N-Doped carbon nanotubes enriched with graphitic nitrogen in a buckypaper configuration as efficient 3D electrodes for oxygen reduction to H₂O₂

Abstract

Buckypapers made with CNx nanotubes.

Vitamin Derived Nitrogen Doped Carbon Nanotubes for Efficient Oxygen Reduction Reaction and Arsenic Removal from Contaminated Water

“…Even more, our Fe@NCNT-rGO exhibits slightly lower, but comparable, current density of 5.7 mA cm −2 when compared to the 5.9 mA cm −2 observed in commercial Pt/C electrodes. A diffusion controlled and effective four-electron ORR pathway can be inferred from the broad current plateau [39] that was observed in the region of 0.2 to 0.65 V. The RDE polarization curves were measured at increasing rotation speeds from 400 to 2000 rpm (plotted in Figure 3c) and the corresponding Koutecky-Levich (K-L) plots of the Fe@NCNT-rGO electrodes that are exhibited in Figure 3d show parallel linearity in the range of 0.2 to 0.65 V, validating the nearly first-order kinetics of the ORR reaction [40,41]. The number of electrons (n) transferred per oxygen molecule, as calculated by K-L equation, and was found to be around 4.0, which is close to the theoretical value of 4.0 for commercial Pt/C, which also reiterates our contention that four electron pathway is followed in our newly developed Fe@NCNT-rGO electrodes.…”

Understanding the Selectivity of the Oxygen Reduction Reaction at the Atomistic Level on Nitrogen‐Doped Graphitic Carbon Materials

“…These results are in very good agreement with reports that found that increasing the graphitic N over the pyridinic N takes the selectivity toward the 2‐electron process. [ 35,36,41,43–45 ]…”

“…Nitrogen can be incorporated into the graphitic carbon materials through different bonding environments, where the three most common N species correspond to pyridinic N, pyrrolic N, and graphitic N. [ 29 ] Several authors have reported that high amount of pyridinic N increases the ORR via the 4‐electron process, [ 30–39 ] some other reports suggest that graphitic N is responsible for the ORR activity, [ 40–42 ] while some others have reported that increasing the graphitic N over the pyridinic N takes the selectivity toward the 2‐electron process. [ 35,36,41,43–45 ]…”

Noble‐Metal‐Free Doped Carbon Nanomaterial Electrocatalysts

“…On the other hand, graphitic‐N favors the formation of H 2 O 2 and therefore the 2 e − mechanism [46] . Thus, N‐CNTs with high graphitic‐N content were obtained in buckypaper configuration by tuning the synthesis temperature and the new catalyst was successfully used to catalyze the 2 e − pathway towards H 2 O 2 formation.…”

“…The correlation between graphitic-N content and ORR onset potentiala sw ell as the buckypaperc onfiguration outperformingc onventional inks were highlighted. [46] Conversely,t he correlationb etween carbond efects and ORR performance was also examined. [47] Briefly,w hen two N-rGO electrodesw ere constructed and H 2 O 2 production was observed in alkaline conditions, it wasr evealed that ether and epoxy groups are most likelya ssociated with the active sites for the H 2 O 2 production.…”