Power Density Of Microbial Fuel Cells Research Articles

Insight into electricity production performance from dried waste activated sludge in dual chamber microbial fuel cells: Influencing factors, neural network modelling and microbial community analysis

Directly deriving electrical energy from waste activated sludge (WAS) by using microbial fuel cell (MFC) is one of the most promising alternatives to resource utilization of WAS. However, obtaining high MFC performance is still a great challenge for the full-scale implementation of MFC. Therefore, this study aimed to quantify and model the effect of different operating parameters on the performance of MFC fed with dried WAS as anode substrate. The results indicated that MFC exhibited a fast start-up time of 3 days at the inoculated anaerobic sludge: dry WAS mass ratio of 1:5. Moreover, the output voltage and power density of MFC were highly dependent of anolyte pH and temperature, WAS concentration, which was well simulated and predicted by the BPANN model. It was revealed that MFC fed with dry WAS exhibited good performance at 55ºC, pH 9.0 and WAS concentration of 16 g/L, while the stable output voltage and power density were 0.705 V and 5.248 W/m3, respectively. The anolyte temperature significantly affected microbial communities of the anode biofilm. At the phylum level, Synergistota and Proteobacteria dominated the anode biofilm at 35ºC, while Firmicutes was absolutely enriched in the anode biofilm at 55ºC. At the genus level, the predominant Advenella is detected in the anode biofilm at 35ºC, whereas the preponderant MBA03 is identified in the anode biofilm at 35ºC. The findings herein may provide a route for efficiently driving power energy from WAS, which can facilitate the fulfillment of full-scale MFC for the resource utilization of WAS.

Bio-carbon microtubules in microbial fuel cells for superior performance of 3D free-standing anode derived from Rhus Typhina

Microbial fuel cells (MFCs) have emerged as a promising technology for sustainable energy production. However, the power density of MFCs is limited by the anode performance. In this study, Rhus typhina was used as a raw material for the synthesis of 3D freestanding electrodes by freeze-drying and one-step carbonization. Based on the unique micron-scale tubular structure, Rhus typhina carbon (RtC) increases the active bacterial colonization surface area several times and improves the extracellular electron transfer (EET) by augmenting the interaction between the bacteria and the anode. In addition, 16S rRNA gene sequence analysis indicates that the obtained RtC-900 anode promotes enrichment of the major exoelectrogens (Geobacter), and the relative abundance reaches 70.3%. The maximum power density of the dual-chamber MFC with the 3D free-standing anode is 6.01 W m−2, and the stable power output over 300 days is superior to that of conventional MFC in performance.

Nano-Fe3O4/polymerize aniline/carbon cathode based microbial fuel cell for efficient power generation and uranium separation

Microbial fuel cells (MFCs) have gained increasing attention in the field of uranium-containing wastewater (UCW) treatment as a self-powered bioelectrochemical system (BES) due to its advantages of recovering uranium resources and generating electricity. However, the lack of catalytic active sites on the carbon fiber cathode significantly hinders the reaction performance of surface electrons with uranium ions in solution, thereby limiting the application of MFC. In this study, we propose a carbon brush (CB) cathode modification process that utilizes cyclic voltammetry synthesis technique (CVS) to polymerize aniline (PA) on the surface of carbon fibers and uniformly load nano-Fe3O4 particles (nFe3O4). The loading of PA/nFe3O4 not only significantly improve the catalytic active sites but also enhance the synergistic effect of adsorption and conductivity of CB cathode. Consequently, the nFe3O4/PA/CB-MFC showed excellent ability to continuous power generation and uranium separation. Over eight cycles of uranium separation, the nFe3O4/PA/CB-MFC exhibited an average maximum power density of 15.17 mW/m2 and a uranium separation efficiency of 95.52 %, showcasing substantial enhancements by 2.10-fold and 1.44-fold compared to the CB-MFC, respectively. Our study presents an efficient approach to enhance the efficiency of uranium separation and boost power density of MFC by increase catalytic active sites on carbon-based cathode.

