Fast oxygen, nitrogen co-functionalization on electrospun lignin-based carbon nanofibers membrane via air plasma for...

The conventional method of thermal post-modification for introducing heteroatom into carbon nanofiber (CNF) generally suffered from some drawbacks in high-cost preparation and requirement of extra chemical agents. Herein, a more cost-efficient method based on air plasma was applied to introduce oxygen/nitrogen into lignin-based carbon nanofiber (LCNF). Massive free radicals (N, O+ 2, O⁺, O- 2, O^-) generating from air plasma contributed to a high content of oxygen (15.24 wt%) and nitrogen (11.48 wt%) within the plasma-modified LCNF (P-LCNF). Furthermore, air plasma also resulted in rough surface of the P-LCNF. Benefiting from the synergistic effect of oxygen/nitrogen co-doped and rough surface, the water contact angle of the P-LCNF was reduced by 64%. In a 6.0 mol/L KOH electrolyte, the P-LCNF electrode exhibited excellent specific capacitance (344.6 F/g at 1.0 A/g), good rate capability (68.5% capacitance retention), low internal resistance (0.34 Ω), as well as high capacitance retention of 102.4% after 2000 cycles.