Gasochromic effect and relative mechanism of WO3 nanowire films

WO3 nanowire films have been prepared by thermal evaporation on both a silicon substrate and a quartz substrate. The gasochromic effect and the colouration mechanism of the films are investigated in detail by ultraviolet–visible–near infrared (UV–vis–NIR) spectroscopy, x-ray diffraction (XRD) spectroscopy, micro-Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and electrical transport measurements. The studies reveal that the gasochromism of WO3 nanowire films is caused by hydrogen injection. Along with the injection, a part of the tungsten ions' valences and the lattice structure change, giving rise to the colouration of the films. Moreover, electrical transport measurements show the lower conductance of the coloured film, which further confirms the hydrogen injection mechanism. Finally, a gasochromic model of the WO3 nanowire films is proposed.

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