Anode Of Microbial Fuel Cell Research Articles

Thermally Expanded Graphite Incorporated with PEDOT:PSS Based Anode for Microbial Fuel Cells with High Bioelectricity Production

Modification of anodes with highly biocompatible materials could enhance bacterial adhesion, growth, and improve the rate of electron-transfer ability in microbial fuel cells (MFCs). As such, there has been increasing interest in the development of innovative anode materials to prepare high-performance MFCs. We report the synthesis of poly(3,4-ethylene dioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) doped with thermally expanded graphite (TEG) composite coated carbon felt (CF) as anode for MFCs. For this purpose, as-synthesized PEDOT:PSS/TEG composite was characterized using high-resolution scanning electron microscopy (HR-SEM), Raman and Fourier transform infrared (FT-IR) spectroscopies which indicated successful incorporation of TEG within PEDOT:PSS film. Furthermore, the electrochemical activity of the PEDOT:PSS/TEG coated CF was employed as the anode in the MFCs with sewage water as an anolyte. PEDOT:PSS/TEG@CF anode exhibited higher ion-transfer ability, superior bio-electrochemical conductivity, and excellent capacitance. Using the PEDOT:PSS/TEG@CF anode, we have constructed MFCs which exhibited good power (68.7 mW m−2) and current (969.3 mA m−2) densities compared to the unmodified CF based anode. The reliability of the MFCs performance was also investigated by testing three independently prepared MFCs with PEDOT:PSS/TEG@CF anodes which all showed a constant voltage (∼540 mV) due to the higher stability and biocompatibility of PEDOT:PSS/TEG@CF.

Enhancing Extracellular Electron Transfer Through Selective Enrichment of Geobacter with Fe@CN Modified Carbon-Based Anode in Microbial Fuel Cells

Enhancing Extracellular Electron Transfer Through Selective Enrichment of Geobacter with Fe@CN Modified Carbon-Based Anode in Microbial Fuel Cells

Performance improvement of microbial fuel cells through assembling anodes modified with nanoscale materials

In microbial fuel cell (MFC), the anode is the carrier of microbial attachment and growth, and its material and surface structure play a vital role in MFC electricity generation. Therefore, anode surface optimization is an effective way to improve MFC performance. Although the power generation of bacteria has been confirmed and studied as early as the beginning of the 20th century, up to now, MFC still has the extremely challenging problem of low current and low power output in practical application. To improve the performance of MFC, several strategies have been applied to enhance the bacterial extracellular electron transfer. One promising technology is the genetic engineering approach, and some outstanding research results have been obtained. Another effective strategy is to design and fabricate a high-performance electrode because anode material is the essential factor affecting MFC performance, which provides surface active sites for microbial adhesion, reproduction and interfacial electron transfer. At present, the MFC anodes mainly include carbon-based electrodes and a variety of metal electrodes, but untreated anodes have always been unable to overcome the obstacle of low power output. Anode modification, a common and effective method, is employed for improving the power output of MFC. For this reason, this review is primarily focused on the applications of various anode materials and its nanoscale modification in the field of MFC, including the influence of different anode materials on the power output of MFC, and analyzes the reasons why anode modification enhances output performance. Furthermore, the influence of anode research on the practical application of MFC in the future is prospected.

