Cathode Microbial Fuel Cells Research Articles

Reduced graphene oxide-supported palladium oxide-MOx for improving the performance of air-cathode microbial fuel cells: Influence of the Sn, Ce, Zn, and Fe precursors

Over the past few decades, microbial fuel cells (MFCs) have attracted significant interest within the realm of renewable energy technologies owing to their capability to generate electricity from low-grade substrates. However, their commercialization and scaling-up are impeded by significant obstacles, including high capital costs, limited durability, and sluggish oxygen reduction reaction (ORR). Here, we demonstrate an environmentally-friendly approach for developing highly efficient electrocatalysts consisting of palladium oxide (PdO) and different transition metal oxides (i.e., tin (IV) oxide (SnO2), ceric oxide (CeO2), iron (III) oxide (Fe2O3), and zinc oxide (ZnO)) embedded within reduced graphene oxide (rGO) framework for improving the efficiency of ORR in neutral medium and MFCs. Among the as-prepared electrocatalysts, the PdO–SnO2/rGO possesses the highest ORR electrochemical catalytic activity in a neutral medium (pH ∼ 7.2) following a four-electron ORR pathway, with a current density slightly lower than that of benchmark Pt/C electrocatalyst. The assessment of MFC performance is conducted by employing activated sludge as the inoculum and glucose as the sole electron donor in the anode chamber of single-chamber, air-cathode MFCs. Consistent with electrochemical performance, the maximum power output of an MFC equipped with PdO–SnO2/rGO as an air cathode is significantly higher than other tested MFCs, reaching 84.6 ± 2.8 mW m−2, which represents ∼ 91 % of the power output of an MFC with Pt/C air cathode. Our results reveal that the incorporation of PdO into transition metal reduced graphene oxide framework has the potential to facilitate their long-term application as air cathodes in MFCs that possess easy fabrication, relatively affordable cost, and outstanding electrochemical catalytic oxygen reduction capability, for enhancing electricity generation from wastewater.

Enhanced performance of microbial fuel cells using electrochemically treated carbon felt anode

The microbial fuel cell (MFC) technology is emerging as an effective technology for wastewater treatment to remove and detect many pollutants and simultaneously generate power. The anode is an essential component for bacterial attachment and extracellular electron transfer (EET). Thus, anode performance is critical for improving an MFC system's overall performance. Materials that are electronically conductive and provide favorable conditions for creating biofilm are good candidates for the anode. Carbon paper and carbon felt are the most used anode materials. However, the characteristics of these materials can be modified to increase their performance. This paper presents a modification of the conventional carbon anode by electrolyzing the carbon felt in a phosphate buffer and an experimental evaluation of the impact of the treatment. The tests were performed using an air cathode MFC, electrogenic bacteria Shewanella Baltica 20 fed on lactose-rich L-B. The treatment with phosphate buffer generates functional groups on the surface of the carbon felt, which establishes robust biofilm on the anode and offers lower charge-transfer resistance compared to the untreated carbon felt. This facilitates electron transfer from exoelectrogens to the anode, increasing the current density and power density output. Three times higher power density was observed in the cell with a modified anode than in an untreated carbon-felt anode.

A Nanofiber-Based Gas Diffusion Layer for Improved Performance in Air Cathode Microbial Fuel Cells.

This work investigates a new nanostructured gas diffusion layer (nano-GDL) to improve the performance of air cathode single-chamber microbial fuel cells (a-SCMFCs). The new nano-GDLs improve the direct oxygen reduction reaction by exploiting the best qualities of nanofibers from electrospinning in terms of high surface-area-to-volume ratio, high porosity, and laser-based processing to promote adhesion. By electrospinning, nano-GDLs were fabricated directly by collecting two nanofiber mats on the same carbon-based electrode, acting as the substrate. Each layer was designed with a specific function: water-resistant, oxygen-permeable polyvinylidene-difluoride (PVDF) nanofibers served as a barrier to prevent water-based electrolyte leakage, while an inner layer of cellulose nanofibers was added to promote oxygen diffusion towards the catalytic sites. The maximum current density obtained for a-SCMFCs with the new nano-GDLs is 132.2 ± 10.8 mA m-2, and it doubles the current density obtained with standard PTFE-based GDL (58.5 ± 2.4 mA m-2) used as reference material. The energy recovery (EF) factor, i.e., the ratio of the power output to the inner volume of the device, was then used to evaluate the overall performance of a-SCMFCs. a-SCMFCs with nano-GDL provided an EF value of 60.83 mJ m-3, one order of magnitude higher than the value of 3.92 mJ m-3 obtained with standard GDL.

