Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
ACS Appl Mater Interfaces. 2017 Sep 20;9(37):32097-32105. doi: 10.1021/acsami.7b09388. Epub 2017 Sep 11.
We synthesized uniform CuInS/ZnS nanocubes by adjusting reaction parameters at the ZnS growth stage. Higher temperature and zinc concentration were shown to drive resultant crystals to have cubic morphology, which could be ascribed to the facet-dependent ligand dynamics on the crystal surface and concomitantly preferred directions of crystal growth. It was found that these nanocubes exhibit sensitive responses, as of photoluminescence quenching, toward hydrogen peroxide, compared to pyramid-shaped nanocrystals. The origin of quenching was further analyzed to be the oxidation of thiolate ligands that leaves the quenching center on the surface. It was noted that the quenched photoluminescence could be fully recovered by introducing additional ligand molecules into the system. Being adopted in the shape-controlled crystal growth, the ligand-to-crystal interaction was shown to still govern the interfacial reaction, the oxidation by hydrogen peroxide, of faceted crystals in our system. It turns out that the reactivity at the crystal surface depends on the exposed facets, especially induced by shape control, and the weak ligand-binding nature of the nanocube renders it vulnerable to the surface reaction.
我们通过调整 ZnS 生长阶段的反应参数合成了均匀的 CuInS/ZnS 纳米立方体。较高的温度和锌浓度被证明会促使所得晶体具有立方形态，这可以归因于晶体表面上配体动力学的各向异性和晶体生长的优势方向。研究发现，与金字塔形纳米晶体相比，这些纳米立方体对过氧化氢表现出敏感的响应，如光致发光猝灭。进一步分析猝灭的原因是硫醇配体的氧化，从而在表面上留下猝灭中心。值得注意的是，通过向体系中引入额外的配体分子，可以完全恢复猝灭的光致发光。在控制晶体生长的形状中，配体-晶体相互作用仍然控制着我们体系中各向异性晶体的界面反应，即过氧化氢的氧化。事实证明，晶体表面的反应性取决于暴露的晶面，特别是由形状控制诱导的晶面，而纳米立方体较弱的配体结合性质使其容易受到表面反应的影响。
