基于羧甲基纤维素钠制备氮掺杂多孔炭及其电容性能研究

以羧甲基纤维素钠(NaCMC)为碳源, 利用直接炭化工艺(无需进一步活化)制备多孔炭材料; 然后, 以CO(NH₂)₂为氮源, 形成了氮掺杂多孔炭材料. 氮的存在形式包括吡啶N、石墨N和吡咯N. 实验结果表明, 羧甲基纤维素钠与CO(NH₂)₂之间的配比可以有效控制氮存在形式、含量、样品的比表面积及孔的结构等. 样品的电化学性能测试表明, 氮掺杂后多孔炭材料的超电容性能得到了显著提升. 以carbon-N-1:20为例, 其比表面积可达858 m²·g^-1, 远高于未经氮掺杂carbon-blank 的463 m²·g^-1, 其质量比电容则由94.0 F·g^-1提高到了156.7F·g^-1.

Synthesis of Nitrogen Doped Porous Carbons from Sodium Carboxymethyl Cellulose and the Capacitive Performance

We demonstrate a direct carbonization method to prepare porous carbons as electrode materials without an activation process, using sodium carboxymethyl cellulose (NaCMC) as the carbon source, which are further doped with varying mass ratios of nitrogen. From X-ray photoelectron data, the nitrogen species include pyridinic N, graphitic N, and pyrrolic N. The relative mass ratios of NaCMC and CO(NH₂)₂ affect the nature of the nitrogen species, dopant dosages as well as specific surface areas and pore structures. The cyclic voltammetry and galvanostatic charge-discharge measurements in 6 mol·L^-1 KOH aqueous solutions reveal that the specific surface areas and capacitive performances improve after nitrogen-doping. Taking carbon-N-1:20 as example, its S_BET can reach 858 m²·g^-1, which is higher than that of carbon-blank (463 m²·g^-1) and the corresponding specific capacitance greatly improves from 94.0 to 156.7 F· g^-1, respectively. The present carbons are excellent electrode candidates for high-rate electrochemical capacitors.