3D-printed conductive polymer lattices for bioelectrochemical systems.

Bioelectrochemical systems (BESs) such as microbial fuel cells (MFCs) and microbial electrochemical cells (MECs) are increasingly investigated for sustainable energy production, chemical manufacturing, resource recovery, and environmental remediation. These systems harness microbial metabolism to oxidize organic substrates at the anode and transfer electrons to electrochemical reactions at the cathode. Consequently, the architecture and material properties of the anode strongly influence the operation and efficiency of any BES. However, conventional materials such as graphite felt and metal oxides present competing trade-offs between conductivity, accessible surface area, microbial accessibility, and manufacturability. Here, we describe a scalable fabrication strategy for conductive polymer electrodes based on 3D-printed polylactic acid (PLA) lattices sequentially modified through the deposition of graphene oxide (GO), reduction to rGO (reduced graphene oxide), and followed by electroless plating of nickel‑phosphorus (NiP). The resulting conductive lattice combines controlled macroporous geometry with electrically conductive surfaces suitable for integration into BESs. The electrodes were evaluated as anodes in batch MFCs employing Shewanella oneidensis MR-1. The Ni-P-coated PLA lattices delivered approximately 2-fold higher current than graphite felt electrodes under the tested operating conditions. Further modification with a polypyrrole-rGO composite increased current generation to approximately 5-fold above graphite felt while improving short-term operational stability over the duration of the experiment. These results demonstrate a practical fabrication strategy for architected conductive electrodes based on additive manufacturing and sequential surface modification.