Anolyte in-situ functionalized carbon nanotubes electrons transport network as novel strategy for enhanced performance microbial fuel cells

Anolyte in-situ electrons transport network from functionalized multi-walled carbon nanotubes is introduced as a novel strategy to compile the electrons from the anode-away microorganisms. The strategy was investigated by a single-chamber air-cathode microbial fuel cell with Escherichia coli. Based on our best knowledge, for the utilized MFC configuration, unprecedented output power (1.1 W m−2) and current density (4.1 A m−2) were obtained when 6.06 mg ml−1 autoclave-treated MWCNTs (in tryptone medium at 121 °C) was used. Moreover, after 6 h working time, the observed current density was almost duplicated in case of using the best sample compared to the carbon nanotubes-free cell. FTIR and Bio-TEM analyses indicated that the proposed hydrothermal treatment leads to functionalize the carbon nanotubes by nitrogenous groups that strongly enhances the attachment with the bacterial cell wall and improves the biocompatibility. EIS measurements confirmed the good adhesion as a small charge-transfer resistance was observed; 33 Ω. Besides the treatment temperature of the carbon nanotubes, which should be 121 °C, the concentration in the anolyte should be optimized; 6.06 mg ml−1 reveals the best performance compared to 1.21, 3.63, 8.48 and 10.9 mg ml−1. On the other hand, due to formation of the carbonyl group, acid treatment converts the carbon nanotubes to have antibacterial activity toward the E. coli that decreases the cell performance drastically.