Monomicelle-Directed Engineering of Strained Carbon Nanoribbons as Oxygen Reduction Catalyst

To date, precisely tailoring local active sites of well-defined earth-abundant metal-free carbon-based electrocatalysts for attractive electrocatalytic oxygen reduction reaction (ORR), remains challenging. Herein, the authors successfully introduce a strain effect on active C-C bonds adjacent to edged graphitic nitrogen (N), which raises appropriate spin-polarization and charge density of carbon active sites and kinetically favor the facilitation of O-2 adsorption and the activation of O-containing intermediates. Thus, the constructed metal-free carbon nanoribbons (CNRs-C) with high-curved edges exhibit outstanding ORR activity with half-wave potentials of 0.78 and 0.9 V in 0.5 m H2SO4 and 0.1 m KOH, respectively, overwhelming the planar one (0.52 and 0.81 V) and the N-doped carbon sheet (0.41 and 0.71 V). Especially in acidic media, the kinetic current density (J(k)) is 18 times higher than that of the planar one and the N-doped carbon sheet. Notably, these findings show the spin polarization of the asymmetric structure by introducing a strain effect on the C-C bonds for boosting ORR.

Automated summary

To improve the electrocatalytic oxygen reduction reaction (ORR), the authors successfully introduce a strain effect on active C-C bonds adjacent to graphitic nitrogen (N), which enhances the spin polarization and charge density of carbon active sites. The resulting metal-free carbon nanoribbons (CNRs-C) with high-curved edges exhibit outstanding ORR activity, surpassing planar structures and N-doped carbon sheets. Notably, in acidic media, the CNRs-C show a kinetic current density 18 times higher than the planar structures and N-doped carbon sheets, highlighting the importance of the introduced strain effect.