Cathode Catalyst In Microbial Fuel Cells Research Articles

Hydrothermal synthesis of tungsten oxide photo/electrocatalysts: precursor-driven morphological tailoring and electrochemical performance for hydrogen evolution and oxygen reduction reaction application.

A hydrothermal approach was adopted to synthesize tungsten oxide (WO3) nanocatalysts with tailored morphology, using oxalic acid (H2C2O4) and hydrochloric acid (HCl) as precursors. This precursor-driven method yielded two distinct WO3 catalysts with unique structural and functional properties, viz. rod-shaped WO3-ox and nanoflower-shaped WO3-h. Characterization by FESEM and XRD revealed variations in morphology and crystallite size, contributing to their specialized catalytic applications. UV-Vis spectroscopy confirmed strong UV absorption by WO3-ox at 283.57nm with an optical band gap of 2.86eV, making it ideal for photocatalytic activities. Electrochemical analysis demonstrated that WO3-ox effectively drives the hydrogen evolution reaction (HER), while WO3-h is more suitable for the oxygen reduction reaction (ORR), an essential process in microbial fuel cells (MFCs). In practical applications, WO3-ox achieved an 83.9% degradation efficiency of methylene blue (MB) within 3h, validating its high photocatalytic efficacy for wastewater treatment. Meanwhile, WO3-h, utilized as a cathode catalyst in MFCs, significantly enhanced system performance, elevating chemical oxygen demand (COD) removal efficiency to 78.7% and improving coulombic efficiency by 3%. These findings underscore the potential of precursor-driven hydrothermal synthesis for optimizing WO3 catalysts tailored for energy and environmental applications, specifically in hydrogen production and sustainable wastewater treatment systems.

Multi-metal ferrite as a promising catalyst for oxygen reduction reaction in microbial fuel cell.

Improving catalytic activity of cathode with noble metal-free catalysts can significantly establish microbial fuel cells (MFCs) as a sustainable and economically affordable technology. This investigation aimed to assess the viability of utilizing tri-metal ferrite (Co0.5Cu0.5 Bi0.1Fe1.9O4) as an oxygen reduction reaction (ORR) catalyst to enhance the performance of cathode in MFCs. Trimetallic ferrite was synthesized using a sol-gel auto-combustion process. Electrochemical evaluations were conducted to assess the efficacy of as-synthesized composite as an ORR catalyst, employing electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). This evaluation revealed that the impregnation of bismuth in the Co-Cu-ferrite structure improves the reduction current response and reduces the charge transfer resistance. Further experiments were conducted to test the performance of this catalyst in an MFC. The MFC with tri-metal ferrite catalyst generated a power density of 11.44 W/m3 with 21.4% coulombic efficiency (CE), which was found to be comparable with commercially available 10% Pt/C used as cathode catalyst in MFC (power density of 12.14 W/m3 and CE of 23.1%) and substantially greater than MFC having bare carbon felt cathode without any catalyst (power density of 2.49 W/m3 and CE of 7.39%). This exceptionally inexpensive ORR catalyst has adequate merit to replace commercial costlier platinum-based cathode catalysts for upscaling MFCs.

Fe-N-C-based cathode catalyst enhances redox reaction performance of microbial fuel cells: Azo dyes degradation accompanied by electricity generation

Microbial fuel cell (MFC) is a promising technology for the treatment of textile industry wastewater and energy recovering. However, insufficient power for redox reaction and costly cathode catalyst limit the application of MFCs. Herein, we proposed an environmentally friendly and convenient approach for Fe-N-C-based catalysts synthesis and confirmed their satisfactory effects. The results showed that graphitized structures, pyridine-N and graphitic-N enhanced the conductivity of pomelo peel-derived carbon (PPC). In addition, the existence of Fe3C nanocrystals, Fe-Nx active sites and the rod-like carbon nanotubes (CNTs) was favorable for the synthetic catalyst. Meanwhile, the effective removal of Congo Red (CR) (99.0%) and COD (86.6%) was achieved at the precursor mass ratio was 2 under neutral conditions, accompanied by a maximum power output of 184 mW·m-2. It was clarified that electrons preferentially break the azo bond (-N = N-) of CR and the intermediates mainly included the benzene ring and the naphthalene ring. Microbial community analysis showed that Proteobacteria (56.5%), Gammaproteobacteria (44.6%) and Acinetobacter (29.5%) dominated at the phylum, class and genus levels of the anodic biofilm, respectively. In general, this study provides an innovative substitute for cathode catalyst in MFCs and the synthesized Fe-N-C-based catalyst could be widely employed in engineering owing to its admirable intrinsic activity.

