Pure eucalyptus Kraft lignin derived carbon fiber mats were produced based on a model workflow. It covers the preparation and characterization of the lignin precursor and the carbon materials and its testing in the final application (supercapacitor). Sequential solvent extraction was employed to produce a eucalyptus Kraft lignin precursor which could be electrospun into

Please cite this article as: Mostazo-López, M.J., Ruiz-Rosas, R., Morallón, E., Cazorla-Amorós, D., Generation of nitrogen functionalities on activated carbons by amidation reactions and Hofmann rearrangement: chemical and electrochemical characterization, Carbon (2015), doi: http://dx. AbstractNitrogen functionalization of a highly microporous activated carbon (BET surface area higher than 3000 m 2 /g) has been achieved using the following sequence of treatments: (i) chemical oxidation using concentrated nitric acid, (ii) amidation by acyl chloride substitution with NH 4 NO 3 and (iii) amination by Hoffman rearrangement. This reaction pathway yielded amide and amine functional groups, and a total nitrogen content higher than 3 at%. It is achieved producing only a small decrease (20%) of the starting microporosity, being most of it related to the initial wet oxidation of the activated carbon. Remarkably, nitrogen aromatic rings were also formed as a consequence of secondary cyclation reactions. The controlled step-by-step modification of the surface chemistry allowed to assess the influence of individual nitrogen surface groups in the electrochemical performance in 1M H 2 SO 4 of the carbon materials. The largest gravimetric capacitance was registered for the pristine activated carbon due to its largest apparent surface area. The nitrogen-containing activated carbons showed the highest surface capacitances. Interestingly, the amidated activated carbon showed the superior capacitance retention due to the presence of functional groups (such as lactams, imides and pyrroles) that enhance electrical conductivity through their electron-donating properties, showing a capacitance of 83 F/g at 50 A/g. 399.8 ± 0.2 Amide, Lactam, Amine, Imide 1.89 50 398.8 ± 0.2 Pyridine, Imine 1.17 31 KUA-NH 2 400.5 ± 0.2 Pyrrole, Pyridone 0.72 27 399.6 ± 0.2 Amide, Lactam, Amine, Imide 1.25 48 398.5 ± 0.2 Pyridine, Imine 0.65 25 KUA-CONH 2 after TPD 398.4 ± 0.2 Pyridine 0.55 49 400.6 ± 0.2 Pyrrole, Pyridone 0.57 51 KUA-NH 2 after TPD 398.3 ± 0.2 Pyridine 0.42 31 400.2 ± 0.2 Pyrrole, Pyridone 0.92 69

Nitrogen functionalization (ca. 4 at. % N XPS ) of a highly microporous activated carbon (S BET >3000m 2 /g) has been achieved by two different approaches at mild conditions: (i) oxidation and post-reaction with nitrogen reactants, and (ii) direct reaction of pristine carbon material with nitrogen reactants. Interestingly, the introduction of nitrogen functionalities allows full preservation of the microporosity when pathway (ii) is followed. The electrochemical performance of the carbon materials as electrodes for supercapacitors was evaluated by using symmetric and asymmetric configuration in 1M H 2 SO 4 . Both nitrogen-functionalized carbon materials showed larger stability and energy efficiency than the pristine carbon material when working at 1.4V. The non-oxidized and functionalized activated carbon evidences the best performance as electrode for supercapacitor, providing energy and power density of 14.5 Wh/kg and 61.2 kW/kg and keeping 83% of original capacitance after 5000 charge-discharge cycles.This improvement is related to the presence of surface nitrogen functionalities that provide a higher electrochemical stability, avoiding the formation of detrimental oxygen groups during the operation of the supercapacitor.

A very simple method to enhance the low volumetric energy density of free-standing carbon nanofiber electrodes.

Two zeolite templated carbons (ZTC) with comparable structure and different surface chemistry have been synthesized by chemical vapor deposition of different precursors, producing a non-doped and a N-doped carbon material (4 at. % XPS) in which most of the functionalities are quaternary N. A larger specific capacitance (farads per surface area) has been measured in acid electrolyte for the N-doped ZTC, that can be related to an improved wettability due to the presence of nitrogen and oxygen. The capacitance of N-doped ZTC is lower in alkaline electrolyte, probably due to the loss of electrochemical activity of certain oxygen functionalities. Interestingly, the electro-oxidation process of N-ZTC implies lower irreversible currents (providing higher electrochemical stability) than for ZTC. The presence of quaternary nitrogen greatly improves the electric conductivity of N-ZTC, which shows a superior rate performance. ZTC and N-ZTC capacitors were constructed using 1M H2SO4. Under the same conditions, N-doped ZTC based capacitor has higher energy density, 6.7 vs 5.9 W h/kg. The power density of N-ZTC is four times higher, producing an outstanding maximum power of 98 kW/kg. These results provide clear evidences of the advantages of doping advanced porous carbon materials with nitrogen functionalities.