Towards new routes to increase the electrocatalytic activity for oxygen reduction reaction of n-doped graphene nanofibers

Abstract A facile preparation of nitrogen doped graphene nanofibers (GNF) is required in order to promote an easy scalable method for the production of batteries using this material as catalyst support. In this work, two simple oxygen pretreatments were developed in order to maximize the nitrogen amount on the structure of the carbon nanomaterial. In that sense, a mild-term oxidation with acid and a high oxidative procedure using potassium permanganate were developed. After that, the two oxidized fibers and the raw ones were doped using a hydrothermal method which use 2-chlorethyl amine as nitrogen donor. All the materials have been deeply studied by SEM, RAMAN, FTIR, CHNS, Zeta potential, XRD, N2 adsorption-desorption and, TGA analysis. The characterization of the material showed that its structure after the treatments was more defective, significantly varying the surface area of the final material. After the hydrothermal treatment different amounts of N atoms (1.2–5.5%) were introduced in the structure depending on the oxidative treatment. The introduction of the nitrogen atoms increases the activity on oxygen reduction reaction (ORR) in almost all the cases, increasing further in the case of the GNF pretreated with acids which increase the electrochemical activity considerably.