氧化石墨超声时间对三维还原氧化石墨烯结构及超级电容性能的影响

Effect of Ultrasonic Time for Graphite Oxide on the Structure and Super Capacitor Performance of Three-dimensional Reduced Graphene Oxide

将氧化石墨凝胶超声不同时间制备氧化石墨烯(GO)溶胶,再以GO溶胶为前驱体采用一步水热法制备了三维还原氧化石墨烯(3DRGO),采用X射线衍射(XRD)、拉曼光谱、原子力显微镜(AFM)、扫描电子显微镜(SEM)和电化学测试等研究了不同超声时间对3DRGO的形貌、结构及超级电容性能的影响.结果表明,当超声时间不超过120 min时,经水热反应后还原氧化石墨烯均能形成稳定的三维结构,但随着超声时间的延长,三维结构尺寸不断减小,强度增加,样品的内部结构也由片状逐渐向多孔网状转化;当超声时间超过120 min时,还原氧化石墨烯虽具有网状结构,但在宏观上不利于形成稳定的三维结构.电化学测试结果表明,经不同超声时间所制备的还原氧化石墨烯均表现出较好的超级电容性能,其中超声时间为120 min时制备的3DRGO具有更均匀的多孔网状结构,表现出了最佳的超级电容性能,在1 A/g电流密度下其比电容可达328 F/g,即使在20 A/g的大电流密度条件下,其比电容仍可高达240 F/g.

Three-dimensional reduced graphene oxide（3DRGO） was prepared from graphene oxide（GO） with different ultrasonic time by one-step hydrothermal method. X-Ray diffraction（XRD）, Raman spectroscopy, atom force microscopy （ AFM ） , scanning electron microscopy （ SEM ） and elctrochemical measurements were used to investigate the structure and supercapacitive performance of 3DRGO. The results show that when the ultrasonic time is less than 120 min, stabilized three-dimensional structure can be formed in the hydrothermal reduced graphene oxide. Along with the increase of the ultrasonic time, the size of 3DRGO decrease while the strength increase, and the inner structure of 3DRGO transforms from schistose to network. When the ultrasonic time is longer than 120 min, the stability of the network in 3DRGO is inferior on a macro level. The results of electrochemical measurements show that all the 3 DRGO samples prepared with different ultrasonic time have good supercapacitive performance. The sample prepared with 120 min has the best supercapacitive perform-ance for its well-proportioned network. The capacity can reach 328 F/g at the current density of 1 A/g and 240 F/g at the high current density of 20 A/g.