Iron-doped cross-linked puffed carbon as capacitive anode for the enhancement of bioelectron storage capacity in microbial fuel cells

Microbial fuel cell (MFC) can utilize the metabolism of electroactive microorganisms to remove organic pollutants from wastewater, and the application of capacitive anodes can enhance the power generation capacity of MFC and the energy storage capacity of bioelectronics. This research aimed to create a capacitive anode with a large specific surface area and excellent electrical conductivity. To achieve this aim, iron-doped cross-linked puffed carbon (CPC–Fe) was prepared for the modification of carbon cloth (CC) substrates by a simple one-step expansion carbonization method using FeCl3·6H2O and maltose as raw materials. The surface structure characterization confirms the successful incorporation of Fe atoms, with Fe3O4 accounting for 79.61%. Fe3O4 exhibits excellent specific capacitance characteristics and can also serve as a good conductor for the transmission or reception of electrons generated by electroactive bacteria. Furthermore, the mesoporous volume of CPC-Fe significantly increases, which contributes to the enhancement of the specific capacitance of material and the improvement of charge storage capacity. Based on these advantages, the maximum power density of MFC equipped with CPC-Fe/CC anode reaches 1850.50 mW m−2. The CPC-Fe/CC bioanode has a cumulative total charge of 1076.02 C m−2, showing good capacitive behaviour and exhibiting a significant enrichment effect on Geobacter species. This study demonstrates that the regulation of extracellular electron transfer (EET) process based on bioelectronic reception steps can not only enhance the power generation performance of MFC, but also effectively improve the energy storage capacity of MFC, which offers significant knowledge for the development of electrode design in other bioelectrochemical systems.

Boosting power output in microbial fuel cells with microwave-assisted synthesis of hierarchical bimetallic anodes for enhanced extracellular electron transport

Microbial fuel cells (MFCs) are a promising technology that can generate electricity from various organic waste sources using bacteria as catalysts. However, the low power density of MFCs due to the inefficient extracellular electron transport (EET) remains a major challenge for MFCs. To address this challenge, researchers have been developing new anodes that can enhance the EET efficiency of MFCs. In this study, we report the fabrication of an efficient anode by embedding FeCo bimetallic nanoparticles on carbon cloth (FexCoy@CC) using a microwave-assisted synthesis and calcination process. We find that the Fe1Co1@CC anode demonstrates excellent electrocatalytic activity for electron transfer between bacteria and the anode. Furthermore, in mixed bacterial culture-based MFCs, the Fe1Co1@CC anode shows exceptional electrochemical performances, achieving a high-power density of 3220 mW m−2, a current density of 6.98 A m−2, and a Coulombic efficiency of 16.74 %. The remarkable performance is attributed to the high electronic conductivity provided, the enrichment of electrochemically active Geobacter species, and the EET efficiency enhancement of microbial redox reactions through FeCo bimetallic nanoparticles. This facile and cost-effective method demonstrates great potential for improving the performance of MFCs, which could lead to more efficient and sustainable wastewater treatment and green energy production.

Adaptive Neuro-Fuzzy Inference System Modeling and Optimization of Microbial Fuel Cells for Wastewater Treatment

Due to their toxicity, Cr(VI) levels are subject to strict legislation and regulations in various industries and environmental contexts. Effective treatment technologies are also being developed to decrease the negative impacts on human health and the environment by removing Cr(VI) from water sources and wastewater. As a result, it would be interesting to model and optimize the Cr(VI) removal processes, especially those under neutral pH circumstances. Microbial fuel cells (MFCs) have the capacity to remove Cr(VI), but additional research is needed to enhance their usability, increase their efficacy, and address issues like scalability and maintaining stable operation. In this research work, ANFIS modeling and artificial ecosystem optimization (AEO) were used to maximize Cr(VI) removal efficiency and the power density of MFC. First, based on measured data, an ANFIS model is developed to simulate the MFC performance in terms of the Cu(II)/Cr(VI) ratio, substrate (sodium acetate) concentration (g/L), and external resistance Ω. Then, using artificial ecosystem optimization (AEO), the optimal values of these operating parameters, i.e., Cu(II)/Cr(VI) ratio, substrate concentration, and external resistance, are identified, corresponding to maximum Cr(VI) removal efficiency and power density. In the ANFIS modeling stage of power density, the coefficient-of-determination is enhanced to 0.9981 compared with 0.992 (by ANOVA), and the RMSE is decreased to 0.4863 compared with 16.486 (by ANOVA). This shows that the modeling phase was effective. In sum, the integration between ANFIS and AEO increased the power density and Cr(VI) removal efficiency by 19.14% and 15.14%, respectively, compared to the measured data.

