Key Laboratory for Soft Chemistry and Functional Materials, Nanjing University of Science and Technology, Ministry of Education, Nanjing 210094, P. R. China.
Nanoscale. 2010 Aug;2(8):1461-6. doi: 10.1039/c0nr00135j. Epub 2010 Jun 4.
Understanding energy transfer mechanisms in graphene derivatives is strongly motivated by the unusually interesting electronic properties of graphene, which can provide a template for the creation of novel nanostructured derivatives. From a synthetic point of view, it is highly attractive to envision being able to synthesize pristine graphene from precursors such as graphene oxide (GO). While this goal may be challenging over large length-scales, it is possible to generate regions of graphene at the nanoscale, confirmed by Raman spectroscopy or other methods. We describe an in situ method of nucleating gold or palladium nanoparticles in the presence of ethylene glycol as a reducing agent, while simultaneously reducing GO to graphene. The Au nanoparticles aid in spectroscopic characterization by both quenching fluorescence, allowing the graphene D and G bands to be quantified, and yielding a surface enhancement of about two orders of magnitude. We observe the excitation profile (488-785 nm) of the surface enhanced Raman spectrum (SERS) of graphene with Au nanoparticles adsorbed on the surface. Both the D and G bands display a resonance at approximately 593 nm (2.09 eV). This resonance may be interpreted as a combination of the plasmon resonance at 548 nm and a likely contribution from charge transfer as well. In addition, we observe a stiffening of the G band compared with that of graphene. The mechanism of the SERS, whether plasmonic or charge transfer-based, enables insight into the electronic pathways available to the graphene-nanoparticle system. We discuss our results in the context of several existing studies of graphene-based nanostructure derivatives.
理解石墨烯衍生物中的能量转移机制是由石墨烯异常有趣的电子特性所驱动的，这为新型纳米结构衍生物的创造提供了模板。从合成的角度来看，设想能够从氧化石墨烯 (GO) 等前体合成原始石墨烯是非常吸引人的。虽然这一目标在大尺度上可能具有挑战性，但在纳米尺度上生成石墨烯区域是可能的，这可以通过拉曼光谱或其他方法来证实。我们描述了一种在乙二醇作为还原剂的存在下原位生成金或钯纳米粒子的方法，同时将 GO 还原为石墨烯。Au 纳米粒子通过猝灭荧光来辅助光谱特性的表征，从而可以量化石墨烯的 D 和 G 带，并产生约两个数量级的表面增强。我们观察到吸附在表面上的 Au 纳米粒子的表面增强拉曼光谱 (SERS) 的激发谱（488-785nm）。D 和 G 带都在约 593nm（2.09eV）处显示出共振。这种共振可以解释为 548nm 的等离子体共振和可能的电荷转移贡献的组合。此外，我们观察到 G 带与石墨烯相比变硬。SERS 的机制，无论是基于等离子体还是基于电荷转移，都使我们能够深入了解石墨烯-纳米粒子系统的可用电子途径。我们将我们的结果在几个基于石墨烯的纳米结构衍生物的现有研究中进行了讨论。
