Carbon-Supported Spinel Nanoparticle MnCo2O4 as a Cathode Catalyst towards Oxygen Reduction Reaction in Dual-Chamber Microbial Fuel Cell

2015 ◽  
Vol 68 (6) ◽  
pp. 987 ◽  
Author(s):  
Dengping Hu ◽  
Guangyao Zhang ◽  
Juan Wang ◽  
Qin Zhong

The poor kinetics of oxygen reduction reaction (ORR) in neutral media and ambient temperature limit the performance of microbial fuel cells (MFCs). So higher-performing, low-cost oxygen reduction catalysts play a key role in power output. Through direct nanoparticle nucleation and growth on carbon black, a nanocomposite of manganese cobaltite and carbon black (in situ-MnCo2O4/C) was synthesized via a facile hydrothermal method. Subsequently, the in situ-MnCo2O4/C samples were characterized. The results show that the MnCo2O4 nanoparticles with a crystalline spinel structure are well dispersed on carbon black. Electrochemical measurements reveal that in situ-MnCo2O4/C demonstrates excellent ORR catalytic activity, which may account for the synergetic coupling effect between MnCo2O4 and carbon black. The ORR on as-prepared in situ-MnCo2O4/C hybrid mainly favours a direct 4-electron reaction pathway in alkaline solution. Moreover, in situ-MnCo2O4/C was used as an alternative catalyst for ORR in dual-chamber MFC. The obtained maximum power density is 545 mW m–2, which is far higher than that of the plain cathode (Pmax = 214 mW m–2) and slightly lower than that of commercial Pt/C catalyst (Pmax = 689 mW m–2). This study implies that in situ-MnCo2O4/C nanocomposite is an efficient and cost-effective cathode catalyst for practical MFC application.

MRS Advances ◽  
2018 ◽  
Vol 3 (53) ◽  
pp. 3171-3179 ◽  
Author(s):  
Indrasis Das ◽  
Md. T. Noori ◽  
Gourav Dhar Bhowmick ◽  
M.M. Ghangrekar

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.


2020 ◽  
Vol 16 (4) ◽  
pp. 625-638
Author(s):  
Leila Samiee ◽  
Sedigheh Sadegh Hassani

Background: Porous carbon materials are promising candidate supports for various applications. In a number of these applications, doping of the carbon framework with heteroatoms provides a facile route to readily tune the carbon properties. The oxygen reduction reaction (ORR), where the reaction can be catalyzed without precious metals is one of the common applications for the heteroatom-doped carbons. Therefore, heteroatom doped catalysts might have a promising potential as a cathode in Microbial fuel cells (MFCs). MFCs have a good potential to produce electricity from biological oxidization of wastes at the anode and chemical reduction at the cathode. To the best of our knowledge, no studies have been yet reported on utilizing Sulfur trioxide pyridine (STP) and CMK-3 for the preparation of (N and S) doped ordered porous carbon materials. The presence of highly ordered mesostructured and the synergistic effect of N and S atoms with specific structures enhance the oxygen adsorption due to improving the electrocatalytic activity. So the optimal catalyst, with significant stability and excellent tolerance of methanol crossover can be a promising candidate for even other storage and conversion devices. Methods: The physico-chemical properties of the prepared samples were determined by Small Angle X-ray Diffraction (SAXRD), N2 sorption-desorption, Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM) and X-ray Photoelectron Spectroscopy (XPS). The prepared samples were further applied for oxygen reduction reaction (ORR) and the optimal cathode was tested with the Microbial Fuel Cell (MFC) system. Furthermore, according to structural analysis, The HRTEM, and SAXRD results confirmed the formation of well-ordered hexagonal (p6mm) arrays of mesopores in the direction of (100). The EDS and XPS approved that N and S were successfully doped into the CMK-3 carbon framework. Results: Among all the studied CMK-3 based catalysts, the catalyst prepared by STP precursor and pyrolysis at 900°C exhibited the highest ORR activity with the onset potential of 1.02 V vs. RHE and 4 electron transfer number per oxygen molecule in 0.1 M KOH. The high catalyst durability and fuel-crossover tolerance led to stable performance of the optimal cathode after 5000 s operation, while the Pt/C cathode-based was considerably degraded. Finally, the MFC system with the optimal cathode displayed 43.9 mW·m-2 peak power density showing even reasonable performance in comparison to a Pt/C 20 wt.%.cathode. Conclusions: The results revealed that the synergistic effect of nitrogen and sulfur co-doped on the carbon substrate structure leads to improvement in catalytic activity. Also, it was clearly observed that the porous structure and order level of the carbon substrate could considerably change the ORR performance.


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