Synthesis of bimetallic iron ferrite Co0.5Zn0.5Fe2O4 as a superior catalyst for oxygen reduction reaction to replace noble metal catalysts in microbial fuel cell

A low-cost electrochemically active oxygen reduction reaction (ORR) catalyst is obligatory for making microbial fuel cells (MFCs) sustainable and economically viable. In this endeavour, a highly active surface modified ferrite, with Co and Zn bimetal in the ratio of 1:1 (w/w), Co_0.5Zn_0.5Fe₂O₄ was synthesised using simple sol-gel auto combustion method. Physical characterisation methods revealed a successful synthesis of nano-scaled Co_0.5Zn_0.5Fe₂O₄. For determination of ORR kinetics of cathode, using Co_0.5Zn_0.5Fe₂O₄ catalyst, electrochemical studies viz. cyclic voltammetry and electrochemical impedance spectroscopy were conducted, which demonstrated excellent reduction current response with less charge transfer resistance. These electrochemical properties were observed to be comparable with the results obtained for cathode using 10% Pt/C as a catalyst on the cathode. The MFC using Co_0.5Zn_0.5Fe₂O₄ catalysed cathode could produce a maximum power density of 21.3 ± 0.5 W/m³ (176.9 ± 4.2 mW/m²) with a coulombic efficiency of 43.3%, which was found to be substantially higher than MFC using no catalyst on the cathode 1.8 ± 0.2 W/m³ (15.2 ± 1.3 mW/m²). Also, the specific power recovery per unit cost for MFC with Co_0.5Zn_0.5Fe₂O₄ catalysed cathode was found to be 4 times higher as compared to Pt/C based MFC. This exceptionally low-cost cathode catalyst has enough merit to replace costly cathode catalyst, like platinum, for scaling up of the MFCs.     

Using rhodium as a cathode catalyst for enhancing performance of microbial fuel cell

Rhodium with activated carbon as carbon base layer (Rh/AC) was exploited as an oxygen reduction reaction (ORR) catalyst to explore its applicability in microbial fuel cell (MFC). Four MFCs were fabricated using the Rh/AC catalyst, adopting varying Rh loadings of 0.5, 1.0 and 2.0 mg cm⁻² and without Rh on carbon felt cathode in order to understand the optimum loading of this catalyst to enhance the performance of MFC. The participation of Rh/AC in ORR was confirmed by cyclic voltammetry and electron impedance spectroscopy analysis, which supported the enhanced charge transfer capacity of the cathode modified with the prepared catalysts. Volumetric power density of MFC was found to be improved by 2.6 times when Rh/AC was used as cathode catalyst (9.36 W m⁻³) at a loading of 2.0 mg cm⁻² in comparison to the control MFC (3.65 W m⁻³) without Rh on the cathode. It was thus inferred that the increase in the Rh loading up to 2 mg cm⁻² can improve the performance of MFC significantly.     

Enhanced bioelectrochemical performance by NiCoAl-LDH/MXene hybrid as cathode catalyst for microbial fuel cell

In this work, NiCoAl-layered double hydroxide (LDH)/MXene was successfully prepared through straightforward hydrothermal method. NiCoAl-LDH was tightly and uniformly coated on MXene, forming a kind of porous structure. NiCoAl-LDH/MXene exhibited the (002) (012) (105) (100) crystal planes of hydrotalcite reflection. NiCoAl-LDH/MXene also showed superior catalytic oxygen reduction reaction (ORR) in response current according to electrochemical test (cyclic voltammetry (CV) etc.). The maximum power density and output voltage of NiCoAl-LDH/MXene as cathode in microbial fuel cell (MFC) was 362.404 mW/m² and 450 mV, respectively, which was 1.54 times of MXene-MFC (234.256 mW/m²) and 1.71 times of NiCoAl-LDH-MFC (211.56 mW/m²). The results indicated that NiCoAl-LDH/MXene was a kind of potential cathode catalyst for MFC and was full of future application.     

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.     

