喷雾干燥法制备中空偏钨酸铵球及中空结构形成机理

WO_3基纳米材料具有光催化降解、光解水、电致变色、热致变色和光致变色等特性,在光催化剂、新能源制备、智能窗口、传感器和平板显示器等领域有广泛的应用前景。采用喷雾干燥法成功制备了中空偏钨酸铵球,分析了其制备过程和中空结构的形成机理。结果表明:采用喷雾干燥法制备的中空偏钨酸铵球球体平均粒径为1.03μm,壁厚约为100 nm;其制备过程分为雾化、闪蒸干燥形成壳、中空结构形成3个阶段;干燥塔内由于热空气初始温度为130℃,远高于水的沸点,使液滴表面的水分迅速蒸发,由于蒸发速度非常快,从而在液滴表面结晶而形成壳,进而形成空心结构。

Preparation and formation mechanism of hollow ammonium metatungstate spheres by spray drying method

Nano-WO3 based materials have many properties,such as photodegradation,water splitting,electrochro-mism,thermochromism and photochromism,etc. Therefore,nanostructured WO3 based materials are potentially used in the fields of photocatalysis,new energy resources preparation,smart windows,sensors and flat-panel display. Hol-low ammonium metatungstate spheres were synthesized by spray drying method,and the preparation process and forma-tion mechanism of the hollow structure were analyzed. Results show that the average diameter of the hollow ammonium metatungstate ball is 1.03μm,and the wall thickness is about 100 nm. The preparation process is divided into 3 stages:atomization,shell formation during flash evaporation and hollow structure formation. Since the initial temperature in hot air drying tower is 130℃,far higher than the boiling point of water,leading to rapid evaporation of droplet surface wa-ter. The fast evaporation speed leads to the droplet surface crystallization and the shell formation,thus the hollow struc-ture forms.