Carbon capture from petrol-engine flue gas: Reviving algae-based sequestration with integrated microbial fuel cells

Strengthening the existing CO2 capture technologies is crucial for averting the imminent climate crisis. The present study undertakes the algae-assisted microbial fuel cell (MFC) for indirect CO2 capture via bicarbonate utilization through natural photosynthesis process. The flue gas is first cooled using a heat exchanger and then directed to a sieve-plate absorption column where sodium carbonate supplemented wastewater absorbs CO2 generating flue gas-derived bicarbonates (FGDBs). The FGDBs are added in the plastic bag photobioreactors (PBRs) coupled with the MFC for absorption by Chlorella vulgaris. Adding FGDB at the MFC cathode increased the algae biomass productivity two times (0.677 ± 0.086 Kg/m3/d) compared to the cathode without FGDB. The algae could efficiently utilize 76.84 ± 1.23 %. More than 50 % of sodium carbonate can be recycled for the next round of CO2 capture. FGDB supplementation at the cathode improved MFC’s electrical energy production (0.0066 kWh/m3) by 1.5 times through enhanced anodic and cathodic currents. Therefore, the present study offers a biochemical CO2 sequestration process that generates power, algae biomass, and treats water by utilizing algae-assisted MFC for flue gas carbon capture.

Vermiculite nanosheet augmented novel proton exchange membrane for microbial fuel cell

Microbial fuel cell (MFC) is promoted as an eco-friendly technology for wastewater treatment. However, the use of synthetic polymeric membrane separators raises concerns about the sustainability of MFC, mandating efforts to develop sustainable polymeric membrane with high protonic transfer for MFC assembly. Low-cost and eco-friendly polymer matrix of agar-polyvinyl alcohol (AP) augmented with exfoliated vermiculite nanosheets (Vm NSs) are used to prepare membrane separators for MFC. A simple and facile method for synthesis of AP membrane without and with Vm NSs concentration of 0.25 mg/mL (0.25 Vm), 0.5 mg/mL (0.5 Vm) and 1 mg/mL (1.0 Vm) is adopted in aqueous phase. The proton mass transfer coefficients of prepared membranes (AP, 0.25 Vm, 0.5 Vm and 1.0 Vm) are respectively 94.4, 134.46, 216.26 and 197.69 % higher than commercially available Nafion membrane. These membranes are tested in three different configurations of MFC: aerated cathode, air cathode and anaerobic dye cathode MFC. Highest current densities of 1515 and 949 mA/m3 are obtained with 1.0 Vm membrane in aerated and air cathode-MFC respectively while Nafion membrane could produce 623 and 405 mA/m3. In anaerobic dye cathode MFC, 0.5 Vm membrane is able to achieve the highest current density of 935 mA/m3 along with 71 % methyl red decolorization while Nafion membrane produced highest current density of 104 mA/m3 with 59 % decolorization. Vm NSs augmentation enhances the properties of base AP membrane which can be conveniently used as an alternative to expensive Nafion membrane in the desired configuration of MFC.

Proposal for a Binder Blended with PTFE and Japanese Sumi Ink for the Cathode in Microbial Fuel Cells

Proposal for a Binder Blended with PTFE and Japanese Sumi Ink for the Cathode in Microbial Fuel Cells

Enhanced Electricity Generation and Heavy Metal Removal by a Rutile–Biochar Cathode MFC

