α‑Fe₂O₃/g‑C₃N₄ Z‑Scheme Heterojunction Photocathode to Enhance Microbial Electrosynthesis of Acetate from CO₂

A visible-light responsive photocathode microbial electrosynthesis (MES) is an attractive method for CO₂ fixation via a microbial electrochemical process. Here, an α-Fe₂O₃/g-C₃N₄ formed a Z-scheme heterojunction structure and exhibits high photogenerated electron–hole separation ability under visible light. The low valence band potential of α-Fe₂O₃ makes binding electrons transferred from the anode easier for photogenerated holes, providing an additional driving force to improve MES performance. Furthermore, the introduction of α-Fe₂O₃ can promote electron transfer between the electrode and microorganisms. α-Fe₂O₃/g-C₃N₄ achieved an acetate production rate of 0.33 g L^–1 d^–1, which increased by 3-fold compared to a carbon felt cathode. This work provides new opportunities for constructing a highly efficient photocathode for MES.