Conjugated polymer-mediated synthesis of nitrogen-doped carbon nanoribbons for oxygen reduction reaction

Nitrogen doped carbon materials, as the most promising non-metal electrocatalyst for oxygen reduction reaction (ORR), have attracted great attention because of their catalytic activities approaching to that of commercial Pt/C, good ethanol tolerance, low price and chemical stability. Here, we demonstrate the conjugated polymer-mediated synthesis of a series of nitrogen doped carbon nanoribbons (NDCNRs) through direct carbonization of polyaniline-polypyrrole (PANI-PPy) nanofibers with different monomer ratios. It is important to point out that ammonium fluoride (NH4F) applied in the carbonization process benefits for the production of more defect sites, higher surface area as well as electrochemically active surface area, and the morphology conversion from nanofibers into nanoribbons, though F element doping is not detected in the F-NDCNRs. With optimized monomer ratio (aniline:pyrrole = 1:3), the as-obtained F-NDCNRs(1:3), with higher content of graphitic-N, graphitic-N/pyridinic-N ratio and defect density, provide admirable ORR catalytic performance with an onset potential of 0.976 V vs RHE and a half-wave potential of 0.864 V vs RHE. This study provides new insights into the synthesis of efficient metal-free nitrogen doping carbon materials for ORR applications.