Air Cathode Research Articles

Optimizing the economic viability of proton exchange membrane fuel cells operated with oxygen-enriched cathode air for residential hydrogen energy storage systems

The recovery and utilization of oxygen in residential hydrogen energy storage systems significantly impact economic factors. This study introduces an algorithm tailored to optimize oxygen concentration (fraction) across varied operational conditions, encompassing considerations for both efficiency (positive aspect) and lifetime (negative aspect). Initially, an enhanced air supply system (ASS), functioning with oxygen-enriched cathode air, is devised following the forefront scheme. Moreover, a dynamic model is formulated based on MATLAB/Simulink® software for the proton exchange membrane fuel cell (PEMFC) system. The model enables quantitative assessment of system gains in relation to various current densities and oxygen fractions, and its accuracy is partially validated through experimental data. Further, a model correlating stack lifetime to oxygen concentration (fraction) is established using experimental data obtained from other researchers. Finally, the optimal oxygen fractions are determined and managed, with a comparison of the effects before and after optimization. The optimized results indicate a 13% improvement in stack net power at rated operating conditions and a 24% improvement at peak operating conditions, and the system efficiency is improved by 24% and 43% at rated and peak operating conditions, respectively. In addition, the minimum value of system efficiency is observed to be 54%, and there is a notable attenuation of the concentration polarization phenomenon. This approach contributes to mitigating the challenge of lower system efficiency in normal PEMFCs for residential hydrogen energy storage systems (RHESSs) attributed to inadequate gas supply pressure.

Polyoxometallate Cluster Induced High-Entropy Oxide Sub-1 nm Nanosheets as Photoelectrocatalysts for Zn-Air Batteries.

The lack of highly efficient and inexpensive catalysts severely hinders the large-scale application of Zn-air batteries (ZABs). High-entropy oxides (HEOs) exhibit unique structures and attractive properties; thus, they are promising to be used in ZABs. However, conventional high-temperature synthesis methods tend to obtain microscale HEOs with a lower exposure rate of active sites. Here, we report a facile solvothermal strategy for preparing two-dimensional (2D) HEO sub-1 nm nanosheets (SNSs) induced by polyoxometalate (POM) clusters. Taking advantage of the special 2D sub-1 nm structure and precise element regulation, these 2D HEOs-POM SNSs exhibit enhanced bifunctional oxygen evolution and oxygen reduction reaction activity under light irradiation. Further applying these 2D HEOs-POM SNSs to ZABs as cathode catalysts, the CoFeNiMnCuZnOx-phosphomolybdic acid SNSs-based ZABs deliver a low charge/discharge voltage gap of 0.25 V at 2 mA cm-2 under light irradiation. Meanwhile, it could maintain an ultralong-term stability for 1600 h at 2 mA cm-2 and 930 h at 10 mA cm-2. The 2D sub-1 nm structure and fine element control in HEOs provide opportunities to solve the problems of low intrinsic activity, limited active sites, and instability of air cathodes in ZABs.

Efficient water recovery and power generation system based on air-cooled fuel cell with semi-closed cathode circulation mode

Air-cooled proton exchange membrane hydrogen fuel cell with on-line hydrogen production by hydrolysis has potential for portable applications due to its high volumetric power density and self-humidification. However, plenty of reserve water significantly reduces the power density of fuel cell system. Moreover, water recovery from fuel cell tail gas is difficult, because the tail gas humidity is very low due to excess cathode air as coolant. In this work, the dead-ended anode and semi-closed cathode proton exchange membrane fuel cell is proposed to achieve efficient water recovery and energy conversion via semi-closed cathode circulation mode. In this mode, cathode O2-poor tail gas is recycled as coolant instead of fresh air, which helps to enlarge the tail gas humidity by reducing the stoichiometric ratio of cathode to anode gas. The system lumped model with detailed component description is developed for optimization. >96% water production can be recycled under atmosphere temperature. The demand of fresh air is greatly reduced from 56 to 2 times of the consumption. Besides, the multi-objective optimization between water recovery and electrochemical performance shows high-efficiency water recovery of 94.70% and high energy conversion efficiency of 54.82%.

