Large-scale synthesis and quantitative characterization of size-controllable potassium tungsten bronze nanowires

Abstract

Single-crystalline hexagonal potassium tungsten bronze K 0.26 WO 3 nanowires with diameters of 10-30 nm and lengths to several micrometers have been successfully synthesized via a hydrothermal method. The diameters of K 0.26 WO 3 nanowires can be well modulated by reducing potassium tungsten oxide K 2 OW 7 O 21 nanowires in hydrogen atmosphere at different temperatures. X-ray quantitative characterization indicates that the lattice constants and crystal lattice microstrains of these K 0.26 WO 3 nanowires exhibit anisotropic behaviors along the radial and axis directions, which can be well explained by the surface effect and K + ion aggregating or ordering. It also indicates that oxygen vacancies will occur in the WO 3 lattice when the reduction temperature is around 650 °C, and the oxygen vacancies will prevent K + ions from aggregating or ordering. Controllable synthesis and quantitative analysis of sizecontrollable K x WO 3 nanowires will contribute to deepen our understanding on their structures and properties, and explore their potential applications in nanoscale resistive switching devices based on the distribution of K + ions.

Hexagonal K2W4O13 Nanowires for the Adsorption of Methylene Blue

“…The full-range XPS spectrum (Figure a) verifies the presence of W, K, and O, calibrated by C 1s (BE = 284.6 eV). The calculated molar ratio of K/W was 0.32, smaller than the stoichiometric value of h-K 2 W 4 O 13 as 0.5, possibly because K + ions prefer to drop inside the tunnel of h-K 2 W 4 O 13 , whereas the detected signals of XPS are mainly from the surface Figure b displays the high-resolution O 1s peaks of h-K 2 W 4 O 13 .…”

“…Figure c and Figure d present the elemental state of K 2p and W 4f . Peaks centered at 35.8 and 37.9 eV are assigned to W 4f 7/2 and W 4f 5/2 for W 6+ and peaks centered at 293.1 and 295.8 eV are attributed to K 2p 3/2 and K 2p 1/2 for K + , respectively …”

“…The calculated molar ratio of K/W was 0.32, smaller than the stoichiometric value of h-K 2 W 4 O 13 as 0.5, possibly because K + ions prefer to drop inside the tunnel of h-K 2 W 4 O 13 , whereas the detected signals of XPS are mainly from the surface. 34 A dominant peak at 531.8 eV and shoulder peak at 530.6 eV stem from the crystal lattice oxygen (WO, W−O−W) and surface adsorbed water (H−OH), respectively. 16 Figure 4c and Figure 4d present the elemental state of K 2p and W 4f .…”

“…Peaks centered at 35.8 and 37.9 eV are assigned to W 4f 7/2 and W 4f 5/2 for W 6+ and peaks centered at 293.1 and 295.8 eV are attributed to K 2p 3/2 and K 2p 1/2 for K + , respectively. 34 3.2. Formation Mechanism of h-K 2 W 4 O 13 Nanowires.…”

A Study of Intermediate for Synthesis of Cs0.3WO3 with Near-Infrared Photothermal Response

“…5 . In the previous study by the Li Group [27], a hydrothermal method based on commercial WO 3 was developed to synthesize Cs 0.3 WO 3 , which is superior to other methods based on WO 3 colloids pre-prepared through acidifying the solution of tungstate [28,29]. However, this study only explored whether cesium tungsten bronze could even be synthesized using commercial tungsten oxide with a micronscale particle size, without further study on the reaction mechanism.…”