Carbon dioxide conversion to acetate and methane in a microbial electrosynthesis cell employing an electrically-conductive polymer cathode modified by nickel-based coatings.

In this study, CO 2 conversion to acetate and CH 4 was achieved in a flow-through laboratory-scale microbial electrosynthesis (MES) cell composed of a 3D conductive polylactic acid (cPLA) lattice cathode with electrodeposited metal electrocatalyst coatings. The MES cell with a bare cPLA cathode showed the poorest performance with the lowest H 2 and CH 4 production rates and low Coulombic efficiency. This was ascribed to a poor electrocatalytic activity of cPLA towards H 2 production and high electrode resistivity. When the cPLA electrode was modified with metal coatings, the CH 4 , acetate and H 2 production rate increased significantly, with the following trend: cPLA < Ni < NiFe < NiFeMn. The better performance of the metal-coated cPLA in terms of CH 4 production was attributed to the lower electrical resistance, enhanced H 2 production and enhanced electron transfer between the cathode and the biofilm. At the cell potential of 2.8 V, the best-performing NiFeMn cPLA cathode showed stable production of CH 4 (50 ± 6 mL d−1), acetate (185 ± 27 mg d−1), and H 2 (545 ± 175 mL d−1) at close to 100% Coulombic efficiency. [Display omitted] • Conductive polylactate (cPLA) lattice cathode developed for microbial electrosynthesis. • CH 4 , acetate, and H 2 continuously produced in a microbial electrosynthesis (MES) cell. • Electrodeposition of Ni, Fe, and Mn increased cPLA performance by up to 80%. • NiFeMn cPLA showed best performance with nearly 100% Coulombic efficiency. [ABSTRACT FROM AUTHOR]