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%.