聚苯胺改性氮掺杂碳纳米管制备及其超级电容器性能

利用苯胺原位化学聚合合成聚苯胺包覆碳纳米管(CNTs), 再炭化处理制备氮掺杂碳纳米管(NCNTs).激光拉曼(Raman)光谱和X射线光电子谱(XPS)分析及透射电镜(TEM)观察表明, 苯胺包覆碳纳米管经炭化处理后, 得到以碳纳米管为核、氮掺杂碳层为壳, 具有核-壳结构的氮掺杂碳纳米管, 而碳纳米管本征结构未遭破坏. 研究表明, 随着苯胺用量的增大, 氮掺杂碳纳米管的氮掺杂碳层变厚, 氮含量从7.06%(质量分数)增加到8.64%, 而作为超级电容器电极材料, 随着氮掺杂碳层厚度降低, 氮掺杂碳纳米管在6 mol·L^-1氢氧化钾电解液中的比容量从107 F·g^-1增大到205 F·g^-1, 远高于原始碳纳米管10 F·g^-1的比容量, 且聚苯胺改性氮掺杂碳纳米管表现出较好的充放电循环性, 经1000次充放电循环后仍保持初始容量的92.8%~97.1%, 表明氮掺杂碳纳米管不仅通过表面氮杂原子引入大的法拉第电容和改善亲水性使电容量显著增大, 其具有的核壳结构特征也使循环稳定性增强。

Preparation and Supercapacitor Performance of Nitrogen-Doped Carbon Nanotubes from Polyaniline Modification

Nitrogen-doped carbon nanotubes (NCNTs) were prepared by carbonization of polyanilinecoated CNTs that were synthesized by in-situ polymerization of aniline on the CNT surface. The laser Raman spectroscopy, transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) indicated that carbonization treatment of the polyaniline (PANI) coated CNTs produced NCNTs owning the core-shell structure of a nitrogen-doped carbon shell and a CNT core, without destroying the intrinsic CNT structure. By increasing the aniline amount, the N-doped layer of the NCNTs became thicker, and the amount of nitrogen doping increased from 7.06% to 8.64% (mass fraction). As the supercapacitor electrode material, the NCNTs capacitance in 6 mol·L^-1 aqueous KOH solution increased from 107 to 205 F·g^-1 as the N-doped layer thickness decreased, which was much higher than the capacitance of 10 F·g^-1 for the pristine CNTs. Especially, NCNT electrodes displayed good cyclability, maintaining 92.8%-97.1% of the initial capacitance after 1000 charge-discharge cycles. The high capacitance and good cyclability of the NCNTs as a supercapacitor electrode material can be attributed to the pseudo-Faradic capacitance and improved hydrophility contributed by the nitrogen functional groups and the core-shell structure of the NCNTs, respectively.