A light-enhanced α-FeOOH nanowires/polyaniline anode for improved electricity generation performance in microbial fuel cells.

Low power density and poor anode performance seriously limit the potential of practical application of microbial fuel cell (MFC). Utilizing solar energy by developing photoanode is one of the effective pathways to improve the performance of MFC. Here solar energy harvesting was integrated into MFC to achieved the comprehensive utilization of multiple energy sources. A hybrid MFC photoanode (α-FeOOH-NWs/PANI anode) was constructed by loading polyaniline (PANI) and α-FeOOH nanowires (α-FeOOH-NWs) on carbon paper through electro-polymerization synthesis method. Compared with clean carbon paper, nanowires and PANI increased the surface roughness of the electrode, which facilitated the biofilm formation. The electrochemical and photoelectric analysis demonstrated that PANI introduced new electroactive groups and reduced the charge transfer resistance, exhibiting excellent electrochemical and photoelectric activites. The MFC with the α-FeOOH-NWs/PANI photoanode had higher voltage output and power density under light illumination, with the power density of 1.95 W/m2 under light, which was 1.4 times higher than that without light. The hybrid α-FeOOH-NWs/PANI photoanode enhanced the separation efficiency of photogenerated electron-hole pairs, thereby improving the photoelectric response capability and generating a high photocurrent. Our research provided a new concept for the combination of solar energy harvesting and MFCs, yielding an overall enhancement of electricity eneration performance in MFC.

α-FeOOH nanowires loaded on carbon paper anodes improve the performance of microbial fuel cells.

Nanowires synthesized from metal oxides exhibit better conductivity than nanoparticles due to their greater aspect ratio which means that they can transmit electrons over longer distances; in addition, they are also more widely available than pili because their synthesis is not affected by the bacteria themselves. However, there is still little research on the application of metal oxides nanowires to enhance power generation of microbial fuel cells (MFC). In this study, a simple hydrothermal synthesis method was adopted to synthesize α-FeOOH nanowires on carbon paper (α-FeOOH-NWs), which serve as an anode to explore the mechanism of power generation enhancement of MFC. Characterization results reveal α-FeOOH-NWs on carbon paper are approximately 30-50 nm in diameter, with goethite structure. Electrochemical test results indicate that α-FeOOH nanowires could enhance the electrochemical activity of carbon paper and reduce the electron transfer resistance (Rct). Furthermore, α-FeOOH-NWs made the power density of MFC 3.2 times of the control device. SEM result demonstrates that nanowires are beneficial to the formation of biofilms and increase biomass on the electrode surface. Our results demonstrate that nanowires not only improve the electrochemical activity and conductivity of carbon paper but also facilitate the formation of biofilms and increase the biomass of the anode surface. These two mechanisms work together to boost extracellular electron transfer and power generation efficiency of MFC with α-FeOOH-NWs. Our study provides further evidence for the electrical conductivity of metal nanowires, promoting their potential applications in electricity generation such as MFC or other energy development fields.