Synthesis of doubly functional nanowhiskers from a colloid solution including a V–Ti complex precursor

Abstract

In this study, we synthesized vanadium (V) nanoparticles precursor (NH4)5[(VO)6(CO3)4(OH)9]·10H2O a two-phase system of toluene and water. Colloid solution including titanium(IV) isopropoxide and polyvinylpyrrolidone (PVP) was subsequently deposited onto the nanoparticles to form urchin-like structures in a toluene solution as the vanadium–titanium (V–Ti) complex precursor. Calcining the urchin-like precursor at 700 °C generated nanowhiskers of the Ti/V oxide complex after annealing process. These nanowhiskers were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron microscopy (XPS). Films of the Ti/V oxide nanowhisker structure exhibited good visible transparency and a large change in transmittance at near-infrared (NIR) wavelengths before and after the metal–insulator phase transition. For a 44-nm-thick single-layer nanowhisker thin film, the transmittances at 700 nm in the metallic (M) and semiconductive (S) states were 75 and 72.2 %, respectively; the NIR switching efficiency (ΔT2000) increased from 17 to 21.3 % at 2000 nm under UV light irradiation. In addition, the nanowhisker thin film of the Ti/V oxide complex significantly enhanced the photodecomposition of methylene blue under UV irradiation, relative to that of the unmodified TiO2. The dual functions of this material—thermochromicity and photocatalytic behavior—suggest that it might have interesting applications in energy-saving smart windows.