Cu, Co embedded N-enriched mesoporous carbon cathode catalyst for the efficient bioelectrochemical removal of phenanthrene in microbial fuel cell

The development of high-efficiency and economical oxygen reduction reaction (ORR) electrocatalysts is vital for the improvement of renewable energy storage and conversion technology. As a promising energy conversion technology, the performance of microbial fuel cell (MFC) has aroused worldwide interest in recent years owing to its power generation capacity and potential for wastewater treatment. In an aquatic environment, phenanthrene (Phe) is one of the most abundant polycyclic aromatic hydrocarbons. We synthesized a series of CuCo samples successfully via simple in- situ growth and thermal decomposition method. In addition, a single-chamber, air-cathode MFC is investigated for the degradation of phenanthrene in neutral solution. The cathode catalyst 1.5 CuCo@NC-800 exhibits a maximum power density (MPD) of 3248.68 ± 28.21 mW m−2 in initial cycles and maintained at 95.25% after the Phe degradation. And in this study, the reactor with 1.5 CuCo@NC-800 catalyst can effectively reduce Phe at low concentrations and remain above the rate of 98%. Therefore, 1.5 CuCo@NC-800 showed great potential to become a material candidate for non-noble cathode catalyst in MFC.

A review on graphene / graphene oxide supported electrodes for microbial fuel cell applications: Challenges and prospects

Microbial Fuel Cell (MFC) has gained great interest as an alternative green technology for bioenergy generation along with reduced sludge production, nutrient recovery, removal of COD and color, etc. during wastewater treatment. However, the MFC has several challenges for real-time applications due to less power output and high ohmic resistance and fabrication (electrode and membrane) cost. Several kinds of research have been carried out to increase energy production by reducing various losses associated with electrodes in the MFC. Though, carbonaceous electrodes (carbon and graphite) are the key materials for the anode and cathode side, since these have a higher surface area, good biocompatibility, low cost, and good mechanical strength. Graphene or graphene oxide-based nanocomposite can be an ideal substitute for electrode modifications and an alternative for an expensive anode and cathode catalyst in MFC. Graphene oxide synthesis from waste material such as waste biomass, agricultural, plastic waste, etc. is added advantages of minimizing the cost of the electrodes. But, the synthesis of graphene is quite expensive and has limitations in economic feasibility for bioelectricity production in MFC. Hence, the present review deals with the anode and cathode electrode modification with graphene-based nanocomposites, synthesis of graphene/graphene oxide from various raw materials, and its application in MFC. The current challenges and future outlook on graphene-based composites on MFC performance are also discussed.

CARBON-BASED CATHODE CATALYSTS USED IN MICROBIAL FUEL CELLS FOR WASTEWATER TREATMENT AND ENERGY RECOVERY

In the past 20 years Microbial fuel cells (MFCs) have been extensively studied regarding the possibility of transforming organic waste directly into electricity. There are significant differences between MFCs and conventional low temperature Fuel Cells (FCs), which make MFCs attractive: biotic catalyst at the anode; the anodic fuel is complex organic waste; MFCs operate under mild reaction conditions (neutral pH, temperature and pressure), close to ambient levels as optimum. Like chemical fuel cells, MFCs are composed of anode and cathode. Oxygen is an ideal electron acceptor for MFCs because of its high redox potential, availability, and sustainability. However, the Oxygen Reduction Reaction (ORR) is kinetically sluggish, resulting in a large proportion of potential loss. Also, working conditions are quite different because of the type of complex media in which MFCs operate. In order to overcome these limitations, catalysts are often used to lower the overpotentials and accelerate the kinetics of the oxygen reduction reaction. One of the main challenges is the development of efficient and stable cathode catalysts for MFCs. By far, Pt and Pt-based catalysts (PGMs) have been extensively used, due to their catalytic efficiency in gas-diffusion electrodes. But the high cost and low durability have significantly lowered their utilization in MFCs. A variety of non-precious metal catalysts have been developed for MFC applications including carbon-based catalysts, carbon supported composite catalysts, Me-based catalysts and biocatalysts. It is supposed that the ORR catalyst used for wastewater treatment in MFCs is simple to synthesize, cost-effective, durable after long-term operation in wastewater, tolerant to poisoning and able to restore catalytic activity after cleaning. In this regard carbon-based catalyst may be the most promising candidate for practical applications. This study reviews different carbon-based ORR catalysts for MFC applications for wastewater treatment and energy recovery.

