Self-Assembled Nanofiber Networks of Well-Separated B and N Codoped Carbon as Pt Supports for Highly Efficient and Stable Oxygen Reduction Electrocatalysis

Abstract

We report a facile synthesis strategy that achieves two goals of carbon support design for oxygen reduction catalysis: (1) self-assembly of hierarchical porous structure, with (2) well-separated nitrogen and boron codoping. The B and N codoped carbon nanofibers (BNCNF) grow directly on a cobalt foil catalyst via a “dissolution–diffusion–precipitation” mechanism using tert-butylamine borane as the source of boron, nitrogen, and carbon. The process releases gaseous boron and nitrogen at different temperatures and times, which greatly inhibits the formation of disadvantageous B–N bonds in the support. BNCNF has hierarchical porosity, large surface area, good structural stability, abundant reaction active sites, and facilitates highly dispersed distribution of platinum nanoparticles. Owing to strong interactions and multiple synergistic effects, Pt/BNCNF has increased oxygen reduction activity and durability in HClO4 solution over that of commercial Pt/C. Pt/BNCNF facilitates a Pt mass activity of 355.4 mA mg–1 (approximate 3.5 times larger than Pt/C) at 0.9 V vs RHE. Furthermore, Pt/BNCNF has better stability and maintains 90.4% of its initial mass activity after 5000 potential cycling tests, which is remarkably higher than that of Pt/C at 50.6%.