Iron chelates as low-cost and effective electrocatalyst for oxygen reduction reaction in microbial fuel cells

• Development of iron chelates on multiwalled carbon nanotubes as catalyst for ORR.
• Iron chelate as catalysts for microbial fuel cells fed with domestic wastewaters.
• High COD removal and high power generation.
• Cost reduction with respect to Pt-based MFCs.

Iron-chelated electrocatalysts for the oxygen reduction reaction (ORR) in a microbial fuel cell (MFC) were prepared from sodium ferric ethylenediamine-N,N′-bis(2-hydroxyphenylacetic acid) (FeE), sodium ferric diethylene triamine pentaacetic acid (FeD) supported on carbon Vulcan XC-72R carbon black and multi-walled carbon nanotubes (CNTs). Catalyst morphology was investigated by TEM; and the total surfaces areas as well as the pore volumes of catalysts were examined by nitrogen physisorption characterization. The catalytic activity of the iron based catalysts towards ORR was studied by cyclic voltammetry, showing the higher electrochemical activity of FeE in comparison with FeD and the superior performance of catalysts supported on CNT rather than on Vulcan XC-72R carbon black. FeE/CNT was used as cathodic catalyst in a microbial fuel cell (MFC) using domestic wastewater as fuel. The maximum current density and power density recorded are 110 (mA m−2) and 127 ± 0.9 (mW m−2), respectively. These values are comparable with those obtained using platinum on carbon Vulcan (0.13 mA m−2 and 226 ± 0.2 mW m−2), demonstrating that these catalysts can be used as substitutes for commercial Pt/C.

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