Nitrogen-doped braided-looking mesoporous carbonaceous nanotubes as an advanced oxygen reduction electrocatalyst

Abstract

Abstract Exploring low-cost, high-active, durable electrocatalysts for oxygen reduction reaction (ORR) in fuel cells and metal-air batteries is highly desirable but remains a great challenge. In this work, with the application of a newly developed metal-free nanocasting method, an in-situ mesoporous nitrogen-doped braided-looking carbon nanotube (MNCNT) catalyst was fabricated. It was examined to possess a high specific surface area (828 m2g-1), and pores with the tunable size. The catalyst shows superb ORR activity with a half-wave potential (E1/2) of 0.77\xa0V vs. RHE in alkaline medium, inferior to that of commercial 20\xa0wt% Pt/C, but superior to those of 5\xa0wt% Pt/C and most other metal-free catalysts reported in previous literature. Besides, a high limited current density of 3.9\xa0mA\xa0cm−2 at 0.2\xa0V vs. RHE is yielded, and strong methanol tolerance as well as good stability of such catalyst is observed. According to the comparable study, the high ORR activity can be attributed to the porous feature of such nanotubes, as it may engender more active sites for ORR (porous nature & more edges), and boost reactivity of the active sites (nitrogen-doping), compared with the general carbon nanotubes. This work may intrigue the inspiration to explore highly efficient metal-free and carbon-based electrocatalysts toward boosting ORR.