Microbial Fuel Cell Cathodes With Poly(dimethylsiloxane) Diffusion Layers Constructed around Stainless Steel Mesh Current Collectors

Type
Article

Authors
Zhang, Fang
Saito, Tomonori
Cheng, Shaoan
Hickner, Michael A.
Logan, Bruce E.

KAUST Grant Number
KUS-11-00313

Date
2010-02-15

Abstract
A new and simplified approach for making cathodes for microbial fuel cells (MFCs) was developed by using metal meshcurrent collectorsandinexpensive polymer/carbon diffusion layers (DLs). Rather than adding a current collector to a cathode material such as carbon cloth, we constructed the cathode around the metal mesh itself, thereby avoiding the need for the carbon cloth or other supporting material. A base layer of poly(dimethylsiloxane) (PDMS) and carbon black was applied to the air-side of a stainless steel mesh, and Pt on carbon black with Nafion binder was applied to the solutionside as catalyst for oxygen reduction. The PDMS prevented water leakage and functioned as a DL by limiting oxygen transfer through the cathode and improving coulombic efficiency. PDMS is hydrophobic, stable, and less expensive than other DL materials, such as PTFE, that are commonly applied to air cathodes. Multiple PDMS/carbon layers were applied in order to optimize the performance of the cathode. Two PDMS/ carbon layers achieved the highest maximum power density of 1610 ± 56 mW/m 2 (normalized to cathode projected surface area; 47.0 ± 1.6 W/m3 based on liquid volume). This power output was comparable to the best result of 1635 ± 62 mW/m2 obtained using carbon cloth with three PDMS/carbon layers and a Pt catalyst. The coulombic efficiency of the mesh cathodes reached more than 80%, and was much higher than the maximum of 57% obtained with carbon cloth. These findings demonstrate that cathodes can be constructed around metal mesh materials such as stainless steel, and that an inexpensive coating of PDMS can prevent water leakage and lead to improved coulombic efficiencies. © 2010 American Chemical Society.

Citation
Zhang F, Saito T, Cheng S, Hickner MA, Logan BE (2010) Microbial Fuel Cell Cathodes With Poly(dimethylsiloxane) Diffusion Layers Constructed around Stainless Steel Mesh Current Collectors. Environ Sci Technol 44: 1490–1495. Available: http://dx.doi.org/10.1021/es903009d.

Acknowledgements
We thank D. W. Jones for help with the analytical measurements. This research was supported by Award KUS-11-00313 from the King Abdullah University of Science and Technology (KAUST), and the National Science Foundation (CBET-0730359).

Publisher
American Chemical Society (ACS)

Journal
Environmental Science & Technology

DOI
10.1021/es903009d

PubMed ID
20099808

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