All-graphite microchannel microbial fuel cells with high-power generation and conversion efficiency

In this work, we present a new “all-graphite” concept in microfluidic fuel cells, applied to microbial fuel cells (MFCs). The all-graphite microfluidic MFCs were fabricated by milling channels directly into the electrodes. Two such electrode channels were affixed face-to-face with separation by an ion exchange membrane to form a complete MFC. Three such MFCs were fabricated with simple straight channels having different channel heights and activated with pure culture anaerobic Geobacter sulfurreducens electroactive biofilm. After the proof-of-principle and correlation between the channel height and electroactive biofilm thickness, we demonstrated improvements on power and current outputs using a fourth design, which featured a high surface area provided by pillars. A high acetate conversion efficiency of more than 80% and low internal resistance of 1.2 kΩ were achieved using the pillar MFC. Additionally, a high-power density of 4.7 W m-2 was obtained with a straight channel MFC.