Growth of Au@Ag Core–Shell Pentatwinned Nanorods: Tuning the End Facets |
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Authors: | Weiqing Zhang Hao Ying Johnny Goh Shaik Firdoz Prof Xianmao Lu |
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Institution: | Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117576 Singapore (Singapore), Fax: (+65)?6779‐1936 |
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Abstract: | 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. |
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Keywords: | bimetallic nanorods core– shell end facets gold seed‐mediated growth silver |
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