Biological bipolar electrodes for bioelectrochemical systems: A proof of concept

This study presents a proof of concept for a novel monolithic bipolar electrode (BE) that is biologically activated on both faces for application in bioelectrochemical systems. The BE was fabricated using 3D techniques using a PLA/carbon-black composite and subsequently functionalized through electrochemical deposition of graphene oxide to enhance surface conductivity. Two stacked configurations (replicates), each comprising two serially connected chambers via a single BE, were constructed and biologically activated in situ . Polarization tests on the individual sides of the BEs showed sustained current generation on both faces: the anodic side reached up to 0.40 A m −2 , while the cathodic side exhibited stable but slower current development. Whole-stack polarization tests demonstrated current densities up to ∼0.5 A m −2 at 3.0 V, with performance limited by the cathodic side of the BE. Microbiological analysis confirmed the colonization of both electrode faces by electroactive microbial consortia. Overall, this study demonstrates, for the first time, the feasibility of using fully biocatalyzed, monolithic BEs in bioelectrochemical systems, to enable compact, modular stack designs with minimized electrical interconnections, reduced volumetric footprint, and simplified assembly. • Novel bipolar electrode supports biofilm growth on both active surfaces. • 3D-printed stack design improves compactness and scalability in BES. • Combined electrochemical and microbial validation of performance. • Stack operated in batch shows stable and reproducible current output. • Compact architecture Favors practical application and scale-up.