polymer after SiO2 doping. The hybrid film exhibited a good photochromic property, which changed from colorless to blue under UV irradiation. The color change intensity of SiO2/PMoA/PVPd film was 1.48 times stronger than that of PMoA/PVPd under the same condition. XPS results indicated that the amount of PMoA in photo-reductive reaction was increased after SiO2 doping.