Fakultät für Physik, Universität Bielefeld, 33615 Bielefeld, Germany.
Small. 2011 Apr 4;7(7):874-83. doi: 10.1002/smll.201001993. Epub 2011 Mar 4.
Carbon nanosheets are mechanically stable, free-standing two-dimensional materials with a thickness of ≈1 nm and well defined physical and chemical properties. They are made by radiation-induced cross-linking of aromatic self-assembled monolayers. Herein, a route is presented to the scalable fabrication of multilayer nanosheets with tunable electrical, optical, and chemical properties on insulating substrates. Stacks of up to five nanosheets with sizes of ≈1 cm(2) on oxidized silicon are studied. Their optical characteristics are investigated by visual inspection, optical microscopy, UV-vis reflection spectroscopy, and model calculations. Their chemical composition is studied by X-ray photoelectron spectroscopy. The multilayer samples are then annealed in an ultrahigh vacuum at various temperatures up to 1100 K. A subsequent investigation by Raman, X-ray photoelectron, and UV-vis reflection spectroscopy, as well as by electrical four-point probe measurements, demonstrates that the layered nanosheets transform into nanocrystalline graphene. This structural and chemical transformation is accompanied by changes in the optical properties and electrical conductivity and opens up a new path for the fabrication of ultrathin functional conductive coatings.
碳纳米片是机械稳定的、独立的二维材料，厚度约为 1nm，具有明确的物理和化学性质。它们是通过芳香族自组装单层的辐射诱导交联形成的。本文提出了一种在绝缘衬底上可扩展制造具有可调电、光和化学性质的多层纳米片的方法。研究了多达五层的纳米片，尺寸约为 1cm²，在氧化硅上。通过目视检查、光学显微镜、紫外可见反射光谱和模型计算研究了它们的光学特性。通过 X 射线光电子能谱研究了它们的化学成分。然后将多层样品在超高真空下在各种温度下退火，最高可达 1100K。随后通过拉曼、X 射线光电子能谱和紫外可见反射光谱以及四点探针电导率测量的研究表明，层状纳米片转化为纳米晶石墨烯。这种结构和化学转化伴随着光学性质和电导率的变化，为制造超薄功能导电涂层开辟了新途径。
