Enhancing Microbial Electrosynthesis of Acetate and Butyrate from CO_2 Reduction Involving Engineered Clostridium Ijungdahlii with a Nickel-Phosphide-Modified Electrode

摘要

Microbial electrosynthesis (MES) is an emerging technology through which autotrophic microorganisms can directly uptake electrons or indirectly uptake electrons through H-2 in the cathode for reducing CO2 to chemicals. In this study, the performance of MES with engineered Clostridium ljungdahlii was improved by electrochemically depositing a nickel phosphide (Ni-P) catalyst on the cathode. The acetate production rate of MES with 15 cycles was 0.17 g L-1 day(-1), which was 1.7 times higher than that of MES without the catalyst. The corresponding butyrate production rate was remarkably enhanced at 0.1 g L-1 day(-1), which was 2.5 times higher than that of MES without the catalyst. Electrochemical studies, scanning electron microscopy, and confocal scanning laser microscopy showed that Ni-P could accelerate the release of hydrogen and promote biofilm formation. These results also implied that more H-2 evolution could provide more reducing power for butyrate production in the presence of Ni-P. This study attempted to provide effective strategies for the accumulation of C-4 products in MES.