An Innovative Approach to Assess the Potentiality of Using Activated Carbon and Rice Husk Ash in Aluminum-Air Battery

Aluminum-air (Al-air) cells have the potential to become vital in energy storage applications in the future because of their high energy density, which is even higher than that of commonly used lithium-ion batteries. However, it is not used widely because the cost of air cathode catalysts and metal anode is high. However, suppose the catalysts are replaced with activated carbon or rice husk ash as an alternative and recycled aluminum foil as an anode. In that case, the production cost might be feasible for the vast use of this type of cell. This study's main objective is to utilize some commonly available material in fabricating an Al-air battery suitable for small and day-to-day usage, reducing production costs and limitations. In this paper, a focused analysis was made on the feasibility of using an activated carbon and rice husk mixture as an air cathode catalyst for an Al-air cell, and the observations were interesting. About 11 samples of a mixture of rice husk ash (RHA) and activated carbon (AC) in different ratios have been made to find the best results from 0.68-0.72 V, which increases by 8-20%, measuring each sample after 3 days. In this study, another attempt was made to replace the graphite cathode of a dry cell with a mixture of AC and RHA. Voltage drop is quite negligible for the mixture of 10% RHA. The resulting voltage is similar to the new 100% activated carbon battery as a cathode. If considering the environmental effect, using recycled activated carbon and rice husk ash will decrease pollution and open a new door to apply in primary cells.

Low-Overpotential Rechargeable Na-CO2 Batteries Enabled by an Oxygen-Vacancy-Rich Cobalt Oxide Catalyst.

Rechargeable sodium-carbon dioxide (Na-CO2) batteries have been proposed as a promising CO2 utilization technique, which could realize CO2 reduction and generate electricity at the same time. They suffer, however, from several daunting problems, including sluggish CO2 reduction and evolution kinetics, large polarization, and poor cycling stability. In this study, a rambutan-like Co3O4 hollow sphere catalyst with abundant oxygen vacancies was synthesized and employed as an air cathode for Na-CO2 batteries. Density functional theory calculations reveal that the abundant oxygen vacancies on Co3O4 possess superior CO2 binding capability, accelerating CO2 electroreduction, and thereby improving the discharge capacity. In addition, the oxygen vacancies also contribute to decrease the CO2 decomposition free energy barrier, which is beneficial for reducing the overpotential further and improving round-trip efficiency. Benefiting from the excellent catalytic ability of rambutan-like Co3O4 hollow spheres with abundant oxygen vacancies, the fabricated Na-CO2 batteries exhibit extraordinary electrochemical performance with a large discharge capacity of 8371.3 mA h g-1, a small overpotential of 1.53 V at a current density of 50 mA g-1, and good cycling stability over 85 cycles. These results provide new insights into the rational design of air cathode catalysts to accelerate practical applications of rechargeable Na-CO2 batteries and potentially Na-air batteries.

Multi-objective optimization for impeller structure parameters of fuel cell air compressor using linear-based boosting model and reference vector guided evolutionary algorithm

As a pivotal part of cathode air supply system, centrifugal air compressors play a central position in ensuring efficient operations of onboard fuel cells. To improve the overall performance of compressors, comprehensive performance tests were conducted and an integrated simulation model was developed by using computational fluid dynamics (CFD) methods. On this basis, the prediction performance of Linear-based Boosting models was investigated, and multi-objective optimization of impeller structural parameters was carried out through the Reference Vector Guided Evolutionary Algorithm (RVEA). Simulation results indicate that the impeller of the original compressor exhibits significant entropy increase, insufficient gas compression and serious energy dissipation, highlighting considerable room for design optimization. The eXtreme Gradient Boosting (XGBoost) model with 29 estimators has superior generalization ability and prediction performance, making it the preferred Boosting model for the compressor. Multi-objective optimizations have strong universality and rationality, resulting in a well-distributed and diversified final non-dominated solution set. The isentropic efficiency and pressure ratio of the Max_σ solution are improved by 18.7% and 70.1%, while those of the Max_ηc solution are enhanced by 23.0% and 48.9%, respectively. After optimization, the gas experiences reduced shock loss, diminished entropy increase and enhanced flow stability. These findings can provide data support, theoretical basis and directional guidance for performance improvement of centrifugal air compressors.

