Improving electron transport efficiency and power density by continuous carbon fibers as anode in the microbial fuel cell

Continuous carbon fibers (CF) were tested as anodes in microbial fuel cells (MFCs) to increase the utilization of anode by using a little of carbon fibers. The long fibers had smaller internal resistance and higher efficiency of electron transfer than short fiber that overlapped each other. By adjusting the electrode spacing, the maximum output voltages and the maximum power density increased to 0.52 V and 5.81 mW g(-1). Compared with the carbon fiber felt (CFF) and the carbon fiber brush (CFB), the CF had finer utilization: this meant that microorganisms could be observed both insider and outsider. After comparison, the excellent CF was selected for modification with carbon nanotubes (CNTs) to increase the anode surface area and roughness. Additionally, the maximum output voltage of the cell was 0.54 V and the maximum power density was 8.3 mW g(-1) after the operation. The SEM images had shown the agglomerated microorganisms on CNTs. (C) 2019 Elsevier B.V. All rights reserved.