热处理温度对沥青基硼氮共掺杂多孔炭结构与电化学性能的影响

摘要

B/N co-doped porous carbons have been synthesized by heat treatment at different temperatures using asphaltene from coal liquefaction residue as a carbon precursor, nitric acid as a nitrogen source, H3BO3 as a boron source and a pore-forming agent. The influence of the heat treatment temperature on the pore-structure and surface chemical properties was investigated, and the electrochemical performance in relation to the pore-structure and surface chemical properties was discussed. The crystal structure, morphology, pore-structure, composition and electrochemical performance were examined using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, element analysis, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), and an electrochemical workstation. The results of these analyses indicated that the crystal structure, pore-structure and surface properties were influenced significantly by the heat treatment process. Increases in the heat treatment temperature led to improvements in the degree of graphitization, as wel as gradual increases in the boron content. In contrast, the nitrogen content decreased and the specific surface area and total pore volume increases gradual y and then decline. The electrochemical performance was found to be dependent on the pore-structure and suitable surface chemical properties. The sample synthesized at 900 °C had a specific surface area of 1103 m2∙g-1, pore volume of 0.921 cm3∙g-1, nitrogen content of 5.256%(w), boron content of 1.703%(w), and a maximal specific capacitance of 349 F∙g-1 at 100 mA∙g-1 in 6 mol∙L-1 aqueous solution of KOH. The sample subjected to a heat treatment at 1000 °C had the best rate capability, with a capacity retention of 75%when the current density increased from 100 mA∙g-1 to 10 A∙g-1.%以煤液化沥青质为碳源、硝酸为氮源、硼酸为硼源和造孔剂制备硼氮共掺杂多孔炭,研究了热处理温度对其孔结构和表面性质的影响,测试了产品作为超级电容器电极材料的性能.用X射线衍射(XRD)、拉曼光谱、扫描电镜(SEM)、透射电镜(TEM)、N2吸附、元素分析、电感耦合等离子体发射光谱(ICP-AES)、X射线光电子能谱(XPS)、电化学工作站等对材料的结构、组成及电化学性能进行了表征.结果表明：随着热处理温度的升高,产品的石墨化程度逐渐升高；比表面积、总孔容呈先增加后减小的趋势；氮含量随着热处理温度的升高逐渐降低,而硼含量则随着热处理温度的升高逐渐增加；材料的比电容随着热处理温度的升高先逐渐增加后减小.其中900°C热处理的样品比表面积达到1103 m2∙g-1,总孔容为0.921 cm3∙g-1,氮含量为5.256%(w),硼含量为1.703%(w),在6 mol∙L-1 KOH电解液中当电流密度为100 mA∙g-1时质量比电容为349 F∙g-1；而经过1000°C热处理的样品表现出最好的倍率特性,电流密度从100 mA∙g-1增加到10 A∙g-1时比电容保持率为75%.