Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore (Singapore), Fax: (+65) 6779-1936.
Chemistry. 2013 Sep 16;19(38):12732-8. doi: 10.1002/chem.201301753. Epub 2013 Aug 9.
Au@Ag core-shell nanorods with tunable end facets are obtained by coating Au bipyramids (BPs) with Ag. The resultant nanorods exhibit a pentatwinned crystal structure with tips terminated with either {110} or {111} facets. The control over the end facets is achieved by varying the capping agents and tuning the reduction rate of Ag. Specifically, when Ag is reduced slowly, Au@Ag nanorods with flat {110} end facets are formed with cetyltrimethylammonium bromide (CTAB) as the capping agent. If CTAB is replaced with cetyltrimethylammonium chloride (CTAC), Au@Ag nanorods with tips terminated with {111} facets are obtained. However, at a high Ag reduction rate, dumbbell-shaped Au@Ag nanorods are formed, with either CTAB or CTAC as the capping agent. The morphological evolution of the nanorods in each case is closely followed and a growth mechanism is proposed.
通过在 Au 双锥体 (BPs) 上包覆 Ag 得到了具有可调端面的 Au@Ag 核壳纳米棒。所得纳米棒具有五重孪晶晶体结构，尖端由 {110} 或 {111} 面终止。通过改变封端剂和调节 Ag 的还原速率来控制端面。具体地，当 Ag 缓慢还原时，以十六烷基三甲基溴化铵 (CTAB) 作为封端剂形成具有平坦 {110} 端面的 Au@Ag 纳米棒。如果用十六烷基三甲基氯化铵 (CTAC) 代替 CTAB，则得到尖端由 {111} 面终止的 Au@Ag 纳米棒。然而，在高 Ag 还原速率下，无论使用 CTAB 还是 CTAC 作为封端剂，都会形成哑铃状的 Au@Ag 纳米棒。在每种情况下都密切跟踪纳米棒的形态演变，并提出了一种生长机制。
