Tailoring of pore structure in mesoporous carbon for favourable flavin mediated interfacial electron transfer in microbial fuel cells

High electrical energy harvesting performance of an integrated microbial fuel cell and low voltage booster-rectifier system treating domestic wastewater

To harvest directly usable electrical energy from real domestic wastewater, a new power management system (PMS), transistor-based low voltage boosters followed by a voltage rectifier (LVBR), was developed and tested for its energy harvesting performance. Three air-cathode MFCs were individually linked with LVBs, which were electrically stacked in parallel and then connected with a single voltage rectifier (MFC-LVBR). The MFC-LVBR system could increase V_MFCto 11.9 ± 0.6 V without voltage reversal, which was capable of charging a lithium-ion batteryand supercapacitor-based power banks. When the integrated MFC-LVBR system was linked with a lithium-ion battery, the highest normalized energy recovery (NER_COD) of 0.76 kWh/kg-COD (NER_volumeof 0.22 kWh/m³) was achieved with a minimal energy loss of 14.4%, whichwas much higher than those previously reported values.Furthermore, the electrical energy charged in the lithium-ion battery successfully powered a DC peristaltic pump requiring a minimum operating power of 0.46 W.

Cellulose Aerogel Derived Hierarchical Porous Carbon for Enhancing Flavin-Based Interfacial Electron Transfer in Microbial Fuel Cells

The flavin-based indirect electron transfer process between electroactive bacteria and solid electrode is crucial for microbial fuel cells (MFCs). Here, a cellulose-NaOH-urea mixture aerogel derived hierarchical porous carbon (CPC) is developed to promote the flavin based interfacial electron transfer. The porous structure of the CPC can be tailored via adjusting the ratio of urea in the cellulose aerogel precursor to obtain CPCs with different type of dominant pores. According to the electrocatalytic performance of different CPC electrodes, the CPCs with higher meso- and macropore area exhibit greatly improved flavin redox reaction. While, the CPC-9 with appropriate porous structure achieves highest power density in Shewanella putrefaciens CN32 MFC due to larger active surface for flavin mediated interfacial electron transfer and higher biofilm loading. Considering that the CPC is just obtained from the pyrolysis of the cellulose-NaOH-urea aerogel, this work also provides a facile approach for porous carbon preparation.