Bifunctional polypyrrole/ferroferric oxide as anode material for enhanced electricity generation and energy storage in microbial fuel cell

The microbial fuel cell (MFC) is an electrochemical electricity generation device that uses microorganisms to degrade organic matter to produce electrical energy. However, due to the limited charge generated by microorganisms, the output power of MFC is relatively low. Additionally, as a traditional MFC, it cannot store charge. In this paper, we designed and developed a dual-function capacitive MFC anode, which could generate electricity and store energy simultaneously. The capacitive anode was prepared by the direct growth of polypyrrole and ferric oxide on the carbon felt matrix, and the two materials played a synergistic effect. The power density of MFC equipped with the CF/PPy/Fe3O4-modified anode reached 6.61 W/m3, 29.8% higher than that of the CF/Fe3O4 anode. When in the charging-discharging 45 min test(C45/D45), the total charge Qt released by the CF/PPy/Fe3O4 anode was increased by 1431.74 C/m2 compared with the CF/Fe3O4 anode. In this paper, the method of preparing a dual-function capacitive bioanode could store the electricity generated by microorganisms in the capacitive anode, which greatly improved the current output of MFC and solved its low output power problem.

Pore-Matched Sponge for Microorganisms Pushes Electron Extraction Limit in Microbial Fuel Cells.

Microbial fuel cells (MFCs) are of great potential for wastewater remediation and chemical energy recovery. Nevertheless, limited by inefficient electron transfer between microorganisms and electrode, the remediation capacity and output power density of MFCs are still far away from the demand of practical application. Herein, a pore-matching strategy is reported to develop uniform electroactive biofilms by inoculating microorganisms inside a pore-matched sponge, which is assembled of core-shell polyaniline@carbon nanotube (PANI@CNT). The maximum power density achieved by the PANI@CNT bioanode is 7549.4±27.6mWm-2 , which is higher than the excellent MFCs with proton exchange membrane reported to date, while the coulombic efficiency also attains a considerable 91.7±1.2%. The PANI@CNT sponge enriches the exoelectrogen Geobacter significantly, and is proved to play the role of conductive pili in direct electron transfer as it down-regulates the gene encoding pilA. This work exemplifies a practicable strategy to develop excellent bioanode to boost electron extraction in MFCs and provides in-depth insights into the enhancement mechanism.

Combination of partial nitrification and microbial fuel cell for simultaneous ammonia reduction, organic removal, and energy recovery

The chemical oxygen demand (COD) in municipal wastewater has become an obstacle for anammox in mainstream applications. In this study, the single chamber microbial fuel cell (MFC) was installed as an influent device for a partial nitrification-sequencing batch reactor (PN-SBR) to realize integrating COD removal and partial nitrification. After 80 days of operation, the nitrite accumulation rate reached 93%, while the COD removal efficiency was 56%. The output voltage and the power density of MFC were 66.62 mV and 2.40 W/m3, respectively. The content of EPS, especially polysaccharides in the stable phase, has increased compared with the seed sludge. The most dominant genus in MFC anode biofilm and SBR granular sludge was Thauera, which has organic compounds degradation capacity and could degrade nitrate. This study revealed the microbial interaction between MFC and partial nitrification and provided a new strategy for stable ammonia and nitrite supply for mainstream anammox plants.

Copper recovery from printed circuit boards leaching solution with bioelectricity generation using microbial fuel cell

Recovery of valuable metals via leaching printed circuit boards (PCBs) has gained moment recently. This work studied the Microbial fuel cell (MFC) performances for recovery of Cu from a Cu2+ solution by examining key operating parameters. A dual-chamber MFC with 6cm × 6cm × 7cm dimensions was constructed. Both anode and cathode electrodes were made of a carbon cloth sheet. The anodic and cathodic chambers were separated by a Nafion membrane. The highest Cu recovery efficiency was 99.7% after 240h batch mode operation, yielding 102 mW/m2 MFC power density output using 1g/L Cu2+ solution as the catholyte (initial pH 3) and an anolyte containing 1g/L sodium acetate inoculated with a sludge from a wastewater treatment plant's anaerobic pond, with 2cm distance between the electrodes made of polyacrylonitrile polymer. The highest open circuit voltage, current density (based on cross-section cathode area) and power density with an external load of 1 kΩ was 555mV, 347mA/m2 and 193 mW/m2, respectively. Additionally, recovery of Cu in the leachate of PCBs using sulfuric acid leaching after 48h was performed and the highest Cu recovery was 50% in 48h.

