Controlled Synthesis, Characterization And Catalytic Study Of Tungsten-based Ultrathin Nanomaterials

After Richard Feynman presented the concept of “small scale” to the world at the American Physical Society Annual Meeting in 1959, nanomaterial and nanotechnology have received great attention from world-wide scientists working in both industry and fundamental research. During the last decade, people have made great development in nanotechnology. It’s possible for us to realize controlled synthesis of nanomaterials with specific physical and chemical properties. Nanomaterial involves many areas, such as semiconductor, metal alloys, oxides and organic macromolecules. They have shown fascinating application potential in photology, electrology, magnetism, industrial catalysis and environmental protection, which drives us to develop new kinds of nanomaterials and find their potential applications. Inspired by “size effect”, we believe that nanomaterial of sub-1 nm scale may present some unexpected properties. Some reports have confirmed our hypothesis. Nowadays there doesn’t exist a common method to synthesis ultrathin nanomaterial. To confine the scale of nanomaterial to 1 nm still remains challenging.Tungsten is a common kind of transition metal and the elementary substance is known to people as lamp filament. As a transition metal element, tungsten possesses unique electron structure. Tungsten oxide has attracted considerable attention and successful applications have been reported in many fields, such as electrochromic devices, gas sensors, optical recording devices and photocatalyst. These applications are closely related to its interesting electronic properties. Tungsten polyoxometalate is an important category of tungsten-based materials. It possesses good electron transfer property for its unique metal-oxygen framwork structure, which makes it potential in electricity and catalysis applicationBased on the analysis above, we chose solvothermal synthesis method and a “good solvent-bad solvent” reaction system widely used in our lab. Through selecting appropriate raw materials, surfactant, reaction temperature and time, we synthesized a series of tungsten-based ultrathin nanomaterials, including tungsten oxide ultrathin nanobelt and tungsten polyoxometalate-based nanoroll and nanotube assemblies. On the basis of characterization results of obtained ultrathin nanomaterials, we tried to observe and monitor the forming process by designed experiments. Surfactant and the composition of solvents are believed to be the key factors for the ultrathin nanostructure. We proposed a hypothesis about how such nanostructure formed.Besides, we found that as-synthesized ultrathin nanomaterials indeed showed some novel properties, such as unique eletron structure, optical property, macroscopical mechanical properties and high activity in catalytic oxidative desulfurization reaction. We believe that these properties are strongly related to the ultrathin structure and special surface characteristic.