Boosting the Microbial Electrosynthesis of Acetate from CO.sub.2 by Hydrogen Evolution Catalysts of Pt Nanoparticles/rGO

Microbial electrosynthesis (MES) is an effective approach to driving the CO.sub.2 reduction to multi-carbon organic products using renewable energy. In this work, the MES of acetate from CO.sub.2 was realized by mixed bacterial consortia, in which Acetobacterium sp. acted as the dominant acetate synthesis microbial flora. To improve synthesis efficiency of MES process, hydrogen evolution reaction (HER) electrocatalyst of Pt nanoparticles on reduced graphene oxide (PtNPs/rGO) was embedded on the biocathode of carbon felt. Results showed that loading the HER catalyst of PtNPs/rGO can significantly improve the MES performance. When 0.04 mg/cm.sup.2 Pt nanoparticles was loaded on the cathode, the highest acetate synthesis rate can reach 26.2 g/m.sup.2/day, which was twofold higher than that of bare carbon felt. Moreover, PtNPs/rGO incorporated carbon felt cathode showed much lower overpotential than bare carbon felt for hydrogen evolution reaction. Hence, the increased local H.sub.2 concentration around cathode enhanced the MES performance. These findings suggested that the artificial composite system composed by HER electrocatalysts will be a promising approach to enhance the electron utilization and CO.sub.2 reduction reaction, which acted as a prospective move to meet the needs of carbon cycling and sustainable energy in the future.