Evaluation of TiO2 as catalyst support in Pt-TiO2/C composite cathodes for the proton exchange membrane fuel cell

Anatase TiO₂ is evaluated as catalyst support material in authentic Pt-TiO₂/C composite gas diffusion electrodes (GDEs), as a different approach in the context of improving the proton exchange membrane fuel cell (PEMFC) cathode stability. A thermal stability study shows high carbon stability as Pt nanoparticles are supported on TiO₂ instead of carbon in the Pt-TiO₂/C composite material, presumably due to a reduced direct contact between Pt and C. The performance of Pt-TiO₂/C cathodes is investigated electrochemically in assembled membrane-electrode assemblies (MEAs) considering the added carbon fraction and Pt concentration deposited on TiO₂. The O₂ reduction current for the Pt-TiO₂ alone is expectedly low due to the low electronic conductivity in bulk TiO₂. However, the Pt-TiO₂/C composite cathodes show enhanced fuel cell cathode performance with growing carbon fraction and increasing Pt concentration deposited on TiO₂. The proposed reasons for these observations are improved macroscopic and local electronic conductivity, respectively. Electron micrographs of fuel cell tested Pt-TiO₂/C composite cathodes illustrate only a minor Pt migration in the Pt-TiO₂/C structure, in which anatase TiO₂ is used as Pt support. On the whole, the study demonstrates a stable Pt-TiO₂/C composite material possessing a performance comparable to conventional Pt–C materials when incorporated in a PEMFC cathode.     

Ameliorated performance of a microbial fuel cell operated with an alkali pre-treated clayware ceramic membrane

Clayware membrane amalgamated with 20% montmorillonite (M-20), acts as an excellent cost effective proton exchange membrane (PEM) for the application in field-scale microbial fuel cells (MFCs). In this investigation, M-20 membrane was pre-treated by acid (M-A), neutral water (M-N) and alkali (M-B), followed by the determination of the membrane properties to access their applicability in MFCs. With alkali treatment of M-20 membrane, maximum proton mass transfer coefficient of 6 × 10⁻⁶ cm s⁻¹ was obtained, which was nearly five times higher than M-A (1.15 × 10⁻⁶ cm s⁻¹) and four times higher than the control membrane, M-N. Proton conductivity was also found to be maximum for M-B (17.9 × 10⁻³ S cm⁻¹), which was four times higher than both M-N (4.4 × 10⁻³ S cm⁻¹) and M-A (4.6 × 10⁻³ S cm⁻¹). Oxygen mass transfer coefficient was found to be minimum for M-B (4.02 × 10⁻⁵ cm s⁻¹), which was considerably lesser than that observed for M-N (16.2 × 10⁻⁵ cm s⁻¹) and M-A (13.8 × 10⁻⁵ cm s⁻¹). Cation transport number of M-B (0.15 ± 0.01) was found to be two folds lower than M-N, demonstrating M-B is more selective towards proton transport compared to other cations. The MFC-B with M-B as PEM performed superior as compared with other MFCs, demonstrating coulombic efficiency (CE) of 10.2%, chemical oxygen demand (COD) removal efficiency of 88% and power density of 83.5 mW m⁻². On the other hand, MFCs using M-A and M-N as PEM, demonstrated mediocre performance with CE of 6% and 7.6%, COD removal efficiency of 80% and 83% and power density of 40.4 ± 6.2 mW m⁻² and 64.0 ± 5.8 mW m⁻², respectively. Hence, alkali treatment of clayware ceramic membrane elucidated its appropriateness for proliferating the efficacy of MFCs and these are recommended for scaling up of MFCs.     

High-capacity polyaniline-coated molybdenum oxide composite as an effective catalyst for enhancing the electrochemical performance of the microbial fuel cell

Microbial fuel cells (MFCs) are a promising technology, which can generate electrical energy by utilizing the organic compound as fuels through central metabolism system of exo-electrogenic bacteria. Anodes have been intensively explored for the development of high-performance MFCs as an alternative to conventional electrodes. Modified anodes were synthesized by the coating of molybdenum oxide (MoO₂) and polyaniline (PANI) composites on the carbon cloth (CC) surface. MoO₂/PANI electrocatalyst anodes have high capacitance and electrical conductivity, experimentally affirmed by cyclic voltammetry (CV)and charge-discharge analysis. The as-prepared modified anodes were found to efficiently enhance the performance of MFCs by facilitating the extracellular electron transfer from bacteria to the anode. MFCs with MoO₂/PANI (1:2 w/w) electrocatalyst anode delivered a maximum power density (PD) of 1101 mW/m², which was 7.8 times higher than unmodified CC anode. EIS results indicate that the composite MoO₂/PANI has also responsible for decreasing the interfacial charge transfer resistance which leads to the improvement in electron transfer between microbes and the modified anode. The results found in the present study will help in the design optimization of novel anode materials to deliver improved PD from MFCs.     

