Furan and Pyran Functional Groups Driven the Surface of Nitrogen- Doped Nanofiber Sponges
Juan L. Fajardo-Díaz, Cristina L. Rodríguez-Corvera, Emilio Muñoz-Sandoval, and Florentino López-Urías

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22/09/2020

Highly surface oxidized, nitrogen-doped, and nitrogen functionalized carbon nanotube sponge

(N-CFS) were produced at 1020°C using two sprayers approach in an aerosol-assisted

chemical vapor deposition (AACVD) experiment. The structure of N-CFS consisted of

entangled and corrugated carbon nanofibers of ~ 200 nm diameter, also showing junctions and

knots. TEM characterizations revealed that the carbon nanofiber exhibits stacked graphitic

layers in a transversal way with positive curvature. Superficial chemical analysis by XPS

showed that the N-CFSs contain an atomic concentration of oxygen and nitrogen of 9.2% and

2.9%, respectively. The high-resolution XPS scans deconvolution-analysis reveale high

percentages for C@O bonds, pyrrolic nitrogen doping, NH3 functionalization, and Si@C

interactions.

The cyclic voltammetry measurements did not display a redox process despite the high oxygen

concentration at the surface. Hydrophobic functional groups containing C@O bonds do not

participate in a redox process (furan, pyran, epoxy, methoxy, ethoxy, among others) could

mostly determine the electroactivity of N-CFS. Based on density functional theory calculations,

we determine that the furans transfer a high amount of electron and promote a positive

curvature in thin carbon nanotubes. Graphitic materials with furans, pyrans, and epoxy

functional groups could be used as an anode in lithium-ion batteries.