Tuning of Surface Characteristics of Anodes for Efficient and Sustained Power Generation in Microbial Fuel Cells

Abstract

The present study reports about the fabrication of a three-dimensional (3D) macroporous steel-based scaffold as an anode to promote specifically bacterial attachment and extracellular electron transfer to achieve power density as high as 1184 mW m–2, which is far greater than that of commonly used 3D anode materials. The unique 3D open macroporous configuration of the anode and the microstructure generated by the composite coating provide voids for the 3D bacterial colonization of electroactive biofilms. This is attributed to the sizeable interfacial area per unit volume provided by the 3D corrugated electrode that enhanced the electrochemical reaction rate compared to that of the flat electrode, which favors the enhanced mass transfer and substrate diffusion at the electrode/electrolyte interface and thereby increases the charge transfer by reducing the electrode overpotential or interfacial resistance. In addition, bacterial infiltration into the interior of the anode renders large reaction sites for substrate oxidation without the concern of clogging and biofouling and thereby improves direct electron transfer. A very low overpotential (−27 mV) with a very low internal resistance (7.104 Ω cm2) is achieved with the fabricated microbial fuel cell (MFC) that has a modified 3D corrugated electrode. Thus, easier and faster charge transfer at the electrode–electrolyte interface is confirmed. The study presents a revolutionary practical approach in the development of highly efficient anode materials that can ensure easy scale-up for MFC applications.

Tuning of Electrode Surface for Enhanced Bacterial Adhesion and Reactions: A Review on Recent Approaches

“…The 3D open macroporous structure of the anode along with the microstructure generated by the composite coating offers an enhanced effective surface area for bacterial interaction, biofilm formation, and EET. 62 The 3D electrode architectures fabricated using different techniques such as in situ growth, physical deposition and selfassembly, 3D porous template, conductive porous template, nonconductive porous template, sacrificial porous template, and natural porous template are also reported to be effective in enhancing the overall performance of MFCs. 214−217 4.4.…”

“…Thus, the electrode materials with tuned characteristics such as surface roughness, biocompatibility, and competent electron transfer ability are preferred as the anode for bio-electrochemical systems. 62 The performance of MFCs is mainly influenced by the nature of electrode materials, membranes, microorganisms, and the configuration of electrodes. Various strategies such as the modification of electrodes, mediators, substrate sources, and reactor configurations have been reported to improve the power output capability of MFCs.…”

“…Various strategies such as the modification of electrodes, mediators, substrate sources, and reactor configurations have been reported to improve the power output capability of MFCs. 43,62 As the efficiency of electron transfer between the electrode and the microorganisms is the main bottleneck challenge that limits the overall performance of MFCs, the anode modification is the widely investigated strategy. The selection or development of new anode materials with specific characteristics that improve the interaction between the electrode surface and bacteria is crucial for the effective bacterial attachment, biofilm formation, and thereby the enhanced performance of MFCs.…”

“…Electrodes (anode and cathode), PEM, electrogenic microorganisms, and substrates are the major components of an MFC. Similar to conventional fuel cells, anodes and cathodes are the integral parts that determine the overall performance of MFCs. , The anode acts as a terminal electron acceptor by facilitating the oxidation of fuel through bacterial respiration, and the generated electrons are transported through the external circuit to the cathode. Hence, the cathode acts as a sink of electrons and a catalytic surface to facilitate oxygen reduction.…”

“…Since an anode is the site of attachment of bacteria, a modification of surface characteristics to enhance the bacterial interactions is an essential deed in promoting microbial reactions. Thus, the electrode materials with tuned characteristics such as surface roughness, biocompatibility, and competent electron transfer ability are preferred as the anode for bio-electrochemical systems …”