Air-breathing Mg-Cu/CuO fuel cell

Magnesium fuel cells deliver higher electrical power output than lithium-ion batteries and have the potential to become an economically attractive alternative power source for domestic purposes. In place of noble metals in the air cathode of Mg fuel cells, we investigate the use of an integrated structure of a catalyst and current collector composed of a Cu/CuO hetero-structure. For a single cell, comprising of electrodes of dimension 3 cm × 1.5 cm with aqueous NaCl as the electrolyte, the Mg- Cu/CuO-based fuel cell shows an open-circuit voltage of 0.7 V and discharge current drain rate of 0.45 mA/s. A power density of 8.75 µWcm−2 is obtained with a CuO-based cathode when 1 M NaCl electrolyte is used. Relative to the magnesium-carbon-based fuel cell, the Mg-Cu/CuO fuel cell shows improved stability of the anode and cathode materials and extended operational time.

Inhibiting effects of humic acid on iron flocculation hindered As removal by electro-flocculation on air cathode iron anode

Activated carbon air cathode combined with iron anode oxidation-flocculation synergistic Arsenic (As) removal was a new groundwater purification technology with low energy consumption and high efficiency for groundwater with high As concentration. The presence of organic matter such as humic acid (HA) had ambiguous effects on formation of organic colloids in the system. The effects of the particle size distribution characteristics of these colloids on the formation characteristics of flocs and the efficiency of As purification was not clear. In this work, we used five different pore size alumina filter membranes to separate mixed phase solutions and studied the corresponding changes in iron and arsenic concentrations in the presence and absence of humic acid conditions. In the presence of HA, the arsenic concentration of < 0.05 µm particle size components was 1.01, 1.28, 3.07, 7.69, 2.85 and 1.24 times of that in the absence of HA. At the same time, the arsenic content in 0.05–0.1 µm and 0.1–0.45 µm particle size components was also higher than that in the system without HA, which revealed that the presence of HA hindered the flocculation behavior of As distribution to higher particle sizes in the early stage of the reaction. The presence of HA affected the flocculation rate of iron flocs from small to large particle size fractions and it had limited effect on the behavior of large-size flocs in adsorption of As. These results provide a theoretical basis for targeted, rapid, and low consumption synergistic removal of arsenic and organic compounds in high arsenic groundwater.

An integrated constructed wetland-Microbial fuel cell system with sewage sludge-biochar to enhance treatment and energy recovery efficiencies

Constructed wetlands and microbial fuel cells (CW-MFCs) are a promising green and sustainable wastewater treatment technology. However, the power production performance of CW-MFCs has long been limited by low-performance cathodes. In this study, we designed two CW-MFC systems using cheap and readily available sewage sludge biochar (SSB) as the substrate for the experimental units. The integration of SSB significantly facilitated the removal of chemical oxygen demand, ammonium nitrogen, total nitrogen, and total phosphorus. Moreover, SSB enhanced the electrochemical performance of the air cathode, resulting in higher power density (44.64 mW/m2) and lower internal resistance (900.00 Ω) compared to gravel-integrated CW-MFC (0.88 mW/m2, 2057.14 Ω). In addition, a typical electroactive bacterium---Geobacter was enriched in the SSB-integrated CW-MFC system. The iron oxides and graphic nitrogen of the SSB favor the growth of Geobacter, and the redox-active groups on the surface of SSB accelerate the extracellular electron transfer process, contributing to the enhancement of treatment performance. Meanwhile, the metal and nitrogen doping improves the oxygen reduction reaction activity and conductivity of SSB, enhancing the cathode area of CW-MFC and improving the energy recovery. Overall, these results demonstrated that SSB-integrated CW-MFC can be a competitive technology for effective wastewater treatment and energy recovery.

Air cathode performance of Fe/N/Cs synthesized from legume biomasses in microbial fuel cells

In this study, Fe/N/Cs oxygen reduction reaction (ORR) catalysts with high specific surface area, catalytic activity were synthesized using legume biomass with different protein content. The catalytic activity of the Fe/N/C catalysts was confirmed to be related to the protein content of the biomass precursor by characterization and electrochemical tests. The catalysts (named as Fe/N/C-T) from lactone tofu have the highest N/C ratio related to ORR, and the air-cathode loaded with Fe/N/C-T catalysts exhibited the best ORR performance in linear sweep voltammetry (LSV) tests, which was comparable to that of commercial Pt/C catalysts. MFCs with AC(Fe/N/C-T) air-cathode produced a maximum power density of 0.486 mW cm−2, higher than Pt/C (0.437 mW cm−2) with the same loading. In addition, the Fe/N/C-T catalyst demonstrated high stability and resistance to toxicity in long-term operation, which can be an alternative to commercial Pt/C.