Proficient Sanitary Wastewater Treatment in Laboratory and Field-Scale Microbial Fuel Cell with Anti-Biofouling Cu0.5Mn0.5Fe2O4 as Cathode Catalyst

For successful field-scale application of microbial fuel cell (MFC), the power recovery from field-scale MFC needs to be improved considerably with simultaneous reduction in its fabrication cost. These problems can be addressed by applying low-cost and efficient cathode catalyst in MFCs. In this regard, Cu0.5Mn0.5Fe2O4 (CuMnFe) was synthesized and applied as cathode catalyst in lab and field-scale MFCs with capacity of 150 ml and 25 l, respectively. Lab-scale MFC having CuMnFe as cathode catalyst demonstrated power density of 176.0 ± 8.2 mW m−2, which was competitive with MFC having Pt as cathode catalyst (183.0 ± 12.6 mW m−2) and it was about seven times higher than control MFC (25.5 ± 4.5 mW m−2) having no catalyst. Application of CuMnFe as cathode catalyst in field-scale MFC produced power density of 7.74 mW m−2, which was three-times higher than the power produced by the field-scale MFC operated without any cathode catalyst (2.58 mW m−2). The cathode catalyst CuMnFe also demonstrated excellent anti-biofouling properties, which in turn improved the power production of field-scale MFC. Therefore, low-cost CuMnFe can be anticipated as an efficacious cathode catalyst for application in MFCs that would produce long term stable higher power, while offering simultaneous treatment to wastewater.

Performance evaluation of poly(aniline-co-pyrrole) wrapped titanium dioxide nanocomposite as an air-cathode catalyst material for microbial fuel cell.

A simple, inexpensive in situ oxidative polymerization of aniline and pyrrole using ammonium persulfate (APS) as oxidant and hydrochloric acid (HCl) as dopant has been used to synthesize a hybrid (PAni-Co-PPy)@TiO2 nanocomposite with titanium oxide (TiO2) nanoparticles (NPs) wrapped into (PAni-Co-PPy) copolymer. The synthesized nanocomposite has been shown with higher oxygen reduction reactions (ORR) as an excellent cathode material for higher performance in the complex of (PAni-Co-PPy)+/TiO2(O-). The charge transport phenomenon between TiO2 and (PAni-Co-PPy)+ were found adequate with subsequent delocalization of electron/s at PAni and PPy. The self-doping nature of TiO2 (O-) played a vital role in oxygen adsorption and desorption process. With higher electrical conductivity and surface area, these were tested in microbial fuel cells (MFCs) for ORRs at cathode. This yielded a relatively higher current and power density output as compared to PAni@TiO2, PPy@TiO2, and commercially available Pt/C cathode catalysts in MFC system. In overall, the prepared (PAni-Co-PPy)@TiO2 nano-hybrid cathode delivered ~2.03 fold higher power density as compared to Pt/C catalyst, i.e. ~987.36±49mW/m2 against ~481.02±24mW/m2. The properties of electro-catalysts established an improved synergetic effect between TiO2 NPs and (PAni-Co-PPy). In effect, the enhanced surface area and electrochemical properties of the prepared (PAni-Co-PPy)@TiO2 nano-hybrid system is depicted here as an effective cathode catalyst in MFCs for improved performance.

