Corrosion of Au particles in air-exposed NaI-treated Au colloidal suspensions

This study examines the influence of the treatment of citrate-capped Au colloidal particles with NaI under exposure to air. Whereas in the NaI-treated centrifugate of the Au colloidal suspension the iodide-induced formation of triiodide runs spontaneously, its accumulation is found to be strongly decelerated in the Au colloidal suspension under the same conditions. In accordance with the experimental findings from electron absorption spectroscopy and transmission electron microscopy, a mechanism is proposed which describes the oxidation of the Au particles by oxygen under intermediate participation of triiodide.     

Colloidal assembly: the road from particles to colloidal molecules and crystals

Colloidal particles may be considered as building blocks for materials, just like atoms are the bricks of molecules, macromolecules, and crystals. Periodic arrays of colloids (colloidal crystals) have attracted much interest over the last two decades, largely because of their unique photonic properties. The archetype opal structures are based on close-packed arrays of spheres of submicrometer diameter. Interest in structuring materials at this length scale, but with more complex features and ideally by self-assembly processes, has led to much progress in controlling features of both building blocks and assemblies. The necessary ingredients include colloids, colloidal clusters, and colloidal "molecules" which have special shapes and the ability to bind directionally, the control over short-range and long-range interactions, and the capability to place and orientate these bricks. This Review highlights recent experimental and theoretical progress in the assembly of colloids larger than 50 nm.     

非离子型微乳状液制备均分散硫化镉

近年来,半导体胶体CdS溶胶或悬浮液已引起人们极大兴趣,其原因在于它的光电性质,特别是它的光化学性质及光催化性质。而上述性质均与CdS胶体粒子的大小和形状密切相关,所以作为光能转换及光催化反应的硫化镉溶胶不仅纯度要求高,而且对粒子的尺寸、形状及均匀性的要求也银严格。目前,主要用水解法、苯硫酚法及用阴离子型表面