Renewable Biofuel Production Using Red Ginseng Marc in Microbial Fuel Cells

Microbial fuel cell (MFC) is one of the clean and sustainable energy technologies, often referred to as renewable energy, and directly chemical energy contained in organic matter into electrical energy by using the catalytic activity of microorganisms. Cellulosic biomass is a particularly attractive renewable resource for its abundant supply at low cost and its neutral carbon balance. However, methanogenesis had been negatively linked to anaerobic cellulosic power generation in MFCs. Ginseng root is a saponin-rich plant material and red ginseng marc (RGM) has not been reused as a high-value resource for industry although its residue contained both electron donors and saponin, the potential power generation enhancers for MFC. In this study, RGM was supplemented into MFC to evaluate its effects on methanogenesis and power generation. Two-chamber H-type MFCs were established using rumen fluid as anolyte to ferment cellulose at 2% (w/v). RGM, the residue from the steam and press process for red ginseng beverage preparation, was freeze-dried and ground to pass 0.5 mm sieve and added to the anode of MFC at 1% (w/v; Exp. 1) or 0.1% (Exp. 2) dose for treatment. Open circuit voltage, voltage and current across an external resistor were measured daily for 10d. On d10 of operation, collected biogases were measured for total gas production and analyzed for its components. In Exp. 1, power density was between 44.0 and 97.2 with an average of 83.8 mW/m2 in 1% RGM MFCs and was between 45.2 and 76.3 with an average of 61.5 mW/m2 in control. In Exp. 2, power density was between 44.8 and 75.6 with an average of 60.9 mW/m2 in 0.1% RGM MFCs and was between 45.1 and 54.1 with an average of 49.7 mW/m2 in control. Total gas production for 10d was 563 and 523 mL for RGM and control, respectively, in Exp 1, and was 546 and 477 mL for RGM and control, respectively, in Exp 2. Methane took up 58.6 and 67.9% of total gas for RGM and control, respectively, in Exp 1, and 59.1 and 67.3% of total gas for RGM and control, respectively, in Exp 2. Both greater (P

Regulating Sulfate-Reducing and Sulfur-Oxidizing Bacteria Via S-Doped Nife2o4 Nanosheets as Microbial Fuel Cell Anode for Simultaneous Enhancement of Sulfur and Energy Recovery

Regulating Sulfate-Reducing and Sulfur-Oxidizing Bacteria Via S-Doped Nife2o4 Nanosheets as Microbial Fuel Cell Anode for Simultaneous Enhancement of Sulfur and Energy Recovery

Hollow Cobalt Ferrite Nanofibers Integrating with Carbon Nanotubes as Microbial Fuel Cell Anode for Boosting Extracellular Electron Transfer

Hollow Cobalt Ferrite Nanofibers Integrating with Carbon Nanotubes as Microbial Fuel Cell Anode for Boosting Extracellular Electron Transfer

N-Doped High-Performance Free-Standing Microbial Fuel Cell Anode for Enhanced Electron Transfer Rates

N-Doped High-Performance Free-Standing Microbial Fuel Cell Anode for Enhanced Electron Transfer Rates

Enhanced copper-containing wastewater treatment with MnO2/CNTs modified anode microbial fuel cell

A microbial fuel cell (MFC) was constructed with CNTs, 0.02gMnO2/CNTs and 0.03gMnO2/CNTs modified graphite anode prepared by coating for enhancing copper wastewater treatment. The SEM, XRD and FTIR results showed that MnO2/CNTs and CNTs were successfully attached to the graphite electrode, indicating that the electrode was modified successfully. The surface wettability test showed that the decrease of the contact angle of the modified anode led to the increase of hydrophilicity, which was more conducive to microbial adhesion. The surface contact angle of CNTs modified electrode was the smallest, which was 11.17°. The maximum output voltage, power density and copper removal rate of 0.03gMnO2/CNTs modified anode MFC were 0.67 V, 1044.21 mW/m2 and 98.93% respectively, which were 52.3%, 466.3% and 50.5% higher than those of unmodified anode. XPS results showed that the reduction products were Cu2O and Cu. Meanwhile，high throughput sequencing showed that CNTs and MnO2 could improve the richness and diversity of microbial community. MnO2/CNTs modified-anode accelerated the enrichment of electro-active bacteria such as Proteobacteria, Firmicutes and Bacteroidetes.

