Fe@NC-hybrid electrode enhancing acetate synthesis from CO₂via microenvironment regulation in microbial...

The practical implementation of CO₂ valorization via microbial electrochemical systems (MES) is constrained by its relatively suboptimal production rate. Rational design of electrode-localized microenvironments offers a promising strategy to overcome this bottleneck. This study provided a regulation strategy with metal-microbial hybrid electrode which synergistically enhanced CO₂ conversion efficiency and microbial activity in MES. The engineered Fe@NC-hybrid electrode demonstrated exceptional performance in modulating the electrode-suspended sludge interface microenvironment, exhibiting outstanding potential for acetate production. Experimentally, with the effect of Fe@NC-hybrid electrode, the mean cumulative amount of acetate increased by 2.9 times approximately as compared with the control group. Notably, the highest acetate production rate reached 3.7 g/(m² h) in the Fe@NC- hybrid electrode group, indicating the great potential of the Fe@NC- hybrid electrode in improving the acetate production rate. The novelty of composite architecture of Fe@NC facilitates enhanced electrochemical activity by reducing charge transfer resistance. Additionally, dual functionality in electrocatalytic hydrogen evolution and high-affinity CO₂ adsorption capacity of Fe@NC synergistically promote the selective enrichment of Acetobacterium (47.5 %) on the electrode interface. Further analysis of the enzyme activities during the Wood-Ljungdahl pathway demonstrated that Fe@NC-hybrid electrode effectively facilitated both the carbonyl and methyl branches. These findings offer valuable insights into a microenvironment regulation for CO₂ utilization and reduction in MES.