Assessment of immobilized cell reactor and microbial fuel cell for simultaneous cheese whey treatment and lactic acid/electricity production

Two biological methods for treatment of cheese whey and concentrated cheese whey were investigated in this research. As the first method, fermentation of cheese whey for production of lactic acid, in an immobilized cell reactor (ICR) was successfully carried out. The immobilisation of Lactobacillus bulgaricus was performed by the enriched cells cultured media harvested at exponential growth phase. Furthermore, the FTIR analysis has been done to prove the production of lactic acid. The COD removal during the continuous process for both whey and concentrated whey was above 70% which showed the capability of reaction for wastewater treatment. The cells were immobilised by sodium alginate as a perfect polymer in this regard. The maximum produced lactic acid from whey was 10.7 g l^?1 at 0.125 h^?1 and 19.5 g l^?1 from concentrated whey at 0.063 h^?1. Finally it can be concluded that the process is efficient for lactic acid production and COD removal simultaneously. As the second studied method, whey and concentrated cheese whey were used as the sources of carbon in a microbial fuel cell. The power densities of 188.8 and 288.12 mW m^?2 were recorded for whey-fed and concentrated whey-fed MFCs while the COD removal were 95% and 86% respectively. Biological wastewater treatment can be a very efficient alternative for traditional wastewater treatment which selecting any and or integrating of them depends on specific applications needed to be achieved.     

Carbon supported nickel-phthalocyanine/MnOx as novel cathode catalyst for microbial fuel cell application

Performance of microbial fuel cells (MFCs) with carbon supported nickel phthalocyanine (NiPc)MnO_x composite (MFC-1) and nickel phthalocyanine (MFC-2) incorporated cathode was compared with a control MFC with non-catalysed carbon felt as cathode (MFC-3) and MFC-4 having Pt on cathode (as benchmark reference control). MFC-1 exhibited power density of 8.02 Wm^?3, which was four folds higher than control MFC-3 (2.08 Wm^?3) and 1.14 times higher than MFC-2 (6.97 Wm^?3). Coulombic efficiency of 30.3% obtained in MFC-1 was almost double of that obtained for control MFC-3 and it was 5.4% lesser as compared to MFC-4 (35.7%). Linear sweep voltammetry study of cathodes revealed that NiPc-MnO_x could enhance the electrocatalytic activity of oxygen reduction reaction (ORR) in comparison to control cathode. However, the power recovery from MFC-1 was noted little lower than what obtained from MFC-4 (10.58 Wm^?3), however the cost normalized power was two times higher than Pt catalyst on cathode. Thus, NiPc-MnO_x based catalyst developed in this study has potential to enhance ORR in cathodes of MFCs in order to harvest more power.     

Novel multi walled carbon nanotube based nitrogen impregnated Co and Fe cathode catalysts for improved microbial fuel cell performance

For application in a microbial fuel cell (MFC), transition metal and nitrogen co-doped nanocarbon catalysts were synthesised by pyrolysis of multi-walled carbon nanotubes (MWCNTs) in the presence of iron- or cobalt chloride and nitrogen source. For the physicochemical characterisation of the catalysts, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) was used. The results obtained by rotating disk electrode (RDE) method showed an extraordinary electrocatalytic activity of these catalysts towards oxygen reduction reaction (ORR) in neutral media, which was also confirmed by the MFC results. The Co-N-CNT and Fe-N-CNT cathode catalysts exhibited maximum power density of 5.1 W m^?3 and 6 W m^?3, respectively. Higher ORR activity and improved electric output in the MFC could be attributed to the formation of the active nitrogen-metal centers. All findings suggest that these materials can be used as potential cathode catalysts for ORR in MFC to replace expensive noble-metal based materials.     

