Kernel Tuning and Nonuniform Influence on Optical and Electrochemical Gaps of Bimetal Nanoclusters

Fine
tuning nanoparticles with atomic precision is exciting and
challenging and is critical for tuning the properties, understanding
the structure–property correlation and determining the practical
applications of nanoparticles. Some ultrasmall thiolated metal nanoparticles
(metal nanoclusters) have been shown to be precisely doped, and even
the protecting staple metal atom could be precisely reduced. However,
the precise addition or reduction of the kernel atom while the other
metal atoms in the nanocluster remain the same has not been successful
until now, to the best of our knowledge. Here, by carefully selecting
the protecting ligand with adequate steric hindrance, we synthesized
a novel nanocluster in which the kernel can be regarded as that formed
by the addition of two silver atoms to both ends of the Pt@Ag12 icosohedral kernel of the Ag24Pt­(SR)18 (SR: thiolate) nanocluster, as revealed by single crystal X-ray
crystallography. Interestingly, compared with the previously reported
Ag24Pt­(SR)18 nanocluster, the as-obtained novel
bimetal nanocluster exhibits a similar absorption but a different
electrochemical gap. One possible explanation for this result is that
the kernel tuning does not essentially change the electronic structure,
but obviously influences the charge on the Pt@Ag12 kernel,
as demonstrated by natural population analysis, thus possibly resulting
in the large electrochemical gap difference between the two nanoclusters.
This work not only provides a novel strategy to tune metal nanoclusters
but also reveals that the kernel change does not necessarily alter
the optical and electrochemical gaps in a uniform manner, which has
important implications for the structure–property correlation
of nanoparticles.

精确调控纳米粒子，一项既令人振奋又极具挑战性的工作，对于调整其性质、理解结构-性质关联以及确定纳米粒子的实际应用至关重要。一些超小硫醇化金属纳米粒子（金属纳米簇）已被证明可以精确掺杂，甚至保护性主链金属原子也可以精确还原。然而，在纳米簇中的其他金属原子保持不变的情况下，精确添加或还原核原子至今尚未成功，据我们所知。在本研究中，通过精心选择具有适当位阻的配体，我们合成了一种新型纳米簇，其中核心可以视为通过向Ag24Pt(SR)18（SR：硫醇）纳米簇的Pt@Ag12二十面体核心两端各添加一个银原子而形成，这一结论由单晶X射线晶体学所证实。有趣的是，与先前报道的Ag24Pt(SR)18纳米簇相比，所获得的这种新型双金属纳米簇表现出相似的吸收特性，但电化学窗口存在差异。一种可能的解释是，核的调整并未本质上改变电子结构，但明显影响了Pt@Ag12核心上的电荷，如自然人口分析所证明，从而可能导致两个纳米簇之间较大的电化学窗口差异。本研究不仅提供了一种精确调控金属纳米簇的新策略，还揭示出核心的改变并不一定以统一的方式影响光学和电化学窗口，这对于纳米粒子的结构-性质关联具有重要的启示。