Renewable Coffee Waste-Derived Porous Carbons as Anode Materials for High-Performance Sustainable Microbial Fuel Cells

Microbial fuel cell (MFC) is a sustainable technology that can produce electrons using microbes. However, low power density and high cost are the two major issues that hamper the development of MFCs. In this study, we demonstrated that renewable coffee waste-derived activated carbons (CWACs) can serve as anode materials in Escherichia coli system-based MFCs. By modifying the CWAC pore size, we achieved a power density of 3927 mW m ^-2 , which was higher than that of commercial activated carbon (975 mW m ^-2 ). The enhanced power density of the CWAC was attributed to its high conductivity and suitable pore size distribution, which led to fast electron transfer and bacterial adhesion. Furthermore, the long-term performance of the MFC with the CWAC anode was investigated; it continuously functioned for more than 100 h at a power density of 2000 mW m ^-2 without any further nutrient resupply. These results indicate that CWAC is a promising anode material for renewable and sustainable energy systems that could significantly reduce the device cost.