Division of Nanomaterials & Chemistry, Hefei National Research Center for Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, Hefei Science Center of CAS, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China.
Nat Commun. 2018 Nov 23;9(1):4947. doi: 10.1038/s41467-018-07422-4.
Epitaxially stacking colloidal quantum dots in nanowires offers a route to selective passivation of defective facets while simultaneously enabling charge transfer to molecular adsorbates - features that must be combined to achieve high-efficiency photocatalysts. This requires dynamical switching of precursors to grow, alternatingly, the quantum dots and nanowires - something not readily implemented in conventional flask-based solution chemistry. Here we report pulsed axial epitaxy, a growth mode that enables the stacking of multiple CdS quantum dots in ZnS nanowires. The approach relies on the energy difference of incorporating these semiconductor atoms into the host catalyst, which determines the nucleation sequence at the catalyst-nanowire interface. This flexible synthetic strategy allows precise modulation of quantum dot size, number, spacing, and crystal phase. The facet-selective passivation of quantum dots in nanowires opens a pathway to photocatalyst engineering: we report photocatalysts that exhibit an order-of-magnitude higher photocatalytic hydrogen evolution rates than do plain CdS quantum dots.
在纳米线中外延堆叠胶体量子点为选择性钝化缺陷晶面提供了一种途径，同时使电荷能够转移到分子吸附物上——要实现高效光催化剂，这两个特性缺一不可。这需要动态切换前驱体来生长量子点和纳米线，这在传统的基于烧瓶的溶液化学中不容易实现。在这里，我们报告了脉冲轴向外延，这是一种能够在 ZnS 纳米线中堆叠多个 CdS 量子点的生长模式。该方法依赖于将这些半导体原子掺入宿主催化剂中的能量差异，这决定了在催化剂-纳米线界面处的成核顺序。这种灵活的合成策略允许精确调节量子点的尺寸、数量、间距和晶体相。纳米线中量子点的面选择性钝化为光催化剂工程开辟了一条途径：我们报告的光催化剂的光催化析氢速率比普通 CdS 量子点高出一个数量级。
