影响热还原氧化石墨烯超级电容器性能的因素比较

通过改进的Hummer法制得氧化石墨烯，并在不同温度的氩气气氛中还原得到一系列热还原氧化石墨烯（T-RGO）. 电化学测试表明，T-RGO作为超级电容器电极材料时，良好的导电性是必需的，但石墨烯表面含氧官能团对其电容性能的影响要远大于导电性和比表面积的影响，900 °C还原的T-RGO比表面积为314 m²·g^-1电导率为2421 S·m^-1，但其容量只有56 F·g^-1，然而300 °C还原的T-RGO比表面积为18.8 m²·g^-1电导率为574 S·m^-1，其容量却达到281 F·g^-1. 材料表征分析表明，300 °C 还原的石墨烯之所以有更高的电容，是因为除双电层电容外，更多的是由其表面含氧官能团提供的赝电容，这使作者以后在设计制备超级电容器等储能设备用石墨烯基电极材料时更加有针对性.

Comparison in Factors Affecting Electrochemical Properties of Thermal-Reduced Graphene Oxide for Supercapacitors

In this paper, thermal-reduced graphene oxide (T-RGO) materials are synthesized by modified Hummer’s method, followed by thermal reduction under argon atmosphere at different temperatures. Electrochemical investigations show that, for T-RGO electrodes, good electrical conductivity is necessary and the surface functional groups play more significant role than the specific surface area in determining the electrochemical capacitance. The T-RGO obtained at 900 °C (T-RGO900) with a relatively high Brunauer-Emmett-Teller (BET) surface area (314 m²·g^-1) and a high electrical conductivity (2421 S·m^-1) shows a low specific capacitance of 56 F·g^-1. In comparison, the T-RGO obtained at 300 °C (T-RGO300) with a relatively low BET surface area (18.8 m²·g^-1) and an electrical conductivity (574 S·m^-1) provides the largest specific capacitance of 281 F·g^-1. The large specific capacitance of T-RGO300 results from the simultaneous contributions of the electrochemical double-layer capacitance and the pseudo-capacitance obtained from the oxygenated groups on the T-RGO surfaces. Therefore, it probably gives a new insight for designing and synthesizing graphene-based electrode materials for supercapacitors and other energy-storage devices.