Journal of Power Sources, Vol.414, 444-452, 2019
Hydrothermal synthesis of Fe-Mn bimetallic nanocatalysts as high-efficiency cathode catalysts for microbial fuel cells
High-efficiency cathode catalysts are essential for microbial fuel cell development since they are one of the key components in chemical energy conversion in organic compounds into electricity. Here, novel Fe-Mn bimetallic nanocatalysts are designed and hydrothermally synthesized for microbial fuel cells. Fe:Mn (atom%) = 1:4, 1:2, 1:1, and alpha-MnO2 are applied in air-cathodes with Pt/C and activated carbon catalysts as benchmarks, and Fe-Mn catalysts can enhance the performance. When Fe:Mn = 1:2, the FeMn2 achieves a maximum power density of 1940 +/- 31 mW m(-2) in microbial fuel cells and a current density of 19.4 A m(-2) at -0.056V in abiotic electrochemical tests, 24% and 37% higher than Pt/C respectively. Material characteristics are systematically analyzed since they are directly related to the catalytic performance. The high catalytic activity of FeMn2 proves to result from a combination of the weak Mn-O bonds, large quantity of defects, large specific surface area and high Mn(III):Mn(IV) ratio, according to the proposed possible mechanisms of Fe-Mn catalysts to enhance the output. This work not only puts forwards an easy-to-accomplish method to design and prepare bimetallic nanocatalysts, but also provides a potential alternative to Pt/C in microbial fuel cells for sustainable energy generation.