Activated carbon nanofibers as an alternative cathode catalyst to platinum in a two-chamber microbial fuel cell

This paper evaluated the oxygen reduction reaction (ORR) in a microbial fuel cell (MFC) system by using chemically and physically activated electrospun carbon nanofibers (ACNFs) in an MFC and comparing their performance with that of plain carbon paper. The chemical and physical activation was carried out by KOH reagents and CO₂ gas to increase the electrode surface area and the catalytic activity. As a result, it was found that the MFC with the chemically activated carbon nanofibers (ACNFs) exhibited better catalytic activity than that of the physically activated ACNFs. Chemically ACNFs with 8 M KOH were found to be one of the most promising candidates for the ORR and could generate up to 3.17 times more power than that of the carbon paper. The ACNFs with 8 M KOH exhibited 78% more power generation than that of the physically activated ACNFs and exhibited 16% more power generation than the chemically activated ACNFs with 4 M KOH. The power per cost of ACNFs with 8 M KOH is 2.65 times greater than that of the traditionally used platinum cathode. Thus, ACNFs are a good alternative catalyst to Pt for MFCs.     

In-situ modified titanium suboxides with polyaniline/graphene as anode to enhance biovoltage production of microbial fuel cell

Microbial fuel cell (MFC) has been the focus of much investigation in the search for harvesting electricity from various organic matters. The electrode material plays a key role in boosting MFC performance. Most studies, however, in the field of MFC electrode material has only focused on carbonaceous materials. The finding indicates that titanium suboxides (Ti₄O₇, TS) can provide a new alternative for achieving better performance. Polyaniline (PANI) together with graphene is chosen to in-situ modify TS (TSGP). The MFC reactor with TSGP anode achieves the highest voltage with 980 mV, and produces a peak power density of 2073 mW/m², which is 2.9 and 12.7 times those with the carbon cloth control. The rather intriguing result could be due to the fact that TSGP has the high conductivity and large electrochemical active surface area, greatly improving the charge transfer efficiency and the bacterial biofilm loading. This study has gone some way towards exploring the conducting ceramics materials in MFC.     

Comparing the performance of microbial fuel cell with mechanical aeration and photosynthetic aeration in the cathode chamber

In this study, the cathode chamber of the microbial fuel cell (MFC) was aerated using the photosynthetic aeration method and was compared with the mechanical aeration method in terms of power generation. Light energy for photosynthetic aeration was supplied in different regimes. The dissolved oxygen of 8.0–9.0 mg/L in the cathode chamber under mechanical aeration was increased to 10.0–11.0 mg/L under photosynthetic aeration of continuous light supply. The maximum power density obtained in the mechanical aeration was increased by 34.5% when photosynthetic aeration employed. Also, the algal assisted cathodic reaction under photosynthetic aeration reduced the internal resistance of the cell by 13.7%. To simulate with natural sun lighting conditions, 12/12 h of dark/light regime was tested to observe the stability of the MFC. During the light phase, microalgae carried out photosynthesis and provided the oxygen required for the cathodic reaction while in the dark phase, the voltage in the cell dropped due to the respiration by microalgae. The dissolved oxygen level dropped to 6.5–7.5 mg/L during the dark phase. Cathode chamber was also operated under 32/32 h of light/dark regime to observe the voltage variation under longer cycles. A higher voltage drop was observed in 32/32 h light/dark regime, as compared with 12/12 h of light/dark regime. Biomass productivity of 0.58 g/L/day was achieved in the MFC conducted under continuous light. It was reduced to 0.51, and 0.39 g/L/day under 12/12 h, and 32/32 h of light/dark regimes, respectively. The results suggested that photosynthetic aeration has the potential to achieve better power generation in the cell than mechanical aeration with an additional advantage of simultaneous microalgal biomass production.     

LaNi0.8Co0.2O3 as a cathode catalyst for a direct borohydride fuel cell

A perovskite-type oxide LaNi_0.8Co_0.2O₃ is prepared as a direct borohydride fuel cell (DBFC) cathode catalyst. Its electrochemical properties are studied by cyclic voltammetry. The results demonstrate that LaNi_0.8Co_0.2O₃ exhibits excellent electrochemical activity with respect to the oxygen reduction reaction (ORR) and good tolerance of BH₄⁻ ions. Maximum power densities of 114.5 mW cm⁻² at 30 °C and 151.3 mW cm⁻² at 62 °C are obtained, and good stability (300-h stable performance at 20 mA cm⁻²) is also exhibited, which shows that such perovskite-type oxides as LaNi_0.8Co_0.2O₃ can be excellent catalysts for DBFCs.     