Trapa natans Husk‐Derived Nanoporous Carbons as Electrode Materials for Sustainable High‐Power Microbial Fuel Cell Supercapacitor Systems

Microbial fuel cells (MFCs), which convert chemical energy into electricity using microbes, are an emerging sustainable energy technology. However, high costs and low power output limit the advanced development of MFCs. This study utilizes the agricultural waste, Trapa natans husks, to obtain low‐cost nanoporous carbons. The Trapa natans husk‐derived nanoporous carbons (TNHs) are used as electrode materials in Escherichia coli system‐based MFCs. After optimization of both anode and cathode materials for MFCs, a high average power density of 5713 mW m−2 is achieved, which is 1.9 times greater than that of commercial activated carbon. It is shown that TNHs have better bacterial adhesion and electrochemical activities owing to their favorable pore size distribution, suitable functional group, high surface area, and excellent biocompatibility and conductivity. Furthermore, the supercapacitors (SCs) with TNH‐based electrodes are utilized to store the energy generated from MFCs. The SC with TNH‐600 electrodes exhibits a high specific capacitance of 84 F g−1 at a current density of 1 A g−1 after 1000 cycles. This study demonstrates that TNH is a promising electrode material for biofriendly and renewable MFCs, and the MFC‐SC system with TNH electrodes is a high‐power sustainable energy generation and storage device.

Tailoring Surface Properties of Electrodes for Synchronous Enhanced Extracellular Electron Transfer and Enriched Exoelectrogens in Microbial Fuel Cells.

An extracellular electron transfer (EET) process between an electroactive biofilm and an electrode is a crucial step for the performance of microbial fuel cells (MFCs), which is highly related to the enrichment of exoelectrogens and the electrocatalytic activity of the electrode. Herein, an efficient N- and Fe-abundant carbon cloth (CC) electrode with the comodification of iron porphyrin (FePor) and polyquaternium-7 (PQ) was synthesized using a facile solvent evaporation and immersion method and developed as an anode (named FePor-PQ) in MFCs. The surface structural characterizations confirmed the successful introduction of N and Fe atoms, whereas FePor-PQ achieved the N content of 9.59 at %, which may offer various active sites for EET. The introduction of PQ contributed to improving the surface hydrophilicity, providing the composite electrode good biocompatibility for bacterial attachment and colonization as well as substrate diffusion. Based on the advantages, the MFC with the FePor-PQ anode produced a maximum power density of 2165.7 mW m-2, strikingly higher than those of CC (1124.0 mW m-2), PQ (1668.8 mW m-2), and FePor (1978.9 mW m-2). Furthermore, with the EET mediated by the binding of flavins and c-type cytochromes on the outer membrane was enhanced prominently, the typical exoelectrogen Geobacter was enriched up to 55.84% in the FePor-PQ anode biofilm. This work reveals a synergistic effect from heteroatom coating and surface properties tailoring to boost both the EET efficiency and exoelectrogen enrichment for enhancing MFC performance, which also provides valuable insights for designing electrodes in other bio-electrochemical systems.

Carbon Nano-Fiber/PDMS Composite Used as Corrosion-Resistant Coating for Copper Anodes in Microbial Fuel Cells.

The development of high-performance anode materials is one of the greatest challenges for the practical implementation of Microbial Fuel Cell (MFC) technology. Copper (Cu) has a much higher electrical conductivity than carbon-based materials usually used as anodes in MFCs. However, it is an unsuitable anode material, in raw state, for MFC application due to its corrosion and its toxicity to microorganisms. In this paper, we report the development of a Cu anode material coated with a corrosion-resistant composite made of Polydimethylsiloxane (PDMS) doped with carbon nanofiber (CNF). The surface modification method was optimized for improving the interfacial electron transfer of Cu anodes for use in MFCs. Characterization of CNF-PDMS composites doped at different weight ratios demonstrated that the best electrical conductivity and electrochemical properties are obtained at 8% weight ratio of CNF/PDMS mixture. Electrochemical characterization showed that the corrosion rate of Cu electrode in acidified solution decreased from (17 ± 6) × 103 μm y−1 to 93 ± 23 μm y−1 after CNF-PDMS coating. The performance of Cu anodes coated with different layer thicknesses of CNF-PDMS (250 µm, 500 µm, and 1000 µm), was evaluated in MFC. The highest power density of 70 ± 8 mW m−2 obtained with 500 µm CNF-PDMS was about 8-times higher and more stable than that obtained through galvanic corrosion of unmodified Cu. Consequently, the followed process improves the performance of Cu anode for MFC applications.

