Microbial electrosynthesis (MES) is a potential sustainable biotechnology for the efficient conversion of carbon dioxide/bicarbonate into useful chemical commodities. To date, acetate has been the main MES product; selective electrosynthesis to produce other multi-carbon molecules, which have a higher commercial value, remains a major challenge. In this study, the conventional carbon felt (CF) was modified with inexpensive nickel ferrite (NiFe₂O₄@CF) to realize enhanced butyrate production owing to the advantages of improved electrical conductivity, charge transfer efficiency, and microbial-electrode interactions with the selective microbial enrichment. Experimental results show that the modified electrode yielded 1.2 times the butyrate production and 2.7 times the cathodic current production of the CF cathode; product selectivity was greatly improved (from 37% to 95%) in comparison with CF. Microbial community analyses suggest that selective microbial enrichment was promoted as Proteobacteria and Thermotogae (butyrate-producing phyla) were dominant in the NiFe₂O₄@CF biofilm (~78%). These results demonstrate that electrode modification with NiFe₂O₄ can help realize greater selective carboxylate production with improved MES performance. Hence, this technology is expected to be greatly useful in future reactor designs for scaled-up technologies.

微生物电合成（MES）是一种潜在的可持续生物技术，可以有效地将二氧化碳/碳酸氢盐转化为有用的化学商品。迄今为止，乙酸盐已成为MES的主要产品。选择性电合成产生具有更高商业价值的其他多碳分子，仍然是主要挑战。在这项研究中，常规碳毡（CF）用便宜的镍铁氧体（NiFe ₂ O ₄由于具有改善的电导率，电荷转移效率以及与选择性微生物富集的微生物-电极相互作用的优势，因此实现了丁酸酯生产的增强。实验结果表明，改性电极的丁酸产量为CF阴极的1.2倍，阴极电流为2.7倍。与CF相比，产品的选择性大大提高（从37％到95％）。微生物群落分析表明，在NiFe ₂ O ₄ @CF生物膜中占主导地位的是Proteobacteria和Thermotogae（生成丁酸盐的门），这促进了选择性微生物的富集（〜78％）。这些结果表明，用NiFe ₂ O修饰电极_图4可以帮助实现具有改进的MES性能的更大的选择性羧酸盐生产。因此，预期该技术在未来用于规模化技术的反应堆设计中将非常有用。