Nitrogen-Doped Graphene Nanoribbons as Efficient Metal-Free\nElectrocatalysts for Oxygen Reduction

Abstract

Nitrogen-doped\ngraphene nanoribbon (N-GNR) nanomaterials with different nitrogen\ncontents have been facilely prepared via high temperature pyrolysis\nof graphene nanoribbons (GNR)/polyaniline (PANI) composites. Here,\nthe GNRs with excellent surface integration were prepared by longitudinally\nunzipping the multiwalled carbon nanotubes. With a high length-to-width\nratio, the GNR sheets are prone to form a conductive network by connecting\nend-to-end to facilitate the transfer of electrons. Different amounts\nof PANI acting as a N source were deposited on the surface of GNRs\nvia a layer-by-layer approach, resulting in the formation of N-GNR\nnanomaterials with different N contents after being pyrolyzed. Electrochemical\ncharacterizations reveal that the obtained N_8.3-GNR nanomaterial\nhas excellent catalytic activity toward an oxygen reduction reaction\n(ORR) in an alkaline electrolyte, including large kinetic-limiting\ncurrent density and long-term stability as well as a desirable four-electron\npathway for the formation of water. These superior properties make\nthe N-GNR nanomaterials a promising kind of cathode catalyst for alkaline\nfuel cell applications.