Application of synthesized porous graphitic carbon nitride and it's composite as excellent electrocatalysts in microbial fuel cell

The performance of microbial fuel cells (MFCs) consisting of exfoliated porous graphitic carbon nitride (ep-GCN) and its composite with acetylene black (AB) as cathode catalyst is evaluated. The cyclic voltammetry and electrochemical impedance spectroscopy of composite ep-GCN-AB indicated excellent oxygen reduction reaction activity and comparable charge transfer resistance with respect to Pt–C. The absence of X-ray diffraction peak at 2θ = 13° (corresponding to stacked structure of bulk GCN) indicated reduction in thickness. Four MFCs were operated with simulated wastewater with chemical oxygen demand (COD) of 3000 mg L−1. The maximum power densities of MFC-GAB (14.74 ± 0.17 W m−3), MFC-PAB (15.68 ± 0.58 W m−3) and MFC-G (12.47 ± 0.30 W m−3) using ep-GCN-AB, Pt–C and ep-GCN electrocatalyst, respectively, were 2.6, 2.7 and 2.2 times higher than MFC-AB operated with only acetylene black coated cathode. The investigation demonstrates that ep-GCN and its composites can be utilized as excellent cathode catalysts in MFCs at 20 folds lesser cost than Pt–C.

Metal–Organic Frameworks-Derived Core/Shell Porous Carbon Materials Interconnected by Reduced Graphene Oxide as Effective Cathode Catalysts for Microbial Fuel Cells

Microbial fuel cells (MFCs) are highly appealing for recovering electricity from organic matter, with the help of electrogenic bacteria. However, the lack of cost-efficient oxygen reduction reaction (ORR) catalysts is the main limitation for the performance of MFCs, and the development of highly electrocatalytic active ORR catalysts for MFCs remains very challenging. Here, core/shell carbon materials doped with Co and N (NC@CoNC) are prepared from bimetallic metal–organic frameworks (MOFs) via a facile pyrolysis method. After being interconnected by reduced graphene oxide (rGO), this unique NC@CoNC/rGO composite exhibits excellent electrocatalytic activity when used as the cathode catalyst in MFCs. The as-fabricated NC@CoNC/rGO catalyst facilitates favorable four-electron ORR, which can be due to the uniform distribution of Co nanoparticles, high N content, large surface area, and conductive graphene framework. Furthermore, the optimized NC@CoNC/rGO achieves a maximum power density of 2350 mW m–², which is even higher than that generated with commercial Pt/C (2002 mW m–²). This work demonstrates that the nonprecious metal catalyst NC@CoNC/rGO can be considered to be an good alternative in MFCs.

Development of an electroactive aerobic biocathode for microbial fuel cell applications.

Microbial biocathodes are gaining interest due to their low cost, environmental friendliness and sustainable nature. In this study, a microbial consortium was enriched from activated sludge obtained from a common textile effluent treatment plant in the absence of organic carbon source to produce an electroactive biofilm. Chronoamperometry method of enrichment was carried out for over 70 days to select for electroactive bacteria that could be used as a cathode catalyst in microbial fuel cells (MFC). The resultant biofilm produced an average peak current of -0.7 mA during the enrichment and produced a maximum power density of 64.6 ± 3.5 mW m-2 compared to platinum (72.7 ± 1.2 mW m-2 ) in a Shewanella-based MFC. Microbial community analysis of the initial sludge sample and enriched samples, based on 16S rRNA gene sequencing, revealed the selection of chemolithotrophs with the most dominant phylum being Bacteroidetes, Proteobacteria, Firmicutes, Actinobacteria and Acidobacteria in the enriched samples. A variety of CO2 fixing and nitrate-reducing bacteria was present in the resultant biofilm on the cathode. This study suggests that microbial consortia are capable of replacing expensive platinum as a cathode catalyst in MFCs.

