Carbon Cloth Anode Research Articles

Identification of biofilm formation and exoelectrogenic population structure and function with graphene/polyanliline modified anode in microbial fuel cell

Improving anode configuration with polymer or nanomaterial modification is promising for enhancing microbial fuel cell performance. However, how anode modification affects biofilm development and electrogenic function remains poorly understood. In this study, the carbon cloth anode modified with polyaniline and reduced graphene oxide was successfully fabricated which obtained the highest power output. Accelerated electrogenic biofilm formation and the better electrogenic bacterial colonization based on the superior material properties (preferable electrochemical characteristics, the film-like structure and the more activated sites) were observed with the in situ biofilm development monitoring. The acclimation time was 2.4 times shorter with graphene and polyaniline modified anode than the bare one when inoculated with wastewater. Biofilm structure and function analysis show that Geobacter is the most predominant with the abundance as high as 81.4%, and meanwhile, electrogenesis related outer-surface octaheme c-type cytochrome omcZ is highly expressed in the modified anode. The anode modified with graphene and polyaniline favors Geobacter colonization, accelerates electrogenic biofilm formation and improves omcZ expression level, eventually leading to the improved performance of microbial fuel cell. The study for the first time reveals the impacts on biofilm development and microbial function by anode modification, which will better guide the potential application of microbial fuel cell for wastewater recovery.

Novel Gas Diffusion Cloth Bioanodes for High-Performance Methane-Powered Microbial Fuel Cells.

Microbial fuel cells (MFCs) are a promising technology that converts chemical energy into electricity. However, up to now only few MFCs have been powered by gas fuels, such as methane, and their limited performance is still challenged by the low solubility and bioavailability of gases. Here, we developed a gas diffusion cloth (GDC) anode to significantly enhance the performance of methane-powered MFCs. The GDC anode was constructed by simply coating waterproof GORE-TEX cloth with conductive carbon cloth in one step. After biofilm enrichment, the GDC anodes obtained a methane-dependent current up to 1130.2 mA m-2, which was 165.2 times higher than conventional carbon cloth (CC) anodes. Moreover, MFCs equipped with GDC anodes generated a maximum power density of 419.5 mW m-2. Illumina high-throughput sequencing revealed that the GDC anode biofilm was dominated mainly by Geobacter, in contrast with the most abundant Methanobacterium in planktonic cells. It is hypothesized that Methanobacterium reversed the methanogenesis process by transferring electrons to the anodes, and Geobacter generated electricity via the intermediates (e.g., acetate) of anaerobic methane oxidation. Overall, this work provides an effective route in preparing facile and cost-effective anodes for high-performance methane MFCs.

Bread-derived 3D macroporous carbon foams as high performance free-standing anode in microbial fuel cells

Microbial fuel cells (MFCs) are a promising clean energy source to directly convert waste chemicals to available electric power. However, the practical application of MFCs needs the increased power density, enhanced energy conversion efficiency and reduced electrode material cost. In this study, three-dimensional (3D) macroporous N, P and S co-doped carbon foams (NPS-CFs) were prepared by direct pyrolysis of the commercial bread and employed as free-standing anodes in MFCs. As-obtained NPS-CFs have a large specific surface area (295.07 m2 g−1), high N, P and S doping level, and excellent electrical conductivity. A maximum areal power density of 3134 mW m−2 and current density of 7.56 A m−2 are generated by the MFCs equipped with as-obtained NPS-CF anodes, which is 2.57- and 2.63-fold that of the plain carbon cloth anodes (areal power density of 1218 mW m−2 and current density of 2.87 A m−2), respectively. Such improvement is explored to mainly originate from two respects: the good biocompatibility of NPS-CFs favors the bacterial adhesion and enrichment of electroactive Geobacter species on the electrode surface, while the high conductivity and improved bacteria-electrode interaction efficiently promote the extracellular electron transfer (EET) between the bacteria and the anode. This study provides a low-cost and sustainable way to fabricate high power MFCs for practical applications.

