Department of Chemistry, University of Victoria, Victoria, BC V8W 3V6, Canada.
J Am Chem Soc. 2012 Jul 11;134(27):11068-71. doi: 10.1021/ja302717u. Epub 2012 Jun 26.
We demonstrate a novel epitaxial layer-by-layer growth on upconverting NaYF(4) nanocrystals (NCs) utilizing Ostwald ripening dynamics tunable both in thickness and composition. Injection of small sacrificial NCs (SNCs) as shell precursors into larger core NCs results in the rapid dissolution of the SNCs and their deposition onto the larger core NCs to yield core-shell structured NCs. Exploiting this NC size dependent dissolution/growth, the shell thickness can be controlled either by manipulating the number of SNCs injected or by successive injection of SNCs. In either of these approaches, the NCs self-focus from an initial bimodal distribution to a unimodal distribution (σ <5%) of core-shell NCs. The successive injection approach facilitates layer-by-layer epitaxial growth without the need for tedious multiple reactions for generating tunable shell thickness, and does not require any control over the injection rate of the SNCs, as is the case for shell growth by precursor injection.
我们展示了一种在反蛋白石结构上利用 Ostwald 熟化动力学进行层层外延生长的新方法，这种方法可以在厚度和成分上进行调节。将小的牺牲型纳米晶（SNCs）作为壳层前驱体注入到大的核型纳米晶（NCs）中，会导致 SNCs 的快速溶解，并将其沉积到较大的核 NCs 上，从而得到核壳结构的 NCs。利用这种 NC 尺寸相关的溶解/生长特性，可以通过控制注入的 SNCs 的数量或者连续注入 SNCs 来控制壳层厚度。在这两种方法中，NCs 都可以从初始的双峰分布自聚焦到具有较窄分布（σ<5%）的核壳 NCs 的单峰分布。连续注入方法有利于进行层层外延生长，而不需要繁琐的多次反应来生成可调的壳层厚度，也不需要对 SNCs 的注入速率进行任何控制，这是前驱体注入法进行壳层生长的情况。
