Novel Oxygen Reduction Catalysts for Air-Cathode Microbial Fuel Cells

S.F.Y. Li
National University of Singapore, SG

Keywords: manganese-polypyrrole-carbon nanotube composite, microbial fuel cells, oxygen reduction reaction, cathode catalyst

Summary:

In this study, a novel manganese oxides-polypyrrole-carbon nanotube (Mn-PPY-CNT) composite was synthesized and incorporated into the air-cathode MFCs as cathode oxygen reduction reaction (ORR) catalyst. The Mn-PPY-CNT composite was prepared by solvothermal method. The electro-catalytic capability of this novel catalyst in neutral electrolyte was investigated by cyclic voltammetry, which showed that Mn-PPY-CNT could catalyze ORR in neutral medium with good catalytic activity, possibly due to manganese-nitrogen (Mn-N) active sites. To further verify catalytic capability of the Mn-PPY-CNT composite, it was utilized as the cathode catalyst in air-cathode MFCs. It was found that Mn-PPY-CNT-based MFCs yield efficient and stable performance with maximum power density of 169 mWm-2 at the loading of 1 mgcm-2, and 213 mWm-2 at the loading of 2 mgcm-2, comparable to MFCs with the benchmark platinum/carbon black (Pt/C) catalyst. Furthermore, the catalyst showed good long-term stability which would be essential for MFC applications. Due to its low cost, low metallic content, easy preparation, good MFC performance and long-term stability, Mn-PPY-CNT catalyst could be a very promising electrocatalyst for air-cathode MFCs. It is believed that that this efficient and economic catalyst could facilitate the scaling up and commercialization of MFC reactors for practical applications.