The issue of heavy metal pollution has gradually emerged as a significant global concern. Microbial fuel cells (MFCs) hold immense potential for clean energy production and pollutant treatment. However, their limited power generation efficiency hampers the large-scale implementation of MFCs. The porous microstructure of biochar and the excellent physical and chemical properties of rutile render both materials promising catalysts with positive potential. In this study, we employed biochar as a carrier for rutile to fabricate a novel rutile–biochar (Rut-B) composite material, investigating its efficacy in enhancing MFC power generation efficiency as a cathode catalyst, as well as its application in heavy metal pollutant degradation. Scanning electron microscopy (SEM) results confirmed the successful preparation of biochar-loaded rutile composites. The MFC achieved maximum current density and power density values of 152.26 mA/m2 and 9.88 mW/m2, respectively—an increase of 102.7% and 224% compared to the control group without the addition of Rut-B. Furthermore, the biochar-loaded rutile MFC exhibited excellent performance in degrading heavy metal pollutants; within 7 h, the Pb2+ degradation rate reached 92.4%, while the Zn2+ degradation rate reached 84%. These rates were significantly higher than those observed in the control group, by factors of 437.2% and 345%, respectively. The cyclic degradation experiments also demonstrated the outstanding stability of the system over multiple cycles. In summary, this study successfully combined natural rutile with biochar to create an efficient electrode catalyst that not only enhances electricity generation performance but also provides an environmentally friendly and cost-effective approach for remediating heavy metal pollution.

Co-culturing Chlorella vulgaris and Cystobasidium oligophagum JRC1 in the microbial fuel cell cathode for lipid biosynthesis.

This study investigated the effect of co-culturing the photobiont and mycobiont in the microbial fuel cell (MFC) cathode on biomass production, lipid generation, and power output. Chlorella vulgaris provides oxygen and nutrients for the yeast Cystobasidium oligophagum JRC1, while the latter offers CO2 and quench oxygen for higher algal growth. The MFC with co-culture enhanced the lipid output of biomass by 28.33%, and the total yield and productivity were 1.47 ± 0.18 g/l and 0.123 g/l/day, respectively. Moreover, with co-culture, the open circuit voltage of 685 ± 11 mV was two times higher than algae alone. The specific growth rate (day-1) at the cathode was 0.367 ± 0.04 in co-culture and 0.288 ± 0.05 with C. vulgaris only. The power density of the system was 5.37 ± 0.21 mW/m2 with 75.88 ± 1.89% of COD removal. The co-culture thus proved beneficial at the MFC cathode in terms of total energy output as 11.5 ± 0.035 kWh/m3, which was 1.4-fold higher than algae alone.

Effects of chemical oxygen demand/nitrogen on electrochemical performances and denitrification efficiency in single-chamber microbial fuel cells: Insights from electron transfer and bacterial communities

The electrochemical performances and denitrification efficiency of microbial fuel cells (MFCs) are often limited by chemical oxygen demand/nitrogen (COD/N) of wastewater. To overcome this limitation, single-chamber air cathode MFCs with varying COD/N (16/1, 8/1, and 4/1) were established to investigate their electrochemical performances, denitrification efficiency, and bacterial communities. The optimal COD/N for maximizing electricity generation and denitrification efficiency was 8/1, as supported by the greatest corrected coulomb efficiency (13.6%) and electron transfer rate (2.36 C/h for electricity generation, 39.77 C/h for denitrification). As COD/N decreased, the electrochemically active genus Geobacter was replaced by the denitrifying genera Un._f_Burkholderiaceae, Dechlorosoma, and Petrimonas. These results indicated that the efficiency of electricity generation and denitrification was not solely determined by the abundance of electrochemically active and denitrifying bacteria. The presence of a faster electron transfer pathway, possibly direct interspecies electron transfer, enhanced simultaneous electricity generation and denitrification in MFCs with COD/N of 8/1.

Accelerating Electricity Generation and Cr (VI) Removal Using Anatase–Biochar-Modified Cathode Microbial Fuel Cells

Microbial fuel cells (MFC) have considerable potential in the field of energy production and pollutant treatment. However, a low power generation performance remains a significant bottleneck for MFCs. Biochar and anatase are anticipated to emerge as novel cathode catalytic materials due to their distinctive physicochemical properties and functional group architectures. In this study, biochar was utilized as a support for an anatase cathode to investigate the enhancement of the MFC power generation performance and its environmental impact. The results of the SEM and XPS experiments showed that the biochar-supported anatase composites were successfully prepared. Using the new cathode catalyst, the maximum current density and power density of the MFC reached 164 mA/m2 and 10.34 W/m2, respectively, which increased by 133% and 265% compared to a graphite cathode (70.51 mA/m2 and 2.83 W/m2). The degradation efficiency of Cr (VI) was 3.1 times higher in the biochar-supported anatase MFC than in the graphite cathode. The concentration and pH gradient experiments revealed that the degradation efficiency of Cr (VI) was 97.05% at an initial concentration of 10 mg/L, whereas a pH value of two resulted in a degradation efficiency of 94.275%. The biochar-supported anatase composites avoided anatase agglomeration and provided more active sites, thus accelerating the cathode electron transfer. In this study, natural anatase and biochar were ingeniously combined to fabricate a green and efficient electrode catalyst, offering a novel approach for the preparation of high-performance positive catalysts as well as a sustainable, economical, and environmentally friendly method for Cr (VI) removal in aqueous solutions.

