水溶液阳离子交换法制备非晶壳层厚度和核壳结构可调的碲化物纳米晶
Telluride nanocrystals with adjustable amorphous shell thickness and core-shell structure modulation by aqueous cation-exchange
摘要：
核-壳胶体半导体纳米颗粒（CSNPs）的结构设计具有很大的吸引力，因为它具有增强光诱导电荷转移（PICT）和诱导有利的光学和电子性质的潜力。尽管如此，碲化物CSNP对高温的敏感性使得精确调节其表面结晶度具有挑战性。在此，我们已经开发了一种有效的策略，用于合成碲化物CSNPs与薄的无定形壳使用水溶液阳离子交换（ACE）。通过在40至110 ℃范围内改变合成温度，CdTe纳米颗粒的结晶度可以从没有可检测的无定形壳的完美晶体（c-CdTe）控制到具有结晶CdTe NP核被厚度高达7- 8 nm的可调无定形壳覆盖的核-壳结构（c@a-CdTe）。第二ACE步骤将c@a-CdTe转化为结晶CdTe@HgTe核-壳NP。在60 ℃下合成的c@a-CdTe纳米粒子具有4-5 nm厚的非晶壳层，表现出最高的表面增强拉曼散射活性，其增强因子约为8.82 × 10^5，这归因于非晶壳层和结晶核之间的耦合。
英文摘要：
Engineering the structure of core-shell colloidal semiconductor nanoparticles (CSNPs) is attractive due to the potential to enhance photo-induced charge transfer (PICT) and induce favourable optical and electronic properties. Nonetheless, the sensitivity of telluride CSNPs to high temperatures makes it challenging to precisely modulate their surface crystallinity. Herein, we have developed an efficient strategy for synthesising telluride CSNPs with thin amorphous shells using aqueous cation exchange (ACE). By changing the synthesis temperature in the range 40 to 110C, the crystallinity of the CdTe nanoparticles was controllable from perfect crystals with no detectable amorphous shell (c-CdTe) to a core-shell structure with a crystalline CdTe NP core covered by an amorphous shell of tunable thickness up to 7-8nm (c@a-CdTe) . A second ACE step transformed the c@a-CdTe to crystalline CdTe@HgTe core-shell NPs. The c@a-CdTe nanoparticles synthesized at 60C and having a 4-5 nm thick amorphous shell, exhibited the highest surface-enhanced Raman scattering activity with a high enhancement factor around 8.82x10^5, attributed to the coupling between the amorphous shell and the crystalline core.
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