流体剪切辅助超临界CO_2技术制备石墨烯

Preparation of graphene from graphite by supercritical CO_2 exfoliation assisted with fluid shear

石墨烯具有的各种优异性能使其在新材料领域具有十分广泛的应用前景,但如何批量低成本制备高质量的石墨烯是实现其大规模应用前亟待解决的问题.本文采用流体剪切辅助超临界CO2剥离法,以石墨粉为原料成功制备出高质量的石墨烯.运用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、原子力显微镜（AFM）及拉曼光谱等技术对所制得的石墨烯进行分析表征,发现得到的石墨烯具有完整的晶格结构及很高的导电率,其中1~10层石墨烯含量达到90%以上.本技术有望提供一种清洁、高效制备高质量石墨烯的方法.

Recently graphene has attracted a great interest in scientific research due to its excellent electronic, mechanical, optical, and thermal properties. Many methods have been explored for preparation of high-quality graphene efficiently. However, it still remains a great challenge for the scalable production of graphene with low cost. Graphite oxide reduction was commonly recognized as the most promising method, but many oxygen-containing groups such as hydroxyl （-OH） and carboxyl （-COOH） are introduced into the graphene framework during the process, which dramatically decreases the quality of graphene. As a green solvent, supercritical CO2 possesses excellent characteristics of high diffusivity and high permeability. In this work, supercritical CO2 is employed as medium for the exfoliation of graphite. The diffusion and exfoliation process are intensively enhanced with the assistance of fluid shear, which strikingly facilitates the graphite exfoliation, resulting in an improvement of graphene yield. The graphene obtained in our work exhibits intact lattice structure and high electronic conductivity. Moreover, it is found that the graphene synthesized by supercritical CO2 exfoliation consists of 90% exfoliated sheets with less than 10 layers. Our work can provide a clean and low-cost way to commercially produce graphene with high quality.