posted on 2013-08-28, 00:00authored byXue Xia, Fang Zhang, Xiaoyuan Zhang, Peng Liang, Xia Huang, Bruce E. Logan
Activated carbon (AC) is a cost-effective
catalyst for the oxygen reduction reaction (ORR) in air-cathode microbial
fuel cells (MFCs). To enhance the catalytic activity of AC cathodes,
AC powders were pyrolyzed with iron ethylenediaminetetraacetic acid
(FeEDTA) at a weight ratio of FeEDTA:AC = 0.2:1. MFCs with FeEDTA
modified AC cathodes and a stainless steel mesh current collector
produced a maximum power density of 1580 ± 80 mW/m2, which was 10% higher than that of plain AC cathodes (1440 ±
60 mW/m2) and comparable to Pt cathodes (1550 ± 10
mW/m2). Further increases in the ratio of FeEDTA:AC resulted
in a decrease in performance. The durability of AC-based cathodes
was much better than Pt-catalyzed cathodes. After 4.5 months of operation,
the maximum power density of Pt cathode MFCs was 50% lower than MFCs
with the AC cathodes. Pyridinic nitrogen, quaternary nitrogen and
iron species likely contributed to the increased activity of FeEDTA
modified AC. These results show that pyrolyzing AC with FeEDTA is
a cost-effective and durable way to increase the catalytic activity
of AC.