Effect of start-up process using different electrochemical methods on the performance of CO2-reducing methanogenic biocathodes

Microbial electrosynthesis of methane holds great promise for renewable energy storage, but its present methane production performance requires to be much improved. In this work, three electrochemical methods including galvanostatic (GS), applying constant voltage (ACV), potentiostatic (PS) were used to investigate the effect of the start-up process on the performance of biocathode. The methanogenic biocathodes for CO2 reduction were evaluated based on the kinetics, performance, morphology, and microbial community. The methane production rate of the ACV biocathode was 145% and 238% higher than that of the GS and PS, respectively. The EIS analysis indicated that the high performance of ACV biocathode was mainly due to its much low charge transfer resistance, which was only 45% of the PS and 71% of the GS. Our study concluded that enough reducing equivalents (e- or H-2) are more significant for the enrichment of high-performance methanogenic biofilms than changing the potential-dependent microbial community. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.