Microbial electrosynthesis (MES) is a renewable energy platform capable of reducing the carbon footprint by converting carbon dioxide/bicarbonate to useful chemical commodities. However, the development of feasible electrode structures, inefficient current densities, and the production of unfavorable electrosynthesis products remain a major challenge. To this end, a three-dimensional (3D) macroporous sponge coated with a carbon nanotube/MXene composite (CNT–MXene@Sponge) was evaluated as an MES cathode. The macroporous scaffold, together with intrinsic electrical conductivity, enhanced the charge transfer efficiency and selective microbial enrichment characteristics of the CNT–MXene@Sponge cathode resulted in an average current density of −324 mA m⁻², which was substantially higher than that of the uncoated (−100 mA m⁻²), CNT (−141 mA m⁻²), and MXene (−214 mA m⁻²) coated sponge electrode. The uniform 3D structure and abundant active sites of the coated material facilitated mass diffusion and microbial growth, which produced 1.5 orders of magnitude higher butyrate than the uncoated sponge. The high-throughput sequencing results showed the selective enrichment of electrogenic and butyrate-producing phylum, Firmicutes. These results suggest that the MES performance could be enhanced using the collective features of large-pore network structure, such as better conductivity, improved capacitance, and selective microbial enrichment.

微生物电合成 (MES) 是一种可再生能源平台，能够通过将二氧化碳/碳酸氢盐转化为有用的化学商品来减少碳足迹。然而，开发可行的电极结构、低效的电流密度和不利的电合成产物的生产仍然是一个重大挑战。为此，评估了涂有碳纳米管/MXene 复合材料（CNT-MXene@Sponge）的三维（3D）大孔海绵作为 MES 阴极。大孔支架与固有导电性一起提高了 CNT-MXene@Sponge 正极的电荷转移效率和选择性微生物富集特性，导致平均电流密度为 -324 mA m ^-2，这显着高于未涂覆的（-100 mA m ^-2）、CNT（-141 mA m ^-2）和MXene（-214 mA m ^-2）涂覆的海绵电极。涂层材料均匀的 3D 结构和丰富的活性位点促进了质量扩散和微生物生长，产生的丁酸盐比未涂层海绵高 1.5 个数量级。高通量测序结果显示了产电和产丁酸盐的厚壁菌门的选择性富集。这些结果表明，可以利用大孔网络结构的集体特征来提高 MES 性能，例如更好的导电性、改进的电容和选择性的微生物富集。