Nature Communications, Published online: 01 September 2026; doi:10.1038/s41467-026-77276-8 Quinone-based conductive materials promote extracellular electron transfer and methanogenesis during anaerobic digestion, in which the material mediates the transfer of electrons produced from exoelectrogens to electrotrophic methanogens, but the underlying mechanism remains elusive. Here, the authors establish the electron transfer interface between reduced anthraquinone (H₂AQC) and Methanosarcina barkeri in a microbial electrolysis cell, and reveal an intrinsic electronic complementarity between the electron donating π-system of H₂AQC and the electron-accepting iron-porphyrin ring of labile heme b.