Polyoxometalate-Based Metal-Organic Framework on Carbon Cloth with a Hot-Pressing Method for High-Performance Lithium-Ion Batteries.

Recently, development of a new type of anode material for lithium-ion batteries that possesses multielectron reaction, sufficient charge transfer, and restricted volume suppression has been considered a huge challenge. Herein, we find a simple hot-pressing method to incorporate polyoxometalate (POM)-based metal-organic frameworks (MOFs) onto three-dimensionally structured carbon cloth (CC), denoted as HP-NENU-5/CC, which immobilizes POMs into the MOFs avoiding the leaching of POMs and employs HP-NENU-5/CC as a flexible, conductive, and porous anode material. The HP-NENU-5/CC anode materials show outstanding electrochemical performance, exhibiting high reversible capacity (1723 mAh g-1 at 200 mA g-1), high rate capability (1072 mAh g-1 at 1000 mA g-1), and superior cycling stability (1072 mAh g-1 at 1000 mA g-1 after 400 cycles). Most importantly, the performance of HP-NENU-5/CC is the best among those of all reported POMs and MOF-based materials. In addition, we perform a comparative study for active materials coated on a two-dimensional current collector and CC, and our experimental results and analysis prove that the active material coated on CC does enhance the electrochemical performance.

Anode modification by biogenic gold nanoparticles for the improved performance of microbial fuel cells and microbial community shift

In this study, carbon cloth anodes were modified using biogenic gold nanoparticles (BioAu) and nanohybrids of multi-walled carbon nanotubes blended with BioAu (BioAu/MWCNT) to improve the performance of microbial fuel cells (MFCs). The results demonstrated that BioAu modification significantly enhanced the electricity generation of MFCs. In particular, BioAu/MWCNT nanohybrids as the modifier displayed a better performance. The MFC with the BioAu/MWCNT electrode had the shortest start-up time (6.74 d) and highest power density (178.34 ± 4.79 mW/m2), which were 141.69% shorter and 56.11% higher compared with those of the unmodified control, respectively. These improvements were attributed to the excellent electrocatalytic activity and strong affinity towards exoelectrogens of the BioAu/MWCNT nanohybrids on the electrode. High throughput sequencing analysis indicated that the relative abundance of electroactive bacteria in the biofilm community, mostly from the classes of Gammaproteobacteria and Negativicutes, increased after anode modification.

Performance evaluation of treating oil-containing restaurant wastewater in microbial fuel cell using in situ graphene/polyaniline modified titanium oxide anode

ABSTRACTMost studies conducted nowadays to boost electrode performance in microbial fuel cell (MFC) have focused on carbonaceous materials. The titanium suboxides (Ti4O7, TS) are able to provide a new alternative for achieving better performance in MFC and have been tested and demonstrated in this study. The Ti4O7 electrode with high electrochemical activity was modified by graphene/polyaniline by the constant potential method. Electrogenic microorganisms were more conducive to adhere to the anode electrode due to the presence of graphene/polyaniline. The MFC reactor with polyaniline /graphene modified TS (TSGP) anode achieves the highest voltage with 980 mV, and produces a peak power density of 2073 mW/m2, which is 2.9 and 12.7 times of those with the carbon cloth anode, respectively, at the 1000 Ω external resistance. In addition, this study evaluates the effects of anolyte conductivity, pH, and COD on the treatment of oil-containing restaurant wastewater (OCRW) in MFC using TSGP anode. The OCRW amended with 120 mS/cm obtains the lowest internal resistance (160.3 Ω). Increasing the anodic pH, gradually from acidic (pH 5.5) to alkaline conditions (pH 8.0), resulted in a gradual increase in maximum power density to 576.4 mW/m2 and a decrease in internal cell resistance to 203.7 Ω. The MFC at the COD 1500 mg/L could obtain steady-state output voltage during 103 h while removing up to 65.2% of the COD of the OCRW.