Nano-Fe3C@2D-NC@CC as anode for improving extracellular electron transfer and electricity generation of microbial fuel cells

Microbial fuel cells (MFCs) are attractive because they can harvest energy from sewage, but challenge remains in achieving valuable power density. To address this issue, we develop a novel binder-free anode, Nano-Fe3C@2D-NC@CC, by assembling 2D Zn-Fe-MOF arrays on the fibers of carbon cloth and subsequently carbonizing MOF. This fabrication results in a unique configuration that nano-Fe3C particles are highly dispersed on N-doped carbon arrays vertically standing on carbon fibers. The standing 2D arrays not only benefit bacterial adhesion but also guarantee nano-Fe3C particles with abundant sites for the charge transfer between bacteria and anode. Consequently, a superior power density (1606 ± 52 mW m − 2) is harvested when the resultant Nano-Fe3C@2D-NC@CC is evaluated as the anode in MFCs based on a mixed bacterium culture. The facile fabrication of Nano-Fe3C@2D-NC@CC paves a promising path for the application of MFCs in large scale.

Living Bacteria Directly Embedded into Electrospun Nanofibers: Design of New Anode for Bio-Electrochemical Systems

The aim of this work is the optimization of electrospun polymeric nanofibers as an ideal reservoir of mixed electroactive consortia suitable to be used as anodes in Single Chamber Microbial Fuel Cells (SCMFCs). To reach this goal the microorganisms are directly embedded into properly designed nanofibers during the electrospinning process, obtaining so called nanofiber-based bio-composite (bio-NFs). This research approach allowed for the designing of an advanced nanostructured scaffold, able to block and store the living microorganisms inside the nanofibers and release them only after exposure to water-based solutions and electrolytes. To reach this goal, a water-based polymeric solution, containing 5 wt% of polyethylene oxide (PEO) and 10 wt% of environmental microorganisms, is used as the initial polymeric solution for the electrospinning process. PEO is selected as the water-soluble polymer to ensure the formation of nanofiber mats offering features of biocompatibility for bacteria proliferation, environment-friendliness and, high ionic conductivity. In the present work, bio-NFs, based on living microorganisms directly encapsulated into the PEO nanofiber mats, were analyzed and compared to PEO-NFs made of PEO only. Scanning electron microscopy allowed researchers to confirm the rise of a typical morphology for bio-NFs, evidencing the microorganisms’ distribution inside them, as confirmed by fluorescence optical microscopy. Moreover, the latter technique, combined with optical density measurements, allowed for demonstrating that after electrospinning, the processed microorganisms preserved their proliferation capability, and their metabolic activity after exposure to the water-based electrolyte. To demonstrate that the energy-production functionality of exo-electrogenic microorganisms was preserved after the electrospinning process, the novel designed nanomaterials, were directly deposited onto carbon paper (CP), and were applied as anode electrodes in Single Chamber Microbial Fuel Cells (SCMFCs). It was possible to appreciate that the maximum power density reached by bio-NFs, which resulted in being double of the ones achieved with PEO-NFs and bare CP. SCMFCs with bio-NFs applied as anodic electrodes reached a current density value, close to (250 ± 5.2) mA m−2, which resulted in being stable over time and was comparable with the one obtained with carbon-based electrode, thus confirming the good performance of the whole device.

High-performance anode material based on S and N co-doped graphene/iron carbide nanocomposite for microbial fuel cells

The power generation performance of microbial fuel cells (MFCs) is greatly influenced by the anode material. Here, iron carbide nanoparticles doped with nitrogen and sulfur are prepared by a simple one-step pyrolysis method and used as the anode of a medialess MFCs. The charge transfer resistance (R ct ) after biofilm formation is 12.36 Ω, while the R ct of the CC anode is 1526 Ω. Most importantly, this anode not only facilitates bacterial adhesion but also effectively promotes the transfer of extracellular electrons. Therefore, this anode has a fast start-up time of 2.9 days, a high voltage value of 636.9 mV, and an impressive power density (PD) of 3.86 W m −2 . The excellent performance of the S,N-GR/Fe 3 C/CC anode can be attributed to its outstanding biocompatibility and electrical conductivity and reveals great potential to be used in practical applications of high-performance MFCs. • Iron carbide doped with S and N can improve the performance of MFCs. • The MFCs with S,N-GR/Fe 3 C/CC anode own the peak power density of 3.86 W m −2 . • The charge transfer resistance is reduced by 123.5 times. • S,N-GR/Fe 3 C/CC anode has excellent biocompatibility.

