Metallic State FeS Anchored (Fe)/Fe3O4/N-Doped Graphitic Carbon with Porous Spongelike Structure as Durable Catalysts for Enhancing Bioelectricity Generation
2017-03-14T00:00:00Z (GMT)
by
The
critical issues in practical application of microbial fuel cells (MFCs)
for wastewater treatment are the high cost and poor activity and durability
of precious metal catalysts. To alleviate the activity loss and kinetic
barriers for oxygen reduction reaction (ORR) on cathode, (Fe)/Fe3O4/FeS/N-doped graphitic carbon ((Fe)/Fe3O4/FeS/NGC) is prepared as ORR catalyst through a one-step
method using waste pomelo skins as carbon source. Various characterization
techniques and electrochemical analyses are conducted to illustrate
the correlation between structural characteristics and catalytic activity.
MFCs with Fe/Fe3O4/FeS/NGC (900 °C) cathode
produces the maximum power density of 930 ± 10 mW m–2 (Pt/C of 489 mW m–2) and maintains a good long-term
durability, which only declines 18% after 90 day operation. Coulombic
efficiency (22.2%) obtained by Fe/Fe3O4/FeS/NGC
(900 °C) cathode is significantly higher than that of Pt/C (17.3%).
Metallic state FeS anchored in porous NGC skeleton can boost electron
transport through the interconnected channels in spongelike structure
to improve catalytic activity. Charge delocalization of C atoms can
be strengthened by N atoms incorporation into carbon skeleton, which
correspondingly contributes to the O2 chemisorptions and
O–O bond weakening during ORR. Energetically existed active
components (Fe and N species) are more efficient than Pt to trap and
consume electrons in catalyzing ORR in wastewater containing Pt-poisoning
substances (bacterial metabolites). (Fe)/Fe3O4/FeS/NGC catalysts with the advantages of durable power outputs and
environmental-friendly raw material can cover the shortages of Pt/C
and provide an outlook for further applications of these catalysts.