• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.653-658
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• 2016

In this work, we developed a synthetic method for preparing one-dimensional $MnO_2$ nanowires through a hydrothermal method using a mixture of $KMnO_4$ and $MnSO_4$ precursors. As-prepared $MnO_2$ nanowires had a high surface area and porous structure, which are beneficial to the fast electron and ion transfer during electrochemical reaction. The microstructure and chemical structure of $MnO_2$ nanowires were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller measurements. The electrochemical properties of $MnO_2$ nanowire electrodes were also investigated using cyclic voltammetry and galvanostatic charge-discharge with a three-electrode system. $MnO_2$ nanowire electrodes showed a high specific capacitance of 129 F/g, a high rate capability of 61% retention, and an excellent cycle life of 100% during 1000 cycles.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.118-124
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• 2005

In this study, a novel deposition method of Pt catalysts onto Nafion membranes modified with polypyrrole (PPy) has been proposed for PEMFC application. The PPy/Nafion composite membranes were fabricated by chemical polymerization of pyrrole using $FeCl_3$ and $Na_2S_2O_8$ as initiator. The proton conductivity and water uptake of the chemically prepared PPy/Nafion composites were investigated. The ionic conductivity and water uptake of PPy/Nafion composite membrane prepared with $Na_2S_2O_8$ were decreased with polymerization time of pyrrole. In the case of $FeCl_3$, the ionic conductivity was almost retained and the water uptake was decreased with polymerization time of pyrrole. When the Pt particle was deposited on PPy/Nafion composites membrane by chemical reduction of $H_2PtCl_6$, the Pt loading on Nafion membrane was enhanced by polypyrrole due to electronic conduction property. The performance evaluation with membrane electrode assembly composed of Pt/PPy/Nafion composite and diffusion electrode was carried out using a single cell. As a result of fuel cell test, current density of $569mA/cm^2$ at 0.3 V has been obtained for MEA contained with Pt/PPy/Nafion composite. This study shows that direct deposition of Pt catalysts on Nafion impregnated polypyrrole is a promising method to prepare thin catalyst layer for the PEMFC.