Metal–Polymer Hybrid Architectures as Novel Anode Platform for Microbial Electrochemical Technologies

Abstract

In this publication, we propose metal-polymer hybrid materials as a novel platform for the development of 3 D anode materials for bioelectrochemical systems, such as microbial fuel cells. Extremely low gravimetric density, high porosity, high electric conductivity, and distinct elastic properties are characteristics that are superior for bioelectrochemical applications. As a proof of concept, we investigated copper-melamine foams (Cu-MF) based on a commercially available, open cell melamine foam. With a low amount of copper (16.3 mg cm for Cu-MF ) used for metallization, such electrode material can be manufactured at low price. The Cu-MF sponges are readily colonized by electrochemically active bacteria and are electrochemically stable over an experimental period of more than 75 days. The Cu-MF-biofilm electrodes exhibit volumetric current densities of up to 15.5 mA cm . During long-term operation, overgrowth of the Cu-MF pore structures by the Geobacter-dominated biofilms occurs, from which demands for future electrode developments are derived.

Application of 3D Printed Porous Copper Anode in Microbial Fuel Cells

“…This observation is within the range of copper concentration obtained by Zhu and Logan (2014), however, is completely different from studies by Baudler et al since no metal ions were detected in the effluent of their MFC chambers (Baudler et al, 2015). This could be probably attributed to the anode potential (−0.2 V vs. Ag/AgCl) set in studies by Baudler et al, which was significantly lower than the copper oxidation potential to prevent the metal corrosion (Baudler et al, 2015(Baudler et al, , 2017. Nevertheless, in our case, the anode potential was never set (due to the lack of proper equipment), resulting in relatively high anode potential in MFCs and dissolving copper ions from the very beginning.…”

“…This also explains the much better performance of MFCs with carbon cloth anodes. However, when we look at the bacterial adhesion on copper anodes, no thick biofilm was found on electrode surface like carbon cloth and copper-based MFC anodes reported by Baudler et al (2015Baudler et al ( , 2017. The huge difference of biofilm thickness between 3D-PPC anodes we observed and copper anode reported by Baudler et al (Baudler et al, 2015 could be probably attributed to the different bacterial cultures as MFC inoculum.…”

“…This is totally different from the Geobacter species which usually exhibit high biofilm thickness on MFC anode surface (Ren et al, 2008). Since mature and thicker biofilms usually possess higher resistance to antibiotics (Stewart, 1994;Mah and O'toole, 2001;Ito et al, 2009) and mixed cultures have been demonstrated to have varying performances under copper suppression (Dell'amico et al, 2008;He et al, 2010), Geobacter-dominated thick biofilm is believed to have the better tolerance against copper and receive interacting supports between different bacterial species, which is probably another reason for the excellent performance of MFCs with copper-based anodes in Baulder et al experiment (Baudler et al, 2015(Baudler et al, , 2017. However, the suppression effect of copper ions in media on MR-1 cell growth agreed with the results obtained by Zhu and Logan (2014) using mixed cultures as inoculum, which indicates the copper corrosion at high anode potential to be the root cause for inferior MFC performances in this study.…”

“…However, it's usually energyintensive to fabricate carbonaceous electrodes, since it requires high temperatures for material carbonization. Considering 3D printed matrixes could also be easily metalized through polymer surface modification with copper (Zhang et al, , 2017 and highly conductive copper anode in MFC with mixed cultures exhibited ambiguous properties (Zhu and Logan, 2014;Baudler et al, 2015Baudler et al, , 2017, it would be of great interest to test whether 3D printed copper anode could enhance the bioelectricity generation and biofilm growth of pure culture in microbial fuel cells.…”

Microbial fuel cells: From fundamentals to applications. A review

“…Among them, stainless steel (plate, mesh, foam or scrubber) has been used with the main characteristic of being very conductive, robust and cheap [276], [277], [278], [279], [280], [281], [282]. More recently, other metals such as copper [229], [283], nickel [229], silver [229], gold [229] and titanium [230], [269] were also successfully investigated as anode electrode materials. Copper and nickel ions, released from electrodes, can be poisonous for microbes, and this has had negative effects on biofilm formation, yet high and stable performance levels have been reported [229].…”