Research progress of MOFs/carbon nanocomposites on promoting ORR in microbial fuel cell cathodes.

With the rapid development of the economy, energy demand is more urgent. Microbial fuel cells (MFCs) have the advantages of non-toxic, safety, and environmental protection, and are considered the ideal choice for the next generation of energy storage equipment. However, the slow kinetics of oxygen reduction reaction (ORR) on MFC air cathodes and the high cost of traditional platinum (Pt) catalysts hinder their practical application, so there is a need to develop efficient, low-cost, and stable electrocatalysts as alternatives. Recently, metal-organic framework (MOFs) has attracted wide attention in electrocatalysis. Electrocatalysts prepared by the nanocomposite of MOFs and carbon nanomaterials have multiple advantages, such as adjustable chemical properties, high specific surface area, and good electrical conductivity, which have been proven to be a promising electrocatalytic material. In this paper, the latest research progress of metal-organic frames (MOFs) and carbon nanocomposites is reviewed, and the preparation methods and modification of MOFs and carbon nanofibers, carbon nanotubes, and graphene composites are introduced, respectively, as well as their applications in MFC cathode. Finally, the main prospects of MOFs/carbon nanocomposite catalysts are put forward.

Oxygen reduction reaction enhancement in microbial fuel cell cathode using cesium phosphomolybdate electrocatalyst

The sluggish oxygen reduction reaction (ORR) is a significant hurdle against microbial fuel cell (MFC) performance. Polyoxometalates are excellent candidates to address this challenge because they have the potential of improving ORR efficiency. Here, cesium phosphomolybdate was successfully synthesized through a facile solid-state method and then used as an ORR catalyst on a graphite cathode in an MFC with sodium acetate as the substrate in the anolyte. The CV analysis demonstrated that modified graphite has two ORR peaks at −0.25, −0.5 V vs Ag/AgCl and a higher current density than the bare graphite. The MFC equipped with the modified cathode displayed a maximum power density of 64.73 mW m−2, higher than that obtained for bare graphite (42 mW m−2). COD removal efficiencies in MFCs with modified and bare graphite cathodes were 86.4% and 85%, respectively which are similar to or better than what is published in the literature. This study offers an efficient ORR catalyst in MFC applications helping in using organic wastewater as a fuel by converting the chemical energy into electricity.

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.

Semi-wet methanogen cathode composed of oak white charcoal for developing sustainable microbial fuel cells

The present study aimed to evaluate a semi-wet biocathode composed of oak white charcoal and agarose gel as an alternative to the standard carbon felt biocathodes used in microbial fuel cells (MFCs). The MFC containing the oak white charcoal cathode (Oak-MFC) recorded a higher current value than that of the MFC containing a carbon felt cathode (CF-MFC). The Oak-MFC produced approximately 4.0-fold more electrons in the external circuit and 1.7-fold more methane (CH4) than the CF-MFC. A real-time PCR targeting mcrA showed that the number of methanogens adhering to the oak white charcoal cathode was approximately 15-fold that adhering to the carbon felt cathode. These results suggest that the methanogens attached to the cathode of both MFCs received electrons and CH4 was produced from carbon dioxide (CO2). Furthermore, Oak-MFC performed better than CF-MFC, thereby suggesting that oak white charcoal bound by agarose gel can be used as an alternative methanogen cathode. The propionic acid degradation rate of Oak-MFC was faster than that of CF-MFC suggesting that the cathodic reaction may affect the anodic reaction. The use of oak-derived electrode as a methanogen cathode also could contribute to sustainable forest management and promote regular thinning of oak trees. Further, its use will enable carbon fixation and efficient energy conversion from CO2 to CH4, thus contributing to sustainable energy use.

