Exploring the impact of surface properties, porosity and lattice size on bacterial energy harvesting with 3D pyrolytic carbon electrodes

Interactions between solid electrodes and electroactive bacteria have garnered increasing attention due to their unique advantages in a wide range of environmental engineering applications. Nevertheless, 3D printed electrodes and how they interact with electroactive biofilm have not yet received the consideration they deserve. Herein, a novel, highly porous neutrally charged 3D pyrolytic carbon electrode was manufactured for harvesting bacterial power. Results prove the biocompatibility of 3D pyrolytic carbon and its successful application as bioanode in microbial fuel cells. The surface-modified pyrolytic carbon conferred the reactors with a shorter start-up time and a more stable voltage output but did not improve the maximum power generation, showing that other aspects of electrode materials might be as important. Furthermore, three different macrostructures with a pitch dimension of 1.2, 1.5 and 2.5 mm before carbonization were tested. The results showed larger current densities for the 1.2 mm pitch electrode when volume was used for normalization, but larger current densities for the 2.5 mm one when geometric area was the normalization parameter. Additionally, the morphology and microbial community of the biofilms on the electrodes differed upon modification. This work highlights the need to balance multiple electrode design parameters to optimize performance in bioelectrochemical systems.