Simulation of OH– and oxygen transport in the air–cathode catalyst layer of microbial fuel cells

The mass transfer of OH– and oxygen within an air–cathode is critical for the performance of microbial fuel cells (MFCs). Improving the understanding of this complex transportation mechanism could help guide the design of air-cathodes to enhance the power density of MFCs. Herein, a 2D-agglomerate model is developed to study OH– and O2 transfer, and electrochemical performance within an air–cathode MFC. The effects of key variables (binder volume fraction, and Pt/carbon mass ratio) on OH– and oxygen transport behavior have been investigated. Simulation results reveal that the OH– and oxygen concentrations within the catalyst layer are closely related to the catalyst layer structure. A lower volume fraction of Nafion® binder is beneficial to OH– and oxygen transfer, while the Pt/carbon mass ratio has complex effects on OH– and oxygen transfer and reactions. This work aims to improve our understanding of OH– and oxygen mass transfer and offers an effective approach to constructing high-performance air–cathode MFCs.

Three-Dimensional Carbon Monolith Coated by Nano-TiO2 for Anode Enhancement in Microbial Fuel Cells.

A three-dimensional (3D) anode is essential for high-performance microbial fuel cells (MFCs). In this study, 3D porous carbon monoliths from a wax gourd (WGCM) were obtained by freeze-drying and carbonization. Nano-TiO2 was further coated onto the surface of WGCM to obtain a nano-TiO2/WGCM anode. The WGCM anode enhanced the maximum power density of MFCs by 167.9% compared with the carbon felt anode, while nano-TiO2/WGCM anode additionally increased the value by 45.8% to achieve 1396.2 mW/m2. WGCM enhancement was due to the 3D porous structure, the good conductivity and the surface hydrophilicity, which enhanced electroactive biofilm formation and anodic electron transfer. In addition, nano-TiO2 modification enhanced the enrichment of Acinetobacter, an electricigen, by 31.0% on the anode to further improve the power production. The results demonstrated that the nano-TiO2/WGCM was an effective anode for power enhancement in MFCs.

A facile synthesis of FeS/Fe3C nanoparticles highly dispersed on in situ grown N-doped CNTs as cathode electrocatalysts for microbial fuel cells.

A novel composite of iron sulfide, iron carbide and nitrogen carbides (Nano-FeS/Fe3C@NCNTs) as a cathode electrocatalyst for microbial fuel cells (MFCs) is synthesized by a one-pot solid state reaction, which yields a unique configuration of FeS/Fe3C nanoparticles highly dispersed on in situ grown nitrogen-doped carbon nanotubes (NCNTs). The highly dispersed FeS/Fe3C nanoparticles possess large active sites, while the NCNTs provide an electronically conductive network. Consequently, the resultant Nano-FeS/Fe3C@NCNTs exhibit excellent electrocatalytic activity towards the oxygen reduction reaction (ORR), with a half-wave potential close to that of Pt/C (about 0.88 V vs. RHE), and enable MFCs to deliver a power density of 1.28 W m-2 after two weeks' operation, which is higher than that of MFCs with Pt/C as the cathode electrocatalyst (1.02 W m-2). Theoretical calculations and experimental data demonstrate that there is a synergistic effect between Fe3C and FeS in Nano-FeS/Fe3C@NCNTs. Fe3C presents a strong attraction and electron-donating tendency to oxygen molecules, serving as the main active component, while FeS reduces charge transfer resistance by transferring electrons to Fe3C, synergistically improving the kinetics of the ORR and power density of MFCs.

Variance-based global sensitivity analysis of a multi-population, single-chamber microbial fuel cell operating in continuous flow mode at steady state