Simple and efficient fabrication of pomegranate-like Fe2O3@C on carbon cloth as an anode for lithium-ion batteries

Pomegranate-like Fe2O3@C nanoparticles on carbon cloth (CC) as an anode for lithium-ion batteries are synthesized via a combination of dip-coating and hydrothermal synthesis. The spontaneous crosslinking reaction between sodium alginate (SA) and Fe3+ first creates a chelate compound, and then the SA-Fe3+ chelate is converted to Fe2O3@C nanoparticles after a simple hydrothermal treatment. The Fe2O3@C nanoparticles exhibit pomegranate-like morphology with an average diameter of 118 nm and are composed of smaller Fe2O3@C secondary nanoparticles of 13.7 nm. Such a hierarchical nanostructure can increase the accessible surface area of the Fe2O3@C/CC electrode, leading to enhanced electrochemical efficiency for the Li+ insertion/deinsertion reaction. Furthermore, by carefully controlling dip-coating time, the Fe2O3@C nanoparticles are individually and uniformly distributed on the CC surface, which supplies expansion space for Li+ insertion and protects the electrode from structural cracks. Owing to these structural characteristics, the Fe2O3@C/CC anode material shows superior electrochemical properties for lithium-ion batteries. The first discharge capacity is as high as 1006 mAh g−1 at the current density of 0.2 A g−1, and it remains up to 1091 mAh g−1 after 100 charge/discharge cycles, implying a stable cycling ability.

Comparison of different electrode materials and modification for power enhancement in benthic microbial fuel cells (BMFCs)

Abstract Modification of electrode material from the environmental point of view and scale-up is as important as increasing the power density in benthic microbial fuel cells (BMFC). Here, we examined two different materials for an anode and their modification via surface treatment and surface coating. Polyaniline incorporated carbon cloth (PANI/CC), acid-treated carbon cloth (CC), grooved and acid treated graphite plate (GGP), and polyaniline coated graphite plate (PANI/GP) are used in this study. Modified anodes were compared through electrochemical techniques. It was observed that kinetic activity of PANI/CC was 376 times higher than CC anode, while PANI/GP possesses 1.8 times more kinetic activity than GGP. Power density was recorded and observed decreasing order as follows PANI/CC > CC > PANI/GP > GGP. A mechanism of electron transport model is proposed based on the structural properties of polyaniline coated carbon nanocomposites that enhances the electron flow efficiently for the generation of power with high degree. Polyaniline coated anode materials show greater wettability than their respective surface treated counterparts. Further enhancement in power generation was successfully achieved by recharging with acetate. The study tried to compare the different material and their modifications in the same environment and helps to optimize the system further based on the results obtained.

Hierarchically Porous N-Doped Carbon Nanotubes/Reduced Graphene Oxide Composite for Promoting Flavin-Based Interfacial Electron Transfer in Microbial Fuel Cells.

Interfacial electron transfer between an electroactive biofilm and an electrode is a crucial step for microbial fuel cells (MFCs) and other bio-electrochemical systems. Here, a hierarchically porous nitrogen-doped carbon nanotubes (CNTs)/reduced graphene oxide (rGO) composite with polyaniline as the nitrogen source has been developed for the MFC anode. This composite possesses a nitrogen atom-doped surface for improved flavin redox reaction and a three-dimensional hierarchically porous structure for rich bacterial biofilm growth. The maximum power density achieved with the N-CNTs/rGO anode in S. putrefaciens CN32 MFCs is 1137 mW m-2, which is 8.9 times compared with that of the carbon cloth anode and also higher than those of N-CNTs (731.17 mW m-2), N-rGO (442.26 mW m-2), and the CNTs/rGO (779.9 mW m-2) composite without nitrogen doping. The greatly improved bio-electrocatalysis could be attributed to the enhanced adsorption of flavins on the N-doped surface and the high density of biofilm adhesion for fast interfacial electron transfer. This work reveals a synergistic effect from pore structure tailoring and surface chemistry designing to boost both the bio- and electrocatalysis in MFCs, which also provide insights for the bioelectrode design in other bio-electrochemical systems.

