水热反应温度对三维还原氧化石墨烯的形貌、结构和超级电容性能的影响

以氧化石墨凝胶制备的氧化石墨烯溶胶为前驱体,在120-220°C条件下,采用水热法制备了系列不同还原程度的三维还原氧化石墨烯,采用扫描电镜(SEM),X射线衍射(XRD),傅里叶变换红外(FTIR)光谱,X射线光电子能谱(XPS)和电化学测试等手段研究了水热反应温度对材料形貌、结构和超级电容性能的影响.结果表明:采用水热法制备的三维还原氧化石墨烯呈多孔网状结构,材料的体积和内部网状孔径随着水热反应温度的升高而减小;同时,氧化石墨烯的还原程度随反应温度的升高而增加,有序度提高,其结构逐渐向着类石墨结构转化;而材料的比电容和能量密度则随反应温度的升高呈现出先增大后减小的趋势,且均以双电层电容为主;相比之下,当水热反应温度为180°C时,制备的三维还原氧化石墨烯具有最佳的超级电容性能,在电解液为6mol·L-1的KOH溶液中,0.5A·g-1电流密度下其比电容达到315 F·g-1,10 A·g-1时仍能保持212 F·g-1的高比容量,能量密度为40.5Wh·kg-1,5000次循环后比电容保持率为86%,表现出了良好的电化学性能.

Effect of the Hydrothermal Reaction Temperature on Three-Dimensional Reduced Graphene Oxide's Appearance,Structure and Super Capacitor Performance

Three-dimensional reduction of graphene oxide with a series of different degrees of reduction was performed by the hydrothermal method in the temperature range from 120 to 220 ℃, with graphene oxide sols as the precursor and prepared by graphite oxide gels. The effect of the temperature of the hydrothermal reaction on the materials appearance, structure, and super capacitor performance was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. The results show that the prepared three dimensional reduction of graphene oxide was porous and reticulated, and its volume and inner mesh aperture gradually decreased with increasing temperature, while its degree of reduction and order increased at the same time, and its structure gradually transformed to the graphite oxide structure. However, thematerials' specific capacitance and energy density showed the tendency of first increasing and then decreasing, with the electric double-layer capacitor mainly remaining. The three-dimensional reduction of graphene oxide materials at 180 ℃ resulted in the best super capacitor performance, with a specific capacitance of 315 F·g^-1 when the current density was 0.5 A·g^-1 and 212 F·g^-1 when the current density was 10 A·g^-1. Its energy density was 40.5 Wh·kg^-1 and its specific capacitance was 86% after 5000 cycles, with all these properties indicating its good super capacitor performance.