一锅溶剂热法制备具有不同形貌特征的CdSe量子点负载石墨烯

利用Hummer氧化法制备了氧化石墨烯,并对氧化石墨烯的NaBH₄化学还原法和乙二胺溶剂热还原法进行了比较,发现用乙二胺还原后可在石墨烯表面引入含氮基团,增加片层间的距离,提高分散性。采用乙二胺溶剂热还原法,发展了一锅法制备CdSe量子点负载石墨烯的简易方法。对CdSe量子点负载石墨烯的表征分析结果显示,氧化石墨烯在负载CdSe量子点的同时自身被还原,氧含量显著减少,而还原后的石墨烯表面引入了含氮基团。考察了反应温度及反应时间的影响,研究结果表明,反应温度的变化对氧化石墨烯的还原过程影响不大,而反应时间的影响相对明显。随着反应时间的延长,石墨烯的还原程度越高,石墨烯表面负载的CdSe则由量子点由颗粒逐渐长大成为纳米棒和支化的星状纳米结构。通过调控反应条件可在控制氧化石墨烯还原程度的同时改变石墨烯表面所负载CdSe量子点的形貌,这为形貌可控的CdSe量子点负载石墨烯的制备提供了一种有效方法。

One-Pot Step Hydrothermal Synthesis of Nano-Composites Composed of Graphene and CdSe Quantum Dots with Different Morphology

Graphene oxides and graphene by using redox method were synthesized and characterized. The properties of graphene obtained by NaBH₄ chemical reduction method and thermal reduction method in ethylene amine solvent were compared. It was demonstrated that thermal reduction of graphene oxides in ethylene amine solvent could introduce nitrogen functional groups to the surface of obtained graphene, increase the distance between the film layers and enhance their dispersity. The results demonstrated that graphene oxides were reduced and simultaneously CdSe quantum dots were loaded, oxygen content were significantly decreased and the nitrogen functional groups were introduced to the surface of graphene sheets. The change of reaction temperature showed little effects on the reduction of graphene oxides, and the longer reaction time, the reduction rate of graphene oxides were higher. With the increase of reaction time, the CdSe quantum dots loaded on the surface of graphene grew into nanorods, nanowires, and even branch-shaped nano structures. By controlling the reaction time and temperature, we can easily control the reduction degree of graphene oxides and the morphology of CdSe quantum dots supported on the surface of graphene. In conclusion, an effective method is established to control the property and morphology of nano-composites composed of graphene and CdSe quantum dots by hydro-thermal methods.