In Situ Synthesis and Electrocatalytic Performance of Fe/Fe2.5C/Fe3N/Nitrogen-Doped Carbon Nanotubes for the Oxygen Reduction Reaction

Graphical Relaxed conditions : A low-cost method is demonstrated for the synthesis of iron-based one-dimensional nitrogen-doped carbon nanotube nanocomposites (Fe/Fe 2.5 C/Fe 3 N/N-CNT). Unlike most Fe−N−C type CNT materials, Fe/Fe 2.5 C/Fe 3 N/N-CNT does not require a variety of templates or strict experimental conditions during the synthesis process to control the structure and morphology of the products, which makes the preparation process simpler with a lower energy consumption. This greatly increases its potential for practical applications. I n this study, a novel one-dimensional iron-based nitrogen-doped carbon nanotube (N-CNT) nanocomposite (Fe/Fe 2.5 C/Fe 3 N/N-CNT) was successfully synthesized in situ by using a facile and low-cost method. In alkaline media, the typical product (Fe/Fe 2.5 C/Fe 3 N/N-CNT-30) showed an good onset potential ( E onset =0.93 V vs RHE), half-wave potential ( E 1/2 =0.79 V vs RHE), and current density ( J =6.62 mA cm −2 at 0.2 V vs RHE), especially compared to the commercial 20 % Pt/C catalyst (0.95 V, 0.82 V, 5.61 mA cm −2 , respectively). In acidic medium, it also exhibits a good oxygen reduction reaction (ORR) activity. Moreover, Fe/Fe 2.5 C/Fe 3 N/N-CNT-30 exhibited superior long-term durability and methanol tolerance compared to Pt/C in both alkaline and acidic media. The excellent electrocatalytic performance of this material is attributed to the abundant carbon defects in the carbon structure, the high content doping of pyridinic N and graphitic N into the CNTs, the multi-model Fe species as active sites, and the fact that most Fe species within the CNTs avoid corrosion from electrolyte. This study paves a new way for highly active ORR electrocatalysts and promotes the rapid development of CNTs in some frontier fields.