Synthesis and electrochemical performance of N-doped carbon aerogels with super-high specific surface area
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摘要: 以间苯二酚和甲醛为反应前驱体, 三聚氰胺为氮源, 通过溶胶-凝胶法制备出氮掺杂碳气凝胶(N-CA), 并对其进行CO2活化后得到活化氮掺杂碳气凝胶(N-ACA), 分别通过扫描电子显微镜、氮吸附、X-光电子能谱和元素分析研究样品的表面形态、孔结构以及含氮官能团的存在形态, 并利用恒流充放电(GV)、循环伏安(CV)、电化学阻抗谱等检测技术评价了其在6 molL-1 KOH电解液中的电化学性能。 实验结果表明: 丰富的孔隙结构和含氮官能团的存在形态是影响碳基电容器性能的决定性因素。 经CO2活化后的N-CA富含较多的的微孔和介孔, 比表面积高达4082 m2g-1, 供电子能力较强的吡咯氮含量有所增加, 在1 mA电流密度下测试的比电容值高达211.9 Fg-1, 经1200次充放电后比电容值保持在98%以上。Abstract: Activated N-doped carbon aerogel (N-ACA) is synthesized by the sol-gel polycondensation of resorcinol with formaldehyde using the melamine as nitrogen source, and then the carbon derivative being activated in CO2 flow. The surface morphology and porous structure are analyzed using scanning electron microscopy (SEM) and N2 adsorption at 77 K. The contained nitrogen of surface and monolith is tested by X-ray photoelectron spectroscopy (XPS) and elemental analysis. The electrochemical performances of N-dope carbon aerogels as electrodes are confirmed using constant-current charge-discharge test (GV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It reveals that the rich porous structure and the chemical state of nitrogen functionalities have crucial effect on the electrochemical performance of the electric double-layer capacitors. The appropriate CO2 activation can increase the number of micropores and mesopores as well as the specific surface area (4082 m2g-1).Furthermore, the presence of amount of pyrrolic nitrogen is reinforced in the electron donor capacity. The specific capacitance of N-ACA electrode is up to 211.9 Fg-1 and retains about 98% after 500 charge-discharge cycles.
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