Inorganic–organic hybrid wood in response to visible light

The inorganic–organic hybrid photoresponsive wood was fabricated by incorporating the phosphomolybdic acid (PMA)/polyvinylpyrrolidone (PVP) composites into the multi-scale hierarchical structure of wood using a simple pressure impregnation method. The as-prepared PMA-/PVP-coated wood (PPW) can change their colors in response to visible light. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy demonstrated that the PMA/PVP composites were coated on the wood surfaces successfully and the wood structures were still clearly visible. The atomic force microscopy images confirmed that the surface topography of the samples was changed after visible light irradiation, which was ascribed to the formation of heteropoly blues. The analysis of the color parameters proved that as-prepared PPW possessed the excellent photoresponsive property. The ultraviolet–visible spectra (UV–Vis) and X-ray photoelectron spectroscopy were conducted in order to explore the photoresponsive mechanism, which confirmed the photoreduction reaction occurred, producing the heteropoly blues during the process of visible light irradiation.