Microbial fuel cells: An overview of current technology

Abstract

Research into alternative renewable energy generation is a priority, due to the everincreasing concern of climate change. Microbial fuel cells (MFCs) are one potential avenue to be explored, as a partial solution towards combating the over-reliance on fossil fuel based electricity. Limitations have slowed the advancement of MFC development, including low power generation, expensive electrode materials and the inability to scale up MFCs to industrially relevant capacities. However, utilisation of new advanced electrode-materials (i.e. 2D nanomaterials), has promise to advance the field of electromicrobiology. New electrode materials coupled with a more thorough understanding of the mechanisms in which electrogenic bacteria partake in electron transfer could dramatically increase power outputs, potentially reaching the upper extremities of theoretical limits. Continued research into both the electrochemistry and microbiology is of paramount importance in order to achieve industrial-scale development of MFCs. This review gives an overview of the current field and knowledge in regards to MFCs and discusses the known mechanisms underpinning MFC technology, which allows bacteria to facilitate in electron transfer processes. This review focusses specifically on enhancing the performance of MFCs, with the key intrinsic factor currently limiting power output from MFCs being the rate of electron transfer to/from the anode; the use of advanced carbon-based materials as electrode surfaces is discussed.

The Potential of Microbial Fuel Cells for Remediation of Heavy Metals from Soil and Water—Review of Application

“…In general, hexavalent chromium Cr(VI) and trivalent chromium Cr(III) are main valence states of chromium in the natural environment. Cr(VI) is water soluble with high toxicity in the full pH range, while Cr(III), being less mobile, is less toxic and tends to form Cr(OH) 3 precipitates. The reduction of Cr(VI) to Cr(III) is a common remediation pathway of wastewater containing Cr(VI) [34].…”

“…The redox potential of the pair Tl(III)/Tl(I) (E 0 = −1.26 V) indicates that the oxidation of Tl(I) to Tl(III) is relatively easier to achieve. Unlike other cathodic reduction of heavy metals in MFCs, Tl(I) was oxidized to Tl(III) in the anode and then precipitated as Tl(OH) 3 which would be easier to be removed from aqueous solution. A single-chamber air-cathode MFC was constructed to support spontaneous Tl(I) oxidation with electricity generation [64].…”

“…This discovery was the advent of MFCs research. Nevertheless, early attention to MFCs was in the 1950s as research communities were looking for a new technique, which could convert human waste to electricity timely during space flights [3]. Until the 1980s, redox-active mediators were widely used in MFCs, and it significantly improved the power density output of MFCs.…”

“…Anodic reaction: CH 3 In MFCs, microorganisms oxidize organic substrates in the anode chamber under anaerobic condition, resulting in the production of protons and release of electrons, and electrons flow from the anode to the cathode through an external circuit. These electrons combine with protons and an electron acceptor (mainly oxygen) on the cathode surface to produce water.…”

A hybrid cyt c maturation system enhances the bioelectrical performance of engineered Escherichia coli by improving the rate-limiting step

“…The flow of electrons can transfer both energy and information between living and non-living systems for bioelectronic and biosensing applications. Extracellular electron transfer (EET) pathways (Shi et al, 2016) can electrically connect living microorganisms with electrochemical cells, enabling applications such as power generation in microbial fuel cells (MFCs) (Gul and Ahmad, 2019; Logan, 2009; Santoro et al, 2017; Slate et al, 2019) and environmental sensing in bioelectronic sensing systems (Chouler et al, 2018; Wang et al, 2013; Zhou et al, 2017). Engineering EET in native electroactive microorganisms, such as Shewanella oneidensis MR-1 (Cheng et al, 2020; Min et al, 2017; West et al, 2017), and non-native hosts, such as Escherichia coli (Jensen et al, 2016; Sturm-Richter et al, 2015), has expanded the range of potential applications (Harris et al, 2017; Su and Ajo-Franklin, 2019).…”