镁热还原CO_2气体制备介孔石墨烯及其电容特性研究

Preparation of Mesoporous Graphene by Magnesiothermic Reduction of CO_2 and It's Capacitance Characteristics

以CO_2为原料,采用金属镁热还原法,制备出富含介孔结构的石墨烯材料。分别利用X射线衍射、扫描电镜、透射电镜、拉曼光谱和N_2吸附-脱附等测试手段对材料的微观结构进行了表征。通过在镁粉中加入不同质量的MgO,可以实现对石墨烯形貌和孔结构的调控,当MgO/Mg质量比为8∶1时,产物(MRG-8)具有均一的介孔结构(4nm)。并对材料的电化学性能进行了测试,在1mol/L KOH的电解液中,MRG-8具有最高的比电容(171F/g),同时具有非常好的倍率特性,循环测试12000周,比电容保持率为94%。当采用[EMIM][BF4]离子液体作为电解液,以MRG-8为电极材料组装成的对称型超级电容器显示出超高功率密度(175k W/kg),对应的能量密度为28.1Wh/kg。因此,采用此方法制备的介孔石墨烯材料在高功率的超级电容器领域具有潜在的应用前景。

Graphene materials with ample mesopores were prepared by a magnesiothermic reaction using CO2 as carbon source. XRD, SEM, TEM, Raman spectroscopy and N2 desorption/adsorption were used to characterize the mierostructure of graphene materials. It was found that the morphologies and pore structure of graphene were controllable simply by changing the mass ratio of Mg and MgO in the starting materials. The product （MRG-8） obtained with MgO/Mg mass ratio of 8：1 showed a uniform mesopore size of 4 nm. The electrochemical properties of products were also evaluated. In 1 mol/L KOH electrolyte, MRG-8 displayed a high specific capacitance of 171 F/g and an excellent rate performance. The capacitance retention rate of MRG-8 is up to 94% after 12000 cycles. Using ionic liquid [ EMIM ] [ BF4 ] as electrolyte, symmetric supereapacitors of MRG-8 exhibited an ultra-high power density of 175kW/kg and a corresponding energy density of 28. lkW/kg. This work is expected to offer a novel method for mesoporous graphene production, which may be promising in the application of high-power supercapacitors.