Enhancing the Proton Exchange Membrane in Tubular Air-Cathode Microbial Fuel Cells through a Hydrophobic Polymer Coating on a Hydrogel.

The usage time of air-cathode microbial fuel cells (MFCs) is significantly influenced by the moisture content within the proton exchange membrane (PEM). Therefore, enhancing the water retention capability of the PEM by applying a hydrophobic polymer coating to its surface has extended the PEM's usage time by three times and increased MFCs' operational duration by 66%. Moreover, the hydrophobic nature of the polymer coating reduces contamination on the PEM and prevents anode liquid from permeating into the air cathode. Towards the end of MFC operation, the internal resistance of the MFC is reduced by 45%. The polymer coating effectively maintained the oxygen reduction reaction activity in the cathode. The polymer coating's ability to restrict oxygen transmembrane diffusion is demonstrated by experimental data showing a significant decrease in oxygen diffusion coefficient due to its presence. The degradation efficiency of the chemical oxygen demand from 16% to 35% increased by a factor of one.

A stepwise thermal migration for inducing copper nanoparticles to boost oxygen reduction activity of single-atomic copper sites

Although single-atom M-N-C electrocatalysts have demonstrated their potential in metal-air batteries and fuel cells, their activity for oxygen reduction reaction (ORR) needs to be further improved. Regulating the electronic structure of M-Nx single sites to accelerate the activity and simultaneously directly identify the enhancement mechanisms is highly desirable but remains a challenge. Here we propose a stepwise thermal migration strategy to in situ introducing Cu nanoparticles (Cu-NPs) adjacent to single atoms Cu (Cu-SAs) confined into hierarchically porous carbon. The optimization of the electronic structure of the Cu-Nx site by adjacent Cu nanoparticles is confirmed by both enhanced ORR activity and theoretical calculations. The optimized CuSA-NP@NC exhibits a more positive half-wave potential (0.870 V) than CuSA@NC (0.842 V) and superior stability with an 86.6% ORR current retention after 24 hours of chronoamperometric test in alkaline electrolyte. When utilized as an air cathode in rechargeable Zn-air batteries, CuSA-NP@NC displays a high-power density of 224.1 mWcm−2 and a specific capacity of 802.0 mAh g−1. Theoretical calculations demonstrate that the introduction of Cu-NPs endows the Cu-N4 site with an enriched electron density, which optimizes the adsorption/desorption of ORR intermediates on the Cu-N4 sites. This work reports an effective way and provides insights into the ORR activity improvement of single-atom electrocatalysts.

Lithium-Induced Oxygen Vacancies in MnO2@MXene for High-Performance Zinc-Air Batteries.

The traditional methods for creating oxygen vacancies in materials present several challenges and limitations, such as high preparation temperatures, limited oxygen vacancy generation, and morphological destruction, which hinder the application of transition metal oxides in the field of zinc-air batteries (ZABs). In order to address these limitations, we have introduced a pioneering lithium reduction strategy for generating oxygen vacancies in δ-MnO2@MXene composite materials. This strategy stands out for its simplicity of implementation, applicability at room temperature, and preservation of the material's structural integrity. This research demonstrates that aqueous Ov-MnO2@MXene-5, with introduced oxygen vacancies, exhibits an outstanding oxygen reduction reaction (ORR) activity with an ORR half-wave potential reaching 0.787 V. DFT calculations have demonstrated that the enhanced activity could be attributed to adjustments in the electronic structure and alterations in adsorption bond lengths. These adjustments result from the introduction of oxygen vacancies, which in turn promote electron transport and catalytic activity. In the context of zinc-air batteries, cells with Ov-MnO2@MXene-5 as the air cathode exhibit outstanding performance, featuring a significantly improved maximum power density (198.3 mW cm-2) and long-term cycling stability. Through the innovative strategy of introducing oxygen vacancies, this study has successfully enhanced the electrochemical catalytic performance of MnO2, overcoming the limitations associated with traditional methods for creating oxygen vacancies. Consequently, this research opens up new avenues and directions for nonprecious metal catalyst application in ZABs.

