在Nafion(上標 ®)與Pt/c觸媒混合製備電極上的氧氣還原反應動力學分析

[[abstract]]本研究以旋轉電極及循環伏安法探討Nafion(上標 ®)與Pt/C混合製備的電極上的電催化氧氣還原反應動力學。結果顯示，隨著Nafion(上標 ®)Pt/C比例的增加，電化學活性表面積會下降。由Tafel圖（未對外界質傳作修正）可知氧氣還原反應的速率會隨著白金負載量增加而增加；然而由修正的Tafel圖則可知氧氣還原反應機制在低過電位和高過電位分別受到化學反應控制及反應與擴散之混合控制。應用修正的Koutecky-Levich方程式，可求出反應動力學參數。根據Pt/C觸媒的白金真實面積，所求得的交換電流密度為6.07×10^(-3)mAcm^(-2)。本研究之結果有助於使用Pt/C觸媒的燃料電池的電極之設計。 The kinetics of oxygen reduction reaction (ORR) on electrodes prepared with Nafion(superscript ®) and Pt/C were investigated by the rotating disk electrode (RDE) and cyclic voltammetry (CV) techniques. It indicated that the electrochemical active surface decreased with the increasing Nafion(superscript ®)/Pt ratio. From the Tafel plots (uncorrected for diffusion), the reaction rate of ORR increased as Pt-loading increased. However, from the corrected Tafel plots, the mechanisms of ORR were found to be chemical reaction control and mixed kinetic-diffusion control at low and high overpotential, respectively. The hydrodynamic voltammograms were analyzed to determine the kinetic parameters by using the modified Koutecky-Levich equation. The exchange current density for the Pt/C catalyst was determined to be 6.07×10^(-3) mAcm^(-2) based on the real Pt surface area. The results of this study may contribute to the design of the fuel cell electrodes using a Pt/C catalyst.