Potential of porous Co3O4 nanorods as cathode catalyst for oxygen reduction reaction in microbial fuel cells

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.

Download Full-text

Metallic Organic Framework-Derived Fe, N, S co-doped Carbon as a Robust Catalyst for the Oxygen Reduction Reaction in Microbial Fuel Cells

Energies ◽

10.3390/en12203846 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3846 ◽

Cited By ~ 1

Author(s):

Xiao Luo ◽

Wuli Han ◽

Han Ren ◽

Qingzuo Zhuang

Keyword(s):

Fuel Cells ◽

Oxygen Reduction Reaction ◽

Oxygen Reduction ◽

Microbial Fuel Cells ◽

Active Sites ◽

Reduction Reaction ◽

Alkaline Media ◽

X Ray ◽

Co Doped ◽

Organic Framework

Oxygen reduction reaction (ORR) provides a vital role for microbial fuel cells (MFCs) due to its slow reaction kinetics compared with the anodic oxidation reaction. How to develop new materials with low cost, high efficacy, and eco-friendliness which could replace platinum-based electrocatalysis is a challenge that we have to resolve. In this work, we accomplished this successfully by means of a facile strategy to synthesize a metallic organic framework-derived Fe, N, S co-doped carbon with FeS as the main phase. The Fe/S@N/C-0.5 catalyst demonstrated outstandingly enhanced ORR activity in neutral PBS and alkaline media, compared to that of commercial 20% Pt-C catalyst. Here, we started-up and operated two parallel single-chamber microbial fuel cells of an air cathode, and those cathode catalysts were Fe/S@N/C-0.5 and commercial Pt-C (20% Pt), respectively. Scanning electron microscopy (SEM) elaborated that the Fe/S@N/C-0.5 composite did not change the polyhedron morphology of ZIF-8. According to X-ray diffractometry(XRD) curves, the main crystal phase of the resulted Fe/S@N/C-0.5 was FeS. The chemical environment of N, S, and Fe which are anticipated to be the high-efficiency active sites of ORR for MFCs were investigated by X-ray photoelectron spectroscopic(XPS). Nitrogen adsorption/desorption techniques were used to calculate the pore diameter distribution. In brief, the obtained Fe/S@N/C-0.5 material exhibited a pronounced reduction potential at 0.861 V (versus Reversible Hydrogen Electrode(RHE)) in 0.1M KOH solution and –0.03 V (vs. SCE) in the PBS solution, which both outperform the benchmark platinum-based catalysts. Fe/S@N/C-0.5-MFC had a higher Open Circuit Voltage(OCV) (0.71 V), stronger maximum power density (1196 mW/m2), and larger output voltage (0.47 V) than the Pt/C-MFC under the same conditions.

Download Full-text