EFFECT OF SPUTTERED FILM OF PLATINUM ON LOW PLATINUM LOADING ELECTRODES ON ELECTRODE-KINETICS OF OXYGEN REDUCTION IN PROTON-EXCHANGE MEMBRANE FUEL-CELLS
EFFECT OF SPUTTERED FILM OF PLATINUM ON LOW PLATINUM LOADING ELECTRODES ON ELECTRODE-KINETICS OF OXYGEN REDUCTION IN PROTON-EXCHANGE MEMBRANE FUEL-CELLS
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DOI：
10.1016/0013-4686(93)85056-5
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发表时间：
1993-08-01
影响因子：
6.6
通讯作者：
APPLEBY, AJ
中科院分区：
文献类型：
--
作者：
MUKERJEE, S;SRINIVASAN, S;APPLEBY, AJ
已知通过在含有负载型电催化剂（20%Pt/C，0.4mg cm-2负载量）的燃料电池电极的前表面上溅射沉积薄膜（500埃）来定位Pt电催化剂，与在没有溅射膜的电极上相比，表现出更高的燃料电池性能。本研究比较了质子交换膜燃料电池中溅射和未溅射电极中氧还原反应（ORR）的电极动力学参数、电化学活性表面积、活化能和反应级数随温度和压力的变化。5个大气压和95摄氏度下的电池性能比较表明，与rhe相比，0.9 V下的ORR活性提高了近4倍，交换电流密度也提高了类似的3.6倍。电化学活性表面积的增量约为两倍，从而表明表面积增量以外的因素是ORR中观察到的活性增强的原因。ORR电极动力学作为温度的函数的评估表明，与未溅射电极上的ORR相比，溅射电极上的ORR的活化能较低。然而，ORR的反应级数对于两个电极是相同的，并且与先前在Pt微电极/Nafion界面处获得的值相似，从而表明ORR的速率决定步骤没有变化。本文还提出了使用SEM/EDAX技术的电极/膜界面的形态表征，这清楚地表明了两种类型的Pt-无支撑和支撑。
Localization of Pt electrocatalyst by sputter deposition of a thin film (500 angstrom) on the front surface of a fuel cell electrode containing a supported electrocatalyst (20% Pt/C, 0.4 mg cm-2 loading) has been known to exhibit higher fuel cell performance as compared to that on the electrode without the sputtered film. This study compares the electrode kinetic parameters, electrochemically active surface areas, activation energies and reaction orders for the oxygen reduction reaction (ORR) in the sputtered and unsputtered electrodes in proton exchange membrane fuel cells as functions of temperature and pressure. Comparison of the cell performance at 5 atm and 95-degrees-C indicates an almost 4 fold improvement in ORR activity at 0.9 V vs. rhe and a similar 3.6 fold improvement in the exchange current densities. The increment in the electrochemically active surface area was about two fold, thereby indicating that factors beyond a surface area increment were responsible for the observed activity enhancement in the ORR. Evaluation of ORR electrode kinetics as a function of temperature indicated a lower activation energy for ORR on the sputtered electrode, as compared to that on the unsputtered electrode. The reaction orders for ORR were, however, the same for both electrodes and were similar to previously obtained values at the Pt microelectrode/Nafion interface, thereby indicating no change in the rate determining step for ORR. This paper also presents the morphological characterization of the electrode/membrane interface using the SEM/EDAX technique, which clearly signifies the two types of Pt-unsupported and supported.