Preparation And Physicochemical Properties Of WO₃-based Nanoparticulate Materials

As a member of the novel semiconductor materials, tungsten oxide has been under an extensive research in recent years for its unique physicochemical properties. It has been widely used in many different applications, such as electrochromic windows, optical devices, fuel cells, gas sensors, and photocatalyst materials, etc. As we known, the morphologies and structures of the material have great influence on its properties. So it is important to study in detail the preparation and physicochemical properties of tungsten oxide-based nano-materials.In this paper, tungsten oxide-based nano-materials were prepared by hydrothermal and sol-gel methods, respectively. The analysis reagents Na₂WO₄·2H₂O and (NH₄)₁₀W₁₂O₄₁ were used as starting materials. The obtained powders, sol and the thin films were characterized by UV-Vis-NIR, TG-DTA, XRD, IR, XPS, SEM and AFM, respectively. The effects of the preparation conditions on the structure, morphology and particle size of products were explored in details and the optimum preparing conditions of tungsten oxide-based nano-materials were obtained. The formation mechanism of tungsten oxides with butterfly-like, spindle and fibers morphologies were discussed. The results show that improved photochromism properties, especially in polyhydric alcohols environment, have been found in tungsten bronze powders, sol and the thin films, and in spindle like tungsten oxide.Furthermore, the catalytic properties of the metastable tungsten oxide-Pt/C composites were investigated as an anode in DMFC. The results show that the pyrochlore phase tungsten oxide doped anode gave the best result. The highest current density reached to 87.4 mA/cm² with 20wt% doping concentration. Whereas 63.4 mA/cm² was found for the tungsten bronze doped composite electrode under the same doping concentration.