Atomically Dispersed Dual-Metal ORR Catalyst with Hierarchical Porous Structure for Zn-Air Batteries.

The metal-nitrogen-carbon (M-N-C)-based catalysts are promising to replace PGM (platinum group metal) to accelerate oxygen reduction reaction due to their excellent electrocatalytic performance. However, the inferior intrinsic activity and poor active site density confining further improvement in their performance. Modulating the electronic structure and reasonably designing the pore structure are widely acknowledged effective strategies to boost the activity of the M-N-C catalysts. However, it is a great challenge to form abundant pores to regulate the electronic structure via the facile method. Herein, a hierarchical, porous dual-atom catalyst FeNi-NPC-1000 has been architectured by the Na2CO3 template method and bimetallic doping modification strategy. Benefitting from the optimized pore and electronic structure, the as-prepared FeNi-NPC-1000 possesses a high specific surface area (1412.8 m2 g-1) and improved ORR activity (E1/2 = 0.877 V vs RHE), which is superior to that of Pt/C (E1/2 = 0.867 V vs RHE). With the evidence of AC-STEM, XAS, and DFT, the FeNi-N8-C moiety is proven to be the key active site to realize high-efficiency ORR catalysis. When assembled it as an air cathode of ZABs, FeNi-NPC-1000 displays superior discharge performance (Pmax = 367.1 mW cm-2) and a stable battery long-life. This article will provide a new strategy for designing dual-metal atomic catalysts applied in metal-air batteries.

P-doped RuPd nanoparticles anchored on Y2Ru2-xPdxO7 pyrochlore oxide surface as oxygen evolution and reduction electrocatalysts for Zn-air battery

Metal-air battery technology is the most promising green technology. However, the sluggish kinetics of the oxygen evolution/reduction reaction (OER and ORR), which are key reactions in air cathode, must be improved. In this study, Pd substitution was introduced into Y2Ru2O7 pyrochlore oxides and the ratio of Pd was varied (YRPO-x). Then, P-doped RuPd nanoparticles were synthesized on Pd-substituted YRPO pyrochlore (YRPO/RuPd-P) by an in situ exsolution process to create bifunctional electrocatalysts facilitating both reactions. The uniquely designed YRPO/RuPd-P catalyst exhibited the OER overpotential and Tafel slope (Ej10 = 232 mV; Tafel slope = 37.1 mV/dec). Furthermore, YRPO/RuPd-P shows an E1/2 of 0.82 V, indicating superior ORR activity. This was further investigated by applying in a unit-cell battery system, which showed an outstanding power density (163 mW/cm2) and robust charge–discharge stability. This study proposes a novel design strategy for bifunctional electrocatalysts.

Many-objective optimization for structural parameters of the fuel cell air compressor based on the Stacking model under multiple operating conditions

As the central element of the cathode air supply system, the centrifugal air compressor is pivotal to the regular and efficient operation of on-board fuel cells. In an attempt to further enhance the overall properties of the air compressor, the computational fluid dynamics (CFD) simulation model and Stacking model are developed and calibrated in this study. On this basis, the Many-Objective Random Walk Gray Wolf Optimizer (MORW-GWO) algorithm is proposed to perform many-objective optimization for compressor structural parameters, and the intrinsic mechanisms of performance improvements are elaborated based on three-dimensional flow analysis. The results indicate that the Stacking model achieves excellent predictive performance and generalization ability through the coupling and mutual error correction of base learners and the meta-learner. The MORW-GWO algorithm demonstrates outstanding many-objective optimization capability, convergence ability and universality. Compared to the original compressor, the optimized air compressor achieves improvements of 2.8%, 2.3%, 9.3% and 16.0% in the pressure ratio, outlet temperature, isentropic efficiency and adiabatic compression work, respectively. Besides, it is found that the internal energy loss, separation loss, friction loss, gas leakage and backflow of the optimized air compressor are reduced through the 3-D flow characteristic analysis. The findings can contribute to the many-objective optimization of compressor structural parameters by giving theoretical guidance, data support and directional evidence.

