Wang Jun, Li Yan, Zhang Bo-Ping, Xie Dan-Dan, Ge Juan, Liu Hui
J Nanosci Nanotechnol. 2016 Apr;16(4):3480-8. doi: 10.1166/jnn.2016.11892.
Graphene quantum dots (GQDs) possess unique properties of graphene and exhibit a series of new phenomena of 0 dimension (D) carbon materials. Thus, GQDs have attracted much attention from researchers and have shown great promise for many applications. Recently, many works focus on GQDs-metal ions and metal nanoparticles (NPs). Although, many researches point out that metal ions and metal NPs have significant effect on photoluminescence (PL) feature of GQDs, mainly focus on PL intensity. Here, for the first time, we reported that metal NPs also affected PL peak position which was dependent on the mix mechanism of metal and GQDs. When GQDs-silver (Ag) composite mixed by physical method and excited at a wavelength of 320 nm, PL peak position of composites first showed blue-shifted then red-shifted with increasing of Ag content. However, if GQDs-Ag composite prepared by chemical method, PL peak position of the composites blue-shifted. Furthermore, the shift of PL peak position of GQDs-Ag prepared both for physical and chemical method displayed excitation-dependent feature. When the excitation wavelength approached to Ag SPR peaks, no obvious PL shift was observed. The mechanism for different PL shifts and the phenomenon of excitation-dependent PL shift as well as the formation mechanism of GQDs-Ag composite by chemical method are discussed in detail in this paper.
石墨烯量子点（GQDs）具有石墨烯的独特性质，并展现出一系列零维（0D）碳材料的新现象。因此，GQDs已引起研究人员的广泛关注，并在许多应用中显示出巨大潜力。最近，许多研究聚焦于GQDs-金属离子和金属纳米颗粒（NPs）。尽管许多研究指出金属离子和金属NPs对GQDs的光致发光（PL）特性有显著影响，但主要集中在PL强度方面。在此，我们首次报道金属NPs也会影响PL峰位置，这取决于金属与GQDs的混合机制。当通过物理方法混合GQDs-银（Ag）复合材料并在320nm波长下激发时，复合材料的PL峰位置随着Ag含量的增加先出现蓝移然后红移。然而，如果通过化学方法制备GQDs-Ag复合材料，复合材料的PL峰位置会发生蓝移。此外，通过物理和化学方法制备的GQDs-Ag的PL峰位置移动均表现出激发依赖性特征。当激发波长接近Ag表面等离子体共振（SPR）峰时，未观察到明显的PL移动。本文详细讨论了不同PL移动的机制、激发依赖性PL移动现象以及通过化学方法制备GQDs-Ag复合材料的形成机制。
