Co₃O₄/C derived from ZIF-67 cathode enhances the microbial electrosynthesis of acetate from CO₂

Microbial Electrosynthesis (MES) is an electrochemical reduction technology that efficiently converts CO₂ into chemicals by electrically driving microbial catalysts. However, the lower mass transfer efficiency of CO₂ and hydrogen H₂ affected the performance of the MES. In this study, Co₃O₄/C is derived from the carbonization of ZIF-67 with different temperature (700 °C,800 °C,900 °C), in which some Co ions are exposed and a large number of catalytically active sites are supplied. Among them, the Co₃O₄/C with 800 °C had the highest hydrogen evolution reaction activity and the lowest internal resistance. The Co₃O₄/C with 800 °C showed the highest hydrogen production rate of 81.34 × 10² mol day⁻¹, which was 4.4 times higher than that of the bare carbon felt. Furthermore, the Co₃O₄/C with 800 °C modified cathode was beneficial to the formation of biofilm and improved the enrichment of Acetobacterium and Arcobacter. The highest acetate yield of 0.19 g L⁻¹d⁻¹ was obtained by Co₃O₄/C with 800 °C, which was 2.1 times higher than that of bare carbon felt, and the corresponding acetate concentration reached 5.61 ± 0.1 g L⁻¹. Co₃O₄/C derived from ZIF-67 with good H₂ production and CO₂ adsorption ability is an effective strategy to improve MES cathode.