Activated carbon-supported multi-doped graphene as high-efficient catalyst to modify air cathode in microbial fuel cells

It is difficult to apply microbial fuel cells (MFCs) basing on activated carbon air cathode in practical application because of the low efficiency of oxygen reduction reaction. Thus, exploring high-efficient catalyst to improve the cathode performance is of emergent significance. Herein, we synthesize an activated carbon-supported FeAgN multi-doped graphene as the air cathode catalyst in MFCs via a simple preparation and calcination of FeAg prussian blue analogues. As proved, the designed catalyst contributes to the decrease of the cathode's diffusion resistance and charge transfer resistance; meanwhile it immensely promotes the kinetics towards ORR by accelerating the migration of electron from the encapsulated bimetals to the surrounding carbon structure, indicating that the deposit of multi-doped graphene catalyst reinforces the cathode's conductivity and expedites the electron transfer process. The output power performances indicate that a highest maximum power density reaches up to 1956.45 mW m−2, which is 7 times higher than that of the control, foreboding the catalyst's potential application in MFCs.

Effectiveness of phase- and morphology-controlled MnO2 nanomaterials derived from flower-like δ-MnO2 as alternative cathode catalyst in microbial fuel cells.

Crystal phase and morphology variations obtained by simple high-temperature annealing offer promising strategies for employing nanostructured manganese oxide as a cathode catalyst for microbial fuel cells (MFCs). This study examines the effectiveness of simultaneous-phase and morphology-controlled manganese dioxide nanomaterials, designed by annealing a hydrothermally synthesized flower-like δ-manganese dioxide precursor at 300-800 °C, as cathode catalysts for MFCs. MFCs with the best-performing catalyst cathode (at a reasonable mass loading) were also analyzed through cyclic voltammetry and electrochemical impedance spectroscopy. Among MFCs with non-annealed and annealed manganese dioxide cathodes (0.5 mg cm-2), those with the catalyst annealed at 500 °C (148 ± 7 mW m-2, CE = 13 ± 1%) generated the most power (5-52%). MFCs with the catalyst annealed at 500 °C at a loading of 1 mg cm-2 as the cathode delivered the highest maximum power density (213 ± 9 mW m-2, CE = 13 ± 1%), representing 44% of that obtained using Pt/C at 0.5 mg Pt per cm2 (483 ± 11 mW m-2, CE = 18 ± 2%) and a comparatively low internal resistance (164 ± 2 Ω). Both cyclic voltammetry and electrochemical impedance spectroscopy results were consistent with empirical data. Compared with previously reported cathode materials, the annealed product from the precursor flower-like δ-manganese dioxide annealed at 500 °C (particularly at a loading of 1 mg cm-2) was a more reliable, efficient, and inexpensive sustainable cathode catalyst for scaled-up MFCs.

Sodium cobalt oxide as a non-platinum cathode catalyst for microbial fuel cells

Abstract Platinum has long been the best catalyst for microbial fuel cells (MFCs), but its high cost and limited resources have prompted us to find more abundant and less expensive alternatives. In this study, the potential of a sodium cobalt oxide (NaCo2O4) as a cathode catalyst for MFCs was investigated. A catalyst ink, prepared by mixing 50 wt% of Ketjenblack with NaCo2O4, was applied (4 mg cm−2 as NaCo2O4) to a waterproofed carbon to make an air-cathode. The activity of oxygen reduction reaction of the cathode was measured by the linear sweep voltammetry technique. The NaCo2O4 cathode exhibited about 50–90% current density of a cathode made with platinum-on-carbon catalyst at the same electric potential. This NaCo2O4 cathode was fit into a MFC, which was then run to treat synthetic wastewater. It exhibited the current density of about 3 A m−2. No decline in the current density or performance was observed over several days of operation. It exhibited the highest power density of 0.6 W m−2. Optimization of the cathode preparation conditions may further improve the cathode performance. This study suggests a promising potential of NaCo2O4 as a cathode catalyst for MFCs.

