Tailoring spatial structure of electroactive biofilm for enhanced activity and direct electron transfer on iron phthalocyanine modified anode in microbial fuel cells

Electroactive biofilm (EAB) has been considered as the core determining electricity generation in microbial fuel cells (MFCs), and its spatial structure regulation for enhanced activity and selectivity is of great concern. In this study, iron phthalocyanine (FePc) was introduced into a carbon cloth (CC) electrode, aiming at improving the affinity between the anode and outer membrane c-type cytochromes (OM c-Cyts) and achieving a highly active EAB. The FePc modified CC anode (FePc-CC) effectively improved the viability of EAB and enriched the Geobacter species up to 44.83% (FePc-CC) from 6.97% (CC). The FePc-CC anode achieved a much higher power density of 2419 mW m−2 than the CC (560 mW m−2) and a remarkable higher biomass loading of 2477.2 ± 84.5 μg cm−2 than the CC (749.3 ± 31.3 μg cm−2). As the charge transfer resistance was decreased by 58.6 times from 395.2 Ω (CC) to 6.74 Ω (FePc-CC), the interfacial reaction rate was accelerated and the direct electron transfer via OM c-Cyts was promoted. This work provides an effective method to improve the EAB activity by regulating its spatial structure, and opens the door toward the development of highly active EAB using metal phthalocyanines in MFCs.