Hydrothermal synthesis of MoS2 nanoflowers for an efficient microbial electrosynthesis of acetate from CO2

Abstract

Microbial electrosynthesis (MES) is an electricity-driven bioreduction of carbon dioxide to a multicarbon chemical process. The structure of catalysts with a high biocompatibility and an enhanced microbe–electrode electron transfer rate is required to improve production rates. Here, carbon felt (CF) cathodes modified with molybdenum disulfide (MoS2) were prepared via a simple one-step hydrothermal method with three different preparation temperatures (160 °C,180 °C, and 240 °C). Results showed that the hydrogen evolution reaction (HER) activity of CF with MoS2 catalysts was higher than that of bare CF. The CF with MoS2 nanoflowers obtained at 180 °C showed the highest volumetric acetate production rate (0.2 g L−1 d−1), which was 2.2 times that of the bare CF, and the final acetate concentration of 6 g L−1 was reached within 30 days. Electrochemical impedance spectroscopy and microbial community analyses suggested that the CF with MoS2 obtained at 180 °C facilitated extracellular electron transfer and improved the enrichment of Acetobacterium and Arcobacter. Scanning electron microscopy revealed that a porous nanoflower structure at 180 °C was conducive to microbial colonization and an increase in indirect and direct electron transfer rates. Graphene-like MoS2 nanoflower was excellent and cost-effective materials for cathode modification to improve MES efficiency.