Microbial fuel cells (MFCs) are environmentally friendly devices which are used to convert chemical energy in organic wastes to electrical energy. MFCs have a strong non-linearity that requires a very sophisticated controlling system. Consequently, this makes optimization and performance study of MFCs a difficult process. For better estimation of the constants used for optimization of MFCs, global sensitivity analysis is performed. The global sensitivity method based on Sobol’s indices coupled with Monte Carlo simulations was applied on multi-population, single-chamber MFC operating in a continuous flow at steady state for the first time. In this paper, first-order and total-order sensitivity indices were used to visualize the impacts associated with six main parameters resulted from the maximization of power density using Matlab. Such parameters are maximum anodophilic-specific growth rate, half-rate constant of anodophilics, curve steepness factor, mediator half-rate constant, number of electrons transferred per mole mediator and decay rate constant of anodophilic bacteria. The results showed that the curve steepness factor has almost no impact on the power density of MFC. While all other studied, factors are sensitive parameters that impact the power density of MFC. It is worth mentioning that maximum anodophilic growth rate and the number of electrons transferred per mole of mediator are the most sensitive parameters that affecting the power density production having total indices of 0.74 and 0.624, respectively. While the half-rate constant of anodophilics, mediator half-rate constant and decay rate constant of anodophilics have almost similar impact by having total-order indices of 0.127, 0.144 and 0.192, respectively. The findings herein are critical in understanding and further model improvement of microbial fuel cells as the most impacting parameters on MFC power density can be optimized further to reduce uncertainty associated with the experimental parameters in the model.Graphical abstract

The use of statin-class compounds to suppress methanogenesis in lake sediment inoculated microbial fuel cells

Methanogenesis conducted by archaea acts as a competing metabolic pathway that diverts available carbon and electrons away from exo-electrogenesis in mixed culture inoculated microbial fuel cells (MFCs). This study demonstrated that the two model statin compounds Simvastatin and Atorvastatin were effective in suppressing methanogenesis in MFCs when applied at concentrations up-to 5 mg/L and 40 mg/L respectively. Power densities increased 2 fold compared to control (to 63 ± 1.8 mW/m2) and 2.5 fold (to 69.5 ± 1.8 mW/m2) with Simvastatin and Atorvastatin addition respectively. There was an almost complete suppression of CH4 production with the addition of both statins into MFC anodes as shown by gas composition analysis. Quantitative FISH (qFISH) analysis showed that methanogens Methanosarcina, Metanobacteria and Methanomicrobiales and all archaea were almost completely suppressed when statins were supplemented into MFC anodes. This study demonstrated that the statins addition can be used to boost power densities in MFCs.

Importance of pyrolysis programs in enhancing the application of microalgae-derived biochar in microbial fuel cells

Nitrogen-doped (N-doped) biochar was prepared by pyrolyzing lipid-extracted microalgae residues under 800 °C for 2 h with different temperature increasing rates (single-segment programs: 3–8 °C/min for room temperature-800 °C; two-segment programs: 5–8 °C/min for room temperature-500 °C and 3 °C/min for 500–800 °C). The obtained biochar was used for oxygen reduction reactions and microbial fuel cell applications. Interestingly, biochar prepared by two-segment programs achieved better performances than those prepared by single-segment programs with higher onset potentials in oxygen reduction reactions and higher maximal power densities in microbial fuel cell. This is likely because the applied two-segment programs improved the porous structure and enhanced the formation of pyridinic N in the biochar. Notably, applying the optimal program (5–8 °C/min for room temperature-500 °C and 3 °C/min for 500–800 °C) obtained biochar with a maximal oxygen reduction reactions onset potential of 0.877 V and a maximal microbial fuel cell power density of 843.6 mW·m−2, both of which are higher than values achieved using Pt/C. This study suggests that simply improving the pyrolysis program for N-rich biomass pyrolysis is promising for producing high-performance N-doped biochar for microbial fuel cells.

Simultaneous boost of anodic electron transfer and exoelectrogens enrichment by decorating electrospinning carbon nanofibers in microbial fuel cell

Microbial fuel cell (MFC) is a promising technology in wastewater recovery driven by microbial metabolism. However, the low power output resulting from the sluggish extracellular electron transfer (EET) between the anode surface and exoelectrogens dramatically restricted the further application. This study fabricated a high-performance anode by decorating porous and conductive electrospinning carbon nanofibers (CNFs). The maximum power density in MFC modified with 14 wt% polyacrylonitrile CNFs (M-CNF14, 9.6 ± 0.2 W m−3) was 1.9 and 2.7 times higher than carbon black modified MFC (M-CB, 5.1 ± 0.1 W m−3) and the blank (M-BA, 3.6 ± 0.1 W m−3), respectively. Denser biofilm and more microbial nanowires were observed in the M-CNF14 anode than in other conditions. Furthermore, the redox peak current of c-type cytochrome was 1.7–21 times higher in M-CNF14 than in the blank control, verifying the preferable EET activity. Several exoelectrogens like Petrimonas and Comamonas were enriched in M-CNF14 and showed a positive correlation to power generation. Besides, more simplified and modular interrelations among exoelectrogens and other bacteria were obtained in M-CNF14. This study revealed the microbial-related mechanism for simultaneously improving EET and exoelectrogens enrichment by CNFs modified anode, providing guidelines for high-performance wastewater recovery.

