Solvothermal synthesis of pyrochlore-type cubic tungsten trioxide hemihydrate and high photocatalytic activity

Abstract

Pyrochlore-type cubic phase tungsten trioxide hemihydrate (c-WO 3 Á0.5H 2 O) has been synthesized for the first time via a simple solvothermal process. The photocatalytic properties have been investigated firstly by the photodegradation of RhB, where the c-WO 3 Á0.5H 2 O sample demonstrated high photocatalytic activity, indicating that c-WO 3 Á0.5H 2 O is a promising candidate for tungsten oxide-based photocatalytic materials. The investigation result of the crystal water effects on the photocatalytic activity showed that crystal water of c-WO 3 Á0.5H 2 O played a key role in the photocatalytic activity. The novel method reported in this study has great potential for the development of tungsten trioxide-based functional materials preparation, to improve their photocatalytic efficiency in the elimination of hazardous substance applications as well as for energy materials.

Fabrication of hexagonal/cubic tungsten oxide homojunction with improved photocatalytic activity

“…In order to study the effect of crystal water of as-prepared tungsten oxides on their photodegradation and water oxidaton properties, dehydration through annealing treatment at 473 K for 10 h is carried out for h-WO 3 ·0.33H 2 O, c-WO 3 ·0.5H 2 O and h/c-WO 3 ·nH 2 O photocatalysts, which is based on the work of Chen and co-workers [43]. The XRD patterns of the three dehydrated samples (as shown in Figure S3) exhibit the peaks shift to a higher 2Â value due to the smaller lattice spacing after the loss of crystal water.…”

“…It is well known that RhB is a colored dye which mainly absorbs visible light of wavelength 552 nm, and the as-prepared h/c-WO 3 ·H 2 O can only absorb light of wavelength shorter than 430 nm. Therefore, the degradation process may be driven by the photosensitization of RhB under visible light irradiation ( > 420 nm) [42,43]. In order to avoid the photosensitization effect of RhB, we further explored water oxidation experiments using different irradiation conditions to clarify the intrinsic photocatalysis of h/c-WO 3 ·nH 2 O homojunction.…”

“…Furthermore, the tungsten oxide-based materials appear some different crystal structures including tungsten bronze-type hexagonal, pyrochlore-type cubic and so on, which suggests a potential in constructing homojunction photocatalysts. In the previous studies, both tungsten bronze-type hexagonal phase and pyrochlore-type cubic phase have received attentions for application to photocatalyst and show a high activity for degrading pollution and splitting water [22][23][24]. It should be emphasized that the realization of efficient homojunction demands the energy structure match between two different phases, which has been used as the standard to constitute homojunction from a series of existing phases.…”

Efficient plasma-assisted approach in nanostructure fabrication of tungsten

“…Although wet chemistry methods can well control the structure of obtained W-based materials, they require prolonged reaction times and highly controlled reaction conditions including temperature, pH value and raw materials ratio [27,28]. In addition, it needs an enormous amount of time to wash the obtained sample and the resulting acid/basic solutions are unfriendly to environment.…”

Large-mesopore hierarchical tungsten trioxide hydrate with exposed high energy facets: Facile synthesis and enhanced photocatalysis

“…Guo et al [34] prepared hierarchical WO 3 Á H 2 O hollow microspheres with 94.8% of Rh B (1 Â 10 À 5 M) degradation in 6 h (500 W). Zheng et al [35] synthesized aggregated nanoparticles of cubic WO 3 Á 0 Á 5H 2 O which could degrade 70% of Rh B (10 mg/L) within 200 min under visible light (300 W). Li et al [36] reported orthorhombic WO 3 visible light (300 W) for 100 min.…”