Preparation of MnO2 catalyst by electrochemical deposition and its application in the microbial fuel cells
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Graphical Abstract
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Abstract
As a green and clean renewable energy technology, microbial fuel cells (MFCs) have attracted extensive attention. The electrocatalysts with high activity and low-cost towards oxygen reduction reaction (ORR) are of great importance for the large-scale commercial applications of MFCs. Among multifarious cathode catalysts, manganese-based oxides showed high catalytic activity close to that of the precious metals. In this work, a sponge-like manganese dioxide (MnO2) electro-catalyst was successfully prepared by the electrodeposition method. The surface morphology and composition of as-prepared MnO2 catalyst were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and so on; the electrocatalytic activity of the obtained MnO2 material towards ORR were evaluated by the linear sweep voltammetry (LSV) in a neutral phosphate buffer solution. The results demonstrate that the as-prepared MnO2 catalyst appears as crystalline γ-MnO2 and has a high Mn3+/Mn4+ ratio, which is beneficial to improving the catalytic activity in ORR. The as prepared γ-MnO2 catalyst exhibits superior activity for the ORR under neutral conditions to the commercial MnO2 catalyst. An MFC coupled with as-prepared catalyst generates an open circuit voltage of 0.52 V, with a maximum power density of 975.6 mW/m2, about 1.7 times of that achieved with the MFC using commercial MnO2 as cathode catalyst, which suggests that the MnO2 catalyst prepared by the electrodeposition could be an economical alternative for Pt free catalysts in practical application of MFC.
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