铂含量对铂炭复合电极电化学参数的影响

以乙炔黑为载体 ,用化学吸附还原法制备了不同铂含量的铂炭复合电极 ,采用恒电位法测定出这些铂炭复合电极的阴极过电势 η随极化电流密度j的变化关系曲线 (阴极极化曲线 )。在此基础上求出了铂炭复合电极的交换电流密度、塔菲尔常数和对称系数等有关电化学参数。实验结果表明 ,在一定范围内 ,随着铂炭复合电极中铂含量的增加 ,其交换电流密度也随之增大。这表明在此范围内 ,随着电极中铂含量的增加 ,铂炭复合电极传输氧化还原反应电流的能力逐渐增强。因此 ,将铂炭复合材料作为离子膜燃料电池电极材料时 ,铂含量高的铂炭复合电极更有利于电化学反应的进行。实验结果还表明 ,铂炭复合电极中的铂含量对电极反应过程中的塔菲尔常数和对称系数都有一定的影响 ,随着复合电极中铂含量的增加 ,电极反应过程中的塔菲尔常数和对称系数也发生规律性的变化

EFFECT OF PLATINUM CONTENT ON ELECTROCHEMICAL PARAMETERS OF PLATINUM CARBON COMPOUND ELECTRODE

Taking acetylene black as carrier, platinum carbon compound electrodes with different platinum contents were prepared by chemical adsorption reduction method. And then, the curves of cathode over voltage versus polarization electrical current were tested. Based on the curves, the exchange electrical current density of the platinum carbon compound electrode, Tafel constant and symmetry coefficient are obtained. The results show that the exchange electrical current density augment with the increase of platinum content of the compound electrode in a certain content range. The phenomenon declares that the capacities of transmit oxidation|reduction electrical currents are strengthened in the certainly content range when the platinum contents of the compound electrode are raised. Therefore, when the electrodes are used for the ion exchange membrane fuel cells, the electrodes with higher platinum contents are more favourable for electrochemical reaction process. Meantime, the platinum contents of the compound electrode also have an effect on the Tafel constant and symmetry coefficient, because both of them are regularly reducing with the increase of platinum content of the compound electrode.