石墨烯/碳纳米管复合材料的制备及其电化学电容性能

Preparation and electrochemically capacitive performance of graphene/carbon nanotube composites

以石墨(G)和碳纳米管(MWCNTs)为原料,通过共同化学氧化-热还原的简便途径,制备了石墨烯/碳纳米管复合材料(RGO/RCNTO)。为便于比较,采用同样方法分别获得了热还原后的石墨烯(RGO)和碳纳米管(RCNTO)。用扫描电镜(SEM)、透射电镜(TEM)、红外光谱(FTIR)、X射线衍射(XRD)对材料进行结构和形貌表征。研究发现:由于氧化石墨(GO)和氧化碳纳米管(CNTO)存在一定的含氧官能团,形成均匀的氧化石墨/氧化碳纳米管复合物(GO/CNTO)。紧接着的热解过程又使得GO层因层间产生的气体膨胀而剥离,RCNTO随之进入层间,还原后石墨烯由于π—π作用吸引,重新堆积并将RCNTO裹在层间形成了三明治结构的RGO/RCNTO。复合材料在电流密度1 A·g^(-1)时的比电容为422.4 F·g^(-1),经过5 000次恒流充放电比电容仍保持在90%以上。良好的电容特性如高比容量和稳定的循环性能归因于该复合材料中RGO和RCNTO有效的协同作用。

In this study, a facile method to prepare graphene-carbon nanotube （RGO/RCNTO） composites by chemical oxidizationthermal reduction of graphite （G） and multi-walled carbon nanotubes （MWCNTs） was demonstrated. Reduced graphene oxide （RGO） and reduced carbon nanotube oxide （RCNTO） were also prepared for comparison. The structure and morphology of samples were examined by SEM, TEM, FTIR and XRD. The results indicated that owing to the existence of some oxygen functional groups in both GO and CNTO, uniform GO/CNTO composites were formed. Subsequent pyrolysis led to the formation of RGO and the exfoliation of GO layers due to the release of gas between GO layers, and thus RCNTO entered into the interlayers of RGO. RGO with RCNTO on layer restacked because of π-π interactions, and RCNTO was tightly embedded into RGO layers, achieving sandwich-structured RGO/RCNTO composites. A specific capacitance of 422.4 F·g^-1 at 1 A·g^-1 and 90% retention of initial capacitance over 5 000 cycles were delivered. Good capacitive characteristic including high specific capacitance and stable cycling performance should be attributed to the synergistic effects of both RGO and RCNTO components.