Flame-Oxidized Stainless-Steel Anode as a Probe in Bioelectrochemical System-Based Biosensors to Monitor the Biochemical Oxygen Demand of Wastewater.

Biochemical oxygen demand (BOD) is a widely used index of water quality in wastewater treatment; however, conventional measurement methods are time-consuming. In this study, we analyzed a novel flame-oxidized stainless steel anode (FO-SSA) for use as the probe of bioelectrochemical system (BES)-based biosensors to monitor the BOD of treated swine wastewater. A thinner biofilm formed on the FO-SSA compared with that on a common carbon-cloth anode (CCA). The FO-SSA was superior to the CCA in terms of rapid sensing; the response time of the FO-SSA to obtain the value of R2 > 0.8 was 1 h, whereas the CCA required 4 h. These results indicate that the FO-SSA offers better performance than traditional CCAs in BES biosensors and can be used to improve biomonitoring of wastewater.

Polyethyleneimine Modified Carbon Cloth Anode for Self-Pumping Enzymatic Glucose Biofuel Cell

This paper proposes a simplified process that immobilizes enzymes onto carbon cloth electrodes to increase biofuel cell functionality. Polyethyleneimine (PEI) is used to modify carbon cloth electrodes to reduce the processing time and increase self-pumping enzymatic glucose biofuel cell (self-pumping EGBC) electricity. PEI is usually used in biochemical engineering gene transfection as GOx support to enhance enzyme immobilization. PEI is a good candidate for increasing enzymatic biofuel cell (EBC) redox current. PEI and GOx have been successfully immobilized onto carbon cloth electrodes through FT-IR analysis. A UV/Vis spectrophotometer was used to investigate the best PEI support concentration. PEI was proven to improve redox current by cyclic voltammetry analysis. The results show that the GOx/PEI electrode has excellent hydrophilicity on the GOx/PEI electrode surface using contact angle measurement. The optical and electrochemical analysis result shows that GOx/PEI was successfully immobilized onto carbon cloth electrodes. Experimental analysis showed that self-pumping EGBC achieved a power output of 0.609 mW/cm2 (126.9 mW/cm3). PEI contributes to the shortening of the process from a few hours to 5–10 minutes and enhances GOx fuel cell performance.

3D printed porous carbon anode for enhanced power generation in microbial fuel cell

3D porous carbon structures, fabricated via 3D printing technique, were first utilized as the anode materials for microbial fuel cells (MFCs). The intrinsic biocompatibility of 3D printed carbon anodes, together with the open porous structures, greatly enhanced the metabolic activities of microorganisms. The secondary 3D roughness generated from carbon formation functioned as an ideal support for microbial growth, which further increased the surface area of anodes as well. All these factors together determined the exclusive electrochemical performances of MFCs for enhanced power generation and scaling up application. Through carefully tuning the carbonization processes, a multiscale 3D porous carbon structure was achieved for bacterial growth and mass transfer, leading to the highest maximum output voltage, open circuit potential (OCP) and power density for a 300µm porosity (453.4 ± 6.5mV, 1256 ± 69.9mV and 233.5 ± 11.6mWm−2, respectively). Such performance is superior to that of carbon cloth anode and carbon fiber brush anode under the same condition.

Enhancing performance of microbial fuel cells by using novel double-layer-capacitor-materials modified anodes