Biocathode electrochemical activity and reduction characteristics of Cr(VI) system in microbial fuel cells

AbstractBACKGROUNDThe biocathode of microbial fuel cells (MFCs) offers a simple method for the reductive treatment of Cr(VI), and Cr(VI) is an electron acceptor in cathodes in MFCs. In this study, MFCs with different Cr(VI) contents (7.07–35.35 mg L−1) were considered to evaluate the overall performance of MFCs.RESULTSThe results of electrochemical analysis confirmed that the MFC‐2 biocathode exhibited a higher effective reaction surface, stronger conductivity, and smaller charge transfer resistance (53.63 Ω) than the others. In addition, Cr(VI) had a power output of 75.6 mW m−2 in MFC‐2 and a Cr(VI) cathodic coulombic efficiency of 103.8%. With 14.14 mg L−1 Cr(VI) content, the cathode microbe had the best activity. Cr(VI) reduction followed a pseudo‐first‐order kinetic model, with the rate constant being 0.0139 h−1. Meanwhile, this study analyzed the Cr(VI) reduction in MFCs and the release and acceptance of electrons and protons. Electrically active bacteria such as Proteobacteria were highly enriched on the anode and cathode biofilm, while the Cr(VI)‐reducing bacteria Gammaproteobacteria increased in the biofilm of the cathode.CONCLUSIONThis study helps in the selection of Cr(VI) concentration for the cathode, guaranteeing microbial activity and power generation performance. Microbes have the best electrochemical activity in MFC‐2 (14.14 mg L−1). Meanwhile, the change in anode microbial activity was affected by cathode performance. The microbial community was significantly influenced by Cr(VI). © 2023 Society of Chemical Industry (SCI).

Nannochloropsis Algae Biocathodes Improve Cathodic Energy Losses in Two-Chamber Microbial Fuel Cells

Microbial fuel cells (MFCs) are currently being researched as alternative energy sources with promising applications in wastewater treatment. However, in two-chamber designs, cathodic oxygen reduction is slow and limits MFC voltage. Biocathodes, cathodes containing microorganisms, show great promise for improving MFC performance. This study investigated how the microalgae Nannochloropsis affects cathodic oxygen reduction via a thermodynamic analysis of energy losses. Voltage, cathode pH, and cathode pO2 (partial pressure of oxygen) were measured in experimental MFCs containing Nannochloropsis biocathodes and compared to controls containing distilled water or abiotic algae media cathodes. Isolated Nanochloropsis cultures were also assayed. Under open circuit conditions, cathodic energy losses in experimental MFCs were 15% (p = 0.038597) and 19% (p = 0.042435) lower than distilled water and algae media controls, respectively. Experimental MFCs produced 73% higher power at 37% higher current density than distilled water MFCs. While the pH and pO2 of isolated Nannochloropsis cultures increased linearly each day, these measurements were constant in experimental MFC cathodes. This result suggests that participation in oxygen reduction reactions induces a change in Nannochloropsis metabolism, leading to reduced oxygen production and limiting pH changes. Taken together, this work presents a promising new type of two-chambered MFC with lower energy losses and greater power production that can also maintain a constant cathode pH and reveals a new behavior of Nannochloropsis algae in response to oxygen reduction reactions in such MFCs.

BaTiO3 Functional Perovskite as Photocathode in Microbial Fuel Cells for Energy Production and Wastewater Treatment.

Microbial fuel cells (MFCs) provide new opportunities for the sustainable production of energy, converting organic matter into electricity through microorganisms. Moreover, MFCs play an important role in remediation of environmental pollutants from wastewater with power generation. This work focuses on the evaluation of ferroelectric perovskite materials as a new class of non-precious photocatalysts for MFC cathode construction. Nanoparticles of BaTiO3 (BT) were prepared and tested in a microbial fuel cell (MFC) as photocathode catalytic components. The catalyst phases were synthesized, identified and characterized by XRD, SEM, UV-Vis absorption spectroscopy, P-E hysteresis and dielectric measurements. The maximum absorption of BT nanoparticles was recorded at 285 nm and the energy gap (Eg) was estimated to be 3.77 eV. Photocatalytic performance of cathodes coated with BaTiO3 was measured in a dark environment and then in the presence of a UV-visible (UV-Vis) light source, using a mixture of dairy industry and domestic wastewater as a feedstock for the MFCs. The performance of the BT cathodic component is strongly dependent on the presence of UV-Vis irradiation. The BT-based cathode functioning under UV-visible light improves the maximum power densities and the open circuit voltage (OCV) of the MFC system. The values increased from 64 mW m-2 to 498 mW m-2 and from 280 mV to 387 mV, respectively, showing that the presence of light effectively improved the photocatalytic activity of this ceramic. Furthermore, the MFCs operating under optimal conditions were able to reduce the chemical oxygen demand load in wastewater by 90% (initial COD = 2500 mg L-1).