Non-Pt catalyst as oxygen reduction reaction in microbial fuel cells: A review

Oxygen Reduction Reactions (ORR) are one of the main factors of major potential loss in low temperature fuel cells, such as microbial fuel cells and proton exchange membrane fuel cells. Various studies in the past decade have focused on determining a method to reduce the over potential of ORR and to replace the conventional costly Pt catalyst in both types of fuel cells. This review outlines important classes of abiotic catalysts and biocatalysts as electrochemical oxygen reduction reaction catalysts in microbial fuel cells. It was shown that manganese oxide and metal macrocycle compounds are good candidates for Pt catalyst replacements due to their high catalytic activity. Moreover, nitrogen doped nanocarbon material and electroconductive polymers are proven to have electrocatalytic activity, but further optimization is required if they are to replace Pt catalysts. A more interesting alternative is the use of bacteria as a biocatalyst in biocathodes, where the ORR is facilitated by bacterial metabolism within the biofilm formed on the cathode. More fundamental work is needed to understand the factors affecting the performance of the biocathode in order to improve the performance of the microbial fuel cells.     

Power generation using polyaniline/multi‐walled carbon nanotubes as an alternative cathode catalyst in microbial fuel cells

Optimization of the cathode catalyst is critical to the study of microbial fuel cells (MFCs). By using the open circuit voltage and power density as evaluation standards, this study focused on the use of polyaniline (PANI)/multi‐walled carbon nanotube (MWNT) composites as cathode catalysts for the replacement of platinum (Pt) in an air‐cathode MFC, which was fed with synthetic wastewater. Scanning electron microscopy and linear scan voltammogram methods were used to evaluate the morphology and electrocatalytic activity of cathodes. A maximum power density of 476 mW/m² was obtained with a 75% wt PANI/MWNT composite cathode, which was higher than the maximum power density of 367 mW/m² obtained with a pure MWNT cathode but lower than the maximum power density of 541 mW/m² obtained with a Pt/C cathode. Thus, the use of PANI/MWNT composites may be a suitable alternative to a Pt/C catalyst in MFCs. PANI/MWNT composites were initially used as cathodic catalysts to replace Pt/C catalysts, which enhanced the power generation of MFCs and substantially reduced their cost. Copyright © 2014 John Wiley & Sons, Ltd.     

Manganese dioxide-coated carbon nanotubes as an improved cathodic catalyst for oxygen reduction in a microbial fuel cell

To develop an efficient and cost-effective cathodic electrocatalyst for microbial fuel cells (MFCs), carbon nanotubes (CNTs) coated with manganese dioxide using an in situ hydrothermal method (in situ MnO₂/CNTs) have been investigated for electrochemical oxygen reduction reaction (ORR). Examination by transmission electron microscopy shows that MnO₂ is sufficiently and uniformly dispersed over the surfaces of the CNTs. Using linear sweep voltammetry, we determine that the in situ MnO₂/CNTs are a better catalyst for the ORR than CNTs that are simply mechanically mixed with MnO₂ powder, suggesting that the surface coating of MnO₂ onto CNTs enhances their catalytic activity. Additionally, a maximum power density of 210 mW m⁻² produced from the MFC with in situ MnO₂/CNTs cathode is 2.3 times of that produced from the MFC using mechanically mixed MnO₂/CNTs (93 mW m⁻²), and comparable to that of the MFC with a conventional Pt/C cathode (229 mW m⁻²). Electrochemical impedance spectroscopy analysis indicates that the uniform surface dispersion of MnO₂ on the CNTs enhanced electron transfer of the ORR, resulting in higher MFC power output. The results of this study demonstrate that CNTs are an ideal catalyst support for MnO₂ and that in situ MnO₂/CNTs offer a good alternative to Pt/C for practical MFC applications.     

