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

Abstract

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.