Li Rongfu, Lee Jeunghoon, Yang Baocheng, Horspool David N, Aindow Mark, Papadimitrakopoulos Fotios
Nanomaterials Optoelectronics Laboratory, Polymer Program, Department of Chemistry, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA.
J Am Chem Soc. 2005 Mar 2;127(8):2524-32. doi: 10.1021/ja0465404.
The treatment of CdSe nanocrystals (NCs) in a 3-amino-1-propanol (APOL)/water (v/v = 10:1) mixture at 80 degrees C in the presence of O(2) causes them to undergo a slow chemical etching process, as evidenced by spectroscopic and structural investigations. Instead of the continuous blue shift expected from a gradual decrease in NC dimensions, a bottleneck behavior was observed with distinct plateaus in the peak position of photoluminescence (PL) and corresponding maxima in PL quantum yield (i.e., 34 +/-7%). It is presently argued that such etching behavior is a result of two competitive processes taking place on the surface of these CdSe NCs: (i) oxidation of the exposed Se-sites to acidic SeO(x)() entities, which are readily solubilized in the basic APOL/H(2)O mixture, and (ii) coordination of the underlying Cd-sites with both amines and hydroxyl moieties to temporally impede NC dissolution. This is consistent with the HRTEM results, which suggest that the etched NCs adopt pyramidal morphologies with Cd-terminated facets (i.e., (0001) bases and either {011} or {21} sides) and account for the apparent resistance to etching at the plateau regions.
在80摄氏度、有氧气存在的条件下，将硒化镉纳米晶体（NCs）置于3-氨基-1-丙醇（APOL）/水（体积比v/v = 10:1）的混合液中进行处理，会使其经历缓慢的化学蚀刻过程，光谱和结构研究证明了这一点。与纳米晶体尺寸逐渐减小所预期的连续蓝移不同，观察到了一种瓶颈行为，即光致发光（PL）的峰值位置出现明显的平台期，且光致发光量子产率相应达到最大值（即34±7%）。目前认为，这种蚀刻行为是这些硒化镉纳米晶体表面发生的两个竞争过程的结果：（i）将暴露的硒位点氧化为酸性的SeO(x)()实体，这些实体很容易溶解在碱性的APOL/H(2)O混合液中；（ii）底层的镉位点与胺和羟基部分配位，暂时阻碍纳米晶体的溶解。这与高分辨率透射电子显微镜（HRTEM）的结果一致，该结果表明蚀刻后的纳米晶体呈现出以镉为终端面的金字塔形态（即（0001）基面和{011}或{21}侧面），并解释了平台区域明显的抗蚀刻性。
