Silver nanoplates: Size control in two dimensions and formation mechanisms
Silver nanoplates: Size control in two dimensions and formation mechanisms
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DOI：
10.1021/jp031077n
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发表时间：
2004-05-06
影响因子：
3.3
通讯作者：
Carroll, DL
中科院分区：
文献类型：
--
作者：
Chen, SH;Carroll, DL
在适当浓度的十六烷基三甲基溴化铵（CTAB）和银晶种存在下，通过简单的室温溶液相化学还原法合成了平均厚度为20-30 nm、平均尺寸为40 ~ 300 nm的银纳米片。在这些单晶纳米片的（111）基面的表面上吸附有CTAB分子，解释了片的各向异性形成及其头对头自组装网络超结构。当纳米片的长径比达到9时，纳米片的面内偶极等离子体吸收带可以在近红外区移动到1000 nm左右，为各种近红外相关应用开辟了新的可能性。通过改变不同反应组分的浓度或用其他对应物替代它们，研究了纳米片形成的机制。已经发现Br-阴离子以及银晶种对于纳米片的形成是必不可少的。反应从与银晶种接触的CTAB胶束稳定的银化粒子开始，通过吸附在晶种（111）面上的CTAB分子调控的催化还原反应继续进行，最后在（111）面内扩展生长。从pH值和不同还原剂的影响研究也支持了上述结论。还讨论了形成其他形状的颗粒如棒状或球形多晶颗粒的详细情况。
Silver nanoplates, with average thickness of 20-30 nm and average size tunable from 40 to 300 nm, have been synthesized via a simple room-temperature solution-phase chemical reduction method in the presence of appropriate concentrations of cetyltrimethylammonium bromide (CTAB) and silver seeds. On the surface of the (111) basal plane of these single-crystal nanoplates are adsorbed CTAB molecules, accounting for the anisotropic formation of plates and their head-to-head self-assembled network superstructures. The size-sensitive in-plane dipole plasmon absorption bands of the nanoplates can be shifted to similar to1000 nm in the near-IR region when the aspect ratio of nanoplates reached 9, opening new possibilities for various near-IR-related applications. The mechanisms of the nanoplate formation were studied by varying the concentrations of different reaction components or substituting them with other counterparts. Br- anions, as well as silver seeds, have been found indispensable for nanoplate formation. The reaction started from the CTAB micellestabilized silver bromide particles that have contact silver seeds, continued through catalytic reductions regulated by CTAB molecules adsorbed on the (111) plane of the seeds, and finally extended the growth within the (111) plane. Studies from the effects of pH and different reducing agents also support the above conclusions. The detailed scenario for the formation of other shaped particles such as rod or spherical polycrystalline particles is also discussed.