Application of Low-Cost Transition Metal Based Co0.5Zn0.5Fe2O4 as Oxygen Reduction Reaction Catalyst for Improving Performance of Microbial Fuel Cell

ABSTRACTOverpotential losses on cathode during oxygen reduction reaction (ORR) causes serious performance depletion in microbial fuel cells (MFCs). High cost of existing platinum based noble catalysts is one of the main reason for growing interest in the research of low cost sustainable cathode catalysts to improve ORR in order to enhance power generation from MFCs. The present study demonstrates application of low-cost bimetallic ferrite, Co0.5Zn0.5Fe2O4, as a cathode catalyst in MFC. The electrochemical tests of cathode having this catalyst revealed an excellent cathodic current response of 25.76 mA with less charge transfer resistance of 0.7 mΩ, showing remarkable catalytic activity. The MFC using this catalyst on cathode could generate a power density of 172.1 ± 5.2 mW/m2, which was found to be about 10 times higher than the power density of 15.2 ± 1.3 mW/m2 obtained from a MFC using only acetelyne black (AB) on cathode and noted even higher than the power density produced by MFC with Pt/C cathode (151.3 ± 2.8 mW/m2). In addition, the wastewater treatment in terms of chemical oxygen demand (COD) removal efficiency of MFC with Co0.5Zn0.5Fe2O4 on cathode was found to be better (87 %) among the tested MFCs. Hence, the results obtained from this study illustrates the applicability of Co0.5Zn0.5Fe2O4 as an excellent and suitable cathode catalyst for scaling up of MFCs.

Ferroelectric LiTaO3 as novel photo‐electrocatalyst in microbial fuel cells

Microbial fuel cells (MFCs) are a promising technology for simultaneous electricity generation and wastewater treatment. Noble materials can offer high catalyst performance in MFCs but their high cost poses an obstacle for the practical implementation of this technology. Ferroelectric materials such as LiTaO3 are a new generation of photocatalysts that could potentially be used for the oxygen reduction reaction in these devices. Thus, this work investigates the performance of LiTaO3 as cathode catalyst in MFCs for the first time. The power performance of carbon cloth cathodes coated with LiTaO3 was assessed in the presence and absence of light irradiation in MFC systems using wastewater. Prior to be tested in MFCs, the synthesized phase of LiTaO3 was mainly characterized by XRD, particle‐size distribution, TEM, and UV–vis spectroscopy analyses. The results show that the performance of the cathode coated with LiTaO3 significantly improves under UV–vis irradiation, with a threefold increase in maximum power density compared with the results obtained in the absence of light source. Under these conditions, COD removal from wastewater reached 66% after 120 h. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1568–1574, 2017

Production of Sustainable Energy by Carbon Nanotube/Platinum Catalyst in Microbial Fuel Cell

Platinum (Pt) is the most efficient and common cathode catalyst that is being applied in fuel cell technology, especially in microbial fuel cells (MFCs). However, its high price makes its use uneconomical in MFCs. Even though there are some other types of new catalysts, their performance could not compete with Pt. This is the main reason why scientists spend all their efforts to decrease the amount of Pt by making some composite of Pt for their use in MFCs thus making it viable and more economical. In this study, carbon nanotube-platinum (CNT/Pt) nanocomposite has been fabricated as a novel cathode catalyst in MFCs and its performance was compared with platinum in MFCs system. The CNT/Pt was synthesized by using the in situ method, and the performance is being compared in terms of power density generation in different concentration. The results have shown that CNT is a suitable support for catalyst in MFCs and CNT/Pt generally has better performance than Pt in MFCs. This can be due to better interaction with oxygen in the cathode chamber and high catalytic activity of CNT/Pt for oxygen reduction reaction. The potential of CNT/Pt nanocomposite in generating electricity from MFCs has been demonstrated and this can be a sustainable source of energy for the future.

Copper-phthalocyanine and nickel nanoparticles as novel cathode catalysts in microbial fuel cells

In this study, four different catalysts (i.e., carbon black, nickel nanoparticle (Ni)/C, Phthalocyanine/C and copper-phthalocyanine/C), were tested in a two-chamber Microbial Fuel Cell (MFC) and their performances were compared with Pt as the common cathode catalyst in MFC. The characterization of catalysts was done by TEM, XPS and EDX and their electrochemical characteristics were compared by cyclic voltammetry (CV) and Linear Sweep Voltammetry (LSV). The results proved that copper phthalocyanine and nickel nanoparticles are potential alternatives catalyst for Pt. Even copper-phthalocyanine generated power is almost the same as Pt. The CV and LSV results reported high electrochemical activity of these catalysts. The maximum power density and coulombic efficiency was achieved by copper-phthalocyanine/C as 118.2 mW/m2 and 29.3%.