压力促进氧化石墨烯水热还原反应的机理  

Mechanism of Pressure-Accelerated Solvothermal Reduction of Graphene Oxide

作　　者：常艳丽[1] 陈胜[1] 曹傲能[1] 

机构地区：[1]上海大学环境与化学工程学院纳米化学与生物学研究所,上海200444

出　　处：《上海大学学报（自然科学版）》2010年第6期577-581,共5页Journal of Shanghai University:Natural Science Edition

基　　金：国家重点基础研究发展计划(973计划)资助项目(2009CB930200);上海市重点学科建设资助项目(S30109)

摘　　要：研究水相中氧化石墨烯(graphene oxide,GO)在敞口容器和密闭容器中的水热还原过程,发现氧化石墨烯还原后更容易通过超声破碎成小片.原子力显微镜(atomic force microscopy,AFM)和动态光散射(dynamic lightscattering,DLS)结果表明,密闭容器中产生的压力不仅能促进氧化石墨烯的还原,而且可使其在超声处理后破碎形成尺寸更小、分布更窄、适合生物医药应用的石墨烯纳米小片.红外(infrared,IR)光谱结果表明,加压和常压下还原的氧化石墨烯的C=O伸缩振动峰和O—H弯曲振动峰没有明显区别,但加压下环氧键C—O—C伸缩振动峰明显减弱.据此推测,氧化石墨烯水热还原的机理是压力促进环氧键转化为C—OH,这一开环反应为水分子参加加成反应,加压有利于反应的进行.开环反应产物进一步以CO_2形式脱除而形成缺陷,氧化石墨烯在超声处理后沿缺陷断裂,从而得到尺寸更小的石墨烯片.Solvothermal reduction of graphene oxide （GO） is a convenient green method to produce graphene. It has been found that the autogenous pressure in the sealed vessel can accelerate reduction of GO comparing to the same reaction in an open vessel at the same temperature. However, the underlying mechanism is unknown. We have investigated the solvothermal reduction of GO in aqueous dispersion in the absence of reduetants in both open and sealed vessels at the same temperature. We found that the solvothermal reduction of GO made it easy to sonicate the reduced GO sheets into small pieces. Atomic force microscopy （AFM） and dynamic light scattering （DLS） results show that the high pressure not only accelerates the reduction of GO, but also makes the reduced GO sheets easily become broken by sonication into smaller pieces with a narrower size distribution. Infrared （IR） spectra shows no apparent difference of C = 0 stretching and O--H bending between the reduced GO under both conditions. However the C--O--C stretching of GO was significantly decreased after reduction at high pressure. We propose that C--O--C bonds of GO can be converted to C--OH, which is an addition reaction with water molecules, therefore can be accelerated at high pressure. The epoxy-converted C--OH is then removed in the form of CO2 , leaving lines of defects on the GO sheets and making the GO sheets more easily be broken into small pieces at those sites.

关 键 词：氧化石墨烯 水热还原 压力 环氧基 

分 类 号：TQ127.1[化学工程—无机化工]