Synergistic Fe and Co binary single atoms based air cathodes for high performance and ultra-stable Zn-air batteries

Cost-effective highly efficient and stable air cathodes are critical for practical applications of rechargeable Zn-air batteries (ZABs). In this work, air cathodes constructed by loading carbon nanotube supported N-doped carbon anchored Fe and Co binary single atoms, f-Fe1Co1/CNT, in carbon paper composited nickel foams, NF/CP, were developed for ZABs, exhibiting outstanding bifunctional oxygen electrocatalytic activities (ΔE = 0.671 V) with a half-wave potential (E1/2) of 0.880 V (vs. RHE) for oxygen reduction reaction (ORR) and an overpotential of 321 mV at 10 mA cm−2 (η10) for oxygen evolution reaction (OER) in 0.1 M KOH, which outperformed the benchmark (Pt/C+IrO2)-based air cathode (ΔE = 0.773 V, E1/2 = 0.850 V, η10 = 393 mV). With the unique air cathode design of compositing catalyst-loading layer (nickel foam) with gas diffusion layer (carbon paper), the f-Fe1Co1/CNT@NF/CP//Zn ZAB delivered a remarkable discharge peak power density of 282.1 mW cm−2 at an ultra-high current density of 427.7 mA cm−2 and maintained an ultra-small potential gap of 0.75 V after operations at 10 mA cm−2 for 3300 cycles (1100 h), largely outperforming the (Pt/C+IrO2)@NF/CP//Zn ZAB (162.4 mW cm−2 at 247.3 mA cm−2, 0.86 V, 590 cycles). Density functional theory calculations revealed the positive long-range synergy between Fe-N4 and Co-N4 single atoms, significantly reducing the free energies of the rate-determining steps, oxygen protonation for ORR and formation of oxyhydroxides for OER at the main active site Fe-N4, to realize the much enhanced oxygen electrocatalytic activities.

High-Density CoSe2 Sites Embedded within 2D Porous N-Doped Carbon for High-Performance Oxygen Reduction Reaction Electrocatalysis.

Designing and fabricating efficient and stable nonprecious metal-based oxygen reduction reaction (ORR) electrocatalysts is a pressing and challenging task for the pursuit of sustainable new energy devices. Herein, porous P-CoSe2@NC electrocatalysts with high-density carbon-coated CoSe2 sites were successfully fabricated based on a pyridyl-porphyrinic metal-organic framework (Co-TPyP MOF) via a molten salt-assisted synthesis method. The hierarchical pore and N-doping carbon substrate of P-CoSe2@NC promotes mass transfer and electron-transfer efficiency, which is beneficial to maximize CoSe2 site utilization. Well-designed P-CoSe2@NC exhibits efficient ORR catalytic activity with a high half-wave potential of 0.863 V and excellent catalytic stability. Meanwhile, rechargeable aqueous primary/quasi-solid-state ZABs based on a P-CoSe2@NC air cathode show a high peak power density and exceptional operating stability, catering to the demands of practical applications. The qualified performance and structure stability of the electrocatalytic system may be mainly attributed to the protection of the CoSe2 nanoparticle by the coated carbon layer. Given the rational design of the structure and the component of the electrocatalyst with enhanced ORR activity, we believe that this work has provided a reliable pathway to the development of high-performance transition-metal chalcogenides for energy-storage and -conversion devices.

Assessing the Performance of Continuous-Flow Microbial Fuel Cells and Membrane Electrode Assembly with Electrodeposited Mn Oxide Catalyst

Microbial fuel cells (MFCs) are considered promising energy sources whereby chemical energy is converted into electricity via bioelectrochemical reactions utilizing microorganisms. Several factors affect MFC performance, including cathodic reduction of oxygen, electrode materials, cell internal and external resistances, and cell design. This work describes the effect of the catalyst coating in the air-cathode membrane electrode assembly (MEA) for a microbial fuel cell (MFC) prepared via electrodeposition of manganese oxide. The characterization of the synthesized air-cathode MFC, operating in a continuous mode, was made via electrochemical impedance spectroscopy (EIS) analyses for the determination of the intrinsic properties of the electrode that are crucial for scalability purposes. EIS analysis of the MFCs and of the MEA reveals that the anode and cathode contribute to polarization resistance by about 85% and 15%, respectively, confirming the high catalytic activity of the Mn-based air cathode. The maximum power density of the Mn-based cathode is about 20% higher than that recorded using a Pt/C electrode.

Performance of a Fe-N-C Catalyst in Single-chamber MFC Air-cathode at Neutral Media

Performance of a Fe-N-C Catalyst in Single-chamber MFC Air-cathode at Neutral Media