The high enrichment of Geobacter by TiN nanoarray anode catalyst for efficient microbial fuel cells

Abstract

Microbial fuel cells (MFCs) can simultaneously realize electricity generation and wastewater treatment with electrochemically active bacteria. As the habitat of the bacteria, the anode of MFCs determines the overall performance of cells. The high enrichment of exoelectrogens on the anode surface is critical for efficiently oxidizing organic wastes as well as generating electricity. In this work, TiN nanoarrays on carbon cloth as the anode gather 97.2% of the model exoelectrogen Geobacter on their surface, which is much higher than that of previous reports. Density functional theory calculation certifies that metallic TiN readily obtains electrons from extracellular c-type cytochromes and then facilitates electron transfer to the external circuit. In addition, the micro–nano-hierarchical structure supplies much more accessible surface area for the exoelectrogens than that of the carbon cloth. More importantly, the structure of the biofilm-covered nanoarrays appears to be similar to bridges set up by piers, which are not restricted by mass transport with the flow of the anolyte.