Super-capacitor (SC) activated-carbon (AC) carbon-nanotubes (CNTs) (SC-AC-CNTs) is a kind of AC-based composite material and it combines the advantages of carbon nanotubes and activated carbon, including a series of peculiar properties such as low charge transmission resistance, super large specific area and excellent power characteristic. In this study, SC-AC-CNTs are first used to modify the carbon cloth (CC) anodes of microbial fuel cells (MFCs) and compared with that of SC-AC and CC. The measurements show that the specific surface area is increased from 219.519 m2 g−1 to 283.643 m2 g−1 after modification. The new anode is assembled in a urine-powered MFC (UMFC) to test its effectiveness. It is found that the amount of microorganisms attached on the new anode is much larger than that on the blank anode in UMFC. The maximum power densities of the UMFC assembled with SC-AC-CNTs and SC-AC modified anodes are 899.52 mW m−2 and 555.10 mW m−2, which are 2.9 and 1.8 times of that of the blank UMFC, respectively. The tests also shows that the UMFC with SC-AC-CNTs-modified anode creates a much longer duration of 105 h at high-voltage plateau in a single cycle that is about 2–3 times of the other two groups. These findings demonstrate that these two double layer capacitor materials can effectively boost overall MFC performance.

Activated microporous-mesoporous carbon derived from chestnut shell as a sustainable anode material for high performance microbial fuel cells

Microbial fuel cells (MFCs) are promising biotechnologies tool to harvest electricity by decomposing organic matter in waste water, and the anode material is a critical factor in determining the performance of MFCs. In this study, chestnut shell is proposed as a novel anode material with mesoporous and microporous structure prepared via a simple carbonization procedure followed by an activation process. The chemical activation process successfully modified the macroporous structure, created more mesoporous and microporous structure and decreased the O−content and pyridinic/pyrrolic N groups on the biomass anode, which were beneficial for improving charge transfer efficiency between the anode surface and microbial biofilm. The MFC with activated biomass anode achieved a maximum power density (23.6 W m−3) 2.3 times higher than carbon cloth anode (10.4 W m−3). This study introduces a promising and feasible strategy for the fabrication of high performance anodes for MFCs derived from cost-effective, sustainable natural materials.

Comparative evaluation of performance and electrochemistry of microbial fuel cells with different anode structures and materials

Various materials and anode structures have been applied to enhance MFC performance. However, their comparative evaluation of performance and electrochemistry has not yet been investigated in detail under a same condition. In this study, a carbon-cloth anode, an anode-cathode assembly, and a brush anode with two different orientations were tested under a same condition for comparative analyses on their performance and electrochemistry, in order to reveal their unique electrochemical characteristics. The brush anode cells exhibited better performance than the carbon cloth cells. The brush anodes showed 41–72% higher maximum power densities, 18–75% higher maximum current density and 24–32% higher optimum current densities than the carbon cloth anodes. The brush anodes showed 25–43 Ω lower anodic polarization resistance than the carbon cloth anodes. The brush anodes showed 1.6–21.2 Ω lower ohmic impedance, 7.7–10.6 Ω lower charge transfer impedance and 9.3–31.8 Ω lower anodic impedance than the carbon cloth anodes. Anodic ohmic impedance was greatest in the carbon-cloth-anode MFC (21.9 Ω), where loose contact between a carbon cloth and a current collector might cause the high ohmic resistance, and large solution resistance in the cell could diminish anode performance due to slow ion transport. In order to improve MFC performance by modifying anode structures, we suggest the followings: 1) an anode should have large surface area, 2) anodic carbon material and a metal current collector must be tightly connected, 3) locating a brush anode closer to a cathode can be important.

Different modified multi-walled carbon nanotube–based anodes to improve the performance of microbial fuel cells

To clearly illustrate the activity effect of multi-walled carbon nanotubes (MWCNTs) and their functionality on anodic exoelectrogen in microbial fuel cells (MFCs), the growth of E. coli and anode biofilm on MWCNT-, MWCNTCOOH and MWCNTNH2 modified anodes were compared with a bare carbon cloth anode. The activity effect was characterized by the amount of colony-forming units (CFUs), activity biomass, morphology of biofilms and cyclic voltammetric (CV). The results showed that MWCNTs, MWCNT-COOH and MWCNT-NH2 exhibited good biocompatibility on exoelectrogenic bacteria. The performance of MFCs were improved through the introduction of MWCNT-modified anodes, especially in the presence of COOH/NH2 groups. The MFCs with the MWCNTCOOHmodified anode achieved a maximum power density of 560.40 mW/m2, which was 49% higher than that obtained with pure carbon cloth. In conclusion, the positive effects of MWCNTs and their functionality were evaluated for promoting biofilm formation, biodegradation and electron transfer on anodes. Specifically, the MWCNTCOOHmodified anode demonstrated the largest application potential for the development of MFCs.

