基于同步辐射光源研究水热合成纳米氧化物的生长机理

Synchrotron Radiation for the Study of Hydrothermal Formation Mechanisms of Oxide Nanomaterials

纳米氧化物的可控制备是提高其应用性能的前提条件。水热反应目前被广泛用于制备纳米氧化物材料,然而由于水热反应是在密闭环境中进行,很难研究前驱体的溶解过程,溶解后在溶液中的配位情况、晶体成核、生长过程以及形成的中间相,因此,难以实现材料的目标制备。同步辐射具有高强度、高亮度、高准直、宽频谱等诸多优点,通过设计和构建特殊的反应装置,可以应用同步辐射光源原位研究纳米氧化物在水热条件下的生长过程。本文结合本课题组及国际的研究工作介绍了原位反应装置的设计原则,以及基于同步辐射光源的原位X射线衍射(XRD)、X射线吸收精细结构谱(XAFS)和小角X射线散射(SAXS)研究纳米氧化物水热生长机理的最新进展,并展望了其发展趋势。

Controlled synthesis of oxide nanomaterials is indispensable to enhance their applications. Recently, hydrothermal methods have been widely applied to synthesize oxide nanomaterials. However, hydrothemal reactions are performed in closed reactor systems. Therefore, it is extremely difficult to investigate the dissolution of precursor, the coordination environment of precursor in solution, nucleation and crystallization process, and the involved intermediates. This is the reason that targeted synthesis of oxide nanomaterials has not been achieved. Synchrotron radiation offers notable analytical advantages for structure elucidation, such as high intensity, high brightness, high collimation and wide tunability in energy/wavelength. Based on the design and construction of specialized in situ reactors, synchrotron radiation can be used to investigate the hydrothermal formation process of oxide nanomaterials. In this paper, the design principle of a hydrothermal in situ reactor is introduced. Moreover, the applications of in situ synchrotron X-ray diffraction （XRD）, X-ray absorption fine structure （XAFS） and small-angle X-ray scattering （SAXS） to understand the hydrothermal formation mechanismsand reaction kinetics of oxide nanomaterials are critically reviewed. Furthermore, future trends of in situ techniques based on synchrotron radiation are discussed.