氢化石墨纳米结构的合成及尺寸相关的荧光性质

摘要

Hydrogenated graphite/graphene nanostructures ( HGNSs ) were synthesized via a solvothermal route at 180℃ using potassium as the reductant and halogenobenzene( bromobenzene and dibromobenzene) as the carbon precursor. Selective cleavage of the relatively lower stable C-Br bonds( compared to C-H bonds) of the carbon precursor( C6 H5 Br and C6 H4 Br2 , respectively) by K metal results in the growth of hydrogenated carbon nanostructures. The HGNSs grow through the polymerization and bonding of the remained hexagonal carbon rings after the debromination. The samples synthesized using C6 H5 Br and C6 H4 Br2 as carbon precursor are visually tawny and black, respectively. Raman and infrared spectra of the samples show that the black product is hydrogenated graphite nanosheets with the size of about 2 nm, while the tawny sample has smaller size. X-Ray diffraction( XRD) measurements show that the products are stacked in a rhombohedral structure, but with low crystallinity. Photoluminescence( PL) measurements of the samples reveal that the fluorescence intensity and energy are related to the size of the formed HGNSs. The fluorescence intensity of the tawny pro-duct is about 15 times higher than that of the black one under the same experimental conditions. A photolumi-nescence mechanism similar to that of graphite oxide has been proposed for the HGNSs.%在溶剂热反应条件下(180℃),利用还原剂金属钾对卤代苯(溴苯和二溴苯)中的C-Br键进行选择性裂解,而含氢的碳六元环仍稳定且之间可以发生聚合成键,成功合成了2种不同的氢化石墨纳米结构,获得的产物分别呈黄褐色和黑色。拉曼和红外光谱分析结果表明,黑色产物为尺寸约2 nm的氢化石墨纳米片,而黄褐色样品为尺寸更小的氢化碳纳米结构；X射线衍射分析结果表明,2种产物都具有菱方结构但结晶性较低。对合成的氢化石墨纳米结构的荧光性质分析发现,样品具有尺寸相关的荧光现象,同等激发条件下,尺寸较小的黄褐色样品的发光强度约为黑色样品的15倍。