The
development of highly active noble-metal-free nitrogen-doped
carbon materials is of great significance to the industrial applications
of renewable and sustainable energy. In this paper, core-shell structural
carbon materials composed of nitrogen-doped carbon-shell-encapsulated
iron–cobalt mixed metal carbides were obtained through pyrolysis
of metal organic framework precursors. Metallic (Co, Fe) carbide nanoclusters
embedded in nitrogen-doped hollow carbon spheres were obtained after
most of the mixed metal cores were removed by heated acid etching.
The composites of carbon materials exhibited significant electrocatalytic
activities toward the hydrogen evolution and oxygen reduction reactions.
Hollow carbon spheres were obtained under optimized conditions for
the hydrogen evolution reaction with overpotentials of 180 mV at a
current density of 10 mA·cm–2 and Tafel slope
of 90 mV·dec–1 in acidic media. The hollow
carbon spheres also exhibited favorable activities toward oxygen reduction
with a rather high half-wave potential of 0.82 V (vs RHE), high methanol
tolerance, and robust stability. These excellent performances demonstrated
their potential for applications in fuel cells, some metal-air batteries,
and water splitting devices.
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