硝酸氧化对沥青烯基有序介孔炭电化学性能的影响

The influence of nitric acid oxidation on the electrochemical performance of asphaltene-based ordered mesoporous carbon

采用硝酸对沥青烯基有序介孔炭（Ordered mesoporous carbon,OMC）进行氧化处理,在硝酸浓度为5mol/L、40℃-100℃下,考察了氧化温度对沥青烯基OMC的孔结构和电化学性能的影响,讨论了不同表面化学氛围的OMC孔道内电解液离子的传输过程。OMC的结构表征和性能测试采用XRD、物理吸附仪和电化学工作站等技术。结果表明：适度的硝酸氧化处理可以有效地改善OMC的电化学性能,低温氧化处理在化学改性OMC表面的同时,仍能保持其规则的孔道结构,比表面积和孔容基本不变;60℃氧化处理时,OMC表现出良好的双电层电化学行为和频率响应特性,电容器可以保持较快的充放电速率,时间常数约为6s;在5mV.s-1的扫描速率下其质量比电容值和能量密度分别为138F.g-1和3.9Wh.kg-1,较改性前分别提高了57%和63%。

Asphaltene-based ordered mesoporous carbon（OMC） was oxidized with 5 mol/L nitric acid at 40-100 ℃.The influence of nitric acid oxidation treatment on its textural properties and electrochemical performance as a supercapacitor electrode material was investigated and the ionic transport behavior in relation to surface chemical structure was discussed.The pore structures and electrochemical performance were examined using XRD,nitrogen adsorption and an electrochemical workstation.Results indicate that electrochemical performance can be improved with nitric acid treatment under mild conditions.The regular mesostructure can be retained,and the surface areas and pore volumes vary slightly when oxidation temperature is below 60 ℃.A capacitor assembled with the OMC sample oxidized at 60 ℃ exhibits excellent electric double layer behavior,improved frequency response characteristics and a fast charge-discharge rate with a time constant of 6 s.The gravimetric specific capacitance and energy density of OMC oxidized at 60 ℃ are 138 F·g-1 and 3.9 Wh·kg-1 respectively at a scanning rate of 5 mV·s-1.These values are respectively 57% and 63% greater than for the un-treated one.