Polyaniline/carbon black composite-supported iron phthalocyanine as an oxygen reduction catalyst for microbial fuel cells

Polyaniline/carbon black (PANI/C) composite-supported iron phthalocyanine (FePc) (PANI/C/FePc) has been investigated as a catalyst for the oxygen reduction reaction (ORR) in an air-cathode microbial fuel cell (MFC). The electrocatalytic activity of the PANI/C/FePc toward the ORR is evaluated using cyclic voltammogram and linear scan voltammogram methods. In comparison with that of carbon-supported FePc electrode, the peak potential of the ORR at the PANI/C/FePc electrode shifts toward positive potential, and the peak current is greatly increased, suggesting the enhanced activity of FePc absorbed onto PANI/C. Additionally, the results of the MFC experiments show that PANI/C/FePc is well suitable to be the cathode material for MFCs. The maximum power density of 630.5 mW m⁻² with the PANI/C/FePc cathode is higher than that of 336.6 mW m⁻² with the C/FePc cathode, and even higher that that of 575.6 mW m⁻² with a Pt cathode. Meanwhile, the power per cost of the PANI/C/FePc cathode is 7.5 times greater than that of the Pt cathode. Thus, the PANI/C/FePc can be a potential alternative to Pt in MFCs.     

An analysis of the performance of an anaerobic dual anode-chambered microbial fuel cell

The performance of a dual anode-chambered microbial fuel cell (MFC) inoculated with Shewanella oneidesis MR-1 was evaluated. This reactor was constructed by incorporating two anode chambers flanking a shared air cathode chamber in an electrically parallel, geometrically stacked arrangement. The device was shown to have the same maximum power density (approximately 24 W m⁻³, normalized by the anode volume) as a single anode-, single cathode-chambered MFC. The dual anode-chambered unit generated a maximum current of 3.66 mA (at 50 Ω), twice the value of 1.69 mA (at 100 Ω) for the single anode-chambered device at approximately the same volumetric current density. Increasing the Pt-coated cathode surface area by 100% (12 to 24 cm²) had no significant effect on the power generation of the dual anode-chambered MFC, indicating that the performance of the device was limited by the anode. The medium recirculation rate and substrate concentration in the anode were varied to determine their effect on the anode-limited power density. At the highest recirculation rate, 5 ml min⁻¹, the power density was about 25% higher than at the lowest recirculation rate, 1 ml min⁻¹. The dependence of the power density on the lactate concentration showed saturation kinetics with a half-saturation constant K_s on the order of 4.4 mM.     

Impact of salinity on cathode catalyst performance in microbial fuel cells (MFCs)

Several alternative cathode catalysts have been proposed for microbial fuel cells (MFCs), but effects of salinity (sodium chloride) on catalyst performance, separate from those of conductivity on internal resistance, have not been previously examined. Three different types of cathode materials were tested here with increasingly saline solutions using single-chamber, air-cathode MFCs. The best MFC performance was obtained using a Co catalyst (cobalt tetramethoxyphenyl porphyrin; CoTMPP), with power increasing by 24 ± 1% to 1062 ± 9 mW/m² (normalized to the projected cathode surface area) when 250 mM NaCl (final conductivity of 31.3 mS/cm) was added (initial conductivity of 7.5 mS/cm). This power density was 25 ± 1% higher than that achieved with Pt on carbon cloth, and 27 ± 1% more than that produced using an activated carbon/nickel mesh (AC) cathode in the highest salinity solution. Linear sweep voltammetry (LSV) was used to separate changes in performance due to solution conductivity from those produced by reductions in ohmic resistance with the higher conductivity solutions. The potential of the cathode with CoTMPP increased by 17–20 mV in LSVs when the NaCl addition was increased from 0 to 250 mM independent of solution conductivity changes. Increases in current were observed with salinity increases in LSVs for AC, but not for Pt cathodes. Cathodes with CoTMPP had increased catalytic activity at higher salt concentrations in cyclic voltammograms compared to Pt and AC. These results suggest that special consideration should be given to the type of catalyst used with more saline wastewaters. While Pt oxygen reduction activity is reduced, CoTMPP cathode performance will be improved at higher salt concentrations expected for wastewaters containing seawater.