High efficiency electrochemical separation of uranium(VI) from uranium-containing wastewater by microbial fuel cells with different cathodes

As an emerging versatile technology for separating uranium from uranium-containing wastewater (UCW), microbial fuel cell (MFC) offers a novel approach to UCW treatment. Its cathode is essential for the treatment of UCW. To thoroughly investigate the efficacy of MFC in treating UCW, investigations were conducted using MFCs with five materials (containing iron sheet (IP), stainless steel mesh (SSM), carbon cloth (CC), carbon brush (CB), and nickel foam (NF)) as cathodes. The results revealed that each MFC system performed differently in terms of carbon source degradation, uranium removal, and electricity production. In terms of carbon source degradation, CB-MFC showed the best performance. The best uranium removal method was NF-MFC, and the best electricity production method was carbon-based cathode MFC. Five MFC systems demonstrated stable performance and consistent difference over five cycles, with CC-MFC outperforming the others. Furthermore, SEM and XPS characterization of the cathode materials before and after the experiment revealed that a significant amount of U(IV) was generated during the uranium removal process, indicating that uranium ions were primarily removed by electrochemical reduction precipitation. This study confirmed that abiotic cathode MFC had a high UCW removal potential and served as a good guideline for obtaining the best cathode for MFC.

Mesoporous LaFeO3 perovskite as an efficient and cost-effective oxygen reduction reaction catalyst in an air cathode microbial fuel cell

Microbial fuel cells (MFCs) produce renewable energy from organic matter in presence of electrochemically active anaerobes at the anode and cathode oxygen reduction reaction (ORR). The ORR catalyst is pivotal for power generation and the overall cost of constructing an MFC. This study uses a synthesized novel LaFeO3 perovskite electrocatalyst as an alternative to the conventional Pt/C cathode catalyst which enhances ORR activity in a pH-neutral electrolyte. LaFeO3-based air cathode MFC produced 726.43 mWm−2 of maximum power density and is comparable to the commercial Pt/C catalyst i.e., 775 mWm−2. Furthermore, it has achieved 2.3 mAm−2 of the maximum current density and 556 mV of voltage. The improved catalytic activity of the synthesized LaFeO3 is associated with a large number of active sites, oxygen vacancies, and its mesoporous nature. Therefore, LaFeO3perovskite was able to catalyze ORR with an electron transfer of 3.8 in a neutral medium which is close to superior indirect four-electron pathways. It is highlighted that LaFeO3 perovskite iscost-effectiveand has comparable electrochemical properties with Pt/C which is evident in its scale-up potential of MFCs for green energy synthesis.

Fe, N, S co-doped cellulose paper carbon fibers as an air-cathode catalyst for microbial fuel cells

The heteroatoms and transition metal co-doped carbon-based catalysts are an important way to improve the catalytic activity of oxygen reduction reaction (ORR). Herein, we reported a facile method to obtain iron, nitrogen, and sulfur co-doped cellulose paper carbon fibers as catalysts (Fe–N–S/CFs) for ORR in microbial fuel cells (MFCs) with the adsorption recovery of Congo red molecules from dye wastewater. The thermal treatment promoted the etching of carbon surface by ferric ions, resulting in increased surface roughness for forming the defective carbon structure. The rich active species and defective carbon formed on the etched surface to enhance the electroactive surface area and effective sites. Fe–N–S/CFs catalysts achieved high half-wave potential due to the synergy effect between chemical components and defect structures. The assembled single-chamber air cathode MFC gained a high maximum power density of 1773 ± 40 mW m−2 versus Pt/C MFC of 1325 ± 94 mW m−2. This work provides a strategy for recovering dye molecules from wastewater to prepare non-precious metal catalysts for enhancing ORR activity.