Mo(2)C-induced hydrogen production enhances microbial electrosynthesis of acetate from CO(2) reduction

BACKGROUND: Microbial electrosynthesis (MES) is a biocathode-driven process, in which electroautotrophic microorganisms can directly uptake electrons or indirectly via H(2) from the cathode as energy sources and CO(2) as only carbon source to produce chemicals. RESULTS: This study demonstrates that a hydrogen evolution reaction (HER) catalyst can enhance MES performance. An active HER electrocatalyst molybdenum carbide (Mo(2)C)-modified electrode was constructed for MES. The volumetric acetate production rate of MES with 12 mg cm(−2) Mo(2)C was 0.19 ± 0.02 g L(−1) day(−1), which was 2.1 times higher than that of the control. The final acetate concentration reached 5.72 ± 0.6 g L(−1) within 30 days, and coulombic efficiencies of 64 ± 0.7% were yielded. Furthermore, electrochemical study, scanning electron microscopy, and microbial community analyses suggested that Mo(2)C can accelerate the release of hydrogen, promote the formation of biofilms and regulate the mixed microbial flora. CONCLUSION: Coupling a HER catalyst to a cathode of MES system is a promising strategy for improving MES efficiency. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13068-019-1413-z) contains supplementary material, which is available to authorized users.