Electricity generation and microbial community of single-chamber microbial fuel cells in response to Cu2O nanoparticles/reduced graphene oxide as cathode catalyst

Metal oxides supported on carbonaceous substrates hold a wide application prospect in replace of Pt-based cathode catalyst for improving performance of microbial fuel cells (MFCs) due to their low cost, abundant storage and excellent oxygen reduction reaction (ORR) catalytic activity. However, there is little information available on Cu2O nanoparticles/reduced graphene oxide (Cu2O/rGO) as cathode catalyst of MFCs and its effect on the electricity generation and microbial community. In this work, the output voltage, coulombic efficiency and microbial community in a single-chamber MFC with Cu2O/rGO cathode catalyst were investigated comparing with commercial Pt/C. The results indicated that the MFC with Cu2O/rGO cathode catalyst produced higher output voltage (0.223 V) and coulombic efficiency (92.5%) comparing with commercial Pt/C (0.206 V, 90.3%). Besides, Cu2O/rGO cathode catalyst possessed excellent ORR catalytic activity and promoted O2 diffusion to cathode surface. Interestingly, the most relative abundance of known electrogenic microorganisms Geobacter in anode biofilm of MFC with Cu2O/rGO cathode catalyst (49.28%) was higher than that with commercial Pt/C (32.33%). The microbial abundance and diversity in cathode biofilm of MFC with Cu2O/rGO catalyst were obviously lower than those with commercial Pt/C due to the antibacterial property of Cu2O/rGO, which could expose more catalytic active sites on cathode and further improve electricity generation performance of MFCs. These results have provided insights into the potential application of Cu2O/rGO as a high catalytic active and antibacterial cathode catalyst to replace commercial Pt/C for electricity generation.