Conductive Geopolymers as Low-Cost Electrode Materials for Microbial Fuel Cells.

Geopolymer (GP) inorganic binders have a superior acid resistance compared to conventional cement (e.g., Portland cement, PC) binders, have better microbial compatibility, and are suitable for introducing electrically conductive additives to improve electron and ion transfer properties. In this study, GP–graphite (GPG) composites and PC–graphite (PCG) composites with a graphite content of 1–10 vol % were prepared and characterized. The electrical conductivity percolation threshold of the GPG and PCG composites was around 7 and 8 vol %, respectively. GPG and PCG composites with a graphite content of 8 to 10 vol % were selected as anode electrodes for the electrochemical analysis in two-chamber polarized microbial fuel cells (MFCs). Graphite electrodes were used as the positive control reference material. Geobacter sulfurreducens was used as a biofilm-forming and electroactive model organism for MFC experiments. Compared to the conventional graphite anodes, the anode-respiring biofilms resulted in equal current production on GPG composite anodes, whereas the PCG composites showed a very poor performance. The largest mean value of the measured current densities of a GPG composite used as anodes in MFCs was 380.4 μA cm–2 with a standard deviation of 129.5 μA cm–2. Overall, the best results were obtained with electrodes having a relatively low Ohmic resistance, that is, GPG composites and graphite. The very first approach employing sustainable GPs as a low-cost electrode binder material in an MFC showed promising results with the potential to greatly reduce the production costs of MFCs, which would also increase the feasibility of MFC large-scale applications.

Modifying Ti3C2 MXene with NH4+ as an excellent anode material for improving the performance of microbial fuel cells

Poor anode performance is one of the main bottlenecks in the development of microbial fuel cells (MFCs) for practical applications. Multilayered Ti3C2 MXene (m-MXene) is an alternative anode modification material because of its high specific surface area and electrical conductivity. However, the multilayered structure, negatively charged surface, and electropositivity of m-MXene could limit its modification effects. In this work, we used a solution-phase flocculation method (ammonium ion method) to restack and aggregate MXene nanosheets as an anode modification material (n-MXene). The n-MXene-modified anode had a higher specific surface area, surface hydrophilicity and surface electropositivity than the m-MXene-modified anode. The n-MXene-modified anode obtained a maximum current density of 2.1 A m−2, which was 31.2% and 61.5% higher than that of the m-MXene-modified anode (1.6 A m−2) and bare carbon fiber cloth anode (1.3 A m−2). This improved anode performance was attributed to both the decrease in the charge transfer resistance and diffusion resistance, which were related to the increased quantity of biomass and microbial nanowire (or pili)-shaped filaments on the electrode surface. This work provides a simple and cost-effective approach to prepare MXene nanosheets for the modification of MFC anodes.

Improving the anode performance of microbial fuel cell with carbon nanotubes supported cobalt phosphate catalyst

Microbial fuel cell (MFC) is a sustainable technology that can convert waste to energy by harnessing the power of exoelectrogenic bacteria. However, the poor biocompatibility and low electrocatalytic activities of surface usually cause weak bacterial adhesion and low electron transfer efficiency, which seriously hampers the development of MFCs. Herein, a novel carbon nanotube supported cobalt phosphate (CNT/Co-Pi) electrode is fabricated by assembling CNTs on carbon cloth, followed by the electrodeposition of Co-Pi catalyst. The deposited amorphous Co-Pi thin film contains phosphate and the cobalt ions of multiple oxidation states. The hydrophilic phosphate can promote the adhesion of microorganisms on electrode. The strong conversion ability of multiple states of cobalt offers excellent electrocatalytic activity for the electron transfer across biotic/abiotic interface. Therefore, the highly conductive CNTs substrate, along with the Co-Pi catalyst, provide an effective electron transfer between the electrogenic bacteria and the electrode, which endows MFC high power densities up to 1200 mW m−2. Our work has demonstrated for the first time that CNT/Co-Pi catalyst can promote the interfacial electron transfer between electrogenic bacteria and electrode, and highlighted the application potentials of Co-Pi as an anode catalyst for the fabrication of high performance MFC anodes.

