Gai Yanzhe, Wang Wucong, Xiao Ding, Tan Huijun, Lin Minyan, Zhao Yaping
School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University Shanghai 200240 P. R. China
RSC Adv. 2018 Mar 9;8(18):9749-9753. doi: 10.1039/c8ra00475g. eCollection 2018 Mar 5.
In this paper, the reversible conversion between pristine graphene nanosheets and pristine graphene nanoscrolls at room temperature was reported. The graphene nanosheets were rolled up into the graphene nanoscrolls by silver nitrate in ethanol solution, and the fabricated graphene nanoscrolls were unfolded back to the graphene nanosheets in ethanol solution by adding ammonium hydroxide. The dynamic conversion state of the process was confirmed by the morphology of the intermediate samples captured using an optical microscope and scanning electron microscope. Also, AFM, TEM and Raman spectroscopy displayed that the graphene transformed from its nanoscrolls remained the structure and morphology of the started graphene. The reason for the formation of the nanoscrolls was assigned to the silver cyanide particles generated on the edge of the graphene. The freshly formed silver cyanide caused the unbalanced energy of the graphene surface by changing the pi electron distribution and triggered off the graphene to roll up. The unfolding of the graphene nanoscrolls back to the graphene nanosheets was attributed to the removal of the silver cyanide by the ammonia forming the complex. This reversible conversion might be a novel and facile approach to make graphene nanoscrolls and to store the graphene. Also, it may bring new sight to the conversion research between two-dimension and one-dimension materials.
本文报道了在室温下原始石墨烯纳米片与原始石墨烯纳米卷之间的可逆转换。在乙醇溶液中，硝酸银将石墨烯纳米片卷成石墨烯纳米卷，通过添加氢氧化铵，制备的石墨烯纳米卷在乙醇溶液中又展开变回石墨烯纳米片。利用光学显微镜和扫描电子显微镜捕获中间样品的形态，证实了该过程的动态转换状态。此外，原子力显微镜、透射电子显微镜和拉曼光谱表明，从纳米卷转变而来的石墨烯保留了起始石墨烯的结构和形态。纳米卷形成的原因归因于在石墨烯边缘生成的氰化银颗粒。新形成的氰化银通过改变π电子分布导致石墨烯表面能量不平衡，从而引发石墨烯卷起。石墨烯纳米卷展开变回石墨烯纳米片归因于氨形成配合物从而去除了氰化银。这种可逆转换可能是制备石墨烯纳米卷和储存石墨烯的一种新颖且简便的方法。此外，它可能为二维和一维材料之间的转换研究带来新的视角。