Facile synthesis of NS@UiO-66 porous carbon for efficient oxygen reduction reaction in microbial fuel cells

Exploiting a facile way to synthesize low-cost and high-performance oxygen reduction reaction (ORR) catalysts is a core issue in microbial fuel cells (MFCs). Hence, a facile and extensible method has been developed to prepare efficient ORR catalysts by using robust UiO-66 as a precursor, modified with melamine and trithiocyanuric via the impregnation method. Benefiting from the hierarchical structure of UiO-66, the NS@UiO-66 has excellent stability, more active sites and improved mass transfer. Significantly, the half-wave potential and the current density of the NS@UiO-66 are 0.546 V vs. RHE and 6.19 mA cm−2 respectively, which is better than that of benchmark Pt/C in neutral conditions. Furthermore, the power density of MFCs assembled with the NS@UiO-66 catalyst is 318.6 ± 2.15 mW m−2. The density functional theory calculation demonstrates that the reaction barrier can be reduced effectively for accelerating the ORR process through the synergistic effect of N and S. The NS@UiO-66, as an ideal candidate to substitute for the commercial Pt/C counterpart, is expected to promote the scaling-up production and application of MFCs due to low-cost elements doping and facilely synthetic method.

Ligand-exchange-induced child-mother metal-organic frameworks derived a novel heterostructured iron-based carbon for neutral oxygen reduction in microbial fuel cell

The slow neutral oxygen reduction reaction (ORR) impedes the efficiency of microbial Fuel Cell (MFC) for pollutants degradation and electricity generation, which requires active electrocatalysts to accelerate electron transfer. Iron-nitrogen-carbons (Fe–N–Cs) derived from Prussian blue analogues (PBAs), acknowledged for low cost and high yield, are generally with unsatisfactory surface structure and low nitrogen/carbon contents, which leads to reduced active sites. To address this issue, herein, an ingenious ligand exchange strategy is proposed for the first time to construct a PBAs-based MOF@MOF precursor (Zn-ZIF-L@Zn–Fe PBA, MOF: metal-organic framework) by utilizing 2D leaf-shaped Zn-based zeolitic imidazolate framework (Zn-ZIF-L) nanoplates to give birth to 3D Zn–Fe PBA nanospheres. Physicochemical and electrochemical results demonstrate that ligand exchange follows diffusion-controlled mechanism and the creatively developed electrocatalyst (C–Zn-ZIF-L@Zn–Fe PBA) with a multi-structure of nanospheres, dense carbon nanotubes and leaf-like carbon nanoplates exhibits remarkable catalytic activity and stability for neutral-pH ORR. The maximum power density of MFC with C–Zn-ZIF-L@Zn–Fe PBA cathode is 2511 ± 69 mW m−2 and chemical oxygen demand (COD) removal efficiency reaches to 90.17%, significantly outperforming the carbonization products of the other two single MOF. For practical application, two MFCs in series can as a power supplier to drive a digital watch for working 24 h constantly.

Synthesis of Non‐precious N‐doped Mesoporous Fe3O4/CoO@NC Materials towards Efficient Oxygen Reduction Reaction for Microbial Fuel Cells

AbstractN‐doped transition metal oxides are strategic materials towards the efficient oxygen reduction reaction (ORR) of microbial fuel cells (MFCs). Non‐precious N‐doped Fe3O4/CoO@NC−T (T represents carbonization temperature) catalysts are prepared by an efficient two‐step strategy for ORR. Fe3O4/CoO@NC‐750 exhibits the best performance with an efficient four‐electron transfer pathway. The optimal power density of MFCs by using Fe3O4/CoO@NC‐750 as the cathode catalyst (1243.4 mW ⋅ m−2) is superior to that of the MFCs with commercial Pt/C catalyst (1080 mW ⋅ m−2), which shows an outstanding activity towards ORR. No significant decrease in output voltage results over 70 days, which shows an excellent electrochemical stability.