Simultaneous energy generation, decolorization, and detoxification of the azo dye Procion Red MX-5B in a microbial fuel cell

Microbial fuel cells (MFCs) are sustainable technologies that can effectively treat wastewater with simultaneous electricity generation. The present study investigated the performance of an MFC highly specific for decolorizing and degrading the azo dye Procion Red MX-5B (PRMX), which eliminates the toxicity of the solution while generating electricity. The MFC anode biofilm was formed from mining sediment after acclimatization in sodium acetate (1 g L-1), followed by the addition of 100 mg L-1 PRMX. The system was totally decolorized, and the color removal occurred fast during the first 70 h of the MFC feed cycle. Total mineralization occurred after 172 h of the feed cycle of the MFC system. Complete degradation of the aromatic intermediates generated after PRMX degradation reduced the toxic potential of the PRMX solution against A. salina larvae and L. sativa seeds to near zero. PRMX supply into the anode increased the voltage output from 360 mV (1 g L-1 sodium acetate - SA) to 520 mV (PRMX/SA 100 mg L-1: 0.25 g L-1). The maximum power density of 156 mW m-2 obtained herein was higher than most values reported for dye remediation in similar devices. Assessment of the microbial community showed that PRMX addition to the acetate diminished the microbial diversity in the bioanode. Pseudomonas and Dysgonomonas accounted for 87% of the biofilm. Therefore, both genera are most probably responsible for external electron transfer and PRMX degradation.

Carbon-Based Composites as Anodes for Microbial Fuel Cells: Recent Advances and Challenges.

Owing to the low price, chemical stability and good conductivity, carbon-based materials have been extensively applied as the anode in microbial fuel cells (MFCs). In this review, apart from the charge storage mechanism and anode requirements, the major work focuses on five categories of carbon-based anode materials (traditional carbon, porous carbon, nano-carbon, metal/carbon composite and polymer/carbon composite). The relationship is demonstrated in depth between the physicochemical properties of the anode surface/interface/bulk (porosity, surface area, hydrophilicity, partical size, charge, roughness, etc.) and the bioelectrochemical performances (electron transfer, electrolyte diffusion, capacitance, toxicity, start-up time, current, power density, voltage, etc.). An outlook for future work is also proposed.

Enhancement of isopropanol removal with concomitant power generation by microbial fuel cells: Optimization of deoxidizing composite anodes using response surface methodology

This study used a response surface method to develop a deoxidizing anode, which was introduced into microbial fuel cells (MFCs) to treat isopropanol (IPA) wastewater and waste gas. By embedding a deoxidizing agent (DA) into the anode of MFCs, a hypoxic environment can be created to enable anaerobic electrogens to be effectively attached to the anode surface and grow. Consequently, MFC power generation performance can be enhanced. The optimal coke and conductive carbon black ratio of an anode and percentage of DA added were 3.61 g/g and 3.15 %, respectively. The research design concurrently achieved the maximum deoxygenation efficiency (0.86 mg O2/bead), minimum disintegration ratio (3.51 %), and minimum resistance (30.2 Ω). The regression model had high prediction power (R2 > 0.93) for anode performance. As determined through multi-objective optimization, the results highly satisfied the target expectation (desirability = 0.82). The optimized deoxidizing anode was filled into an air-cathode MFC, which had a higher IPA removal efficiency (1.15-fold) and voltage output (1.24-fold) than an MFC filled with coke. The results for the trickling-bed MFC filled with a deoxidizing anode revealed that when the inlet concentration was 0.74 g/m3, the voltage output and power density were highest at 416.3 mV and 486.6 mW/m3, respectively. The deoxidizing anode developed has the potential to increase the MFC voltage output and the pollutant removal.