Xide Chang,Xu Dong,Xianhua Liu,Yindong Tong,Kaixiang Li,Zhenguo Li,Yiren Lu
Mixed-phase composites with an optimal phase ratio show greater light utilization than their monophasic counterparts. This approach can be applied to develop mixed-phase photochromic tungsten oxide (WO 3 ), which shows a rapid photoresponse and high-contrast coloring. Therefore, this paper optimized the phase ratio of hexagonal WO 3 ( h -WO 3 ·0.33H 2 O) and orthorhombic WO 3 ·H 2 O ( o -WO 3 ·H 2 O) to form a homojunction. To enhance its photochromism, nanostructured WO 3 was produced via a one-step hydrothermal strategy, in which its phase structure and morphology were controlled by regulating the reaction temperature during precursor synthesis. Various material characterization techniques were carried out to reveal the complex crystal nucleation and growth of phase junctions. h -WO 3 ·0.33H 2 O nanoparticles dominated the systems, while o -WO 3 ·H 2 O nanoblocks also appeared from 41.77 wt% to 56.50 wt% at a low hydrothermal synthesis temperature, producing a mixture of both polymorphs. The improved photochromic properties (from light yellow to black-green) of the mixed-phase WO 3 composite compared with pure h -WO 3 ·0.33H 2 O (from gray-white to dark gray) was attributed to the formation of a phase junction between h -WO 3 ·0.33H 2 O and o -WO 3 ·H 2 O. The photoelectrochemical results showed that this resulted in highly efficient charge carrier separation and transfer. The strong visual rendering of the black-green state may be useful for developing intelligent displays and similar devices.
Ping Yu,Lin Wang,Huan Liu,Anfeng Yu,Xinmei Liu,Zhe Yang
Developing reliable and cost-effective optical hydrogen sensors detecting hydrogen leakage at room temperature is of paramount importance. It requires that hydrogen sensors show a rapid and significant color change in low concentration H 2 /air mixtures, which remains challenging. Herein, we demonstrate an eye-readable hydrogen sensor based on Pt decorated hexagonal WO 3 (W 0 /300/Pt). It is evidenced W 0 /300/Pt exhibits excellent gasochromic properties, with reflectivity differences of 78% and 73% and fast coloring times of 3.10 s and 2.64 s in 10% H₂/Ar and 10% H₂/air. Moreover, W 0 /300/Pt shows an obvious color change from light gray to dark blue finally with ΔE value of 71, and exhibits a detect limitation less than 0.1% H 2 in 1 s. The gasochromic mechanism related to crystalline phase structure was unveiled via in situ characterization techniques. This study also presents novel evidence that bolsters the “localized water molecules” model and provides theoretical insights for the advancement of highly sensitive WO 3 gasochromic materials.
危险品化学品经营许可证（带存储）