Masuda Katsuya, Sano Masahito
Department of Polymer Science and Engineering, Yamagata University, 4-3-16 Jyonan, Yonezawa, Yamagata 992-8513, Japan.
Langmuir. 2015 May 5;31(17):4934-9. doi: 10.1021/acs.langmuir.5b00327. Epub 2015 Apr 22.
The effects of treating SiO2/Si with either acidic or alkaline solutions on single-layer graphene were investigated using Raman microscopy. It is well-known that in air graphene on SiO2 is unintentionally strained and hole-doped to different degrees, varying widely by sample. It is also known that various amine compounds act as electron donors to graphitic materials. In this study, a SiO2/Si substrate was simply dipped in either a concentrated HCl solution or pH 9.0 NaOH solution and then rinsed, prior to transferring graphene on it. The G and 2D peaks were followed at a fixed position on a single-layer graphene flake in water and various concentrations of pH 7.4 tris(hydroxymethyl)aminomethane (Tris) buffer. The results demonstrate that these treatments reduce the sample variation, improve the stability against Tris, and even bring some graphene samples close to a freestanding state. The Raman analysis reveals that the main effect of dipping is to relieve strain. The undoping effect on some samples is explained by the HCl solution becoming trapped between the graphene and SiO2 surface.
使用拉曼显微镜研究了用酸性或碱性溶液处理SiO₂/Si对单层石墨烯的影响。众所周知，在空气中，SiO₂上的石墨烯会意外地受到不同程度的应变和空穴掺杂，不同样品之间差异很大。还已知各种胺化合物可作为石墨材料的电子供体。在本研究中，在将石墨烯转移到SiO₂/Si衬底上之前，先将其简单地浸入浓HCl溶液或pH 9.0的NaOH溶液中，然后冲洗。在单层石墨烯薄片上的固定位置跟踪水和各种浓度的pH 7.4三（羟甲基）氨基甲烷（Tris）缓冲液中的G峰和2D峰。结果表明，这些处理减少了样品差异，提高了对Tris的稳定性，甚至使一些石墨烯样品接近独立状态。拉曼分析表明，浸渍的主要作用是缓解应变。HCl溶液被困在石墨烯和SiO₂表面之间，这解释了对某些样品的去掺杂作用。
