A three-dimensional phenolic-based carbon anode for microbial electrochemical system with customized macroscopic pore structure to promote interior bacteria colonization

Microbial electrochemical system (MES) is an emerging wastewater treatment technology that compensates the energy demands of containments removal by in situ converting the chemical energy of organic pollutants. As the structure for exoelectrogens and the reaction site of extracellular electron transfer (EET), the anode is essential for MES. The future commercial application of MES requires efficiency and large-scale fabrication available anode. In this study, a 3D anode with millimeter-scale pores (3D-MPA) was successfully constructed by sacrificial template method, with low-cost phenolic resin as carbon precursor and polymethyl methacrylate (PMMA) pellets as template. With customized and ordered pore of 1 mm, the 3D-MPAs allowed the microorganisms to colonize inside, improving anodic space utilization efficiency. Different carbonization temperature in tested range from 700 °C to 1000 °C regulated the micrometer-scale convex structures and surface roughness of 3D-MPAs, causing electrochemical performance changes. The 3D-MPA-900 obtained the largest electroactive surface area (102 ± 4.1 cm²) and smallest ohmic resistance (1.8 ± 0.09 Ω). Equipped with MES, 3D-MPA-900 reached the highest power density and current density (2590 ± 25 mW m⁻² and 5.20 ± 0.07 A m⁻²). Among tested 3D-MPA, the excellent performance of 3D-MPA-900 might be attributed by its convex structures with suitable size and surface coverage. The surface roughness of 3D-MPA-900 enhanced the microorganism adherence, which then promoted EET on anode surface. Generally, phenolic-based 3D-MPA made of sacrificial-template method had controllable porous structure, large-scale fabrication availability, high chemical stability and excellent mechanical property, which could be promising for the commercial application of MES.