Research on electrocatalytic reduction of CO2 by microorganisms with a graphene modified carbon felt

Abstract

At present, reduction of CO2 to organics with microbial electrosynthesis (MES) has been a popular research direction in environmental fields. One key factor that governs electron exchange is the electrode material. This study evaluated the effect of graphene as electrode modification materials on organics production from CO2 in microbial electrosynthesis with a mixed-culture biocathode. The Cathode potential was set to −0.8 V (vs Ag/AgCl), When the cathode material changed from a non-modified carbon felt electrode to the graphene modified carbon felt, the density of current of MES was increased from 1.4 ± 0.1 A·m−2 to 2.6 ± 0.1 A·m−2, the density of current has increased by 85.7%, and acetate accumulation increased from 142 mg/L to 262 mg/L, butyrate accumulation increased from 45.8 mg/L to 84.8 mg/L. The total electron recovery of MES more than 90%. The results of SEM analysis showed that compared with non-modified carbon felt, the amorphous shape of graphene makes graphene-modified carbon felt exhibit a three-dimensional structure, which gave the electrode surface a larger specific surface area and enrich more microorganisms and a large number of graphene/bacteria composites shaped on the graphene modified electrode surface, which indicated that the graphene had good biocompatibility. The results of the cyclic voltammetry curve show that the MES of the graphene modified electrode has better electrochemical performance.