pH-Induced Simultaneous Synthesis and Self-Assembly of 3D Layered beta-FeOOH Nanorods

Higher-ordered architectures self-assembly of nanomaterials have recently attracted increasing attention. In this work, we report a spontaneous and efficient route to simultaneous synthesis and self-assembly of 3D layered beta-FeOOH nanorods depending oil a pH-induced strategy, in which the continuous change of pH is achieved by hydrolysis of FeCl3 center dot 6H(2)O in the presence of urea under hydrothermal conditions. The electron microscopy observations reveal that the square-prismic beta-FeOOH nanorods are self-assembled ill a side-by-side fashion to form highly oriented 2D nanorod arrays, and the 2D nanorod arrays are further stacked in a face-to-face fashion to form the Final 3D layered architectures. Oil the basis of time-dependent experiments, a multistage reaction mechanism for the formation of the 3D layered beta-FeOOH nanorods architecture is presented, involving the fast growth and synchronous self-assembly of the nanorods toward I D, 213, and 3D spontaneously. The experimental evidence further demonstrates that the urea-decomposition-dependent pH continuously changing in the Solution, spontaneously altering the driving force competition between the electrostatic repulsive force and the attractive van der Waals force among the nanorods building blocks, is the essential factor to influence the self-assembly of the beta-FeOOH nanorods from 1D to 3D.NSFC,20525103,20801045,20531050,20725310 973 Program 2007CB81530

Single-crystal-like hematite colloidal nanocrystal clusters: synthesis and applications in gas sensors, photocatalysis and water treatment

A facile and efficient one-pot solvothermal synthetic route based on a simplified self-assembly is proposed to fabricate spherical hematite colloidal nanocrystal clusters (CNCs) of uniform shape and size. The as-prepared hematite CNCs are composed of numerous nanocrystals of approximately 20 nm in size, and present a single-crystal-like characteristic. A possible formation process based on the nucleation-oriented aggregation-recrystallization mechanism is proposed. Our experiments demonstrated that both the surfactant and the mixed solvent play very critical roles in controlling the size of primary nanocrystals and the final morphology of single-crystal-like spherical CNCs. Compared with other hematite nanostructures, the spherical hematite CNCs show outstanding performance in gas sensing, photocatalysis and water treatment due to their large surface area and porous structure. In addition, interesting tertiary CNCs formed by further assembly of secondary spherical CNCs were observed for the first time.NNSFC,20525103,20531050,20721001,20725310,20801045,2007CB81530

湘江长潭株段河床沉积物重金属污染Pb同位素地球化学分析

湘江长沙-湘潭-株洲(简称"长潭株")段是湘江流域重金属污染最严重的河段。以往研究得到沉积物严重受Cd、Cu、Pb、Zn、Mn等多种重金属的污染。但河流沉积物是一个复杂的环境单元,其物质组成既是流域岩石风化的产物,又是人为作用的反映。且湘江流域基岩(如花岗岩等)、土壤等环境介质本身就存在Cd、Cu、Pb、Zn、As等重金属元素高背景值。加上城市工业活动等人为排放,使得沉积物重金属的来源复杂化。因此,认识沉积物重金属