Catalytic Cooperation between a Copper Oxide Electrocatalyst and a Microbial Community for Microbial Electrosynthesis

Abstract

Electrocatalytic metals and microorganisms can be combined for CO 2 conversion in microbial electrosynthesis (MES). However, a systematic investigation on the nature of interactions between metals and MES is still lacking. To investigate this nature, we integrated a copper electrocatalyst, converting CO 2 to formate, with microorganisms, converting CO 2 to acetate. A co-catalytic (i. e. metabolic) relationship was evident, as up to 140 mg L À 1 of formate was produced solely by copper oxide, while formate was also evidently produced by copper and consumed by microorganisms producing acetate. Due to nonmetabolic interactions, current density decreased by over 4 times, though acetate yield increased by 3.3 times. Despite the antimicrobial role of copper, biofilm formation was possible on a pure copper surface. Overall, we show for the first time that a CO 2 -reducing copper electrocatalyst can be combined with MES under biological conditions, resulting in metabolic and non-metabolic interactions.

Concentration-dependent effects of nickel doping on activated carbon biocathodes

“…Amorphous or crystalline solid artefact formation has been previously reported during SEM sample preparation. 35,36 Alternatively, crystallization may have occurred during cathodic operation (at −1.06 V vs. Ag/AgCl and pH of approximately 6.7).…”

Microbial Electrosynthesis Using 3D Bioprinting of Sporomusa ovata on Copper, Stainless-Steel, and Titanium Cathodes for CO2 Reduction

“…The copper oxides deposited on the cathodes are known for their electrochemical catalysis of CO 2 reduction, and the combination of CuOx and microbial catalyst was reported to enhance CO 2 reduction [23,35]. Layers of copper oxide formed after annealing at 300 • C were visible on the SEM image of Figure 3B.…”

“…The copper electrode was first annealed at 300 • C for 8 h to form a CuO x layer [35]. Annealed electrodes are efficient in catalyzing CO 2 reduction and are less sensitive to the deactivation phenomena that destroy bulk metal electrodes [23,35].…”

“…This phenomenon of high current at the starting phase was also mentioned by Chatzipanagiotou et al [35,36] while using Cu and Ni as cathodes. Electrochemical reduction of metal oxides could be associated with the initial high currents [23,35]. Annealing of Cu produced a uniform layer of CuO x (Figure 3A,B) on the electrode surface that was expected to resist the possible corrosion of Cu and to some extent prevented the anti-bacterial effect of Cu ions.…”

“…One of the difficulties in designing ideal MES cathodes is that they need to meet several requirements simultaneously, namely high electrical conductivity, good biocompatibility, and a high surface area, while having a high durability and low production cost [22]. Some of these properties tend to be difficult to meet; for example, copper foam electrodes fulfill all the requirements, except for biocompatibility, since copper can be toxic to several microorganisms [23]. But investigations on suitable and cost-effective metal cathodes for MES are still lacking.…”