Abstract:

Ti/IrO₂+MnO₂ coated electrodes with different compositions were prepared by the thermal decomposition method. The electrochemical surface of Ti/IrO₂+MnO₂ electrodes were studied by potentiostatic cyclic voltammetry in sulfuric acid solution, and the electrochemical active surface area of electrodes were evaluated quantitatively by a linear extrapolation. The results show that the voltammetric charge of Ti/(0.7)IrO₂+(0.3)MnO₂ is the highest, along with the largest electrochemical active surface area. With the increase of the potential scanning speed, the voltammetric current density increases continuously, while the voltammetric charge decreases gradually until a constant value is reached. For all the Ti/IrO₂+MnO₂ electrodes, the “inner” electrochemical active surface area is much larger than the “outer” electrochemical active surface area, by about two times. It means that there are a lot of micropores inside the electrodes with a very large real surface area, thus the Ir⁴⁺/Ir³⁺ valence state transition occurs at the ”inner” electrochemical active surface.

Key words: IrO₂+MnO₂, electrochemical active surface, electrochemistry, catalysis, interface

摘要：

采用涂覆热分解法制备不同成分的Ti/IrO₂+MnO₂电极，利用恒电位循环伏安法研究Ti/IrO₂-MnO₂电极在硫酸溶液中的电化学表面行为，并用直线外推法定量地评价电极的电化学活性表面积。结果表明，Ti/(0.7)IrO₂+(0.3)MnO₂的伏安电荷达到最高，为电化学活性表面积最大；随着电位扫描速率增大，伏安电流密度不断增加，而伏安电荷容量逐渐减少，直到维持恒定；所有Ti/IrO₂+MnO₂电极的“内部”电化学活性表面积远大于“外部”电化学活性表面积，约为“外部”电化学活性表面积的2倍，说明电极内部存在丰富的多孔结构，真实表面积巨大，因此Ir⁴⁺/Ir³⁺转化反应多发生于内电化学活性表面区域。

关键词: IrO₂+MnO₂, 电化学活性表面, 电化学, 催化, 界面