Nickel oxide/carbon nanotube/polyaniline nanocomposite as bifunctional anode catalyst for high-performance Shewanella-based dual-chamber microbial fuel cell.

A novel nickel oxide/carbon nanotube/polyaniline (NCP) nanocomposite has been prepared and used to modify the electrocatalytic properties of carbon cloth anode in fabricating dual-chamber MFC. The prepared nanocomposite was characterized by scanning electron microscopy, X-ray diffraction, and fourier transform infrared spectroscopy. The carbon cloth coated with the NCP nanocomposite showed the enhanced electrochemical performance as compared to bare carbon cloth anode. The electrochemical properties of the fabricated MFC with the modified anode have been investigated by linear sweep voltammetry and electrochemical impedance spectroscopy. The maximum power density of the MFC using the novel NCP nanocomposite-carbon cloth anode increased by 61.88% compared to that of the bare carbon cloth anode. In comparison to the bare carbon cloth anode, the new composite anode showed 26.8% enhancement of current density output which it can be due to the enhancement of the charge transfer capability.

Impact of modified electrodes on boosting power density of microbial fuel cell for effective domestic wastewater treatment: A case study of Tehran

Utilizing microbial fuel cells (MFCs) is a promising technology for energy-efficient domestic wastewater treatment, but it still faces practical barriers such as low power generation. In this study, the LaMnO3 perovskite-type oxide nanoparticles and nickel oxide/carbon nanotube/polyaniline (NCP) nanocomposite (the cathode and anode catalysts, respectively) have been prepared and used to enhance power density of MFC. The prepared La-based perovskite oxide catalysts were characterized by X-ray diffraction (XRD) and scanning electron microscopies (SEM). The electrocatalytic properties of the prepared catalysts were investigated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and Tafel plot at ambient temperature. Results show the exchange current densities of LaMnO3/carbon cloth cathode and NCP nanocomposite/carbon cloth anode were 1.68 and 7 times more compared to carbon cloth cathode, respectively. In comparison to the bare carbon cloth anode, the MFC with the modified electrodes shows 11 times more enhancement in power density output which according to electrochemical results, it can be due to the enhancement of the electron transfer capability. These cathodic and anodic catalysts were examined in batch and semi-continuous modes to provide conditions close to industrial conditions. This study suggests that utilizing these low cost catalysts has promising potential for wastewater treatment in MFC with high power generation and good COD removal efficiency.

Medium-chain-length poly-3-hydroxyalkanoates-carbon nanotubes composite anode enhances the performance of microbial fuel cell

Insufficient power generation from a microbial fuel cell (MFC) hampers its progress towards utility-scale development. Electrode modification with biopolymeric materials could potentially address this issue. In this study, medium-chain-length poly-3-hydroxyalkanoates (PHA)/carbon nanotubes (C) composite (CPHA) was successfully applied to modify the surface of carbon cloth (CC) anode in MFC. Characterization of the functional groups on the anodic surface and its morphology was carried out. The CC-CPHA composite anode recorded maximum power density of 254mW/m2, which was 15-53% higher than the MFC operated with CC-C (214mW/m2) and pristine CC (119mW/m2) as the anode in a double-chambered MFC operated with Escherichia coli as the biocatalyst. Electrochemical impedance spectroscopy and cyclic voltammetry showed that power enhancement was attributed to better electron transfer capability by the bacteria for the MFC setup with CC-CPHA anode.

Surface modification of carbon cloth anodes for microbial fuel cells using atmospheric-pressure plasma jet processed reduced graphene oxides

Surface modification of a carbon cloth anode by screen-printing rGO and APPJ is promising for manufacturing large-scale MFC stacks.