Electrospun N-S-Codoped Carbon Nanofibers As Metal-Free Electrocatalysts With Catalytic Activity For The Oxygen Reduction Reaction In Alkaline Media

Abstract

In this work, we have developed metal-free electrocatalysts based on sulfur and/or nitrogen-doped carbon nanofibers (CNFs) by in situ electrospun doping method. Heteroatom-doped CNFs have diameter ≈ 350 nm and nitrogen and sulfur species on their surface. Moreover, the catalytic activity for the oxygen reduction reaction (ORR) is evaluated in alkaline electrolyte (0.5M KOH). The most active metal-free electrocatalyst labelled as S-CNF has an onset potential of 0.817 V vs. RHE, HO2 - % yield of ≈12-15% and n = 3.7 and high ethanol tolerance. The Accelerated Degradation Test (ADT) show that S-CNF catalytic activity decrease only 13% evaluated at a potential range of 0.6 to 1.0 V vs. RHE. Furthermore, S-CNF even is evaluated by ADT as support (1.0 to 1.6 V/RHE, 6000 cycles) showing high long-term stability decreasing only 11% its catalytic activity. These results indicate N-S-codoped CNFs are a promising and eco-friendly alternative for fuel cells applications.